Photo Credit: Road to Malapa, South Africa. John Hawks [CC-BY-NC-ND]
It is notable that we now have evidence for interbreeding among every kind of hominin we have DNA from, and some we don’t.
Neandertals and humans. Denisovans and humans. Neandertals and Denisovans. Some living sub-Saharan Africans and one or more unknown ancient populations. Denisovans and one or more unknown, even more ancient populations. They were all mixing.
The picture of Pleistocene human evolution has come rapidly into focus during the last two years. Before the last 30,000 years, the world was full of human populations that were around twice as different from each other as the most diverse recent human groups. Some of these ancient groups grew at the expense of others, but the "losers" over the long term still survived within the genomes of the "winners".
The process of selection on human genes spanned these different human populations, as genes of adaptive value were exchanged between them, long surviving their progenitor populations. Each of the groups shared genetic variation from their common ancestors, but some local populations were markedly restricted in variation by inbreeding. All in all, humans of the past had a population structure rather like today's chimpanzees, although ancient humans were slightly more alike across a much larger geographic range.
Last spring we heard that the Max Planck Institute for Evolutionary Anthropology had successfully sequenced a high-coverage genome from a hominin toe bone found at Denisova Cave, Russia. In the announcement they made clear that this genome was substantially different from the existing high-coverage genome from Denisova. That first genome, from the bone of a pinky finger, represented a previously-unknown human population, quite different from Neandertals. This new genome, from the Denisova toe bone, is much more similar to the genomes of other Neandertals already known from Vindija, El Sidrón, Feldhofer and Mezmaiskaya. That seems like enough to call the toe a Neandertal.
Yet this week's paper makes clear that this genome is not just another Neandertal. Kay Prüfer and colleagues (2013) describe several kinds of analyses on the high-coverage data. The most important of these analyses establish the pattern of similarities and differences between this genome and others, allowing us to test some hypotheses about the relationships of Neandertals, Denisovans and modern humans.
At the moment, I am just going to present and explain a few of the major conclusions of the study. The paper itself is only 7 pages long, but the supplementary data stretch across 248 dense pages of text and figures. It's much more than a dissertation's worth of information, and it is going to take some time for me to completely digest. There will be much more to discuss over the next few weeks. Further papers that use these data are in the pipeline, with some interesting additional results. This is good work and I am excited by it, but I am going to present some notes of caution as well. I think some interpretations are likely to shift as we learn more.
Here are the major insights of the present study:
The new genome appears to represent an individual that has fewer new derived mutations than the Denisovan high-coverage genome. The research suggests this as a means of "molecular dating" of the specimens, proposing that the Denisovans lived in Denisova cave after this Neandertal population.
The Denisovan high-coverage genome includes portions that reflect ancestry from Neandertals.
The new genome groups with previously known Neandertals in a genome-wide cluster analysis, but represents a more divergent population of Neandertals than those yet described. Under a model where genetic differences reflect a branching population history, the "Altai Neandertal" population seems to have diverged from other Neandertals sometime between 77,000 and 114,000 years ago.
The high-coverage Neandertal genome shares many derived mutations with sub-Saharan Africans, while the high-coverage Denisova genome shares fewer. If these archaic populations were equally related to Africans, they would have the same number of shared derived mutations with Africans. Prüfer and colleagues infer that the Denisovan genome had ancestors who belonged to a yet more ancient hominin population. They suggest this population represents around 4 percent of the ancestry of Denisovans, and that it diverged from the common ancestors of Neandertals and sub-Saharan Africans sometime around a million years ago. The confidence intervals on both estimates are large.
The new genome has many extended runs of homozygosity, consistent with inbreeding. The study concludes that the parents of this individual were likely 1/4 degree relatives -- such as uncle/niece or half-sibling mating.
A comparison of the archaic human genomes with the 1000 Genomes Project samples shows only 96 amino-acid-coding changes shared by nearly all of the 1094 recent humans but absent from Denisovan and Neandertal genomes. A larger number (over 3000) of mutations that "possibly affect gene regulation" are also near fixed in recent humans. These are potentially interesting because they may be related to recent behavioral or anatomical evolution of modern humans.
The paper reports on new sequencing of the Mezmaiskaya Neandertal to 0.5x coverage. This genome is substantially closer to recent humans than are the other Neandertal genomes. Presumably the population of Neandertals that accounts for present-day Neandertal genes in living people was closer to the Mezmaiskaya Neandertal than others.
The high-coverage Neandertal and Denisova sequences allow a new estimate of the amount of Neandertal and Denisovan ancestry in human populations. Neandertal ancestry of living non-Africans is now estimated between 1.5 and 2.1 percent. This is lower than previous estimates, a discrepancy that the paper does not explain.
The paper finds significant evidence for Denisovan ancestry of mainland Asian and Native American populations. The Denisovan fraction in these populations is small, only around two tenths of a percent on average, but the ancestry is spread throughout these populations into the New World.
The Denisovan ancestry of living populations of New Guinea represents a substantially different genetic background than the Denisova high-coverage genome. The divergence between the Siberian Denisovan high-coverage genome and the Denisovan intermixture with humans is greater than the divergence between any living groups of humans with each other.
We can now see that the original description of the Denisovan genome in 2010 and follow-up analyses in 2011 were based on a number of inaccurate assumptions. The current high-coverage data have added a lot of precision to some analyses, but several of the changes in this new research have actually come from the adoption of new assumptions and more refined models.
Some of the conclusions in this paper will not last long as more ancient genomes are sequenced. We have recently seen with the publication of the Sima de los Huesos mtDNA that many assumptions about the Denisova population are questionable ("The Denisova-Sima de los Huesos connection").
Why should we assume that the Denisovan ancestry includes only a single "mystery population"? The Sima de los Huesos result shows that several populations may have been in a position to mix with the ancestors of Denisovans.
Why should we assume that the Denisovans were a single population? The genetic differences among "Denisovan" groups by our current definition were greater than those between any two human groups today.
This current paper is noncommittal about the rate of mutations that should be applied to the ancient genomes, which leads to an uncertainty of more than a factor of two in the date estimates presented. This is unfortunate because the uncertainty prevents the DNA from shedding light on the relationships of pre-Neandertal, Neandertal and modern human fossil remains. But the uncertainty is real, as the relevant mutation rates remain a matter of debate ("A longer timescale for human evolution", "What is the human mutation rate?").
At any rate, the new genome has tremendous value for the further study of how we evolved. As I continue to study the supplements of the paper, I will be updating on several areas of interest.
Prüfer, K. et al. (2013). The complete genome sequence of a Neanderthal from the Altai Mountains. Nature (in press) doi:10.1038/nature12886
Reich, D., Green, R. E., Kircher, M., Krause, J., Patterson, N., Durand, E. Y., ... & Pääbo, S. (2010). Genetic history of an archaic hominin group from Denisova Cave in Siberia. Nature, 468(7327), 1053-1060.
Reich, D., Patterson, N., Kircher, M., Delfin, F., Nandineni, M. R., Pugach, I., ... & Stoneking, M. (2011). Denisova admixture and the first modern human dispersals into Southeast Asia and Oceania. The American Journal of Human Genetics, 89(4), 516-528.
Two things have always driven my writing online.
One is the desire to share with a broader public the exciting work that is changing the way we understand human origins. I worked very hard to find ways to do this with traditional websites during the late 1990's and early 2000's. Blogging software solved my problem: it gave me a way to write incrementally, making my notes into a way to share with everyone.
The other is my secret love of hacking. I find it so appealing to tinker with a new programming system to see how it works. I began with HTML 3 in the mid-90's, moved to CSS/HTML 4 in the early 2000's, worked with early blogging systems built on Perl scripts, experimented with database-driven stacks and transitioned to a fully MySQL-PHP-based system with Drupal. In the process I have programmed the back-end to research sites, designed three different public-facing websites and three different web systems for students.
Even though I love to tinker with the site, I wouldn't have undertaken a complete overhaul right now without some very compelling reasons.
Let me tell you, having my mom not able to get through to the server was pretty compelling.
The site has greatly increased in popularity over the last several months. Daily usage has grown by nearly 50%. Peak demand for the site has scaled even higher. Obviously my upcoming course, Human Evolution: Past and Future has driven a lot of interest, with an enrollment of more than 28,000. Last month's Rising Star Expedition also brought in many new readers. I am so pleased at the people who are finding new information about the science of paleoanthropology here! I'm even more excited that our long work preparing open science projects has begun to make a real impact on how we do paleoanthropology in the field.
Drupal 7 has been very flexible, allowing me to design a unique structure and layout for the site. But it's a memory hog. Even with advanced caching on the server, the site was not able to keep up with peak demand. As the server began to drop connections, people weren't able to get through. Even after shifting my Rising Star posts off the site, new readers looking for information about the Sima de los Huesos DNA results brought the site to a standstill.
Ironically, technology has allowed me to go back to the solution that I first implemented in 1996: plain static pages.
When I started this blog in 2004, I relied on a scripting system to take plain text files and template them as a blog. That system, Blosxom, worked extraordinarily well for me for a long time, but couldn't handle the demand of an increasingly large site. I didn't want to abandon it, but with nearly 2000 posts and a readership growing toward 3500 visits a day, I had to make a change. The next stage was a huge advance in content and performance, but left some compromises that have really started to show this year.
I've done a bit of a facelift for the site. I've taken the mobile-first layout to the next level with a theme that works seamlessly from phone browser to desktop. The sidebar is entirely gone, and I for one don't miss it.
Well, maybe I'll miss some Amazon referrals. I've put the Amazon link down at the bottom of the page, and you can still support the site with 6% of all purchases without any additional cost to you. I do rely on the funds to maintain my server, but I will be moving to a different strategy to maintain the site during the next few months.
What's not working yet?
My transition to the new system has left some strings untied.
The bibliography system will require a separate solution instead of being integrated live. For the moment older posts are missing bibliography data. As I transition to the new bibliography system I will be scripting the citations back in.
Tags and search are up and working, but both are a bit unwieldy because of the size of the archives. I'll be working to increase the value of the sitemap and curating content for use outside the site.
I have not retained the old links for tag pages, in favor of establishing a clear new organization. If you've been following tag feeds, these will not work now.
Moving the posts from the database has introduced errors in some of the content quoted from other sources -- basically, losing some smart quotes and apostrophes that were not encoded for HTML. Those glitches have a pretty low priority for me, but I'll probably fix them.
Undoubtedly some other things are broken but many, many more old problems have been fixed!
The new layout enables me to feature more of my field photography, and I'll be adding more and more graphical elements back into some of the older material. I will also be updating some of the posts that are long-term traffic magnets, evolving the site into a more useful resource for students and researchers.
The next project to unfold is the open science component of my massive open online course. One of the key pieces is a system that will send personalized reports to students, presenting their data in direct comparison with the entire course. Another piece is obviously the interviews, field footage and lectures themselves, with associated transcripts. I'll be making all that material available to the public outside the course, and that will affect this site.
Events have really moved fast for me this year. When 2013 began, I expected one of my big accomplishments would be to blog my way through Darwin's Descent of Man. Instead I found myself developing a course for 30,000 students, traveling the world to interview and visit field sites, and spending a month in the field supporting a team as they excavated one of the most significant fossil hominin sites ever discovered.
A few more surprises await in 2014.
Rising Star team advance scientist Elen Feuerriegel has another new post on the Rising Star Expedition blog, discussing her work with the collection after the close of excavations: "A Bone in Hand Is Worth Ten in a Book".
Nevertheless, between working on the RS material and the PVT fossil collection, it was easy to start drawing connections (and disconnections) between the hominins of Rising Star and the fossil material from Sterkfontein and Malapa that I may not have made had I only been dealing with these populations in the abstract.
I think this, more than anything, drove home the importance of open access to fossils for me. Allowing other researchers to study the primary specimens has the potential to reveal connections that may not have been immediately obvious. Returning to the blank slate is an important step that reduces the possibility of building on an error.
In case you wonder whether I've stopped blogging about anything else, I have been busy this week preparing the site to move to a new server and new platform. The Rising Star Expedition finally put my readership over the top of what my server could handle -- visits now number up around 14,000 per day, and peak traffic is generating slowdowns in viewing the site. Some readers have not been getting through at all, and that's not acceptable to me.
So I've been working on that, and I should have the site onto the new platform sometime before the end of the year. Much more exciting stuff is coming!
The latest entry on the Rising Star Expedition blog is a link to the National Geographic Weekend radio show, in which Lee Berger tells the story of the discovery from beginning to end. "A Voice From the Cave: Lee Berger on the NG Weekend Radio Show"
Over the course of the three-week-long Rising Star Expedition in November, Lee Berger posted individual updates by the minute on Twitter, and we had blog posts and videos almost daily, revealing chapters of the story right as they happened.
Now that the field season has wrapped theres been time to look back and see the story as a whole, from Pedro Boshoffs original commission to seek out new fossil sites in the caves of the Cradle of Humankind, to the phenomenal final tally of more than a thousand hominid fossil elements discovered and identified.
It's highly recommended!
Fascinating article in the New York Times about a new film illustrating the concept of science in art and art in science: "Engineering His Own Vermeer".
For reasons he cannot quite explain, Mr. Jenison hit upon a technological sleight of hand, using optical gadgetry that has been available for centuries, that he believed could have aided the work of the old master painters particularly Johannes Vermeer, the 17th-century Dutchman with a startling talent for photorealistic work.
Finding no literature that he felt proved or disproved his thesis, Mr. Jenison determined he had only one course of action: use his discoveries to recreate a Vermeer work, despite his lack of painting experience.
Mr. Jenisons four-year journey to produce his own version of The Music Lesson is chronicled in Tims Vermeer, a documentary film that Sony Pictures Classics will open in limited release on Dec. 6, and that was created by the illusionist duo of Penn & Teller.
These theories about Vermeer and other old masters have been around for a long time, as the article makes clear, with some dispute. I hope the documentary comes to Madison!
I direct your attention to a new paper by Mattias Meyer and colleagues describing a mitochondrial DNA sequence from Sima de los Huesos, Spain (Meyer et al. 2013). It is super awesomely cool work, and I can't wait for the further development as they attempt to get more DNA sequence data from the Sima sample. The recovery of cave bear DNA earlier this year from Sima presaged the current paper, and it seems we are now in a time where we can expect more results from Middle Pleistocene human remains. Very, very good.
Still, there seems to be a widespread confusion about the current result, which shows the Sima mtDNA sequence to be on the same clade as the mtDNA sequences from Denisova, Russia.
I mean, take a look at the quotes from these news articles:
In the New York Times story by Carl Zimmer ("At 400,000 Years, Oldest Human DNA Yet Found Raises New Mysteries"):
Dr. Meyer is hopeful that he and his colleagues will be able to get more DNA from the Spanish fossil, as well as other fossils from the site, to help solve the puzzle they have now stumbled across. Its extremely hard to make sense of, Dr. Meyer said. We still are a bit lost here.
From Ewen Callaway's Nature news article ("Hominin DNA baffles experts"):
Even Pääbo admits that he was befuddled by his teams latest discovery. My hope is, of course, eventually we will not bring turmoil but clarity to this world, he says.
I sort of understand the confusion.
For more than a hundred years, scientists have been drawing straight lines connecting different fossils, to try to understand the human family tree. Those straight lines always diverged over time, leading toward increasing specialization and extinction of fossil groups. And for more than twenty-five years, geneticists have been assuming that the lines connecting the genealogy of mtDNA should be the same as the lines connecting the fossils. When those lines were different, geneticists have been happy to toss the fossils out of the human family tree, content to accept the story that the fossil people had become too specialized, too peripheral to be ancestors of today's people.
But the last five years have made clear that both groups -- the fossil scientists drawing straight lines of diverging fossil populations, and the geneticists drawing straight lines of diverging -- were wrong.
Just look at the evidence. Humans today descend in part from Neandertals, even though Neandertal mtDNA is gone. Europeans today are largely different from the Europeans of 10,000 years ago, with a massive mtDNA replacement along with the introduction of Neolithic culture, and at least a second later large-scale replacement of genetic diversity. Earlier Neandertals in Europe have different mtDNA diversity than later Neandertals in Europe. Denisova cave was home to an earlier population of hominins with different mtDNA than the later Neandertals who lived there. Mitochondrial DNA has never been a straight line linking earlier and later populations within a single location. Whenever we look at ancient DNA in hominins, the earlier populations have different mtDNA diversity than the later ones. Moreover, wherever we have ancient mtDNA from other species -- bison, mammoths, cave bears, and others -- we find that later mtDNA sequences do not represent the earlier diversity. The Sima cave bear mtDNA is a direct example of this, but the same phenomenon has happened again and again.
The fossil evidence, we now know, is no different. Paleoanthropologists have widely assumed that the Sima de los Huesos hominins are ancestors of Neandertals. That's a straight line.
There are essentially two reasons for this assumption. One is that Neandertals need ancestors, and the Sima sample seems to be in the right place at the right time---300,000 years ago or more, in western Europe.
The other reason is a bit more substantial: the Sima sample exhibits a number of features that are shared with Neandertals but not African fossil humans, and are rare in recent humans. So the sample is not only at the right place and the right time, it sort of looks the part of incipient Neandertals. Jean-Jacques Hublin and others have described this idea as an "accretion" of Neandertal features in European populations over time. Go back far enough in Europe---say, to the Gran Dolina sample---and you don't see fossils with Neandertal features. As you proceed forward through the Middle Pleistocene, you start seeing more similarity to Neandertals. Scientists fitted this data to a straight line, projecting a gradual divergence of the European population away from other human populations, eventually becoming Neandertals.
However, over the last few years, neither of these straight-line reasons has been looking especially good. First, the mtDNA landscape of Neandertals has shifted our knowledge of their population dynamics. Dalen and colleagues (2012) showed that later Neandertals do not have the same diversity as earlier Neandertals in western Europe, and that central Asian Neandertals have more diversity than European ones. From this perspective, the evolution of Neandertals looks less and less like a European phenomenon. Instead, Europe may have been invaded repeatedly by Neandertal populations that were much more numerous elsewhere, such as western or central Asia. I developed that idea last year (Hawks 2012), but in fact it is an old idea going back to the 1950s or earlier.
Now that we know that the last 100,000 years of Neandertal evolution was complex and not centered in western Europe, I don't see why we should assume a straight line between Sima de los Huesos at more than 300,000 years ago and later Neandertals.
Second, the Denisova discoveries have made it clear that other populations existed outside the current visibility of our fossil and archaeological evidence. Why should we assume that these populations looked different from Neandertals? The reality is that we know essentially nothing about the morphology of West or Central Asian hominins of 300,000 years ago. South Asia and Southeast Asia were likewise inhabited throughout this period but we have only the barest hints about the morphology of their inhabitants. These peoples existed just inside the range of archaeological visibility but we lack any but the most rudimentary fossil evidence of them.
To be sure, many people have been assuming that the Denisovans were some kind of East Asian population, for example in China or Southeast Asia. In the process, they have projected the characteristics of the Asian fossil record upon them. That idea has been supported by the existence of Neandertals to the west, and also the sharing of some Denisovan similarity in the genomes of living Australians and Melanesians.
But that's a big assumption. Let's explore an alternative: that the Denisovans we know are in part descendants of an earlier stratum of the western Eurasian population. Although they are on the same mtDNA clade, the difference between Sima and Denisova sequences is about as large as the difference between Neandertal and living human sequences. It would not be fair to say that Denisova and Sima represent a single population, any more than that Neandertals and living people do. But they could share a heritage within the Middle Pleistocene of western Eurasia, deriving their mtDNA from this earlier population.
We know that the Denisovan nuclear genome is much closer to Neandertals than the Denisovan mtDNA. We are still waiting for the long-rumored publication of the idea that Denisovan genomes have a "mystery hominin" element in their ancestry. They could be a mixture of any number of earlier populations. None of these have to be East Asian, and as yet we have no suggestion that this "earlier" element of Denisovan ancestry could be as ancient as the first known habitation of Eurasia, as much as 1.8 million years ago. Maybe the Sima hominins represent this "mystery hominin" population.
Maybe the Denisovans were west Asian Neandertals. It does seem like known genetics of Neandertals may represent something like an earlier iteration of the origin of modern humans -- more African than earlier hominins like the Sima sample, less influenced by Eurasian mixture than the Denisova genome, only a subset of the diversity of surrounding contemporaries. But we have no idea what the Neandertals of the Levant or southwest Asia may have been like genetically -- maybe they were more like Denisovans. This is all basically speculation, which indicates how little we still understand about the dynamics of these populations.
They were complicated. Their relationships cannot be described by drawing straight lines between fossil samples. There were multiple lines of influence among them, small degrees of mixture and large-scale migrations. Europe was far from a slowly evolving population "accreting" Neandertal features over time. The Neandertals we know did not lumber into their doom; they expanded rapidly, multiple times, from non-European origins. They were as dynamic as the Middle Stone Age Africans who would later mix with them and expand across the world.
So I don't find the Sima mtDNA to be the least bit surprising. It's refreshing!
Dabney, J. et al. Complete mitochondrial genome sequence of a Middle Pleistocene cave bear reconstructed from ultrashort DNA fragments. Proc. Natl Acad. Sci. USA 110, 1575815763 (2013)
Meyer, M. et al. A mitochondrial genome sequence of a hominin from Sima de los Huesos. Nature (2013) doi:10.1038/nature12788.
Hawks, John (2012) Dynamics of genetic and morphological variability within Neandertals. Journal of Anthropological Sciences 90:81-87.
Malapa showed that a concerted system of exploration could discover important new hominin fossil sites, where no one had noticed them previously. The story about how Lee used Google Earth followed by systematic ground survey to identify sites has by now become famous. But the implications have not been widely absorbed.
The Rising Star Expedition resulted from a similar deliberate survey. Lee employed geologist and caver Pedro Boshoff to explore known cave systems looking for undescribed fossil deposits. In the Rising Star system, Pedro found a slot that he couldnt fit through, so he enlisted Rick Hunter and Steve Tucker, two experienced cavers with the right physique to navigate what we now call the Chute. The discovery followed from cooperating with experts with very different skill sets, bringing them together to explore.
I highly recommend the post by one of our advance cavers, Rick Hunter: "The Journey Into Darkness:.
Deceptively it opens up into large chamber where the only hope of passage is a vortex where only the smallest of brave souls could dare enter. Blocked by a steady and stubborn, unrelenting stone gatekeeper who is the only one that decides who may pass and who may only plot its demise. Once into this tunnel where simple claustrophobia seems a pleasant alternative, there is still the mammoth task of inching your body through this tiny gun-barrel. Dust and unforgiving stone carry on for what seems to never end, then you suddenly stop and view a road block that once hung from the ceiling as a pendulum.
These cavers have been heroic, serving long shifts underground to keep our advance scientists safe.
In the process of clearing the Puzzle Box, Alia and I excavate a critical section of frontal bone that can begin to reveal the face of the ancient hominids in this chamber. Our hands shake visibly as we painstakingly remove it from the ground and I finally hold it up to the camera for Lee to see. Theres a moment of breathless suspense as he looks at the camera and finally seems to register what hes seeing. When his delighted exclamation of Wow! finally comes over the coms, its the cue for everyone to breathe out. The fossil is beautifully preserved. Its exactly what we needed to start making some sense of this site.
Were ecstatic. I know I can hardly contain my excitement long enough to pass off the fossil to Alia for recording and packing to take to the surface.
This is a great piece, giving her perspective through the cave system. If you're following the expedition from a classroom, it's the one to get your students reading!
I tackle questions about the dating of the site, the context, the fossil collection so far, and most importantly, how we are proceeding with an open science strategy with the excavation:
Aren't you afraid that other scientists will scoop your results? The most important implication of open access is the change in the scientific culture. When you have a culture of secrecy, you breed people who trade in secrets. When you have a culture of openness, you must train people in responsible sharing. Our team and the curatorial practices at the University of the Witwatersrand will facilitate collaboration and sharing of datasets, and we expect the field will embrace these open standards.
Here's a photo of the caver's tent and Science tent, now humming with activity as we process and catalog the fossils:
I've been posting Venus pictures the last couple of months as it rises in the evening sky. I swear I had no idea I'd be working on an excavation called "Rising Star" when I started this. But last night's sky was exceptionally appropriate:
I just love the work of the National Geographic blogger Andrew Howley and the filmmakers onsite. This video shows the two cavers who discovered the advance chamber and gives an incredible viewpoint of their work inside the cave: "First Look Inside the Fossil Cave (Expedition Update)"
My first Rising Star Expedition update has been posted on the expedition blog: "In the hot seat".
Ive had an extraordinary number of new fossils pass through my hands in the last four days. But heres what finally brought me to tears: Our young scientists and cavers running up to the command center, cranking up the generator, so they could do a spontaneous Skype call to a third grade class in Rhode Island.
The post has already gotten some attention, and if you're looking for a good news story on yesterday's events at the site, I recommend this one from Alan Boyle: "Cave women unearth skull of unknown human ancestor". Yes, the headline is awful for these young scientists, but the story really gives a good overview of what is going on.
But of course the best source is the Rising Star Expedition blog, and the Twitter updates from @johnhawks and @LeeRBerger.
For the past five days, I've been cataloguing dozens of fossils from the Rising Star site. The National Geographic Rising Star Expedition blog has some incredible video shorts from the site, and some short blog posts describing what is coming out. Here's one: "See First Fossil Recovered from Cave (Expedition Update)".
We are experimenting with many different ways of sharing what we are doing here. Both Lee Berger and I are live-tweeting the excavation as it goes on; the cavers and scientists have done Skype sessions with schools; we have the exceptional coverage from the National Geographic bloggers; and we are immediately releasing lots of info on what we are finding. Even the team was recruited with social media.
Shortly I will start blogging about our progress here. Many of those posts will be cross-posted with National Geographic. Initially I will link to them from here, later I'll cross-post them. We have good internet here but if anything happens with my server I may not be able to fix it quickly, so I'll be updating first to NatGeo.
UPDATE (2013-11-15): The NatGeo blog has been reorganized and has a new address. Correct link above and: http://newswatch.nationalgeographic.com/blog/rising-star-expedition/
Jerry Coyne has a guest post by Andrew Berry recognizing the history of Alfred Russel Wallace, co-innovator of the concept of natural selection: "A guest post for Wallace Day".
The reasons for Wallaces relative obscurity are many and complex but its worth noting two things. It started early: his eclipse by Darwin is not solely a function of hindsights preference for one over the other. During the years after the publication of On the Origin of Species, when Darwin was at the height of his powers and Wallace was scientifically at his most productive, it was Darwin, and Darwin alone, who was co-identified in the public eye with the theory of evolution. A survey of contemporary cartoons and caricatures lampooning the idea reveals a plethora of Darwin-themed (or Darwin-apeing) images, and nonezerothat feature Wallace.
Second, Wallace himself was partially responsible for this. His wonderful account of his 8 years in Southeast Asia, The Malay Archipelago, which recounts what he did and what he saw in some considerable detail (a contemporary review in The Atlantic Monthly put it a little unkindly, Mr. Wallace apparently exhausts a very copious diary in the production of his book, and seems almost to have made it a point of conscience not to leave anything out), does not mention, even in passing, the events surrounding his evolutionary discoveries. In The Malay Archipelago Wallace refers repeatedly to the idea of natural selection, but always calls it Mr. Darwins theory. There is something pathologically modest about Wallace.
Anthropologists often note the importance of Wallace. During the decade following Darwin's publication of the Origin, Darwin himself was publicly silent about the implications of his theory for understanding humans. During this time, Wallace took the fore, delivering public lectures and publishing on the importance of natural selection as applied to people. Wallace unfortunately disagreed strongly with Darwin's perspective on human evolution. Wallace argued that natural selection had ceased affecting humans in any important way very long ago, and that the divergence of the present races of humans must go very far back in time -- as far as the Eocene. This was not an outlandish view relative to the physical anthropologists of the day. But it laid the groundwork for a scientific polygenism -- the idea that human races have long separate origins. Darwin by contrast was a fervent monogenist, and believed that natural selection has been operating in the recent past to generate human differences.
Wallace would soften to some extent in his interpretation of human evolution, but retained throughout his life a conviction that natural selection by itself was not sufficient to explain many of the qualities of humans today.
I will be flying to South Africa on Friday to take (an exceedingly small) part in a unique excavation just getting started in the Cradle of Humankind World Heritage Site, the "Rising Star Expedition". The name refers to a new cave site, where a recovery excavation project is just starting under the direction of Lee Berger. The University of the Witwatersrand has a story about the expedition: "Rising Star Expedition launched".
The key challenge is that the new site is in the cave structure of the Cradle and is about 30 metres underground, with a very small opening through which only persons with a bust size of 18cm and less can fit.
This compelled Berger to call on his community of Facebook, Twitter and LinkedIn friends to help him find tiny and small, specialised cavers and spelunkers with excellent archaeological, palaeontological and excavation skills.
Within days Berger had a list of 57 qualified candidates, of which six scientists were selected to participate in the excavation, all of them women.
Obviously my bust size doesn't qualify, and compared to the select group going inside the cave, my role is pretty minor! I will be hoping to update from the field, and as the project goes forward I anticipate some really interesting news.