A. afarensis

Science has a very important paper in the current issue about the evolution of a gene enhancer in hominids, expressed in forelimb development and concentrated toward the first digit. The enhancer is a conserved sequence named HACNS1, it exhibits a stronger signature of recurrent selection on the human lineage than any other conserved enhancer sequence. In transgenic mice, the human version of this enhancer triggers gene expression in the forelimb, concentrated toward the thumb side, and some other parts of the body, notably the pharyngeal arches (which give rise to elements of mouth, throat and larynx), eye and ear. The research is by Shyam Prabhakar and others at Lawrence Berkeley National Lab, and involves Edward Rubin and James Noonan, otherwise prominent in the Neandertal genome sequencing.

I think this is an extraordinarily important result. You don't see me write those words very often. This is a paper that every biological anthropologist should read. It gives an extremely good example of the importance of developmental regulation to human evolution. We will see many more papers like this one in the coming years. This is one of the genes that makes us human.

Ed Yong of Not Exactly Rocket Science has written a nice online review of the research, and Science has accompanied it with a perspective piece by Gregory Wray and Courtney Babbitt. Here's a quote from that article:

To test the function of this region, they genetically engineered mouse embryos to express a construct composed of human HACNS1, the promoter element of a heat shock gene, and a reporter gene. Their results show that human HACNS1 drives expression in the mesenchyme of the early developing forelimb, and later developing hindlimb, in these mouse embryos. A comparison of expression patterns driven by macaque, chimpanzee, and human orthologs of HACNS1 revealed that consistently strong forelimb expression is a unique property of the human version. By testing various combinations of human and chimpanzee HACNS1 sequences, the authors narrowed down the relevant functional mutations to an 81-base pair region containing 13 substitutions that arose during human evolution. This concentration of substitutions is highly unusual relative to the genome as a whole, implying positive selection on this region during human origins.

The press are going with the story that the evolution of this gene may underlie the unique evolution of human manual dexterity. It's a good hypothesis, but I think there is a more accurate way of putting the situation. We see that the enhancer has effects in different areas of the developing embryo. Its action is therefore pleiotropic: changing its function in one area might well screw up its action somewhere else. So at the very least, this is an enhancer that must satisfy multiple constraints. Strong evolutionary change in its sequence may reflect changes in one of those functions, or more than one. But at the very least, it implies that the hominid developmental program not only satisfies different fitness constraints than in the human-chimpanzee common ancestor, but that these changes required repeated changes.

We don't know how long it would have taken all these nucleotide substitutions to happen. But we might find signs in the fossil record of such a sequence of events, if we had enough bones, and if we had more information about the effects of different forms of the gene on the adult phenotype. For example, the relatively long thumbs of the Hadar hominids (compared to chimpanzees and gorillas) suggest that the sequence of changes started early in hominid evolution. There's a hypothesis.

But like I said, I wouldn't rule out other possible functions of the enhancer as targets for selection. It is plausible (as a hypothesis) that the enhancer with the most selected substitutions on the human lineage might be more likely than others to have been selected for multiple functions. And we have plenty of reasons to suspect selection on its other targets, particularly the developing mouth, throat and ear.

It may even be that the evolution of human thumbs was a side effect of evolution in the throat, or vice versa. That's the kind of weird world evo-devo makes for us!

References:

Prabhakar S and 9 others. 2008. Human-specific gain of function in a developmental enhancer. Science 321:1346 - 1350. doi:10.1126/science.1159974

Wray GA, Babbitt CC. 2008. Enhancing gene regulation. Science 321:1300-1301. doi:10.1126/science.1163568

I've followed the literature on early hominid diets from the beginning of the weblog. In 2005 I discussed Peter Ungar's analyses of dental occlusal morphology in A. afarensis versus Homo, concluding:

The contrast between Homo and A. afarensis is in the same direction as the contrast in occlusal morphology between primarily meat-eating carnivores like felids and canids as opposed to more omnivorous carnivores like bears. Another observation is that meat is a major food resource of chimpanzees, although this is hardly a fallback resource. Indeed, if meat eating was indeed an important component of the behavioral repertoire of early Homo, it probably is not fair to assert that the difference in diet between Homo and Australopithecus was primarily a difference in fallback resources. It may be true that australopithecines and early Homo overlapped in their food resources, particularly in plant species consumed. But considering the likely effectiveness of early humans as predators, I think it likely that the fallback foods of early humans--when hunting was ineffective--may well have been the preferred foods of australopithecines. And when australopithecines were forced to abandon their preferred foods by early humans, they were forced to fall back upon resources that either were common or were difficult for early Homo to exploit. The disappearance of early small-bodied Homo by around 1.6 million years ago, and the ultimate extinction of the robust australopithecines after a progressive increase in their molar sizes (Wood and Lieberman 2001) indicate that this fallback strategy could not be maintained in the face of increased hunting effectiveness by large-bodied Homo.

The concept of "fallback foods" has captured a large mindshare in explaining early hominid diets. The idea is that a species may depend on preferred, staple foods for most of the year, but adopt less preferred, "fallback" foods when their staple is not available -- for instance, during the dry season.

What can fallback foods explain about early hominids? For one thing, they could explain the difference between robust and non-robust australopithecines. We know from isotope data (reviewed in this 2005 post about Matt Sponheimer's work) that A. africanus and A. robustus had similar fractions of C₃ and C₄ plant source foods in their diets. Across the year, they may have eaten roughly the same mix of foods. A 2005 paper by Greg Laden and Richard Wrangham (discussed here) explored the idea of underground storage organs of plants, or tubers, as fallback foods for australopithecines. Later studies of isotope data using laser ablation of small segments of the enamel (discussed here) showed that diet proportions may have substantially varied across the time that teeth were developing -- possibly concordant with the idea of seasonal or longer-period fallback foods. An earlier analysis of dental microwear in the two hominids by Scott and colleagues (discussed here) came to a similar result: there was great variability in wear properties, especially within A. robustus, although the average in the two species showed a possibly greater fraction of brittle, hard foods consumed by the robust australopithecines.

So I've written about the topic a lot, and followed it closely.

Now, Peter Ungar, Frederick Grine and Mark Teaford have examined the wear properties of the molars of Australopithecus (Paranthropus) boisei. They find that -- unlike A. robustus -- none of the seven specimens showed any evidence of having eaten hard or brittle foods:

Comparisons with the extant baseline series suggest that none of the Paranthropus boisei individuals examined consumed extremely hard or extremely tough foods in the days before death. All of these specimens lacked the extremes of Asfc evinced by Lophocebus albigena and especially Cebus apella, both known to consume hard, brittle foods. Paranthropus boisei molars also lacked the extremes of epLsar seen in Trachypithecus cristata and Alouatta palliata, both known to consume tough leaves and stems. The P. boisei individuals examined evidently avoided such metabolically challenging foods, at least in the days before death. This is notably consistent with Walker's [23] early assertion that P. boisei microwear patterns resemble those of living frugivores, and differ from those of living grazers, leaf browsers, and bone feeders.

Comparisons with the South African hominins suggest that while Paranthropus boisei may have consumed foods with similar ranges of toughness as those eaten by Australopithecus africanus, the eastern African "robust" hominin did not eat harder and brittler foods than the South African "gracile" form. Further, the patterns for P. boisei and P. robustus are very different. Paranthropus robustus likely ate foods that were on average much harder and less tough than P. boisei. The differences in both central tendencies and ranges of variation suggest different feeding strategies, and by implication, that the two species of Paranthropus probably had markedly different diets or foraging strategies (Ungar et al. 2008, italics lost).

That is very interesting that A. robustus and A. boisei are so different in their microwear patterns. It makes me wonder whether there may have been substantial habitat variation in the use of hard foods -- maybe the extant A. robustus sample, mainly drawn from a small area of South Africa, had access to some food items that were rare or absent across the larger East African range of A. boisei. But if some A. boisei populations had also depended on such hard resources some of the time, you might expect that we would have found one, or at least a bit more variability. Yet the sampled specimens, drawn from a distance from Ethiopia to Tanzania and well over a half million years of time, are pretty uniform in their microwear, showing some variability in the anisotropy dimension (here, high values have mostly parallel striations, attributed to fibrous food consumption).

So we can return to the question: the major hominid competitor of A. boisei was Homo. Both lineages appeared in the period around 2.5 million years ago, and remained sympatric throughout the next million years. Some of the dynamics of that interaction must have involved diet (considering the different dietary adaptations of the two). We can speculate that A. boisei didn't get much meat, which would then be an important difference. But what else was A. boisei eating?

Meanwhile, the data are still consistent with the idea of fallback foods in A. robustus as a driver of dental morphology, but the story for A. boisei now seems less clear. With only seven specimens, there is almost certainly not enough data to test the hypothesis -- which after all predicts that the use of hard brittle foods may be rare. But that's not positive evidence either. Is there some other food that might explain the hyperrobust craniodental morphology?

References:

Ungar PS, Grine FE, Teaford MF (2008) Dental Microwear and Diet of the Plio-Pleistocene Hominin Paranthropus boisei. PLoS ONE 3(4): e2044. doi:10.1371/journal.pone.0002044

There's nothing especially surprising about the functional interpretations in Richmond and Jungers' paper about the Orrorin BAR 1002'00 femur. They conclude it was an australopithecine-like biped, because it shared several features with australopithecine femora: in particular, it has a long, narrow, anteroposteriorly flattened neck and a broad thick proximal shaft.

In this, they mirror the conclusions of the original description of the Lukeino fossils by Senut et al. (2001). Richmond and Jungers also reiterate the evidence for arboreality in the Lukeino fossils, including the well-developed musculature of the distal humerus and the chimpanzee-like curved finger bone. I wonder why their analysis could not have made something more out of the other two femoral fragments, one of which is fairly large (but lacking the head). Still, the paper reiterates the quite good evidence for bipedality in the most complete femoral specimen.

I wonder sometimes how closely people actually read the papers they comment on. The associated coverage, including Ann Gibbons' article, has made a lot out of a small point in the paper, but I think that the commenters have it wrong.

Here's the story: When the Orrorin materials were first published, Brigitte Senut and Martin Pickford put forward the argument that these may be more closely related to Homo than to known australopithecines. They based their argument mainly on Orrorin's relatively thick-enameled molars, which they viewed as different from the thin-enameled molars of Ardipithecus, but lacking the enlarged dentition of Australopithecus. So, they suggested that Orrorin might be a plesiomorphic ancestor of Homo, and that Ardipithecus and Australopithecus represent divergent lineages derived in their dental anatomy.

I don't find that suggestion very compelling, because it seems to put too much faith in the absence of evolutionary reversals. There's no reason why a large-molared australopithecine should not have given rise to small-molared Homo, particularly since smaller-toothed Homo habilis is apparently derived from earlier, larger-toothed "Homo" specimens like A. L. 666-1 and Omo 75-14. And Haile-Selassie, Suwa and White (2004) claimed that the Orrorin, Sahelanthropus, and Ardipithecus dentitions were so similar that they might represent one taxon. So the dental contrasts among these early hominids are probably not great enough to justify the idea that Orrorin is an exclusive Homo ancestor.

The femur also formed a part of this phylogenetic story, with Senut and Pickford having noted the lack of extreme australopithecine-like features in the femur. The Orrorin femur has a less exaggerated neck length than many australopithecine specimens, it is larger than many, and appears to have a higher neck-shaft angle. To the extent those features differ from later Australopithecus, they resemble the human anatomy.

Richmond and Jungers address this argument very briefly in their last paragraph, by noting that the functional elements of the Orrorin femoral anatomy are entirely consistent with the australopithecine pattern of bipedality:

The similarity between O. tugenensis and australopith femora weakens support for scenarios in which O. tugenesis is ancestral to Homo to the exclusion of A. afarensis (4). Instead, the overall primitive hominin morphology of the O. tugenensis femur, along with primitive dental anatomy, is consistent with the more parsimonious hypothesis that it is a basal member of the hominin clade.

I think that's fair, as far as it goes. The overall morphological pattern of this femur, with its long neck and broad shaft, is much like known australopithecine femora. But to go a bit further, their metric comparisons show BAR 1002'00 to be the most Homo-like of the early hominid femora they examined, and their phenetic cluster puts it basal to the other australopithecines. That's pretty much exactly what Senut et al. have consistently said. So I have a hard time understanding how those observations refute the idea that Orrorin has a more Homo-like femur than later australopithecines!

Again, I don't put much stock in the phylogenetic argument for an Orrorin-Homo link. I don't see any difficulty deriving Homo from Australopithecus, especially given the likely effects of body size evolution on the locomotor pattern. And at least one or two early Homo femoral specimens, like KNM-ER 1481, share most of the Australopithecus-like pattern of proximal femur anatomy. But this paper surely doesn't add anything new to the critique of Senut and Pickford's preferred phylogenetic hypothesis. The details simply don't detract from their story.

References:

Richmond BG, Jungers WL. 2008. Orrorin tugenensis femoral morphology and the evolution of hominin bipedalism. Science 319:1662-1665. doi:10.1126/science.1154197

Gibbons A. 2008. Millennium ancestor gets its walking papers. Science 319:1599-1601. doi:10.1126/science.319.5870.1599

Haile-Selassie Y, Suwa G, White T. 2004. Late Miocene teeth from Middle Awash, Ethiopia, and early hominid dental evolution. Science 303:1503-1505.

Senut B, Pickford M, Gommery D, Mein P, Cheboi K, Coppens Y. 2001. First hominid from the Miocene (Lukeino Formation, Kenya). C R Acad Sci Paris, Sciences de la Terre et des planètes 332:137-144.

The coming attractions bin at Journal of Human Evolution includes a paper by Kaye Reed, reviewing the evidence of paleoenvironment in the Hadar formation:

Habitat reconstructions of 12 submembers of the Hadar and Busidima formations (˜3.8-2.35 Ma) are presented here along with faunal differences in these submembers through time. Habitats with medium density tree and bush cover dominated the landscape through much of the earlier time period in the Hadar Formation. The lowermost Sidi Hakoma Member is the most closed habitat. The Denen Dora Member shows the influence of frequent floodplain edaphic grasslands with high abundances of reducin bovids. There is an influx of ungulates in the Kada Hadar Member (˜3.2-˜2.96 Ma) that indicates a more arid habitat populated by mammals that were recovered from earlier deposits further south in Ethiopia and Kenya. In the younger deposits from the Busidima Formation at Hadar, the landscape was open wooded grassland with some floodplain environments. The fossil assemblages from the Busidima Formation show a substantial species turnover. Although high numbers of A. afarensis specimens are associated with the lower Sidi Hakoma Member, they clearly inhabited a variety of habitats throughout the entire Hadar Formation. Australopithecus afarensis from Laetoli through Hadar times appears to have been a eurytopic species.

This is a nicely detailed paper, focusing on the amount of wooded/bush habitat, the relation of the hominids to those habitats, and the relative lack of early faunal exchanges with areas further to the south.

The discussion focuses on the range of paleoecologies in which fossil A. afarensis has been found -- including not only Hadar but also nearby Maka and Dikika, and more distant Koobi Fora and Laetoli. Altogether, these localities cover a long time (from before 3.5 up to around 2.9 million years ago). From the range of paleoecologies reconstructed in this paper at Hadar, Reed concludes that A. afarensis did not have a "narrow" habitat preference. It is found in relatively closed woodland, open woodland/bush, and wet grassland/marshland.

There are some differences between localities. At Koobi Fora, relatively few specimens of A. afarensis have been found in the Tulu Bor Member, despite the fact that it occupies the same time as the Hadar sequence. Based on the paleoecological data, Reed suggests that Hadar was a wetter, more closed woodland habitat than Koobi Fora at that time -- Koobi Fora would have included more scrubland punctuated with wetlands and floodplains (here she cites her own 1997 paper).

The early end of the A. afarensis sample is represented at Laetoli. Reed gives a brief review of the paleoecology of that site, which has been interpreted differently by different authors but broadly appears to have had a fairly high amount of rainfall and some patches of forest amid closed woodland:

Thus, the earliest known A. afarensis material was found in deposits showing habitats in which trees and or bushes were fairly plentiful. It is also interesting to note that while the deposits of A. afarensis at Laetoli and Hadar share some perissodactyls, giraffids, suids, and proboscideans, the bovid taxa and those primates other than A. afarensis are not very similar.

Reed concludes that A. afarensis was a "eurytopic" species -- one that inhabited a wide range of habitats and moved broadly across space. It contrasts with the more habitat-selective ("stenotopic") species, which include most of the bovids.

White et al. (1993) suggested broad habitat tolerance for A. afarensis, and indeed, the species has thus far been recovered from regions in which the reconstructed habitat ranges from closed woodland through more open, but wet woodland and shrubland. There is no direct evidence that A. afarensis only existed in riverine forests or grassland habitats, or that they preferred one habitat over another. It is tempting to equate the aridification in the Kada Hadar Member with the extinction of A. afarensis. However, sediments at Hadar are sparse or missing altogether from ˜2.90-2.35 Ma thus obscuring details of the species' demise. All that can be said is that they are no longer present at 2.35 Ma and most of the fauna, including hominins, has been replaced.

References:

Reed KE. 2008. Paleoecological patterns at the Hadar hominin site, Afar Regional State, Ethiopia. J Hum Evol (in press) doi:10.1016/j.jhevol.2007.08.013

I've been trying to spread the interviews across the field in various directions. I (virtually) talked with Mica Glantz about Neandertals, Adam Van Arsdale about early Homo, and Anne Weaver about human brain evolution, all the australopithephiles in the readership are probably feeling neglected.

So I wrote to Michelle Drapeau, who was very generous in answering questions about her work on the anatomy of early hominids and her recent field work in Ethiopia. Michelle is on the faculty of the Université de Montréal, in the Department of Anthropology. She serves as co-director of field operations in the Bala Paleoanthropological Research Area of southern Ethiopia.

Hawks: I will start out by asking about your dissertation work, which centered on the new partial skeleton from Hadar, A.L. 438-1. How did you get involved in that analysis?

Drapeau: It's a case of being at the right place at the right time. Bill Kimbel and Don Johanson had asked my advisor at the time, Carol Ward, to describe all the postcranial material recovered from the field in Hadar since 1990. Among those specimens was the partial skeleton of A.L. 438-1 which included associated fragments of the humerus, clavicle, radius, right ulna, mandible, and frontal as well as a complete left ulna, right and left second metacarpals and left third metacarpal. Considering the relatively numerous body parts from one individual, Carol thought the specimen deserved a more detailed analysis. I was Carol's Ph.D. student at the time and the 438-skeleton (as we started to call it) appeared like an ideal subject.

Hawks: What did you have to learn to be able to undertake the work?

Drapeau: I had to learn a lot! My master's thesis was in the history of science field, so all the functional anatomy, including the descriptive and comparative aspects were completely new to me. It was something I really wanted to do, however, so I really enjoyed immersing myself into it.

Hawks: A.L. 438-1 exhibits more curvature across its length than A.L. 288-1, an issue that you discussed in your analysis of the fossil. I have always been puzzled by the problem of ulna curvature -- mainly because I've always been puzzled by the comparison of later, larger, and more curved fossils like Omo L40-19 and OH 36 -- and then, of course, KNM-WT 15000 is a lot more like most recent humans. Do you have any insights about these contrasting morphologies?

Drapeau: Forearm bone curvature is an intriguing issue. Intuitively, it makes sense to assume that curvature reflects arboreality since the curvature of both the ulna and radius give greater area on the interosseous membrane for attachment of forearm muscle important for arboreal locomotion such as the finger flexors. However, orangutans and gibbons do not have the most curved forearm bones. It is an honor that goes to gorillas, definitely not the most arboreal animal of the bunch. If the area of muscle attachment is the variable that interests us, then it is important to take into account forearm length as well. When that is done, species generally sort by locomotor preference, with the most arboreal having the greater ‘area' for muscle attachment relative to body size and humans having the smallest (at least, when measured on the ulna). So gorillas appear to have very curved forearm bones because they also have relatively short forearms when compared to other apes.

The differences between A.L. 438-1 and A.L. 288-1 are fairly minor and probably reflect normal within-species variation. Neither is very curved and they may belong to a population with slightly more curved ulnae than modern humans but definitely less curved than any extant apes.

The KNM-WT 15000 specimen is pretty much what you would expect an ulna belonging to a completely terrestrial biped to look like, i.e., it is not particularly curved. Since it is a juvenile, it is difficult to compare it to other fossils, but there is nothing really surprising about it.

That said, what about the intriguing Omo L40-19 and OH 36? These specimens present combination of morphologies that are difficult to underscore in quantitative analyses. The former had a human-like proximal morphology but a really long and curved (ape-like) diaphysis. The latter, OH 36, has a general ape-like morphology with a pronounced curvature, but is unique in a few characters. The whole bone (proximal articulation and diaphysis) is very constricted medio-laterally, more comparable what is observed in monkeys (and it is not the result of distorsion). Despite its general ape-like morphology, it has an olecranon process that projects proximally like no other ape of its size. It is definitely much more human-like for that trait and it is generally agreed that it is a hominin. McHenry and colleagues argue in a recent article (AJPA, 134: 209-218) that these two fossils are very different and can hardly be accommodated into the same genus (Paranthropus) as it is usually done (probably by default). McHenry and colleagues argue that it may indicate Paranthropus is in fact a polyphyletic taxon. They also conclude, as I stated above, that OH 36 is unlike anything living today.

So, if curvature of the ulna reflects arboreality, does it mean that these fairly recent fossils were much more arboreal than A. afarensis? Remember that they are big ulnae, particularly L40-19, likely belonging to large individuals.... Maybe the Paranthropus clade (if indeed it is a clade) is more arboreal than A. afarensis? This would imply either reversal of behavior or that A. afarensis is not ancestral to Paranthropus. Or, alternatively, could the curvature in these individuals reflect forelimb muscularity but not necessarily related to arboreality? As you can see, I have many more questions than answers. All this variability suggests that the behaviors of fossil hominin species were much more variable than what we have been used to think and may have been (very?) different from the behaviors of extent species.

Hawks: Of course, the big debate about forelimb proportions is the idea that they may have been very different (and more apelike) in A. africanus compared to A. afarensis. (reviewed by Green, Gordon, and Richmond 2007) What do you think about the issue?

Drapeau: That idea first met with some resistance because it involved a reversal of proportions from A. afarensis to A. africanus and implied a more arboreal behavior in the latter than the former. Given that Homo habilis is often described has having more ape-like proportions than A. afarensis, it also implied that A. afarensis may not be the ancestor of the Homo lineage (an idea more recently suggested by Yoel Rak and colleagues based on mandibular data). Since I remain unconvinced of the primitive proportion of H. habilis, I am not so certain that the 'derived' proportions of A. afarensis exclude it from being an ancestor to the Homo lineage.

Back to the differences between the two australopithecine species. Despite original skepticism, the data appears to be robust and the differences in joint size between A. afarensis and A. africanus appear to be real. As observed in the previous question, this variability may reflect locomotor differences possibly related to differences in the environment. If A. afarensis was still occasionally arboreal, is it too hard to imagine that, if the environment is changed (more wooded, greater predator pressure, more resources found in trees, etc.), the percentage of arboreal behavior would increase and that the proportions would revert to being more chimp-like in A. africanus? Again, there is no reason to assume that all early hominins, because they were bipedal, were identical in their locomotor behaviors.

I want to underscore that these differences are in joint SIZE, not in limb length, and reflect relative loading of the limbs. Usually, the major source of loading of the limbs is related to locomotion, but it is an assumption that cannot be verified in early hominins. If, as stated above, OH 36 is unlike anything living today, maybe it did things that have no modern equivalent. And the same can be said of other hominin species including A. africanus with its 'apparent' primitive proportions.

Hawks: You have recently been involved in field research in the Bala-Weyto region of southern Ethiopia. Can you describe the site, and your role?

Drapeau: The Bala–Weyto basin is part of a series of small parallel rifts that link the northern limit of the East African Rift to the southern limit of the Main Ethiopian rift. These small rifts constitute today a string of many small basins. The Bala-Weyto basin is located east of the Omo river basin. It is a region more difficult to survey when compared to dryer region because of the vegetation coverage that limits exposures visibility and access. However, it is little-explored paleoanthropologically speaking. Work in the Konso, another small basin a few kilometers away, but at a higher altitude, has a fauna with a certain degree of endemism and an A. (P.) boisei specimen with unique morphological variations. Among other things, we want to know if this variation and the faunal endemism are due to the relative isolation of the basin or to its particular environment. These answers may be found in contiguous basins that vary in their physical characteristics, such as the Bala-Weyto basin.

I am co-director of that project with Elizabeth Harmon of the City University of New York. At this stage of the project, being co-director involves organizing the whole expedition, securing funding, and coordinating the work of other team members. I would say that the most time consuming aspect is coming up with money and getting everything moving in the field. As a director, I am responsible for the team's well-being and it is a pressure that can sometimes weigh heavily on my shoulders. It is nice to be able to share the burden with a co-director.

Hawks: Do you involve students in your work?

Drapeau: My funding is limited and field work in Ethiopia is not particularly cheap. However, I plan to bring one student in the field this summer. I look forward to share this experience with a highly motivated student!

Hawks: Many of us have heard about the difficulties of field research, particularly in East Africa. What are some of your biggest challenges?

Drapeau: Doing field work in Ethiopia can be a challenge for many reasons. As can be expected, there are numerous permissions, letters, official documents, etc., that are required and the bureaucracy is somewhat heavy. However, I find Ethiopians very helpful and professional and, usually, the quest for documents goes smoothly, particularly once you know what to do and in what order.

A second difficulty is the access to the sites. Ethiopia did not have one highway until relatively recently and road traveling remains an experience that can be frightening. A lot of work is being done on the roads, however, and I believe that things will keep improving. Access to the research area involves off-road traveling as well, with all the difficulties that it entails. When you leave for the field, you have to be a self-sufficient unit, relying on the local environment as little as possible. It is still necessary to get gasoline on a regular basis, but except that, we try to be as autonomous as possible. It is particularly important when you go to a new area and don't know what (if anything) will be available to you.

A third aspect of field work, particularly in Ethiopia, is the politics, the paleoanthropological politics that is. Although most scientists are polite and civilized to each other, I really feel that we had to walk on eggs when we were researching an area in which to conduct field work.

A final difficulty (and certainly not the least) in our situation, is to find an area that has fossiliferous exposures of a time period that interests us and in which we can work at least a few years. The numerous discoveries that are made in East Africa give the impression that finding hominin fossils is something easy to do, but it usually involves many years of surveying. We are still at the exploratory phase of our project, i.e., we are still actively looking for an area that could sustain scientific work for a few years. Hard work (and perhaps a little luck) is essential.

Hawks: You had a lot of field experience before going to Ethiopia. How did you get your start?

Drapeau: At the end of my undergraduate degree, I had the chance of getting a couple of paying jobs in prehistoric archaeology. It was the beginning of a series of jobs in field archaeology conducted in parallel to my studies. I used to think (and still do) that these were the best summer jobs an anthropology student could have. The pay check was very descent and it usually came with room and board. These jobs allowed me to see many regions of Quebec and Canada that I would otherwise have never visited and to do things I would probably have never done otherwise. I have flown in helicopters for hours (and even survived a major crash), piloted a hydroplane (just for a few minutes, but still!), hear wolves howl into the night while trying to sleep in a tent hundreds of miles from any road or civilization, dipped my foot in the arctic ocean (too chicken to swim), seen the midnight sun, and I could go on. This fieldwork experience, and a stint in the Caune de l'Arago in Tautavel, France, opened another door: to be invited to do field work in Hadar in 2000.

Hawks: Any interesting stories?

Drapeau: I have an anecdote that I find amusing, but mostly informative on the nature of humans. When we were doing field work in the Bala basin, our camp was set up about a 2-hour drive off the road. It was clear that the local people had seen very few foreign workers. For the whole time we were there, we had a constant group of people just sitting in the shade observing us like zoo animals, watching our every move, laughing when we did things unexpected, etc. We were quite the entertainment. The occupation of the local Mali people appeared to be tending their few sorghum fields, but mostly to take their sometime large herds of cows, goats and sheep a few miles down to the river for a drink every day. Even though it was not that hot, the men walk around wearing only colorful underwear (the Speedo-type) and it was sometimes literally falling apart. From our western perspective, they really seem to have almost nothing. Anyhow, after a few days in the field, some crew members were starting to crave fresh meat. We agreed to allow the cook to purchase one goat from a local herder. We didn't think it would be a problem given the large quantities of these animals around and our willingness to pay a fair price for it. It came as quite a surprise that no one was willing to sell us any! It turned out that goats, sheep and cows were not herded to be eaten or even milked, but were really just status items. One man from the village nearby apparently owned more than a hundred head of livestock but was still unwilling to sell. We were all quite shocked of the apparent frivolity of it all, particularly considering that food (for humans and beasts) did not appear to be particularly abundant in the region. But then, we couldn't miss seeing the connection to what we can observe in the western world: huge houses for one or two people, oversized and overpriced cars. These are just to show off. The same frivolities, although expressed slightly differently, can be found anywhere. I guess it really is in the human nature. We were finally able to convince someone to sell us a goat, but we paid a really high price.

Hawks: Congratulations! You seem to be a very busy person right now, both professionally and personally. What's next for you?

Drapeau: I just started one of the most challenging projects of my life, a project that will keep me busy for the rest of my life. His name is Henri and he is almost 8 months old. Professionally speaking, I am investigating manipulatory adaptations in the early hominin hands and the morphology of muscle markings. However, one of my main objectives in the next two years is to settle on a specific field research area with good scientific potential.

It's that time of year again -- the time when those boring ``Year in Review'' magazines are on newsstands, and when pundits make fools of themselves predicting what will happen in the next year.

Well, I'm not too proud to join the fools, as I've shown the last two years. In 2006, I got five predictions right out of ten. Not bad for my first outing, but you'll see that last year's predictions fared even better:

• 10. Sahelanthropus postcrania will be published. I'm frankly shocked that this didn't happen. I don't doubt the rumors, but I'm starting to wonder whether this story is more interesting than it looks....
• 9. Two words: Holocene evolution. OK, this was a little unfair, considering that my work was an important part of making this prediction come true. Still, Discover made ``recent human evolution'' one of its top 100 science stories of the year, even before our December paper came out -- mainly on the strength of the paper by Scott Williamson and colleagues from earlier this year. And "Human genetic variation" was Science's "Breakthrough of the Year" -- most of that variation representing recent evolution.
• 8. Despite (or because of) the success of the Neandertal genome project, there will be no genetics of any kind published on early modern skeletal material. Puzzling, isn't it? But then, considering the trouble with Neandertal contamination reported in August, maybe we're better off leaving the early Upper Paleolithic alone for a while.
• 7. The mitochondrial history of human dispersals will become more and more detailed, but no paper will test against other loci. D'oh! Reading this one a year later, it's pretty obvious that I should have included Y chromosome in this one, since those two get compared all the time! Proofread, Hawks!
• 6. Another (yes, another) paper about the chimpanzee-human divergence will peg it between 5 and 7 million years ago. Will they never tire of these? Hobolth et al. (2007, PLoS Genet 3:e7) pegged the divergence at 4.1 million years. That's too recent to fit my prediction. Instead, I have to turn to Ebersberger et al. (2007, Mol Biol Evol 24:2276), who placed the divergence at 5.7 million years ago. Both estimates are too recent for Sahelanthropus, which the geneticists have started to figure out....
• 5. Three papers with new Ethiopian fossils. The last few years, one annual Ethiopian find seemed to be predictable enough. So I figured, why not three? We got a not-nearly-noted-enough paper this summer by Gen Suwa and colleagues descringing the Konso Homo erectus remains. Then, Suwa brought us Chororapithecus -- hey, I didn't say "hominid!" That's two. But despite the long-ago announcement of the Woranso-Mille skeleton, its appearance in a meetings abstract and a mid-summer press release about further Mille fossils, all we got from the peer review system is a lousy faunal list. Well, the faunal list does include the hominids. Should it count as a "paper with new Ethiopian fossils?" I'll say yes -- hey, unlike Aramis, at least the Mille fossils are new!
• 4. Another early Upper Paleolithic specimen will emerge from a museum collection. The only bizarre thing about this one was the location: South Africa. Hoffmeyr may not be that convincing as a European early Upper Paleolithic skull, but it was sure sold that way. Weird.
• 3. A big year for Miocene apes, which will look increasingly important in the story of human brain evolution. No brains, but it sure was a big year for Miocene apes, with two significant East African discoveries claiming to push back the timeline of African ape divergence.
• 2. Maturation rate in early Homo becomes a dead issue, because of the variation in dental and skeletal maturation in living people. Wishful thinking. Still, did Tanya Smith (2007) breathe new life into perikymata? Let's just say that unresolved questions remain.
• 1. The year will end without a single new hominid species having been named. This one was like dodging a bullet, since new species riffle out of paleoanthropologists' minds all the time. From 2001 to 2006, there were six (six!). In 2007, none.
• BONUS: A dramatic development in the problem of pre-2.0-million-year-old Homo. Rats.

OK, that's seven out of ten. It's beyond belief that I did better in the top five than the bottom five -- I picked those because they were far out there. I mean, really -- a new Upper Paleolithic specimen from a museum collection? After Muierii, that's like calling lightning to strike twice. But there it is, and in January, no less.

I'm clearly going to have to pick stranger predictions this year. And I'll have to be careful about that "dramatic development" line -- I mean, it's appropriately Delphic, but what is it supposed to mean, really? I wonder whether "operatic development" might be better.

And do I dare call down my non-lightning strike for a third year? It's ruining my percentage! It's starting to reek of desperation -- I mean, it starts to look like the stopped watch effect even if it happens.

Oh, well. I mean, those are just the risks of predictions, right? Suppose in the preseason I had picked Kansas to win the Orange Bowl!

• 10. A dramatic development in the Sahelanthropus story.
• 9. Both major-party candidates for the 2008 U.S. Presidential election will accept evolution.
• 8. This year's featured piece of anatomy: the femur.
• 7. No new hobbits, at least, not from Flores.
• 6. An incisive example of introgression in East Asia.
• 5. A viral insertion in the human genome will tell us about a disease of the australopithecines.
• 4. Another language gene joins FoxP2. No word on whether Neandertals have the human version.
• 3. Homo habilis: an endangered species?
• 2. This year, something new from three A's: A. afarensis. A. africanus. Atapuerca.
• 1. Oh, and one more A. Ardipithecus.
• BONUS: A big, big year for Neandertals. I mean, besides the election.

There you have it. I'm not sure which of these is the riskiest, but I'm sure they're more out on a limb than last year!

This week, Johannes Krause and colleagues from the Max Planck Evolutionary Anthropology institute announced that they had tickled FoxP2 out of two Neandertal specimens from El Sidrón, Spain. The bones were excavated in sterile (clean-cave?) conditions, immediately frozen and then shipped to Leipzig, where extracts were taken in clean-room conditions.

Here's an FAQ about what they found.

Why is this paper really important?

Isn't it obvious? It's important because it demonstrates that more than one Neandertal is suitable for nuclear genome recovery. We will know about genetic variation in Neandertals, sooner rather than later. These two bones come from different individuals, because the Leipzig group found two different mtDNA sequences in them. Together with the Vindija Vi 33.16 specimen in the original Neandertal genome papers, this makes three nuclear genome Neandertals. There will be more.

It also shows the possibility of probing ancient skeletons for specific genes. Here, they went in looking for Y-DNA, X-DNA and particular sites on FoxP2, and they found them. That is definitely the way to go if you want to test a biologically significant hypothesis fast -- otherwise, you just have to wait until the sequence comes up in your genome project.

However, I question the value of probing for individual genetic variants in this way. Every probe takes a bit of sample, which might be more efficiently used in whole-genome sequencing. We have 25,000 genes, and every one is potentially interesting. Every small sample used to assay only one of those genes may destroy many sequences from the others. It would be one thing if samples were trivial and easily replaced, but they obviously aren't.

Still, we will certainly see additional probes for genes that are of particular interest. I wouldn't be surprised to see MC1R results soon, to probe whether there were pigmentation variants in Neandertals. The same has already been done for woolly mammoths.

So, Neandertals had the human-specific FoxP2 form. Did they talk?

I think the genetic observation leans toward that direction, but doesn't really change our understanding. Consider:

Neandertals have a hyoid bone with humanlike anatomy, as did the Atapuerca people at more than 300,000 years ago, even though A. afarensis did not. So something related to vocalization evolved in humans by the Middle Pleistocene. Although Neandertal vocal tracts may not have been identical to recent humans, there is nothing about them that would preclude speech. The only paleoneurological observation about language puts a developed Broca's area on the KNM-ER 1470 endocast, Homo habilis.

Like other Middle Paleolithic/MSA people, their technology required more information to learn than earlier, Lower Paleolithic industries, leading to regional differentiation and more task-specific facies. Late Neandertals made use of some technology otherwise used only by Upper Paleolithic modern humans. Their hunting methods must have required cooperation and may have been impossible without a more sophisticated communication strategy than used by other primates.

All of these things argue for some kind of Neandertal language irrespective of FoxP2.

Then again, most of the arguments against humanlike language facility in Neandertals also have nothing to do with FoxP2, either. The slow technological progress, limited collection strategies, the rarity of any artistic or symbolic expression, their high mortality rate, and -- of course -- the fact that they no longer exist have all been considered as evidence that Neandertals lacked some essential aspect of "behavioral modernity." If language is a prerequisite for the modern human pattern of behavior, then Neandertals may not have talked, at least not in the way we do.

I think the FoxP2 story has really confused people much more than necessary. But in this case, the confusion is the same that results from every other gene study: when the press says we've found a gene "for" something, what it ought to say is that we've found an allele that affects something.

No macromutation happened. Language did not spring full-formed into the mind of some ancient African. All members of Homo used communication systems including some (possibly minimal) elements of language, and the evolution of the human brain, along with technological changes throughout the Paleolithic, reflect the evolution of communication. Human language evolved -- like all things -- over a long time, and like all complex phenotypes it required a series of mutational changes. Many of these mutations became fixed during recent human evolution, some may still be changing in frequency today. Language evolution is probably a continuing process.

That means that it must have involved many more genes than FoxP2 -- which after all experienced only two amino acid substitutions in all of human evolution. I would imagine the number of genes involved in language evolution is more than 500, and I wouldn't be surprised if it were much more. In that context, it seems quite silly to say FoxP2 is the "critical" evolutionary change for anything.

Then you agree with Language Log. They told me that FoxP2 isn't a "language gene."

The case is strong that the two FoxP2 coding substitutions in humans were selected because of their role in language. The gene sequence is strongly conserved in most mammals, and shows similar changes in some other species with unusual vocal adaptations, such as echolocating bats (Li et al. 2007). Its expression pattern delineates areas related to vocalizations in both humans and birds, and the pattern itself differentiates between song-learning versus nonlearning bird species (Haesler et al. 2004, Teramitsu et al. 2004, Webb and Zhang 2005). And of course, mutations to FoxP2 can result in specific language impairment (SLI) in humans.

Still, that case is only circumstantial. We know that FoxP2 was under selection, that it became fixed in humans, probably during the Late Pleistocene, and that breaking the gene changes brain development and damages language skills. But we don't know what a human would be like with the chimpanzee form of the protein. We don't know whether both of the human-specific amino acid substitutions have a different effect than one. Most important, we don't know what other genetic changes may have been necessary backgrounds for selection on FoxP2.

This means Neandertals were really modern humans, right?

This study should put an end to the "sudden mutation" model of modern human origins.

There was not a single mutation that made the critical difference in the ancestry of today's people. There was no cognitive Rubicon leading to modern human evolution. I would analogize the process as a slow-motion avalanche: at first a few small sands began to tumble, and then selection on a large number of genes became inevitable. FoxP2 is one of those genes, and as yet we don't know whether it was near the beginning or near the end of the process.

But it is clear that the process began before the Neandertals were gone. Some aspects of behavioral complexity did begin to evolve rapidly sometime after 70,000 years ago. This rapid evolution was multiregional in context -- it was not limited to a single human population. In particular, it was not limited to Africans: the last Neandertals clearly manifested technological and behavioral strategies otherwise defined as "behaviorally modern" (d'Errico 2003). There's a reason why the Neandertal-produced Châtelperronian industry of France and Spain was historically considered the first Upper Paleolithic industry.

But we have undergone light-years of change since the last Neandertals lived. This is not a question of "modern human origins" anymore. We can now show that living people are much more different from early modern humans than any differences between Neandertals and other contemporary peoples. I think that "modern humans" is on its way to obsolescence. What matters is the pattern of change across all populations. Possibly that pattern was initiated by changes in one region but the subsequent changes were so vast that the beginning point hardly matters.

We all know that the Neandertal genome is riddled with contamination from modern humans. Isn't the null hypothesis that we have a modern human sequence here because it is a modern human?

Well, as you know, I'm not all that convinced that contamination explains the interpretive discrepancies between last year's genome papers. But still, this study has done some things to address the problem of contamination.

It is notable that Green et al. (2006) found 25% modern human mtDNA in one of the El Sidrón bones: this shows that even "sterile" excavation, immediate freezing and extraction under clean-room conditions cannot exclude contamination. There is at the moment nothing more that can be done. We will always have the problem of a contamination fraction in ancient Neandertal skeletons. So we have to judge each study by the extent to which we can exclude contaminants with statistical analysis.

For this study, Krause et al. (2007) developed a test of nuclear DNA contamination: they identified seven gene variants that differ between the recovered Vindija Vi 33.16 nuclear genome and all known living humans. In other words, these are human-derived mutations that are absent from the only known Neandertal nuclear genome. Then, they probed the El Sidrón bones for these sites. They found only the ancestral form in their extracts of both bones -- presumably because no human contaminants were present in their samples.

That seems like a pretty good indication that the other sites in their sample represent the true gene variants of the ancient Neandertals. I wouldn't go so far as to say that contamination is ruled out, but it seems like these are good results.

Did FoxP2 introgress into Neandertals?

It sure looks that way to me. Let's consider the evidence:

FoxP2 recently fixed in humans. According to Enard et al. (2002:871):

Under a model of a randomly mating population of constant size, the most likely date since the fixation of the beneficial allele is 0, with approximate 95% confidence intervals of 0 and 120,000 years.

Now, Enard et al. (2002) noted that human populations have grown over time, and that they are not randomly mating, so that this date estimate might be too recent. Allowing for population growth since "10,000--100,000 years ago," they asserted that fixation of FoxP2 must have happened "during the last 200,000 years of human history." But this is not quite accurate. Unlike genetic drift, positive selection can and often does fix genes rapidly in a growing population. It simply doesn't matter that the human population has been rapidly growing: FoxP2 may still have just become fixed yesterday.

Last year, Green and colleagues (2006) considered that the Neandertal-modern population divergence time might have been quite recent, depending on the ancestral population size. According to the estimates of Wall and Kim (2007), the Green et al. data are consistent with a Neandertal-modern population divergence time as recent as 30,000 years ago. Of course, that date would predict substantial admixture between contemporary Neandertal and non-European populations -- they would have been exchanging genes up to the very lifetimes of the last Neandertals. According to those data there would be nothing surprising about Neandertals and living people sharing the human-derived FoxP2 allele. But as mentioned above, Wall and Kim (2007) used the recent divergence estimate as evidence that the Neandertal genome data from Green et al. must be contaminated.

So, if we cannot trust the data, then we have to fall back on some other estimate of the divergence date. Noonan and colleagues (2006) estimated a divergence date between Neandertals and modern populations between 170,000 and 570,000 years ago. If we accept that, then the confidence intervals of the Neandertal-human divergence and the FoxP2 selective sweep might barely overlap. Might. But I will note that a minimal overlap between the 95% confidence intervals of two point estimates does not mean that they are not significantly different. Only if the expected value of one estimate falls within the 95% confidence interval of the other do they fail to be significantly different. It is pretty unlikely that the most recent FoxP2 sweep is older than 170,000 years ago and the Neandertal-modern population split is as recent as 170,000 years.

That is, unless the "split" time reflects widespread genetic introgression.

The current paper (Krause et al. 2007) goes to some contortions to try to establish that the FoxP2 sweep could really have been older than 300,000 years ago (where they place the lower confidence limit on the N-M split):

The third scenario is that the selective sweep started before the divergence of the ancestral populations of Neandertals and modern humans around 300,000-400,000 years ago

Let me just say that I was surprised to read this explanation in a paper from this group. One of the main arguments they have been posing as a scientific value of the Neandertal genome sequencing is that conventional methods don't detect selection at 300,000-400,000 years ago. But here, they consider such an ancient mutation to be the most likely hypothesis. This seems like quite a shift just to avoid the unpleasant idea of Neandertal introgression. Ooooh -- can't have those Neandercooties!

In reality, there is no reason to think the fixation of FoxP2 happened as early as 300,000 years ago, and indeed the very high frequencies of the linked derived alleles (over 97% for six of the linked alleles) suggest strongly that the sweep probably happened within the last 100,000 years -- otherwise, subsquent genetic drift should have caused these linked derived alleles to show more dispersion in their current frequencies. The same features that make the inference of selection so strong at FoxP2 -- it is far (>286 kilobases) from the nearest gene and it includes many high-frequency derived alleles in addition to reduced polymorphism -- make it very unlikely that the selective sweep was ancient.

So, considering that the El Sidrón samples both share the human-derived amino acid substitutions on the same haplotype as modern humans, complete with all the high-frequency derived SNPs, it seems almost certain that the gene introgressed into Neandertals from modern humans.

Or, there's one other option. One of the El Sidrón bones includes a relatively rare (in humans) ancestral SNP allele at one of those linked sites where the derived allele is at very high frequency in humans. One explanation: the selected mutation arose in Neandertals and introgressed into other humans. That would explain why this Neandertal didn't have a SNP variant on its FoxP2 haplotype that later became very common in humans: Neandertals had the new FoxP2 first.

What about that Y chromosome thing?

The El Sidrón bones both tested positive for the Y chromosome site assayed in the study. That means they were both male (duh!). But more important, the Y chromosomes of both individuals lacked the human-specific derived mutation that the researchers tested for. Since all human males yet surveyed have this human-derived mutation, this means that a Y chromosome variant has fixed in modern humans that Neandertals did not have. Since the entire nonrecombining portion of the Y chromosome is completely linked, we can infer that the entire modern human Y chromosome has undergone at least one fixation not shared with the ancestors of these Neandertals.

Here's the text (from page 2):

Both Neandertals yielded products for Y chromosomal primer pairs, indicating that they were males. Strikingly, all 15 Y chromosomal products for the five assayed positions show the ancestral allele. This includes two polymorphisms that define the deepest split among current human Y chromosomes (Y2 and Y4, Figure S1) as well as two polymorphisms that cover less common African Y chromosomes (Y3 and Y5, Figure S1). These Y chromosome results must derive, then, either from Y chromosomes that fall outside the variation of modern humans or from the very rare African lineages not covered by the assay (Figure S1). For our purposes, this result shows that neither the maternally inherited mtDNA nor the paternally inherited Y chromosome shows evidence of gene flow from modern humans into Neandertals or of subsequent contamination of their mortal remains.

That's not such a big surprise. Already we knew that the fixation of the human Y chromosome was very recent -- probably within the last 70,000--100,000 years, and possibly even more recently. Every man on earth shares recent Y chromosome mutations that were completely absent in Middle Pleistocene humans. That is one radical recent evolutionary change.

The paper elsewhere suggests that this absence of the human-derived Y chromosome in Neandertals as evidence that they did not contribute other genes to us. I could not disagree more.

The very recent fixation of the Y chromosome in an expanding human population is extremely unlikely to have resulted from genetic drift. Drift does not eliminate rare variants as quickly in an expanding population. Instead, one or more Y chromosome mutations must have been positively selected, resulting in the fixation of the entire NRCY in recent humans.

In that context, the Neandertal result is quite expected: they had an earlier Y chromosome lacking one or more mutations later selected in the other ancestors of living people.

References:

Briggs AW, Stenzel U, Johnson PLF, Green RE, Kelso J, Prüfer K, Meyer M, Krause J, Ronan MT, Lachmann M, Pääbo S. 2007. Patterns of damage in genomic DNA sequences from a Neandertal. Proc Nat Acad Sci USA doi:10.1073/pnas.0704665104

d'Errico F. 2003. The invisible frontier. A multiple species model for the origin of behavioral modernity. Evol Anthropol 12:188-202. doi:10.1002/evan.10113

Green RE, Krause J, Ptak SE, Briggs AW, Ronan MT, Simons JF, Du L, Egholm M, Rothberg JM, Paunovic M, Pääbo S. 2006. Analysis of one million base pairs of Neanderthal DNA. Nature 444:330-336. doi:10.1038/nature05336

Haesler S, Wada K, Nshdejan A, Morrisey EE, Lints T, Jarvis ED, Scharff C. 2004. FoxP2 expression in avian vocal learners and non-learners. J Neurosci 24:3164-3175. doi:10.1523/JNEUROSCI.4369-03.2004

Krause J, Lalueza-Fox C, Orlando L, Enard W, Green RE, Burbano HA, Hublin J-J, Bertranpetit J, Hänni C, Fortea J, de la Rasilla M, Rosas A, Pääbo S. 2007. The derived FoxP2 variant of modern humans was shared with Neandertals. Curr Biol 17:1-5. doi:10.1016/j.cub.2007.10.008

Li G, Wang J, Rossiter SJ, Jones G, Zhang S. 2007. Accelerated FoxP2 Evolution in Echolocating Bats. PLoS ONE 2(9): e900. doi:10.1371/journal.pone.0000900

Noonan JP, Coop G, Kudaravalli S, Smith D, Krause J, Alessi J, Chen F, Platt D, Pääbo S, Pritchard JK, Rubin EM. 2006. Sequencing and analysis of Neanderthal genomic DNA. Science 314:1113-1118. doi:10.1126/science.1131412

Wall JD, Kim SK. 2007. Inconsistencies in Neanderthal genomic
DNA sequences. PLoS Genet 3:e175. doi:10.1371/journal.pgen.0030175.eor

Just noticing, in this John Noble Wilford article:

A new report, to be published Thursday in Nature, will review more skeletal evidence of the transitional aspects of the Dmanisi specimens.

More later...

UPDATE(2007/09/18): Wilford doesn't directly state the article's theme but it clearly has one: Why the heck can't these people agree about these fossils that have been out of the ground for thirty years?

The first answer that everyone has given him is about the "million year gap" between 3 million and 2 million years ago. People can't agree about early Homo because they can't decide what its ancestors looked like. Without any ancestors, they don't know which of the traits of early Homo are derived.

For a good example, we can turn to a feature Wilford doesn't mention: limb proportions. Recently, a lot of ink has been spilled discussing the evolution of arm size in later australopithecines and early Homo. OH 62 (probably Homo habilis) and A. africanus have been argued to have large arms compared to their legs. A. afarensis and Nariokotome (KNM-WT 15000, probably Homo erectus) have relatively small arms compared to their legs. Did H. habilis and H. erectus have different ancestors? Did H. erectus evolve from H. habilis, reverting its limb proportions to earlier A. afarensis? Or are all these comparisons just batty, since only three specimens have arm and leg elements whose length can be compared? There's no clear answer; but one of the most important specimens in the question (with sort-of-intermediate limb proportions) is the Bouri skeleton, BOU-VP 12/1, which at 2.5 million years old is right in the middle of that "gap."

The more you look at the "gap," the less gap-like it looks. For one thing, we have a pretty good idea of what was going on behaviorally during that million year span. The first stone tools are 2.6 million years old. The technology of these toolmakers -- although simple -- included all the basic manufacturing methods used before 1.5 million years ago. The tools were used to butcher animals and break bones for marrow; so we know that the toolmakers were depending on meat.

Second, we actually have quite a lot of fossils from this time period. The entire South African A. africanus fossil record, with the exception of a few early specimens like STW 573, come from this "gap." A fairly extensive record of the appearance and evolution of early robust australopithecines comes from this time period in East Africa.

And, here and there, a few specimens look Homo-like. Wilford's article discusses AL 666-1. To this we can add the Uraha mandible, Omo 75-14, an additional series of teeth from Omo, and possibly the Bouri BOU-VP 35/1 skeleton.

Properly considered, the rarity of early Homo in these contexts is not a problem; it is information. Wilford quotes Philip Rightmire to this effect, and we can easily expand on the basic concept. Early toolmakers did not undergo an immediate geographic expansion upon their origin. They spread across a relatively narrow strip of East Africa and stayed there for more than a half-million years. They were initially rare. That means that their adaptation was not immediately a barnburner of a success -- the early toolmakers took a while to perfect the adaptation of later Homo.

The middle part of the article takes in another reason for disagreement: whether H. habilis and H. erectus were ancestor-descendant:

Several scientists, notably Dr. White of Berkeley, took issue with the interpretation seeming to imply that evidence for the two species overlapping in time and exhibiting variable sizes was new. That, he said, had been recognized for a couple of decades.

Dr. Kimbel, who was not involved in the new research, defended the authors, saying that they had not "meant to imply that habilis could not have been ancestral to erectus, presumably on the basis of their being contemporaneous at Turkana," the site in Kenya where the fossils were found.

Susan C. Anton, an anthropologist at New York University who was a member of the Spoor-Leakey team, said, "My money is still on habilis as the potential ancestor, but there is a lot of room for additional knowledge, given the dearth of fossils."

None of these statements really disagree with each other. If anything, this particular question may have gotten easier to resolve lately, not as a consequence of new fossils, but as a result of new dates for many of the old ones. Susan Anton is later quoted saying that anagenesis "is the only option that is no longer on the table," and it seems to me that this is the clearest statement most likely to invite some hypothesis testing. But it is fairly clear that this problem cannot be resolved in terms of earlier fossils: I don't think there's any compelling evidence of H. erectus before 1.6 million years ago.

There is one significant word that doesn't appear in the article -- an absence that is especially interesting considering the quoted scientists:

Kenyanthropus

Remember, the dominant theme is about complexity and bushiness. And yet, here's that forgotten branch of the family tree; the one that was supposed to clarify everything by providing a different ancestor for KNM-ER 1470 from other H. habilis specimens, the one that showed a distinct line leading to Homo originating in the Early Pliocene.

I think our bush may have been pruned.

In case you're following the debate about Homo habilis limb proportions, there's a new contribution by Martin Haeusler and Henry McHenry in the JHE holding pen. They examined the partial KNM-ER 3735 skeleton.

KNM-ER 3735 is often assigned to Homo habilis, but it's not exactly an easy diagnosis. There are a few pieces of the skull preserving anatomy, including the cheek, frontal and temporal. Here's what Bernard Wood (1991) had to say about the skeleton:

The form of the mandibular fossa and malar region virtually preclude this specimen from being attributed to A. boisei. Its general affinities are with Homo. Some features (e.g. vault thickness) ally it with a Homo erectus-like hominid, but in other areas (e.g. the frontal) it is more like crania such as KNM-ER 1813, a conclusion endorsed by Walker (1987) and by Leakey et al. (1989). Tobias (1989) includes KNM-ER 3735 within H. habilis.

Provisional taxonomic assessment: Homo sp. indet.

Well, that's not exactly a rousing endorsment. You can see the problem --- and it's a common tale for hominid fossils. It has a smaller brain than early H. erectus (that would be the "frontal looks like KNM-ER 1813 bit). But its cranial bones are thick. The most complete of the bones in the skeleton is a radius, but it's not complete. The best bone for estimating joint surface area is the sacrum; a femur shaft is there, but it falls short of the midshaft length.

And there's a problem: the radius seems pretty big, but the sacrum is little. If it were a human, the radius looks like it came from a body twice the size of the sacrum. There's something going on here. Previous work has assumed that the sacrum is more likely reflective of the size of the body, and the radius is therefore big compared to a small body mass. Maybe that means more climbing, leading to a greater role in weight support for the arms. Or maybe it means a retention of more apelike proportions.

This is a frustrating literature to follow, because pretty much every other early specimen except Lucy (AL 288-1) and the Nariokotome skeleton (KNM-WT 15000) present exactly the same problem. You can't estimate limb sizes very accurately from small pieces of bone. And you can't estimate proportions accurately at all without estimates of size. Plus, it's not clear that you can interpret limb proportions without a decent estimate of body mass. Two years ago, there was a huge go-around about the limb proportions of OH 62. Like KNM-ER 3735, it looks to have a relatively large arm compared to its body. Or maybe the legs are short. Or maybe the estimates are bad. You get the picture. So everybody has a different clever statistical transformation to try to make these fossils comparable to each other. I have no argument with any of the work; but it seems like the error involved in these assessments of proportions is pretty large relative to the information content of the bones.

Here's some of the conclusion from Haeusler and McHenry:

Our analyses suggest that the idea that KNM-ER 3735 had more primitive body proportions than A.L. 288-1 (e.g., Leakey et al., 1989) needs to be refined. We found a unique but distinct mosaic of modern and ape-like limb proportions in the two early hominid species. H. habilis shares a gracile humerus and radius and a small base of the hand phalanges with the earlier A.L. 288-1 and modern humans. In addition, other characteristics, including the relatively small size of the sacrum and a robust midshaft of the phalanges, are common to both early hominids and extant great apes. Surprisingly, however, those upper limb proportions that differ between the two fossil species, such as a robust scapula, a long radial neck, and a long forearm, are all more ape-like in H. habilis.

In KNM-ER 3735, the shoulder muscles that originate on the scapula (trapezius, deltoid, supraspinatus, and infraspinatus) as well as the biceps brachii were, therefore, probably not only more powerful than in modern humans, but also stronger than in A.L. 288-1. On the other hand, the extraordinarily short lever arm of A.L. 288-1's biceps muscle, the minute elbow size, and the small radial head may indicate a weaker arboreal component in its behavioral repertoire than in H. habilis. However, in the absence of modern correlates, caution is needed with respect to possible behavioral implications of the different forearm proportions in the two species.

They also note the Homo-like anatomy of the femur shaft, including a marked pilaster.

Seth Dobson (2005) claimed that that the sacrum of STW 431 (A. africanus) is also small -- it certainly yields a small mass estimate compared to other elements of the skeleton. Heck, all of the early hominid sacra yield small mass estimates. Well, you can see it's confusing.

References:

Haeusler M, McHenry HM. 2007. Evolutionary reversals of limb proportions in early hominids? Evidence from KNM-ER 3735. J Hum Evol (in press) doi:10.1016/j.jhevol.2007.06.001

Dobson SD. 2005. Are the differences between Stw 431 (Australopithecus africanus) and A.L. 288-1 (A. afarensis) significant? J Hum Evol 49:143-154. doi:10.1016/j.jhevol.2005.04.001

A nice piece in The Guardian about the chimpanzee population near Bili, DRC. The lede is the suspicion of an apparent leopard kill -- that's chimpanzees killing a leopard -- but the other details are interesting:

[Cleve] Hicks said the animals also have what he calls a "smashing culture" - a blunt but effective way of solving problems. He has found hundreds of snails and hard-shelled fruits smashed for food, seen chimps carrying termite mounds to rocks to break them open and also found a turtle that was almost certainly smashed apart by chimps.

Like chimp populations in other parts of Africa, the Bili chimps use sticks to fish for ants, but here the tools are up to 2.5 metres long.

All these observations of chimpanzee behavioral diversity are pretty exciting, since they really provide an interesting model of early hominid diversification. Longstanding subspecies-level populations with strong behavioral differences involving food collection and diet may describe both A. afarensis (along with regional variants) and Late Pliocene Homo.

A mention is in the article about whether they should be considered a new (fifth) chimpanzee subspecies. I'd say that's probably a given at this point; doubtless the Fongoli chimpanzees will become a sixth.

Do they deserve it? Well, I suppose they're at least as distinct as the others behaviorally and anatomically, which isn't saying much. Genetically, it's an open question so far, but I wouldn't be surprised if they were as distinct as central and eastern chimpanzees, and certainly moreso than P. t. vellerosus. It's hard for me to see where ape subspecies taxonomy is going to end, since there are few scientific interests vested against further taxonomizing. Sure, there are conservatives, but none with enough firepower to roll back P. t. vellerosus, apparently. So, more subspecies lie in our future: I would guess two or three more for Bornean orangutan populations and who knows how many Western lowland gorilla populations will qualify?

(via Gene Expression)

Out of this week's Science Times special on evolution, I clicked into John Noble Wilford's article first, titled "The Human Family Tree Has Become a Bush With Many Branches".

Now, I don't know about you, but that seems like a boring headline to me. They've been talking about human evolution being a bush for going on 20 years now. It was an old idea when I was in graduate school. So it seems like, if this is all we have going on, the "new frontier" of paleoanthropology must be pretty dull.

The writer doesn't write the headlines, and the headline doesn't describe Wilford's story, which is basically a verbal slide show of fossil discoveries over the last decade or so. Some bone pictures (of the actual species discussed) accompany the article, and it's a good enough sort of account of new finds since 1990, framed around the tension between fossil finders and molecule mavens.

But I'll be a little critical. The thesis is that paleoanthropologists suffered a crisis of confidence after molecular data came online in the 1980's, and "a rapid succession of fossil discoveries since the early 1990's has restored" it.

Well, OK, maybe. But consider the listed discoveries: Kenyanthropus, Ardipithecus ramidus, Ardipithecus ramidus, Orrorin tugenensis, Sahelanthropus tchadensis, Homo floresiensis, and Australopithecus anamensis. Of all of these, only Ar. ramidus and Au. anamensis have gone without significant controversy.

We can set aside H. floresiensis for a moment -- the controversy about it being possibly the loudest, it also stands apart as the only species listed younger than 3.9 million years. All of these early Pliocene and Miocene species have also been challenged -- by the discoverers of the others, by old hands, and by young upstarts like me. At least one research group has claimed that all of the Miocene "genera" may actually belong to one species. Another has claimed that most of these "hominids" may actually be apes.

Whether there was any crisis of confidence among paleoanthropologists, all this disagreement is certainly business as usual.

And, contrary to the article, every one of these species would be thrown from the hominid line, if we believe the molecules. Here's the text from the article:

Genetic clues also set the approximate time of the divergence of the human lineage from a common ancestor with apes: between six million and eight million years ago.

Fossil researchers were skeptical at first, a reaction colored perhaps by their dismay at finding scientific poachers on their turf. These paleoanthropologists contended that the biologists' "molecular clocks" were unreliable, and in some cases they were, though apparently not to a significant degree.

...

The new finds have filled in some of the yawning gaps in the fossil record. They have doubled the record's time span from 3.5 million back almost to 7 million years ago and more than doubled the number of earliest known hominid species. The teeth and bone fragments suggest the form -- the morphology -- of these ancestors that lived presumably just this side of the human-ape split.

It is true that the new fossils date as far back as 7 million years; with Sahelanthropus just under that date, Orrorin at around 6 million, Ar. kadabba at 5.5, Ar. ramidus at 4.4, and Au. anamensis at around 4.1.

But it has been many years since a genetic comparison indicated a human-chimpanzee common ancestor as old as 6-8 million years. This year's study by Holbolth et al. (2007) estimated a human-chimpanzee speciation time of 4.1 +/- 0.4 million years. That makes Au. anamensis possibly too young to be a hominid. The rest of those species would presumably be just so many apes.

Now, I don't believe for a second that Au. anamensis is an ape and not a hominid. It just looks too much like Au. afarensis -- so much so that some would put them in the same species. The evolutionary transition between these two is well documented, and will be more so when some as-yet-unpublished fossils come out. So anything younger than 4.1 million years is almost certainly not right for the human-chimpanzee divergence.

But the 4.1 million year estimate is not unusual compared to other recent studies. My post from last May covers many of these recent studies, including last year's problematic "hominid-chimpanzee hybrid speciation" paper by Nick Patterson and colleagues. The conclusion in that paper about hybridization was certainly wrong, but the date of 5 million years was right in line with other estimates.

These genetic comparisons are not easily dismissed. Possibly there has been a rate deceleration of mutations in the human lineage that means that the estimated dates are too recent. Maybe 4.1 million years can be stretched into 6 million. Maybe it can even be stretched into 7 million. But all this stretching does have other effects -- on the estimated dates of earlier divergences -- and those are compounded by a large multiple of the few million years we may try to push the human-chimpanzee speciation date. That 4.1 million year estimate is calibrated from an African-Asian great ape divergence at 18 million years ago. Push the human-chimpanzee divergence to 7 million, and you push the orangutan-human divergence back into the Oligocene. Are silent sites in humans evolving more slowly than cercopithecines? Probably. Are they evolving that much slower than orangutans? I suppose nothing is impossible, but maybe we should take another look at those fossils.

All this is to point out that there really is a conflict between these Miocene "hominids" and genomic evidence about human-chimpanzee speciation time. I don't see any magic solution to this problem from the molecular side -- those dates keep coming up again and again from different regions, and from comparisons across many regions -- including estimates that are not calibrated by other fossil divergences. This is not an easy "the molecular clock must be wrong" kind of problem.

Nor are the fossils an easy problem. There is pretty good evidence for vertical posture or hindlimb-dominant movement in all of these "hominids." Up to now, we've accepted these kinds of features as de facto evidence of bipedality, and assumed that bipedality is such a unique character of hominids that it is unlikely to be any older. Yet few of these fossils provide really good evidence for obligate bipedality, and some of them provide none at all.

Is it possible that bipedal apes long preceded the divergence of humans and chimpanzees? Was the common ancestor of the two lineages a biped? Or was significant vertical posture a common feature of many Miocene apes -- making Sahelanthropus a possible homologue of Oreopithecus?

Which feature is the important one? The long nuchal plane of Sahelanthropus? The femur neck cortical bone distribution of Orrorin? The toe bone of Ar. kadabba? Heck, I can hardly convince my undergraduates about that toe bone!

I've talked to people about this. Some think that all the molecular stuff is just jibberjabbing, and any day now we will find out that the date estimates were wrong all along.

I think it may be time to start doubting our confidence again.

UPDATE (6/28/2007): I've gotten into rather an interesting e-mail discussion about whether I should have included Homo georgicus on the list of new species. Frankly it didn't occur to me: Wilford didn't mention it.

Actually if you start to think about all the new names that have been proposed in the last 15 years, it is a quite bushy list. It will be no surprise that I think this bushiness has more to do with the listers than the listees.

Anyway, there is something interesting about early Homo right now that goes beyond the simple splitter/lumper questions. I'll have more to say about it in a few days.

References:

Hobolth A, Christensen OF, Mailund T, Schierup MH. 2007. Genomic relationships and speciation times of human, chimpanzee, and gorilla inferred from a coalescent hidden Markov model. PLoS Genet 3:e7. doi:10.1371/journal.pgen.0030007

Patterson N, Richter DJ, Gnerre S, Lander ES, Reich D. 2006. Genetic evidence for complex speciation of humans and chimpanzees. Nature 441:1103-1108doi:10.1038/nature04789

Afarensis reviews the book The First Fossil Hunters: Paleontology in Greek and Roman Times, by Adrienne Mayor:

In Chapter Three, Mayor discusses discovery of bones in the Greek Pre-classic and Classic. Classical scholars should be familiar with these in a different context. For example, the Spartan discovery of the bones of Orestes or the shoulder of Pelops kept at the sanctuary of Olympia. The bones of Theseus were discovered by the Athenians (who also swiped the bones of Oedipus from Thebes). As Mayor points out there was a veritable bone rush at that time with skeletons of heroes popping up all over the place. One of the traits that united these finds was the large size of the bones. The ancient Greeks felt that their heroes were larger in stature than they were. An idea that traces back to Hesiod's Works and Days (where he discusses the five ages of Man) and probably earlier. Over time, according to the ancient Greeks, humans have grown shorter. So when giant bones were discovered - especially those that looked vaguely human - they were interpreted as the bones of Greek heroes. The Roman emperors Augustus and Tiberius also collected bones. What unites a lot of these discoveries is that they come from areas with a lot of fossils - mainly from the Miocene to the present and composed of large megafauna such as mammoths, mastodon, giraffe and rhinoceros to name a few.

According to the review, the book includes a number of archaeological instances where fossils were found in classical or preclassical contexts. I like Afarensis' point that despite the possibility that such finds guided mythological formulations of ancient giants and the like, classical philosophers "made little mention of such discoveries."

It makes you wonder what might have been done with the same evidence and the right person. As I was reading the review, I was reminded of Thomas Jefferson and the mastodon, and I went looking up some details:

In 1784, Jefferson had bravely argued against Buffon's statement that the "mammoth" bones of North America represented the same species as those of the modern elephant. Lacking professional confidence, Jefferson successfully enlisted the support of Ezra Stiles, president of Yale College, but Buffon never wavered in his identification. Ultimately, Jefferson's position was sustained by Georges Cuvier (1769-1832), the brilliant French anatomist, who recognized the bones as those of the mastodon (Coonen and Porter 1976:747).

In the eighteenth century, those knowledgeable about fossils and anatomy to a sufficient degree to argue such facts were rare. In classical times, such people simply did not exist. Considering the spacing of natural historians in the late eighteenth century (a handful per nation-state), it is probable that no conversation could have been sustained among them without technologies, particularly printing. This is particularly true because the comparative study of such remains requires visual representations -- diagrams at a minimum; ideally casts or original specimens -- which could hardly have been distributed to a critical number of people very much earlier in time.

It's no surprise that there was some change in mindset between classical times and the Enlightenment. Still, one wonders which innovations were essential to the growth of science. As indicated by the review, classical peoples were evidently interested in ancient remains and even collected them. This acquisitiveness had increased by the eighteenth century -- with a substantial number of avocational antiquarians -- but was hardly different in character.

The interpretation that ancient mastodons and other such fossils were the remains of an ancient race of "giants" was perfectly straightforward. Although clear evidence is rare, it seems probable that every culture with exposure to such ancient bones arrived at similar mythology-inspired conclusions. In Europe and America, such explanations persisted in Jefferson's day. Even post-Renaissance antiquarians arrived at semi-mythological explanations for ancient artifacts -- for instance, ancient stone tools as "thunderstones." Most straddled the boundary between mythology and naturalism.

The Enlightenment was the first point at which the tide of science was capable of formulating and testing a coherent alternative. The fossil record provided clear evidence directly on the origins of the earth and its history, and the logical options were clear enough once some connection between rock layers and time was made. As an example, Jefferson already knew enough to predict overkill as a cause for the disappearance of ancient megafauna:

Jefferson argued that an animal as large as the "great-claw" [the giant sloth] must always have been rare because, he reasoned, the "ordinary economy of nature" would provide "sufficient barriers" to large populations:

If lions and tygers multiplied as rabbits do, or eagles as pigeons, all other animal nature would have been long ago destroyed, and themselves would have ultimately extinguished after eating out their pasture (Jefferson 1799, p. 256)

Referring to Africa, Jefferson also claimed that a "new population" -- namely, man -- tended to drive off large animals to the continental interior. He suggested that in North America the pressure of Indian hunters had accomplished the same shift. This analogy was the rationale behind his seemingly whimsical instruction that Lewis and Clark look for signs of the living mammoth west of the Mississippi. Furthermore, Jefferson hinted that, by preferential hunting of these giant animals for an obviously great store of meat and hides, the Indians had probably exterminated them (Coonen and Porter 1976:747).

Two assumptions had crystallized by the eighteenth century: exponential (or "Malthusian") growth of populations, and the progressive decay of ancient things. Both assumptions are products of everyday observations that may have gotten more ordinary over time.

Old cities decay and are replaced; old things are buried and unburied. Sometimes the cities themselves get higher as a result -- a fact increasingly known as excavations into the subterranean layers of cities (for foundations and sewers) increased. The classics surely knew these things, but the recognition of old things must have grown as human history piled itself up into deeper and deeper layers.

The fleeting nature of life and youth was a standard of classical authors, but the disappearance and decay of entire civilizations was particularly part of the Enlightenment zeitgeist. Perhaps it was no accident that the beginnings of paleontology coincided with Edward Gibbon's Decline and Fall of the Roman Empire. Lost signs of ancient things became a staple of early Romanticism, and several scenes in Wordsworth's work wear on the implications of hidden histories. Better-known is Shelley's "Ozymandias," written in 1817:

I met a traveller from an antique land
Who said:—Two vast and trunkless legs of stone
Stand in the desert. Near them on the sand,
Half sunk, a shatter'd visage lies, whose frown
And wrinkled lip and sneer of cold command
Tell that its sculptor well those passions read
Which yet survive, stamp'd on these lifeless things,
The hand that mock'd them and the heart that fed.
And on the pedestal these words appear:
"My name is Ozymandias, king of kings:
Look on my works, ye mighty, and despair!"
Nothing beside remains: round the decay
Of that colossal wreck, boundless and bare,
The lone and level sands stretch far away.

A paleontologist reading the poem may find that it evokes a great fossil eroding from a desert badlands; replace "Ozymandias" with "Tyrannosaurus", and the verse sums up the present-day attitude toward the dinosaurs, far more than that toward ancient Egypt.

Imperial Rome, at over a million souls, was the apotheosis of classical population growth, but a clear reflection on the implications of such growth may have needed post-medieval mathematical insights or monetary and economic insights. London reached its first million shortly before 1800 -- the first city to do so since classical Rome. By that time, economics and mathematics were ready to infer the consequences of rapid population growth.

We now know that both insights were necessary for evolutionary theory to emerge, and the strands of evolutionary thought emerged before Darwin in the Enlightenment. This short-term history of thinking in the eighteenth and nineteenth century certainly benefits from considering just how much had changed in human existence since classical Greece and Rome.

References:

Coonen LP, Porter CM. 1976. Thomas Jefferson and American biology. BioScience 26:745-750.

I was checking on the Thomas Jefferson mastodon story for the last post, and I came across an episode I hadn't been aware of. After Edward Jenner's development of the smallpox vaccine in England, it was Jefferson who advocated its use and spread in America. And more:

Jefferson became as directly involved as if he had been the health commissioner in a small city. At the time, however, he presided over five million citizens. As a public endorsement of the procedure, he had his entire family vaccinated. But he did not stop there; in 1800 he received cowpox vaccine from [Benjamin] Waterhouse and turned it over to a Dr. Grant in Washington. When it was learned that the substance was inactive (the virus had died), Jefferson himself suggested a new and successful method for maintaining live cultures during shipment (Martin 1952; pp. 39-41).

He personally directed and encouraged the distribution of vaccine to various parts of the country. On one occasion, when Chief Little Turtle and nine of his braves came to Washington on official business, Jefferson persuaded the entire party to be vaccinated. Beyond that, he sent a virus preparation with them for inoculating others in their tribe. When Lewis and Clark left on tehir long trek into the unknown northwest, they were counseled, "carry with you some matter of the kine pox. ... Instruct them [the Indians] ... in the use of it" (Martin 1952, p. 63) (Coonen and Porter 1976:747).

If you had a president in a piece of fiction who did this sort of thing, nobody would believe it. Which is sad.

References:

Coonen LP, Porter CM. 1976. Thomas Jefferson and American biology. BioScience 26:745-750.

Martin ET. 1952. Thomas Jefferson: Scientist. Henry Schuman, New York.

I'm about two-thirds of the way through Mike Morwood's new book, The Discovery of the Hobbit, and I'll be posting a review when I'm through. Generally, I have a positive opinion of the book so far.

Henry Gee has reviewed the book in this week's issue of Nature. I wanted to point out my generally positive attitude about the book, so that you'll know that my miserable opinion of Gee's review has little to do with the book's merits.

Consider how Gee starts his review:

The unicorn, wrote Jorge Luis Borges (in Kafka and His Precursors), is universally regarded as a supernatural being of good omen. But there's a problem: despite its folkloric familiarity, we wouldn't know how to recognize a unicorn if we met one in real life. It "does not figure among the domestic beasts, it is not always easy to find, it does not lend itself to classification," Borges continues. "It is not like the horse or the bull, the wolf or the deer. In such conditions, we could be face to face with a unicorn and not know for certain what it was."

Is Gee smoking crack? What kind of blather is this?

First of all, I know I'm being terribly literal, but a unicorn is a horse with a horn. One horn. Not so hard to recognize! Maybe my 3-year-old daughters could help edit at Nature.

Let's see, where have I seen one of those that Gee might recognize? Oh, yeah:

Photo credit: Simon Stratford (via stock.xchng)

There it is, sound as a pound.

Next, Gee spends several paragraphs expositing on his own role in the publication of the Homo floresiensis announcement. We learn some interesting little facts, like how the authors wanted to name the species "Sundanthropus floresianus" until a reviewer pointed out that future students would confuse the name with a flowery butt.

I kid you not. Nature has a layer of reviewers to take tushie references out of taxonomy. Somehow they can't tell a left femur from a right, but they're on the watch for sphincter-species!

The review i