Anthropology.net

Yesterday evening I attended the American Museum of Natural History’s SciCafe with guest speaker Nina Jablonski. She gave a talk about the evolution of skin. If you are a follower of this blog, you would know the genetics of skin color is one of my favorite topics. It has been a while since I have kept up with the research, but I do remember most of the major alleles. Suffice to say, it was a pleasure to be back in the midst of it all.

The talk was engaging. Many people got a chance to ask questions. This was an outstanding feature of this format in this sort of venue. Most lectures I’ve been to leave such pressed time for questions that only 2-3 get fired away. That often leaves patrons at a loss. But SciCafe did it well, offering a good hour or so of discussion.

Nina’s talk is a good segway into some news that I came across today. As we know blond hair is a phenotype and carried by at least one a recessive allele in European populations. But many Oceanic peoples also have blonde hair, specifically those from Melanesia — distinct from Polynesia and Micronesia.

Melanesian Blond Hair

In a new Science paper, researchers identified a new missense mutation in TYRP1 in about half of the blondes in Micronesia which was not found in any of the 900 other individuals sampled from outside the South Pacific. This novel blond mutation in Solomon Islanders is thought to have popped up around 10,000 years ago. Furthermore, it appears to be the same one behind blondness in Fiji and other regions of the South Pacific.

Nina Jablonski eluded to the evolution of lighter phenotypes, like light skin occurring at least twice in the evolution of Homo sapiens and at least once in Homo neanderthalensis. But light skin need not be light hair, which is often a misconception. Research like this shows us that in dark-skinned people, one base pair mismatch leads to light hair.

Kenny, E., Timpson, N., Sikora, M., Yee, M., Moreno-Estrada, A., Eng, C., Huntsman, S., Burchard, E., Stoneking, M., Bustamante, C., & Myles, S. (2012). Melanesian Blond Hair Is Caused by an Amino Acid Change in TYRP1 Science, 336 (6081), 554-554 DOI: 10.1126/science.1217849

In 2010 the draft genome for Neandertals was released by Svante Pääbo and colleagues. It was reported that European and Asian populations are between 1-4% Neandertal—but what percentage Neandertal are you?

Researcher extracts DNA from a Neandertal specimen

The company known as 23andMe recently released an analysis that claims to answer precisely this question. While personal genome sequencing has not yet hit the mainstream market, 23andMe looks at SNPs, or variations in single nucleotide pairs. Through a comparison between your SNPs and those found in the Neandertal genome draft, for a couple hundred dollars you will be given a percentage. The service has been given the name “Neanderthal Ancestry Estimator.”

Computational biologist Eric Durand developed the project, and has previously worked on both the Neandertal genome draft and Denisova genetics.

I encourage you to take a look at an outline of the methodology, online in a white paper. Are we really at the point where a private company can tell us a likely percentage of our Neandertal ancestry for $207? I’ll let you be the judge.

By Matthew Magnani

Last week at the Royal Society in London, research was presented suggesting that Neandertals not only interbred with H. sapiens sapiens, but that their genes were helpful to modern people moving out of Africa.

This pioneering study was led by Peter Parham of Stanford University, and was only possible after the draft genome of H. neanderthalensis was published. The researchers looked at human leukocyte antigens (HLAs), genes important to the functioning of the immune system.

Different regions of the world are known to have unique HLAs, because different variations create specific disease resistances. It would have been advantageous for the earliest modern humans to breed with a species (or subspecies) already adapted to living in a different climate. Moderns could have picked up helpful genes that were already in existence from Neandertal populations, which would have possibly allowed their populations to expand more rapidly. Why wait for random mutation when you can interbreed with a people already successfully adapted to an area?

Neandertal Child Reconstruction

While only approximately 6% of the modern European genome was contributed from earlier hominins, around half of specific HLAs can be attributed to these earlier forms of people. As a form of further substantiation, Europeans have HLA variations present within the Neandertal genome not found in Africans. Interestingly, Asian populations today also have a variation not present anywhere else, which could indicate Denisovan (mystery Siberian hominin) admixture.

As if the draft sequence showing interbreeding was not enough last year– this study has raised the bar on the type of information we can hope to glean from looking at ancient DNA. There was a time when archaeology and anatomy were the only windows we had into our ancestral relatives. It will be exciting to see what is uncovered next.

By Matthew Magnani

Carol Ward1, William Kimbel, and Donald Johanson have published a paper in Science on the arch seen in a newly discovered fourth metatarsal of Australopithecus afarensis (AL 333-160). A lot of the popular press are publishing misleading headlines that this proves bipedalism in australopithecines. No, we’ve known they were bipedal — we just didn’t have a true idea as to what extent they were bipedal. So a find like this helps investigate the degree of bipedalism.

AL 333-160 left fourth metatarsal in dorsal, lateral, medial, plantar, and proximal views.

How does this tell us how bipedal A. afarensis were?

) Box plots of angular relations of the proximal and distal metatarsal ends to the diaphysis in chimpanzees, gorillas, humans, and AL 333-160.

If you’ve ever had the pleasure of visiting a podiatrist, you’d know flat feet are not conducive to bipedalism. The two-way arch helps support upright walking and distribute recoil force. Other great apes like, chimps and gorillas have flatter feet than us. The authors of this paper confirmed this by comparing the fourth metatarsal of chimps, gorillas, and humans to AL 333-160.

On all their comparisons, AL 333-160 fell within range of humans. There were some occasions where there’s a lot of gray area which I’ll address later. Nonetheless, to the right you can see the best comparison, in my opinion, which the comparison of the arch of the diaphysis of the bone between the two species. You can have a look at the rest of the figures here.

The problem I am seeing here is that this metatarsal is not Lucy’s (AL 288-1). AL 333 is designated to fossils from the site where the “First Family” came from and not the same  locality as AL 288. Nonetheless, they are not the same individual. Kimbel is quoted in the BBC News, saying,

“Lucy’s spine has the double curve that our own spine does,” Professor Kimbel said.

“Her hips functioned much as human hips do in providing balance to the body with each step, which in a biped of course means that you’re actually standing on only one leg at a time during striding.

“The knees likewise in Lucy’s species are drawn underneath the body such that the thighbone, or femur, angles inwards to the knees from the hip-joints – as in humans.

“And now we can say that the foot, too, joins these other anatomical regions in pointing towards a fundamentally human-like form of locomotion in this ancient human ancestor.”

This is a flawed association to make; a form of what I would call confounding bias. We don’t have Lucy’s 4th metatarsal to see what it looks like and unfortunately we don’t have the rest of the this specimens skeleton to say it looked like Lucy’s. In fact, we have very little australopithecine appendicular and skeletons other than AL 288-1 (most notable are AL 129-1 and STS 14). So how can Kimbel say that the foot joins other anatomical regions when we don’t know what the other regions really looked like?

See, the n of this sample is 1. Looking at the intervals in the figures, especially Fig 3 & 4, there a a significant amount of variation in humans and chimpanzees that overlap. Chimps aren’t bipedal but we are. So imagine you are a paleoanthropologist way in the future looking at one metatarsal of a now-current then-ancient chimpanzee way and comparing it to a humans — surely you could make the same conclusion as these three have. And herein lies the big issue with sensationalism… as is the problem often in paleoanthropology, we just don’t have many comparative samples but people want definitive conclusions.

Ward, C., Kimbel, W., & Johanson, D. (2011). Complete Fourth Metatarsal and Arches in the Foot of Australopithecus afarensis Science, 331 (6018), 750-753 DOI: 10.1126/science.1201463

Image via Wikipedia

A Homo floresiensis premolar will be drilled, and DNA extracted, according to a Nature News piece passed on by Razib, John Hawks, and Dienekes. This is not the first attempt at extracting hobbit DNA, the news article explains,

“Five years ago, two teams, one from ACAD and one from the Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany, attempted to recover DNA from another H. floresiensis tooth excavated in 2003. Both attempts failed.

Now, a team led by Christina Adler, a geneticist at ACAD, has found that standard sampling procedures could be responsible for the failure to get DNA from the hobbit and some other ancient specimens.”

I’ve been out of the loop for a couple years and have lost track on the advances made in ancient DNA studies. I do remember there was a big hub-bub regarding contamination from excavators and degradation of DNA. Maybe some of the new techniques overcomes these problems.

The lead, Adler, recently published a paper on the advances, titled, “Survival and recovery of DNA from ancient teeth and bones.” Again, I don’t have time to read it and give you a summary because I am studying for my board exams. It seems like the paper advises extracting DNA from the cementum of teeth which has way more DNA than the normal source of aDNA, dentin… But if you’re curious about ancient DNA sequencing, this should be an interesting read.

Nonetheless, it should be very interesting to see what comes from this attempt. I wish the team the best of luck and eagerly await the results.

A colleague of mine has developed a new online human fossil record, in the likes of my own database of fossils. The project is Fossilized.org and although it is in beta, it has some remarkable features already. I am particularly impressed with the phylogeny plot view, which offers a chronological color coded map of many important hominin fossils. What’s unique about this view how it helps visualize localities different hominin species lived and spread throughout the world. Here’s a sneak peak….

Fossilized Phylogeny View

Furthermore there is an interesting history of prehistory section the database, which I have never seen be done before, as well as a geochronological timescale. The latter view offers a way to visualized oxygen levels throughout prehistory. Be sure to check out Fossilized.org and poke around. If you are an educator, let your students and colleagues know about this resource.

Personally, I’ve constantly advocated for more online resources like this. To my knowledge, there isn’t one as focused on localities. So, I’m glad to see there’s another database of the human fossil record out there, especially one that offers up some new features and more complete dataset than some currently out there.

I don’t know who this is worse for, the editors & reviewers over at Nature or the authors of the article who can’t tell the difference between crocodile teeth markings and stone tool modification, nor raise the possibility. The paper, “Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia,” very confidently proclaims unambiguous evidence for,

“stone-tool-inflicted marks on bones found during recent survey work in Dikika, Ethiopia, a research area close to Gona and Bouri. On the basis of low-power microscopic and environmental scanning electron microscope observations, these bones show unambiguous stone-tool cut marks for flesh removal and percussion marks for marrow access.”

Butchered by early humans or eaten by crocodiles? Image: David DeGusta

Given that the said rib fragment, DIK-55-2, came from a prehistoric lacustrine site. These markings could have been produced by crocodiles. Crocs, if you aren’t aware of (ahem editors and publishing group) are very abundant in the Rift Valley — both currently and prehistorically. On top of that, crocs like to eat meat and scavenge. Yes its true, they are carnivores. Australopithecines were at most ominivores, with wide based teeth useful in grinding tubers and nuts. Crocs have more meat shearing, bone crushing teeth than 3.39 million year old stone tools, which there are none of at the moment.

Given that there really isn’t an archaeological record for Australopithecine tools, I’ll take a gander and say crocs like to eat meat and scavenge more effectively than A. afarensis could make and use said tools to butcher a large ungulate. They have been on this Earth for roughly 197 million years more than hominins have and they are really good at what they do… Again, probably better than a species of hominins who did not live in the Stone Age. It is just as likely (if not more) that the markings were produced by crocodiles just given the ecological context.

Now just how different at cut marks from crocodile teeth marks? David DeGusta, from Stanford University, compared and contrasted the two different markings using images from Njau and Blumenchine (2006) paper titled, “A diagnosis of crocodile feeding traces on larger mammal bone, with fossil examples from the Plio-Pleistocene Olduvai Basin, Tanzania,” to those published in the current Nature article. I’ve inserted DeGusta’s image into this post on right for your own inspection. DeGusta was also on Science Friday, discussing this possibility, with one of the article’s authors, Zeresenay Alemseged. What do you think? Do they look completely different or similar? Seriously, I am asking you to comment. I’d like to know what you see.

Personally I don’t see much of a difference. I agree that stone tools marks are more V shaped, while croc teeth are more pitted/rounded. But take this into light: tool use, especially butchery, is a very human behavioral trait. In their search to attribute this human behavior to a primitive hominin species who roamed 800,000 years earlier, to the era of Australopithecus afarensis, without considering another possible explanation, the authors and editors of Nature were somewhat foolish.

Many paleoanthropologists are in this mad rush to claim their precious find is the most human of hominins, so as to etch their name into the textbooks in rewriting human evolution, that they sometimes forget about doing thorough comparative science. And many publications are in this mad rush to publish the most human of findings, that they sometimes forget about thoroughly editing scientific works. Think that could be the case? I sure do… Why should we settle on secondary evidence for Australopithecine stone tools when none have been found yet, and when another possibility hasn’t been extensively exhausted?

McPherron, S., Alemseged, Z., Marean, C., Wynn, J., Reed, D., Geraads, D., Bobe, R., & Béarat, H. (2010). Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia Nature, 466 (7308), 857-860 DOI: 10.1038/nature09248

Ciarán Brewster, a.k.a. adhominin, just tweeted about three book reviews. The reviews, written by Robin McKie of The Observer, cover recent books on cooking and human evolution which were written by some pretty big names in anthropology:

• Catching Fire: How Cooking Made Us Human by Richard Wrangham
  Wrangham’s thesis is that the advent of cooking reduced our energy demands of actually chewing, we do have a smaller muscles of mastication, jaws and teeth. This shift diverted the energy we would be spending on the act of eating, along with eating more easily digestable nutrients, to developing massive brains. Something I didn’t know and learned in the reviews is that people who eat only on uncooked meat or veggies will slowly starve, sucks for those on the raw food diet.
• The Well-Dressed Ape: A Natural History of Myself by Hannah Holmes
  Holmes addresses the fact that human females are the only primates with enlarged breasts and discusses theories on why. She says that the large breasts allow more feeding time for infants, which kept the babies more compliant and less likely to cry, which would otherwise attract predators. Our relatively hairless skin also evolved as a direct function of predator pressure, early human ancestors needed greater surface area to cool off our skin with sweat as they ran from predators in the savannah.
• The Humans Who Went Extinct: Why Neanderthals died out and we survived by Clive Finlayson
  Finlayson discusses why and possibly how Neandertals were so easily replaced by modern humans. He argues that the harsh landscape of early Africa, about 100,000 years ago, when modern humans emerged forced them to learn new technologies and lifestyles that were, “more inventive and intelligent as they struggled for survival. European Neanderthals, untutored in the school of hard knocks, were no match for our ancestors when they met.”

These books seem to be entertaining, you should check them out if you haven’t already. Also, if you’re on Twitter and looking to follow some active anthropology minded folks, I’ve compiled what I believe to be a pretty comprehensive list of anthropology Twitterers. Check that out too, and follow it… If I’m missing anyone please let me know on Twitter or via this post’s comment thread.

October 2nd 2009 Cover of Science Magazine

There’s more than 11 citations here, but the others are associated news and media covered by Science. They’ve even dedicated a special issue to it. Very impressive thorough volume of information. Now you have a some understanding why it took so long to publish… Anyways get to reading.

News Focus

Gibbons, A. (2009). A New Kind of Ancestor: Ardipithecus Unveiled Science, 326 (5949), 36-40 DOI: 10.1126/science.326_36

Gibbons, A. (2009). Habitat for Humanity Science, 326 (5949), 40-40 DOI: 10.1126/science.326_40

Gibbons, A. (2009). The View From Afar Science, 326 (5949), 41-43 DOI: 10.1126/science.326_41

Introduction & Video

Hanson, B. (2009). Light on the Origin of Man Science, 326 (5949), 60-61 DOI: 10.1126/science.326_60a

N/A (2009). Video: The Analysis of Ardipithecus ramidus–One of the Earliest Known Hominids Science, 326 (5949), 60-60 DOI: 10.1126/science.326_60b

Research Articles

White, T., Asfaw, B., Beyene, Y., Haile-Selassie, Y., Lovejoy, C., Suwa, G., & WoldeGabriel, G. (2009). Ardipithecus ramidus and the Paleobiology of Early Hominids Science, 326 (5949), 64-64 DOI: 10.1126/science.1175802

WoldeGabriel, G., Ambrose, S., Barboni, D., Bonnefille, R., Bremond, L., Currie, B., DeGusta, D., Hart, W., Murray, A., Renne, P., Jolly-Saad, M., Stewart, K., & White, T. (2009). The Geological, Isotopic, Botanical, Invertebrate, and Lower Vertebrate Surroundings of Ardipithecus ramidus Science, 326 (5949), 65-65 DOI: 10.1126/science.1175817

Louchart, A., Wesselman, H., Blumenschine, R., Hlusko, L., Njau, J., Black, M., Asnake, M., & White, T. (2009). Taphonomic, Avian, and Small-Vertebrate Indicators of Ardipithecus ramidus Habitat Science, 326 (5949), 66-66 DOI: 10.1126/science.1175823

White, T., Ambrose, S., Suwa, G., Su, D., DeGusta, D., Bernor, R., Boisserie, J., Brunet, M., Delson, E., Frost, S., Garcia, N., Giaourtsakis, I., Haile-Selassie, Y., Howell, F., Lehmann, T., Likius, A., Pehlevan, C., Saegusa, H., Semprebon, G., Teaford, M., & Vrba, E. (2009). Macrovertebrate Paleontology and the Pliocene Habitat of Ardipithecus ramidus Science, 326 (5949), 67-67 DOI: 10.1126/science.1175822

Suwa, G., Asfaw, B., Kono, R., Kubo, D., Lovejoy, C., & White, T. (2009). The Ardipithecus ramidus Skull and Its Implications for Hominid Origins Science, 326 (5949), 68-68 DOI: 10.1126/science.1175825

Suwa, G., Kono, R., Simpson, S., Asfaw, B., Lovejoy, C., & White, T. (2009). Paleobiological Implications of the Ardipithecus ramidus Dentition Science, 326 (5949), 69-69 DOI: 10.1126/science.1175824

Lovejoy, C., Simpson, S., White, T., Asfaw, B., & Suwa, G. (2009). Careful Climbing in the Miocene: The Forelimbs of Ardipithecus ramidus and Humans Are Primitive Science, 326 (5949), 70-70 DOI: 10.1126/science.1175827

Lovejoy, C., Suwa, G., Spurlock, L., Asfaw, B., & White, T. (2009). The Pelvis and Femur of Ardipithecus ramidus: The Emergence of Upright Walking Science, 326 (5949), 71-71 DOI: 10.1126/science.1175831

Lovejoy, C., Latimer, B., Suwa, G., Asfaw, B., & White, T. (2009). Combining Prehension and Propulsion: The Foot of Ardipithecus ramidus Science, 326 (5949), 72-72 DOI: 10.1126/science.1175832

Lovejoy, C., Suwa, G., Simpson, S., Matternes, J., & White, T. (2009). The Great Divides: Ardipithecus ramidus Reveals the Postcrania of Our Last Common Ancestors with African Apes Science, 326 (5949), 73-73 DOI: 10.1126/science.1175833

Lovejoy, C. (2009). Reexamining Human Origins in Light of Ardipithecus ramidus Science, 326 (5949), 74-74 DOI: 10.1126/science.1175834

Ardipithecus ramidus

I want to be the first to break news to you that Science has published White’s contentious 4.4-million-year-old Ardipithecus ramidus! I caught news of the release on the internet. The link is not live yet, but when it is I’ll fill you in.

Owen Lovejoy is one of the authors of the paper, and he says that the fossil changes the notion that humans and chimps, our closest genetic cousins, both trace their lineage to a creature that was more like today’s chimp and we’ll have to be rewriting our text books soon. This is big folks. What this means is that our common ancestor was a bipedal forest forager and that chimps were an evolutionary offshoot.

White, the lead author, describes the fossil with flexible hands and a brain about a quarter the size of a human’s,

“We can’t say this species was a direct ancestor of modern humans, so we have to be careful. But it suggests that the direction of early hominids was away from the chimp.”

There are a lot of other implications that I won’t get into just yet, but keep checking us out from time to time as we get more!

Here are some of the press releases/news coverage that have come out since I’ve published this post:

• Kent State University Professor C. Owen Lovejoy helps unveil oldest hominid skeleton
• Fossil finds extend human story
• Before ‘Lucy,’ there was ‘Ardi’: First major analysis of early hominid published in Science
• Oldest hominid skeleton provides new evidence for human evolution
• Humanity Has a New 4.4 Million-Year-Old Baby Mama
• Ancient Skeleton May Rewrite Earliest Chapter of Human Evolution
• Fossil Skeleton From Africa Predates Lucy
• Ethiopian desert yields oldest hominid skeleton
• Ardi displaces Lucy as oldest hominid skeleton
• Fossil Primate Ardipithecus Ramidus Described (Finally)
• Oldest “Human” Skeleton Found–Disproves “Missing Link”
• ‘Ardi,’ Oldest Human Ancestor, Unveiled