Notable paper: Bos, K. I., Harkins, K. M., Herbig, A., Coscolla, M., Weber, N., Comas, I., ... & Krause, J. (2014). Pre-Columbian mycobacterial genomes reveal seals as a source of New World human tuberculosis. Nature, 514(7523), 494-497. doi:10.1038/nature13591
Synopsis: The authors sequenced bacterial genomes from three 1000-year-old Peruvian skeletons to determine the source of their tuberculosis bacilli. These genomes were most similar to those from seals and sea lions, even though the modern New World and Old World tuberculosis strains are clustered together with each other (and with the chimpanzee bacillus strain). The implication is that ancient Americans came across the Bering land bridge without tuberculosis, and acquired it as a zoonosis from pinnipeds in South America.
Important because: The close relationships of present strains throughout the New World with European strains challenged the interpretation of ancient skeletal remains with tuberculosis. Bos and colleagues show that these modern strains probably replaced earlier strains that had existed in the Pre-Columbian New World.
Problematic because: The paper suggests the common ancestor of all these bacilli -- including the non-human strains -- lived around 5000 years ago. Transoceanic tuberculosis transfer by seal does make it possible to get the disease to the Americas in that time frame. But this estimate for the age of the common ancestor is an order of magnitude more recent than previous estimates for just the human strains. It conflicts with skeletal evidence for tuberculosis in even earlier specimens. The paper does defend its high mutation rate estimate in several ways, but I found it puzzling that the authors did not do more to explain why their estimates conflict with so much previously-published evidence.
Josephine Joordens and colleagues describe the utilization of freshwater mussels by ancient humans at Trinil, Java. The Trinil fossils were recovered by Eugene Dubois beginning in 1891, from the same site that produced the famous skullcap, tooth and femur that he named Pithecanthropus erectus. This set of hominin specimens was collected from an ancient river terrace, together with thousands of fossil bones of other animals, and the shells of a number of mollusc species. Joordens and colleagues worked with that original collection of shells to understand whether the hominins, which we now call Homo erectus, could have been using these aquatic resources.
The study has two interesting findings. First, the shells show that Homo erectus was a discerning mollusc predator. The most common shell in the deposit is of a freshwater mollusc called Pseudodon vondembuschianus, and the collection of 166 individuals includes mostly large individuals from a varied range of river habitats, indicating that they were concentrated in this area by the gatherers. Out of these individual molluscs, a third show characteristic small puncture marks in the shell at just the point where a predator would need to sever the adductor muscles that hold the shell closed. It seems that the ancient humans were systematically using a shark tooth or similar pointed tool to pierce these shells, opening them and eating the mussel inside.
Second, Joordens and colleagues found a shell with a geometric pattern incised on its surface:
Naturally with an artifact of this nature, one may raise questions as to whether the pattern may be explained not by intentional human agency but instead by taphonomic processes or incidental markings from some functional activity. The authors considered many alternative scenarios and convincingly show that the design was created deliberately by early humans:
One of the Pseudodon shells, specimen DUB1006-f, displays a geometric pattern of grooves on centre of the left valve (Fig. 2). The pattern consists, from posterior to anterior, of a zigzag line with three sharp turns producing an ‘M’ shape, a set of more superficial parallel lines, and a zigzag with two turns producing a mirrored ‘N’ shape. Our study of the morphology of the zigzags, internal morphology of the grooves, and differential roughness of the surrounding shell area demonstrates that the grooves were deliberately engraved and predate shell burial and weathering (Extended Data Fig. 5). Comparison with experimentally made grooves on a fossil Pseudodon fragment reveals that the Trinil grooves are most similar to the experimental grooves made with a shark tooth; these experimental grooves also feature an asymmetrical cross-section with one ridge and no striations inside the groove (Extended Data Fig. 6). We conclude that the grooves in DUB1006-fL were made with a pointed hard object, such as a fossil or a fresh shark tooth, present in the Trinil palaeoenvironment. The engraving was probably made on a fresh shell specimen still retaining its brown periostracum, which would have produced a striking pattern of white lines on a dark ‘canvas’. Experimental engraving of a fresh unionid shell revealed that considerable force is needed to penetrate the periostracum and the underlying prismatic aragonite layers. If the engraving of DUB1006-f only superficially affected the aragonite layers, lines may easily have disappeared through weathering after loss of the outer organic layer. In addition, substantial manual control is required to produce straight deep lines and sharp turns as on DUB1006-fL. There are no gaps between the lines at the turning points, suggesting that attention was paid to make a consistent pattern. Together with the morphological similarity of all grooves, this indicates that a single individual made the whole pattern in a single session with the same tool.
So what can we make of this artifact? I think the most important thing to take away is that it is unlikely to be unique.
It's a recurrent phenomenon in the study of early "art" objects that they lay unrecognized in museum collections for years after their initial excavation. The shell ornaments from Skhul, Israel and Oued Djebbana, Algeria were both found recently by Marian Vanhaeren and colleagues, despite having been excavated decades earlier ("Old shell beads in Dorothy Garrod's stuff"). The importance of many such objects is not obvious until they are examined in comparative perspective.
The Trinil engraved shell is an example of this phenomenon. It lay in a museum for more than a hundred years, unrecognized, until the right person went to study the shells for an entirely different reason. It took looking at 166 individual mussels, most of which probably passed through the hands of ancient humans, to find one with clearly intentional markings. It is not going to be the last Homo erectus intentionally marked artifact.
Nor is it probably the first. Robert Bednarik looked at objects with engravings or other alterations made by early humans, in a 1995 article titled, "Concept-mediated marking in the Lower Paleolithic". The record includes many bone and ivory objects with engraved lines that are not consistent with functional activities such as defleshing or disarticulation. Along with several later sites from Neandertal times, Bednarik considered objects from Bilzingsleben, Germany, a site that preserved evidence of human activity from around 350,000 years ago. The lines engraved on bone and ivory are sometimes arranged in parallel rows, or sometimes with lines appearing to radiate from a single point. For example, here is an illustration of several of the objects from Bilzingsleben:
Who made the Bilzingsleben artifacts? The taxonomic question is boring -- who cares what species we call them? We cannot answer the cognitive question by citing taxonomy; we must examine what we know of their behavior. Pre-Neandertal European populations and Middle Pleistocene Asian populations were genetically more different from each other than living human populations are today, but the genetic evidence from Denisova suggests that those populations were interbreeding with each other at the margins -- in a similar way that archaic and early modern human populations interbred within the Late Pleistocene. This is not enough to conclude that the cultural abilities of all these populations were identical, but it does suggest that they substantially overlapped in cognition and communication.
What we know about the marking behavior of later humans helps to illustrate just how much the record of behavior has decayed due to the normal taphonomic destruction of sites. Only by using more intensive and careful collection strategies are we beginning to overturn the inevitable loss of information. The discovery of ochre droplets from an early Neandertal context, more than 200,000 years ago in the Netherlands, as reported by Wil Roebroeks and colleagues (2012) is another example of something that would have been completely missed by a less careful excavation protocol. The ochre droplets are an instructive case because ochre marking is an activity that leaves no permanent archaeological trace unless it occurs deep inside caves on geologically inert surfaces. Only the discovery of ochre crayons with signs of use, such as grooves produced for pigment removal, have in the past provided some archaeological documentation of ochre marking, and even then the archaeologist may not be able to reject the hypothesis that the ochre was used for quotidian purposes like mastic instead of marking of skin or objects.
The engraved ochre pieces from Blombos are an excellent example of the variability of marked objects from Middle Stone Age and earlier contexts. The most famous piece of Blombos ochre, dating to between 75,000 and 100,000 years old, has served as an iconic artifact for illustrating the sophistication of MSA people:
The engraved side of this piece clearly has a high design content, with complementary sets of zigzag or diamond shapes and lines demarcating the ends of this row. Whatever it represents, it is clearly intentional.
But every other engraved piece from Blombos is much more ambiguous. For example, this small piece has engraved lines that converge toward a point. Possibly they are purely a side effect of removing ochre in powder form from this small piece, or possibly the lines were intentionally placed in this arrangement. Or maybe the removal of powder was done by someone with an intentional eye for design, and never meant to last.
In fact, we can't assume that any of these pieces were meant to communicate, or to last for any length of time. They were created by someone capable of design, but the design that they encompass may only be incidental. Bednarik discusses the regularities among the early marked artifacts in thematic or stylistic elements:
There are still other consistencies in these early marking strategies. Most seem to be reactions to aspects of the form or shape of the surface decorated in their extent, orientation, and "focus." For instance, the sets of seven convergent lines on the Stranskh skala vertebra and on the Prolom z phalanx both radiate from the object's end, as do the lines on the Prolom z tooth; the bundles of lines on Bilzingsleben objects I and 3 reflect the geometry of the support area, although not in the conceptually sophisticated way that the marks on the Tata nummulite do this. As I have noted before (e.g., Bednarik 1994a), all of the markings of the Lower and Middle Palaeolithic resemble modern doodling, which is spontaneous and subconscious. Contemporary doodling, the scientific value of which remains almost entirely ignored, could well have its neuropsychological roots in our early cognitive history.
It is precisely these kinds of regularities that enable us to recognize the objects as "concept-mediated", that is, guided by an intentional mind in some way. Even though they are not representational -- at least not in an iconic, pictorial sense -- the markings can be recognized as intentional. Most of these objects are much more ambiguous than the shell from Trinil. The shell marks required the maker to match the beginning and ending points of lines with each other, requiring deliberate precision.
I do not think we can dismiss doodling as meaningless. But neither do I think we can promote it as highly meaningful. Meaning is something that archaeologists cannot reach. What we can say is that these artifacts carry information about the capabilities of their makers. The few non-perishable marked objects also speak to the likely presence of design in perishable elements of material culture. Clothing, however rudimentary, was likely to have been decorated in some way. Wooden tools were also probably notched and zigzagged -- as the occasional bone and ivory implements suggest.
They lived for the first time in a world that they could change.
Joordens, J. C. A., d’Errico, F., et al. (2014). Homo erectus at Trinil in Java used shells for tool production and engraving. Nature (in press). doi:10.1038/nature13962
Bednarik, R. G. (1995). Concept-mediated marking in the Lower Palaeolithic. Current Anthropology, 605-634.
Henshilwood, C. S., d'Errico, F., & Watts, I. (2009). Engraved ochres from the middle stone age levels at Blombos Cave, South Africa. Journal of Human Evolution, 57(1), 27-47. doi:10.1016/j.jhevol.2009.01.005
Ann Gibbons has a very nice profile of biological anthropologist Nina Jablonski in last week's Science: "Shedding light on skin color". Jablonski is well-known as an expert in the paleontology of Old World monkeys, and starting more than twenty years ago began to investigate the evolutionary background of skin, hair and eye pigmentation in human populations around the world.
Gibbons reviews this research, including Jablonski's proposal that the selective value of dark pigmentation lies mostly in preventing folate destruction by ultraviolet light in the skin, instead of skin cancer or other causes.
Some of Jablonski's ideas remain unproven. Yet her work is injecting a shot of evolutionary perspective into medicine and influencing researchers to test how sunlight affects health. Jablonski has “opened my eyes to so many things I hadn't thought about,” says perinatal epidemiologist Lisa Bodnar of the University of Pittsburgh in Pennsylvania. Radiation epidemiologist Michael Kimlin of the Queensland University of Technology in Brisbane, Australia, agrees. “We have this brand-new field in which people are suggesting that when we put our bodies in the sun, there are complex interactions,” he says. “What Nina's doing is not only contributing to evolutionary science … she's creating ripples in [biomedical] science and giving people like me hypotheses to test.”
I found that quote interesting because it really is illustrative of the thought mold in biomedical research circles. Thinking about human biology in an evolutionary framework really can lead to new (and sometimes unexpected) insights, but only a small proportion of medical researchers have any background or interest in evolutionary biology. I've worked with a number of such researchers and hope to do so more in the future.
The study of pigmentation is one of the topics of classic physical anthropology, but only now are we beginning to understand that pigmentation variation is diverse in its origins, most of which are surprisingly recent. Many of the genes that influence human variation in pigmentation have been subject to strong natural selection during the last 20,000 years; others have variation that has come in from archaic human populations. This is a rapidly changing story in human evolution.
Jablonski's book, Skin: A Natural History is an account of the biology of skin in humans, touching on not only pigmentation but also other uniquely human aspects such as sweating.
In the UK, a documentary program called "Woolly Mammoth: The Autopsy" has recently run, featuring an international team of scientists involved in a recent mammoth discovery from Maly Lyakhovsky, Siberia. The program not only follows the scientists studying this unique specimen, it also presents the ideas of scientists interested in using preserved mammoth tissue to clone the ancient beasts.
The Guardian has an opinion piece by one of the team of scientists, Toni Herridge, of the Natural History Museum in London. The headline tells the thesis: "Mammoths are a huge part of my life. But cloning them is wrong".
Any attempt to clone a mammoth would probably require a living elephant – likely to be Asian – to act as a surrogate. To go through 22 months of pregnancy, carrying an animal of a completely different species as part of the experiment. An intelligent, social animal, at the brink of extinction, and one we know doesn’t do all that well in captivity.
And not just one elephant. In reality, many surrogates would be needed before a successful baby mammoth was born.
Does the potential benefit to humanity of cloning a mammoth outweigh the suffering an Asian elephant surrogate mother might experience? I’ve yet to hear a convincing argument that it does.
The only reason George Church and others are talking about cloning a mammoth is ego. Admittedly, the effort to clone a large extinct mammal would advance biotechnology. But that technology can be developed for other, more practical and less ethically problematic goals just as easily. At the same time, the resources spent on mammoth cloning could instead save critical habitat for many endangered species.
The magazine of the College of Literature, Science and Arts at the University of Michigan has a nice piece profiling Dan Fisher: "The dead elephant in the room". Fisher is a paleontologist well-known for his work understanding the biology of mammoths and mastodons. One thing the article doesn't mention is his part in analyzing the famous "baby mammoth" from Siberia several years ago.
This article by Elizabeth Wason is fun because it focuses on a human-centered aspect of proboscidean biology, their possible use as food by prehistoric people. The article begins with a sketch of Fisher faced with a unique problem: excavating the carcass of a zoo elephant from a landfill. Despite resting amid the junk of Toledo for more than two decades, the elephant's flesh had not decayed -- indeed, it remained surprisingly resistant to decomposition after three years after Fisher dismembered the carcass and buried the pieces under a mountain of manure. If that sounds like the beginning of a research project, well, you're thinking like a paleontologist!
The elephant gave a clue that ancient humans might have found a way to preserve edible meat, allowing them to exploit larger animals than they could profitably consume in a short time on the landscape. So Fisher started tossing heads into frozen ponds.
By this point, Fisher has gathered enough experience and evidence to understand why. The cheese-like odor of the meat suggested that lactobacilli, the bacteria responsible for creating cheese and yogurt, readily colonized the dead animals, at least under acidic conditions. Lactobacilli release lactic acid as they metabolize, which probably created an environment that—in tandem with the acidic, low-oxygen conditions of the water—naturally pickled the meat and prevented the growth of putrefying bacteria. But cold water temperatures were not necessary to preserve the meats effectively; the lactobacilli kept meat from spoiling through the spring thaw and even into the summer.
All of this means that that old, waterlogged horsemeat should be okay to eat, right?
Fisher, of course, knows how to find out.
This idea might seem off-the-wall, but it has some basis from the archaeological perspective. John Speth at Michigan has long traced the importance of brain consumption as a source of dietary fat. Some Neandertal-era sites show a pattern that might be consistent with preserving the heads of large herbivores in frozen ponds. Mammoth heads so far are not among them, but mammoth consumption was important for some Neandertals and for later people of Upper Paleolithic times in Europe.
Meanwhile, if you're a foodie, Lactobacillus is commonly used in classic charcuterie as a way of preserving and flavoring meat.
In case you're skeptical of pond-preserved mammoth heads...
Notable paper: Macho GA, Lee-Thorp JA. (2014). Niche Partitioning in Sympatric Gorilla and Pan from Cameroon: Implications for Life History Strategies and for Reconstructing the Evolution of Hominin Life History. PLoS ONE 9(7): e102794. doi:10.1371/journal.pone.0102794
Synopsis: Even though chimpanzees and gorillas eat an overlapping range of foods, both almost entirely dependent on C3 plants, they have slightly different ratios of stable isotopes of carbon and nitrogen. Macho and Lee-Thorp show that the gorilla and chimpanzee populations that coexisted in the late 1920s in Cameroon can be clearly distinguished in their carbon-13 content. Additionally, from infants to adults the two species have different trajectories of nitrogen-15 content, likely reflecting different weaning strategies.
Important because: A very close study of the local resources may enable finer distinctions about diet preferences from stable isotope data than have been made so far for early hominins and prehistoric humans. In this case, the subtle differences in carbon-13 content between different C3 plant species, or between leaves and fruits within a plant, have left a mark on the chimpanzees and gorillas. The authors suspect that the gorillas were feeding in more closed-canopy context, not only eating different foods than chimpanzees but actively using different space.
Interesting... The data here come from hair samples taken from museum specimens collected by Major Percy Powell-Cotton, wild-shot between 1927 and 1935. It is a case where museum collections show the potential for interesting research -- in this case hair samples taken non-invasively from the field may prove useful for the same kind of analyses.
From Nautilus this month, a long profile article by Kat McGowan describing the work of Michael Tomasello: "Cooperation is what makes us human". The focus of Tomasello's experimental work has been uncovering the ways that chimpanzees act as individuals where humans seem naturally to intuit that others can help us.
“We naturally inform people of things that are interesting or useful to them,” Tomasello says. “That’s unusual. Other animals don’t do that.” Pointing is an attempt to change your mental state. It is also a request for a joint experience: She wants you to look at the dog with her.
Chimps, by contrast, do not point things out to each other. Captive chimps will point for humans, but it’s to make a demand rather than to share information: I want that! Open the door! They do not understand informational human pointing, because they do not expect anyone to share information with them. In one of Tomasello’s experiments, food is hidden in one of two buckets. Even if the experimenter points to where it is, the chimp still chooses randomly. “It’s absolutely surprising,” Tomasello says. “They just don’t seem to get it.”.
The end of the article briefly describes work on dogs and the Belyaev fox experiment; in both cases these species have taken on the ability to see humans as helpers, including an ability to understand pointing.
The noted television popular science educator Bill Nye has a new book in which he looks at the evidence for evolution: Undeniable: Evolution and the Science of Creation.
Popular Science is running an excerpt of his book, in which he looks at the future of human evolution: "Is the human species still evolving?".
I give a great many talks or lectures at universities and for general audiences. I enjoy performing, the part where I’m doing the talking and all, but my favorite part of any evening is when audience members come up to microphones and ask me questions. One of the most common themes is what people call “The Singularity.” This is a supposed imminent time (2029, in some versions of the story) when computers will become as sophisticated as human brains. From there, it is proposed, machines will be able to outcompete humans at just about everything. There will be superior car-parking algorithms, disaster-relief coordination, legal briefs, rocket science, great thinking in general. Taking it to the next logical step, this artificial intelligence will have to be managed carefully, because after all, any of these future brain machines will outthink and outmaneuver us at every practical turn.
The chapter excerpt doesn't include any of the actual evidence of ongoing human evolution. Anthropologists and demographers have uncovered quite a lot of evidence about ongoing evolution in the last 50 years, and geneticists over the last 15 years have documented an immense store of information about evolution across the last few thousand years. Readers who want to find out more about this can check out my recent article in Scientific American, which has the online headline, "No, humans have not stopped evolving". And a free link on the theme of recent human evolution is my 2007 post, "Why human evolution accelerated", discussing our genetic work on the topic.
I pointed earlier this week to an article by Lydia Pyne about perceptions of Neandertals over the years, and hinted at a second recent article. That article is "To Russia, With Love", and details a correspondence between Raymond Dart, discoverer of the Taung skull, and a Professor Plissetzky, director of the State Museum and the Institute of Anthropology in Moscow.
Plissetzky wrote to Dart requesting a cast of the Taung child for a museum exhibit. Pyne followed the correspondence in the archives of the University of the Witwatersrand, which includes original copies of the letters, order requests and photographs of the anthropological exhibition at the Institute of Anthropology.
Ultimately Dart arranges to have a cast of Taung sent to Moscow, for exchange of some Russian casts. I don't know if the cast of the Kiik-Koba foot at the Evolution Studies Institute (originally from the Medical School collection) resulted from this exchange, but it might well have.
The episode is interesting on its own, and Pyne uses the historical event to explore the history of casting in paleoanthropology. She recounts the origin of hominin fossil casting under the direction of R. F. Damon at his company in London. Originally devoted to collecting and selling original fossils, production and sale of fossil replicas to museums and institutions became an increasing part of their business during the early twentieth century.
Dart held the “copyright” on the Taung Child fossil, according to R.F. Damon & Company’s paperwork and Dart was paid royalties based on how many fossil casts were sold. Dart worked with the company’s Mr. F.O. Barlow on both the nitty-gritty details of creating and describing the fossil casts as well as in sorting out the financial ledgers; dozens of letters between Barlow in London and Dart in Johannesburg hashed out the fossil’s financial deals. When Dart originally approached R.F. Damon & Company, he thought that each fossil cast ought to sell for more than what other, similar hominin casts had sold for (e.g. Pithecanthropus). Mr. Barlow begged Dart to reconsider his position about the cost of the cast, as Barlow noted, “The prices you suggested would result in killing the demand and would create in my customers a feeling of resentment which I am not willing to incur.” Once the question of price was properly sorted out, the company sold a lot of casts.
For more information on the history of casting fossil hominins, I recommend an article by Alan Mann and Janet Monge, published in the University of Pennsylvania Museum magazine Expedition in 1987: "Reproducing Our Ancestors". Mann and Monge have a detailed description of Barlow's cast-making technique.
In the 1920s and 1930s, F.O. Barlow, a leading mold and cast maker in Europe, fabricated more than 600 plaster-of-Paris molds of hominid fossils. In order to ease the removal of plaster from an often fragile fossil specimen, these molds were made of many pieces, waxed and keyed to each other. A complete mold of a skull, for example, could easily be composed of more than 100 plaster pieces, each replicating a small part of the whole fossil; fitted precisely together, they form what can only be described as a large three-dimensional jigsaw puzzle. Casts produced from Barlow’s molds have a surprising amount of detail. They appear to be dimensionally accurate replicas, but many cannot be adequately assessed because in the meantime, the original fossil has been modified, reconstructed, or even damaged. About 500 Barlow-produced molds of fossil hominid bones have survived, and are now in The University Museum Casting Program collection .
The article goes on to describe the development of the casting program of the Wenner-Gren Foundation for Anthropological Research, which was the source of the majority of fossil casts now used in university teaching and research. As they describe, Wenner-Gren instituted a research initiative to find better materials and better mold-making techniques for fossils. Molds are presently made from flexible silicone instead of hard plaster-of-Paris, and the resulting casts in epoxy reproduce the details of fossils with much higher fidelity than the old plaster versions. With this new mold-making technology in hand, Wenner-Gren instituted a much broader program of producing and distributing casts of fossil hominins than ever before:
From 1962 to 1976 the WennerGren Foundation sent mold makers all over the world. Using techniques developed by Gilbert, they were able to produce over 900 molds of the most famous human and primate fossils, including Zinjanthropus or “Nut Cracker Man,” Mrs. Ples and the Taung child from South Africa, and Kabwe Man. During this time the Wenner-Gren Foundation produced nearly 16,000 high-quality plastic casts of fossil remains, and distributed them to scientists and research and teaching institutions throughout the world.
In addition to the historical context of casting, Mann and Monge gave a detailed account of the process of making molds and casts, and the importance of the "patterns" that enable the long-term archiving of the shape of original fossils, sometimes even after the fossils themselves have been lost or damaged by later study.
Inclusion of fossils in a museum collection does not guarantee their safety. Ancient bones are very frequently fragile: some are only partially mineralized or fossilized, others are not mineralized at all. Often, they are held together by toothpicks and bits of wire. With the interest in human origins expanding each year, and the number of professional scholars involved in active research steadily increasing, these fossils are being handled, examined, photographed, measured, and broken with greater frequency. Many researchers have had the experience of examining a fossil they had first looked at several years before, only to find that, due to handling or an accident, the fossil specimen is now different in appearance.
The PDF version of the article (at the link) includes illustrations of the process of molding and casting; these are not included in the HTML version of the article.
In addition to its importance as a way to archive fossils, the casting process retains its original role of communicating the three-dimensional properties of casts and artifacts to international colleagues. The world created by Barlow, Damon and others was an enormous advance over the previous generation, in which only a fortunate few internationally-traveled scientists might have examined the primary evidence of fossil forms.
International travel has become much easier, which has enabled many more researchers to see fossil collections first-hand in their countries of origin. But in the past the fossil record was very sparse, while today the fossil record is an order of magnitude greater. No expert has seen every important original fossil. Most major fossil collections and research universities keep collections of casts to facilitate the study and comparison of these fossils. We now train a much broader number of students in the details of the human fossil record, not only those who will enter the speciality of paleoanthropology, but also those who will bring insights about human evolution into fields as disparate as archaeology, human ecology, evolutionary medicine. Paleoanthropology relies upon the widespread distribution of high-resolution casts of fossils; without these casts, what we do would not be science.
A recent issue of Current Biology has a short interview with paleoanthropologist Bernard Wood: "Bernard Wood". The interview covers his transition from a training in medicine to human evolution, and his subsequent work on the hominin fossil remains from East Turkana:
Why did you choose to work on skulls and teeth? I didn’t. I was one of three anatomists (the others were Michael Day and Alan Walker) Richard Leakey had invited to describe and interpret the hominin fossils recovered from Lake Rudolf. The majority of the fossils were from the skull and dentition, but each of us wanted to work on the limb bones. In 1972, we met in New York to discuss the impasse, but none of us would give in. So, not a little frustrated, Richard broke three matches into different lengths and made us draw. Mine was the shortest match, so I had no choice but to work on the cranial remains. This task, which involved determining how many taxa were represented among the hominin cranial fossils, led to the topic of my PhD, sexual dimorphism, and my interest in patterns of intra- versus interspecific variation.
I always find it so illuminating to think about how today's well-known paleoanthropologists started doing the work that would bring them scientific prominence. Having just come from working with so many early career scientists on the Rising Star Workshop, it is valuable to remember that most of today's experts in paleoanthropology got their start as PhD students describing new fossil remains, before substantial datasets of fossil variation even existed.
Vox writer Joseph Stromberg visited the Forensic Anthropology Center at Texas State University, and has written an in-depth description of his visit: "The science of human decay: Inside the world's largest body farm". The article features the work of Daniel Wescott at Texas State, and provides a great account of how the science of human decomposition developed.
The article gives some historical perspective, describing how Bill Bass got started studying decomposition at Tennessee, and goes into some detail about how today's research differs from that history. Among other things, forensic anthropologists have developed a much stronger understanding of the microbes that are involved in decomposition:
For Wescott and the other researchers, caged decomposition presents the most interesting scientific experiment at the body farm. It was once thought that the bacteria that drive decay are simply the same species inside you while you're alive, but it's since been discovered that a succession of different species carries it out over time. Some of them are indeed present during life, but others are brought to the body by flies and beetles. Meanwhile, some bacteria species release chemicals that actually attract particular kinds of insects — and proteins in those insects' saliva kill off competing bacteria. Further, these insects are prey for mice, which in turn attract rattlesnakes and other larger predators. A decomposing human body, it turns out, creates a remarkably complex, tightly evolved, and underappreciated ecosystem. Scientists are now calling it the necrobiome.
This seems to be decomp week in the media, which is probably due to Halloween coming up this Friday. But this article is really superb. I will be distributing it to my introductory anthropology students when we approach our forensic anthropology inquiry at the end of the semester.
One important thing to note is that all the research is done upon bodies that are donated for this purpose. Body donation has become incredibly important to anthropological work of all kinds. The article has a sidebar that discusses the reasons why people donate their bodies for science, and why the study of decomposition can be a really important avenue for body donation.
One thing that the article doesn't discuss is the scientific value of the bones, after the body's use in decomposition research has ended. Some decomposition research does involve damage to the bones (the article discusses the effects of vultures; some decomposition research also investigates the effects of cremation). But the overwhelming majority of bones become available for accession into study collections at these forensic anthropology research centers.
The skeletal material from the University of Tennessee forensic research unit constitutes the single most important collection for understanding variation within the skeletons of living Americans. Most collections of human skeletal material in museums and universities were acquired early in the twentieth century, or represent archaeological remains. Those are important collections, but do not represent today's biology -- people today are much heavier, live longer, suffer fewer ill health episodes early in their lives, and often survive surgeries and skeletal implants when they reach advanced ages. To understand how human biology affects bone today, and to understand the variation in bones of living people, new collections are incredibly important. They are literally priceless, because collections of this kind cannot be bought. They result only from the generosity and interest of donors who leave their remains for this purpose.
John Ioannidis is well known as a critic of the way science has usually been practiced. I've linked to his work before ("Link: John Ioannidis and the scientific workforce core", "Conference criticisms"), although I haven't written directly about his most famous work on the reasons why most scientific findings go unreplicated.
Ioannidis has a recent article in PLoS Medicine that discusses ways to change the scientific research enterprise. He focuses on two criticisms of the present scientific research practice: Most published articles are based on samples that lack sufficient power to justify the claimed associations or effects, and a large majority of resources (he cites 85% as an estimate) are "wasted". Based on these considerations, he writes about several ways that scientific research could be changed to increase the pace of genuine discovery and reduce the rate of spurious results.
The current system values publications, grants, academic titles, and previously accumulated power. Researchers at higher ranks have more papers and more grants. However, scholars at the very top of the ladder (e.g., university presidents) have modest, mediocre, or weak publication and citation records . This might be because their lobbying dexterity compensates for their lack of such credentials, and their success comes at the expense of other worthier candidates who would bring more intellectual rigor and value to senior decision making; equally, it could be because they excel at the bureaucratic work necessary to keep the mind-boggling academic machine going, and their skills enable more scientifically gifted colleagues to concentrate on research. The current system does not reward replication—it often even penalizes people who want to rigorously replicate previous work, and it pushes investigators to claim that their work is highly novel and significant . Sharing (data, protocols, analysis codes, etc.) is not incentivized or requested, with some notable exceptions –. With lack of supportive resources and with competition (“competitors will steal my data, my ideas, and eventually my funding”), sharing becomes even disincentivized. Other aspects of scientific citizenship, such as high-quality peer review, are not valued. Peer review can be a beneficial process, acting as a safety net and a mechanism for augmenting quality. It can also be superficial, lead to only modest improvements of the reviewed work, and allow for the acceptance of blatantly wrong papers ,. That it is so little valued and rewarded is not calculated to encourage its benefits and minimize its harms.
I don't endorse all of his arguments, which are heavily skewed toward the biomedical research fields. These areas are after all his specialty, and more "pure science" areas of research such as paleontology and astronomy are not his aim. On the other hand, physics and genetics share a great deal in the way they approach new scientific research projects today: Both fields have come to rely more strongly upon large-scale collaborations, both have begun to institute more quality assurance in their software and tool development, and both have adopted more open access protocols toward data collection. Both also have recognized that very stringent standards on statistical significance are necessary to reduce the reporting of results that will almost certainly fail to be replicated in larger-scale studies.
Paleoanthropology has begun to embrace a scientific approach with wider-scale collaboration and data sharing. I think we are fortunate in being a relatively small field in which the contributions of peer reviewers and editors are much more recognized than in many fields. I think this recognition would be even greater if the reviews were less anonymous, and I have encountered an increasing number of reviewers who have refused anonymity (often including myself). But even more important than peer review is a greater discussion and conversation about research directions and priorities. If we can get students and professionals collaborating with each other on larger-scale research datasets instead of working alone in isolation, we'll increase the replicability of results and improve the significance of everyone's work.
Ioannidis JPA (2014) How to Make More Published Research True. PLoS Med 11(10): e1001747. doi:10.1371/journal.pmed.1001747
Notable paper: Kopp GH, Roos C, Butynski TM, Wildman DE, Alagaili AN, Groeneveld LF, Zinner D. (2014). Out of Africa, but how and when? The case of hamadryas baboons (Papio hamadryas). Journal of Human Evolution (in press) doi:10.1016/j.jhevol.2014.08.003
Synopsis: Humans are not the only primate to have dispersed from Africa during the Pleistocene. Savanna baboons, widespread across eastern Africa, established a population on the Arabian peninsula during the last 150,000 years. Gisela Kopp and colleagues show that the diversity of baboons increases from north to south along the Red Sea coast in Arabia, and suggest that the baboons may have crossed the Strait of Bab-el-Mandab during the low water period of the Late Pleistocene, more than 70,000 years ago.
Important because: Archaeologists and geneticists have recurrently suggested that humans may have made a Bab-el-Mandab crossing via a "southern route", instead of coming across land via the Sinai peninsula. The interest in a southern route for humans has most recently been spurred by archaeological similarties between Arabian and African Middle Paleolithic-era assemblages. Those similarities date to the same general time period that baboons were establishing this Arabian population.
But... The genetic data here don't exclude an overland or mixed source for the Arabian baboon population. And of course, the dispersal abilities of baboons are probably not the same as humans, so the baboon analogy may not be relevant to us. Still, along with other African fauna like cheetahs and striped hyenas, the baboons help to show that Arabia was repeatedly colonized by African forms.
The historian of science Lydia Pyne has published a couple of recent articles that detail interesting aspects of the history human evolution. The first is about science's changing perspective on Neandertals, "Our Neanderthal complex", which appears in the most recent issue of Nautilus.
I must say my favorite part is how she traces Boule's concept of stupid and inferior Neandertals up through the years: Instead of describing these ideas as simply outmoded, she recognizes how they contributed to the work of recent anthropologists, with Richard Klein as a visible manifestation.
Even the language of extinction imbued Neanderthals with an aura of evolutionary fatalism: “demise,” “fate,” and “loss” helped us cast our interspecies interaction as a relationship between winners and losers. “It is not difficult to understand why the Neanderthals failed to survive,” noted Richard Klein in the third edition of his seminal textbook, The Human Career, in 2009. “The archaeological record shows that in virtually every detectable aspect—artifacts, site modification, ability to adapt to extreme environments, subsistence, and so forth—the Neanderthals lagged their modern successors, and their more primitive behavior limited their ability to compete for game and other shared resources.”
Pyne comes at the end to an essential point about Neandertals: We long defined ourselves as whatever the Neandertals are not. Now we have begun to explore the implications of defining them as part of our family.