Anthropology.net

Bipedalism has graced our blog several times before, but we’ve mostly stuck to using comparative anatomy to explain the how’s and why’s to our unique way of movement. There’s new research coming from the Kennedy Krieger Institute that gives us a window into the adaptations and specific requirements the brain has made to accommodate bipedalism.

Specifically, after subjugating people to a whole lot of different experiments on treadmills with fancy infared computerized tracking, Amy Bastian observed that people can learn and,

“store different walking patterns for forward versus backward walking simultaneously, with no interference between the two, revealing that separate brain systems control the two directions of walking….”

This lead her to conclude that,

“there are separate adaptable networks controlling each leg and there are also separate networks controlling leg movements, e.g., forward or backward walking. These findings are contrary to the currently accepted theory that leg movements and adaptations are directed by a single control circuit in the brain.”

Her work is published in Nature Neuroscience, and I’ll forewarn you that this paper doesn’t have an anthropological scope as much as it has a clinical, rehabilitation one. Bastian aims to use this research to help people recover from strokes, hemispherectomies, and other forms of brain damage. But how this research supplements physical anthropology is pretty remarkable.

This paper gives us examples of how a pattern of pattern of changes in independent neural controllers for left and right legs can be rewired. That tells us the human brain is very modular and malleable. I feel that being able to reroute the neural networks involved in controlling movement is testament to the adaptive capacity of the brain. And I wonder if similar studies can be done with chimps, considering they have been working out on treadmills recently? I wonder how hardwired other primates are to their form of motility?

I hate to be bugging you with these half-assed side notes, but the PNAS paper that I’ve been swooning over the last couple of days is now out.

Here are the good bits: Dental evidence on the hominin dispersals during the Pleistocene,

“A common assumption in the evolutionary scenario of the first Eurasian hominin populations is that they all had an African origin. This assumption also seems to apply for the Early and Middle Pleistocene populations, whose presence in Europe has been largely explained by a discontinuous flow of African emigrant waves. Only recently, some voices have speculated about the possibility of Asia being a center of speciation. However, no hard evidence has been presented to support this hypothesis. We present evidence from the most complete and up-to-date analysis of the hominin permanent dentition from Africa and Eurasia. The results show important morphological differences between the hominins found in both continents during the Pleistocene, suggesting that their evolutionary courses were relatively independent. We propose that the genetic impact of Asia in the colonization of Europe during the Early and Middle Pleistocene was stronger than that of Africa.”

You’d think this would be good news to me. But it is actually really unfortunate for me, because my school’s library hasn’t updated access to this hot off the press paper, so I can’t download the full text just yet. Unless someone wants to graciously email it to me. I’ll be very grateful if you do, and will read and review it thoroughly plus share some of the good photos up here. Nevermind, I got it, and am reading it right now!

Since I’ve expressed interest in the drama that is unfolding about Lucy’s tour, I got passed a link to a Guardian article which writes on the topic and has a very poignant quote criticism from Louise Leakey,

“If [Lucy] has to be displayed it should only be in Ethiopia, [so] that the country draws some benefit from it.”

Guys, Louise gets it.

Ethiopia will benefit very little from the tour.

It really bugs me that all the press is toting phrases that lending out Lucy will generate money for musueum building in Ethiopia, as if the US museums are doing Ethiopia a favor… When really the case is that the museums in the US will be raking in the cash, and Ethiopia will be risking one of the most important hominid fossils out there.

So to say that I see the this move by the ‘hosting’ museums as hegemonic, is an understatement.

I’ve got sort of a time machine of an article that will get you to ask yourself, “Boy, how times have changed anthropology… or have they?” I read the transcribed 1941 article, and wonder how we view Asian ‘races’ any different now in 2007? Be sure to digg this too.

This is basically the whole article, but it is my favorite excerpt,

“U.S. citizens have been demonstrating a distressing ignorance on the delicate question of how to tell a Chinese from a Jap. Innocent victims in cities all over the country are many of the 75,000 U.S. Chinese, whose homeland is our stanch ally. So serious were the consequences threatened, that the Chinese consulates last week prepared to tag their nationals with identification buttons. To dispel some of this confusion, LIFE here adduces a rule-of-thumb from the anthropometric conformations that distinguish friendly Chinese from enemy alien Japs.

To physical anthropologists, devoted debunkers of race myths, the difference between Chinese and Japs is measurable in millimeters. Both are related to the Eskimo and North American Indian. The modern Jap is the descendant of Mongoloids who invaded the Japanese archipelago back in the mists of prehistory, and of the native aborigines who possessed the islands before them. Physical anthropology, in consequence, finds Japs and Chinese as closely related as Germans and English. It can, however, set apart the special types of each national group.

The typical Northern Chinese, represented by Ong Wen-hao, Chungking’s Minister of Economic Affairs (left, above), is relatively tall and slenderly built. His complexion is parchment yellow, his face long and delicately boned, his nose more finely bridged. Representative of the Japanese people as a whole is Premier and General Hideki Tojo (left, below), who betrays aboriginal antecedents in a squat, long-torsoed build, a broader, more massively boned head and face, flat, often pug, nose, yellow-ocher skin and heavier beard. From this average type, aristocratic Japs, who claim kinship to the Imperial Household, diverge sharply. They are proud to approximate the patrician lines of the Northern Chinese.”

Okay, so I’ve got kinda sorta a good news/bad news situation. The good news, more informative news is coming out about the big fossil tooth study that I shared with’ya last night. National Geographic is covering it better than anyone else, so until the publication comes out (tomorrow, hopefully — and that’s the bad news), all we got is what they have to share.

First and foremost, the sample size of this study is pretty remarkable. 5,000 teeth were studied. The analysis started way back from 2 mya Australopithecines to modern Homo and each tooth was scrutinized to over 50 different measurements and observations.

Paraphrased from National Geographic, what they found is that European teeth were more similar to Asian teeth than they were to African teeth. They conclude that Europe’s first early human colonizers were from Asia, not Africa. I’ve asked this before, why teeth? I’ll answer it again, the shape of the teeth offered clues about each species’ genetic lineages because teeth change shape very little once they are formed, and their shape is strongly influenced by genetics.

Lead author, Marcos Martinón-Torres, commented on these results,

“This finding does not necessarily imply that there was not genetic flow between continents… Just because people had come out of Africa didn’t mean that they couldn’t turn around and go back again.”

I think a much more safe conclusion to make is that it appears as if the current fossil record of hominid teeth is showing us that human ancestors spread in many directions before arriving in Europe. I wonder if and how does the genetic, archaeological, and linguistic evidence supplement this?

Here is a set of some of the human evolution publications that Martinón-Torres has been a part of:

• An Early Pleistocene hominin mandible from Atapuerca-TD6, Spain
• Paleobiology and comparative morphology of a late Neandertal sample from El Sidrón, Asturias, Spain
• Rates of anterior tooth wear in Middle Pleistocene hominins from Sima de los Huesos (Sierra de Atapuerca, Spain)

Way back in October of 2006, I and other anthro-bloggers covered the debacle that surrounds Lucy’s trip to the United States. To most of us, it sounded awesome at first. It gave most of us a chance to see the actual fossils, as well as a way to support Ethiopian museums. Then as we began to assess the circumstance, especially the risk for the fossils to be damaged, we began to second guess our enthusiasm.While I was in Ethiopia, I got a chance to see the boxes that held Lucy’s remains be packed and readied for shipment over at the National Museum. The overall consensus in the museum was a bit somber.It seems like Ethiopians outside of their country and others in the United States are a bit more ticked off than somber about the whole situation. BBC News is covering a short little blurb where they quote, Zelalem Assefa, a Ethiopian academic who works at the Smithsonian Institution, saying,

“These are original, irreplaceable materials. These are things you don’t gamble with.”

After almost a year after I reported Lucy’s travel plans, I noticed it has almost always been me sharing my opinion or quotes of professional paleoanthropologists stating how they think about this. I want to hear from you, so I’ll open this thread up and ask what your opinion is on the matter? Will you try and see Lucy in New York, Denver, and/or Colorado?

This hat tip goes out to Razib, who just broke the news of a soon to come out publication which analyzes human fossil teeth. The findings suggest that ‘Asian populations played a larger role than Africans in colonizing Europe millions of years ago’… so we’re still on a multiregional hypothesis kick as far as human evolution goes, and this one seems to be pretty bold.

Why did they study teeth? Because the,

“tooth fossil record of modern man’s ancestors [has a] high component of genetic expression. (Huh? What does that really mean?)

The investigators examined the shapes of more than 5,000 teeth from human ancestors from Africa, Asia and Europe dating back millions of years.

They found that European teeth had more Asian features than African ones.

They also noted that the continuity of the Eurasian dental pattern from the Early Pleistocene until the appearance of Upper Pleistocene Neanderthals suggests that the evolutionary courses of the Eurasian and African continents were relatively independent for a long period.

“The history of human populations in Eurasia may not have been the result of a few high-impact replacement waves of dispersals from Africa, but a much more complex puzzle of dispersals and contacts among populations within and outside continents,” the researchers wrote, as reported by AFP.

“In the light of these results, we propose that Asia has played an important role in the colonization of Europe, and that future studies on this issue are obliged to pay serious attention to the ‘unknown’ continent.”

The paper will be published in PNAS. I’ll do my best to keep my eyes out, it seems like it will be an interesting read.

After yesterday’s post, I’ve become curious and began digging up some more on Erik Trinkaus’ claims of hybridization of humans and Neandertals. I came across an article he published in 2003 where he rexamined Eyasi 1,

a later Middle Pleistocene east African neurocranium, reveals the presence of a suite of midoccipital features, including a modest nuchal torus that is limited to the middle half of the bone, the absence of an external occipital protuberance, and a distinct transversely oval suprainiac fossa. These features, and especially the suprainiac fossa, were considered to be uniquely derived for the European and western Asian Neandertals. These observations therefore indicate that these features are not limited to Neandertal lineage specimens, and should be assessed in terms of frequency distributions among later archaic humans.      

I’ve bolded the second to last sentence of the abstract because the suprainiac fossa is the same feature that Trinkaus has honed in on with the Cioclovina crania. And he drew the same conclusions from it! His Eyasi 1 paper has two crappy photos of the crania, where I can’t quite distinguish the suprainiac fossa as Neandertal like, and unfortunately there aren’t many photographs of Eyasi 1 online for me to show to you. What I could find is a cartoon of the cranial anatomy of a Neandertal:

Without any other pictures than the drawing above to illustrate my point, you’re gonna have to imagine that the suprainiac fossa, a groove above the inion in the back of the skull is considerably more robust or pronounced in Neandertals and less so in modern humans. So when one comes across a human with a pronounced suprainiac fossa, are we to assume its hybridization? What I also wonder, is Trinkaus looking high and low in the fossil record for evidence that fits his theory?

After reading the article that Razib linked up earlier this week and also Tim’s introduction to this specific topic, I had a feeling we’d hear more on the Neandertal interbreeding debate. So I’m not completely surprised to read that Erik Trinkaus is back at it at it again, suggesting that Neandertals became absorbed into Homo sapiens.

He and several other colleagues just published in the August issue of Current Anthropology, this paper, “The Human Cranium from the Pesceditera Cioclovina Uscat, Romania.” I have the PDF if anyone wants it.

They argue that they see mosaicism in the remains of a Homo sapiens skull. There is a,

“groove at the base of the back of the skull, just above the neck muscle, that is ubiquitous in Neandertal specimens but has never been seen in the remains of a modern human.”

Furthermore,

“the skull supports interpretations of other remains found in France, Romania, and the Czech Republic that also have “archaic” or unusual features suggesting interbreeding.”

I don’t know what to think of all of this. Trinkaus has been at this for sometime, last year he published on this hypothesis of his right about the time the sequence data from the Neandertal genome project started to come out. I reviewed the paper, in my post, An introduction to and anatomical evidence supporting Neandertal introgression (Part 1). Personally, even though the genetic evidence is overwhelming, I can’t rule out the theory of human-Neandertal interbreeding. It sure coulda been a possibility.

But what the nuclear and mitochondrial evidence shows us is that hybridization didn’t happen. And this fossil nor the Pestera Muierii crania don’t do a good enough job convincing me… just as probable as it is that Neandertal features developed due to interbreeding is the possibility that Neadertal features in H. sapiens came about due to genetic drift and/or variation.

More publications that may interest you:

• Andrei Soficaru, Adrian Dobos, and Erik Trinkaus. 2006. Early modern humans from the Pestera Muierii, Baia de Fier, Romania. Proceedings of the National Academy of Science 103:17196-17201.
• Patrick D. Evans, Nitzan Mekel-Bobrov, Eric J. Vallender, Richard R. Hudson, and Bruce T. Lahn. 2006. Evidence that the adaptive allele of the brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo lineage. Proceedings of the National Academy of Science Early Edition, Proceedings of the National Academy of Science 10.1073/pnas.0606966103 (open access).

I’ve harvested a photo of a 20,000 year-old footprint from the appendix of a report linked up by Nature’s Newsblog. This footprint is one of many tracks left by humans in the Willandra Lakes region of Australia… there are actually over 700 of them!

From the Nature News blog,

“Steve Webb of Bond University presented here some findings about the Ice Age footprints in the Willandra Lakes area of southeastern Australia. This is a World Heritage site with the biggest collection of fossil footprints — more than 700 of them! — anywhere in the world. They show aboriginal children, teenagers, and adults walking around in what was once a wetland swamp but now is a dried-up lakebed.

Some sets of trackways appear to be converging, as if people were running toward the same point – could it have been a race? In another spot, Webb and his colleagues spent a long time pondering a strange mark which involved a footprint and another sort of hole-like depression. Their conclusion: A one-legged person was helping himself or herself along with a stick.

See some of the pictures of this vanished world in the appendix of the paper available online here.”