Anthropology.net

About two weeks ago, I blogged on how variation mtDNA was used to reconstruct an idea of Pleistocene population growth. That study was very remarkable because illuminated a large 5 fold increase in South Asian populations about 50,000 years ago. But we haven’t been able to use polymorphisms in autosomal loci to the same. A new paper in Molecular Biology and Evolution tries to figure out a way to overcome this limitation, by testing to see whether or not mitochondrial and Y chromosomal DNA show similarities in the spread of polymorphisms in populations that have experienced a recent increase in effective population size.

The paper, “Contrasting Signatures of Population Growth for Mitochondrial DNA and Y Chromosomes among Human Populations in Africa,” honed in a large sequence from the Y-chromosome and the cytochrome c gene in the mtDNA from 172 males from 5 African populations. Four different statistical tests were applied to test for population expansion: Fu’s Fs statistic, the R2 statistic, coalescent simulations, and the mismatch distribution.

The authors find,

“…Patterns of mtDNA polymorphism better fit a model of constant population size for food-gathering populations and a model of population expansion for food-producing populations. In contrast, none of the tests reveal evidence of Y chromosome growth for either food-gatherers or food-producers. The distinct mtDNA and Y chromosome polymorphism patterns most likely reflect sex-biased demographic processes in the recent history of African populations. We hypothesize that males experienced smaller effective population sizes and/or lower rates of migration during the Bantu expansion, which occurred over the last 5,000 years.”

Pilkington, M.M., Wilder, J.A., Mendez, F.L., Cox, M.P., Woerner, A., Angui, T., Kingan, S., Mobasher, Z., Batini, C., Destro-Bisol, G., Soodyall, H., Strassmann, B.I., Hammer, M.F. (2008). Contrasting Signatures of Population Growth for Mitochondrial DNA and Y Chromosomes among Human Populations in Africa. Molecular Biology and Evolution, 25(3), 517-525. DOI: 10.1093/molbev/msm279

The creative PNAS study that Razib pointed out the other day is out, and I’ve read it. It comes from two biologists at Stanford, Deborah Rogers and Paul Ehrlich, who studied the canoe design of 10 Polynesian groups and one Fijian group for functionality and symbolism. The paper, “Natural selection and cultural rates of change,” is open access, so please download a copy and read what the authors have to say first hand. They decided on these Oceanic cultures because they were colonized by one cultural group that radiated and became relatively isolated from one another. In other words, little outside influence, or noise, from other cultures has theoretically impacted Oceanic canoe design.

They find that functionality (traits that affect whether or not the occupants of the canoe will survive or not) changes very little, whereas symbolism in canoe design (such as aesthetic, spiritual, and decorative) changes much faster. From this observation, they conclude that “cultural change, like genetic evolution, can follow theoretically derived patterns,” and that natural selection is the driving force behind the evolution of cultural traits. The authors rationalize boats are being selected naturally through a quote from the French philosopher Alain,

“Every boat is copied from another boat… Let’s reason as follows in the manner of Darwin. It is clear that a very badly made boat will end up at the bottom after one or two voyages and thus never be copied… One could then say, with complete rigor, that it is the sea herself who fashions the boats, choosing those which function and destroying the others.”

This quote doesn’t make much sense to me. It sure is a simplified analogy… one that is supposed to help us digest and reduce… But I’m left a bit confused on how the authors found evidence of natural selection out observing intelligent boat design. Unlike boat designers, who learn and modify boat design based upon past experiences, natural selection does not operat with conscious understanding of trial and error. Natural selection in nature is independent. Boat design is not independent. Boat designers can go study past designs, learn from their mistakes, and make modifications… So is not functional boat design just selection?

That’s one flaw I see in this paper, one that I haven’t really completely thought out. I do appreciate how the authors are one of the first, in my knowledge, to attempt to integrate how ‘cultural things’, such as items that serve a life or death purpose in everyday life, have a functional constraint. Often we’re taught that ‘cultural things’ are arbitrary but we know we want our things to work, and we’ve will always design them to work better.

I’ll leave you with words from, Nina Jablonski, an anthropologist that I really respect and whose work I appreciate immensely. She christened this paper as, “one of the most significant papers to be written in anthropology in the last 20 years.” Man, that’s a pretty amazing endorsement to have, but just cause Jablonski casted her vote doesn’t mean I’m sold, nor does this make it into the trophy cabinet for classical anthropology papers.

Rogers, D.S., Ehrlich, P.R. (2008). Natural selection and cultural rates of change. Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0711802105

So you probably just saw the new post, the one announcing an upcoming linguistic conference on a possible link between the Yeniseic and Na-Dene language families. Well, I, Kambiz Kamrani, did not publish that post. It was actually authored by Alex Greengaard, who’s a new blogger here at Anthropology.net. Usually, I introduce new contributors to Anthropology.net prior to their first post, but I’ve been really sick and been out of commission for the last 5 days. That’s why I haven’t posted until today. I extend my apologies to you all and Alex for dropping the ball.

I’m sure you wanna know more about Alex. He’s a recent graduate of the University of Arizona, and specialized in Linguistic Anthropology. He’s got close ties to Jane Hill and Lyle Campbell. He now teaches social sciences at La Paloma Academy in Tuscon, Arizona. His anthropological interests shouldn’t be surprising, given that he did focus on linguistic anthropology. Nonetheless, here’s some of them:

• The linguistic varieties of English
• Sound change in Polynesian languages
• Language and astronomy in Africa
• Assimilation codeswitching and obsolescence in music
• Dialects in theatre

He’s also a musician, a swimmer, a cycler, a illustrator and actor.

I welcome Alex to our blog, I really appreciate that he’s made the effort to contact me, show interest in volunteering, and following through by posting his first post regardless of my absentminded neglect to introduce him. Again, I’m sorry. I’m sure you all will appreciate him too, until now, the anthropology blogosphere did not really have an active front in linguistics.

Following up on recent discussion of the peopling of the Americas, The University of Alaska at Fairbanks is hosting a conference about the possible link between Siberian (Yeniseic) and Na-Dene language families. The conference, titled Dene-Yeniseic Symposium, will be held on February 26, 27 and 29, 2008, and will feature a lecture from Edward Vajda, Professor of Modern and Classical Languages and Director for the Center for East Asian Studies at Western Washington University. Vajda will be discussing several linguistic parameters connecting the Siberian and Na-Dene families and providing new insights to the question of the origin of human presence in the Americas.

All known Yeniseic languages seem to be related at a time depth of about 2,500 years. The large number of cognates between them permits the reconstruction of much basic vocabulary, suggesting a proto-language spoken by mobile bands of hunter-gatherer-fishers in the boreal forests of northern Inner Asia.

The reconstruction of proto-languages by way of the comparative method has always been an excellent support to migration theories. Comparison with recent biological and archaeological studies should turn some interesting conversation. When Vajda publishes, it should stir up some controversy in the anthropology community as a whole.

The American Association for the Advancement of Science just wrapped up its annual meeting yesterday and the press is releasing a lot of summaries on what was presented. Of interest to anthropology are these four postulates, presented by Marc Hauser, the factors that differentiate human cognition.

Before I jump into this, I wanna review that in the past we thought episodic memory, non-linguistic mathematical ability,  the capacity to navigate using landmarks, and our ability to make and use tools were all unique human traits. But they’ve all been documented behaviors in other animals.
That being said, Marc Hauser present what he considers four unique human traits,

1. The ability to combine and recombine different types of information and knowledge in order to gain new understanding.
2. Apply the same “rule” or solution to one problem to a different and new situation.
3. To create and easily understand symbolic representations of computation and sensory input.
4. To detach modes of thought from raw sensory and perceptual input.

Hauser comments that these four unique cognitive traits,

“may have opened up other avenues of evolution that other animals have not exploited, and this evolution of the brain is the foundation upon which cultural evolution has been built.”

Unfortunately, the press release doesn’t indicate that Hauser presented his hypothesis with any data, and I believe that’s why they’re being labeled as postulates, assumptions without proof as a basis for reasoning. Given that we’ve debunked other behaviors once thought to be unique human traits, how do you feel about Hauser’s four? For example, have you ever seen other animals recombine other information to solve new problems, or understand symbolism?

The Neolithic revolution is a really important transition in human prehistory, one that is identified by an increase in technology. During this time people became skilled agriculturalists, adopted more sedentary lifestyles that revolved around more complex, structured city-state societies.

Not every area of the world experienced the Neolithic at the same time. It is believed that the Neolithic revolution began about 12,000 years ago in Levant, a region of the world we know now as the area occupied by Syria, Lebanon, Israel, and Jordan. As the Neolithic lifestyle radiated, we see it emerge in large settlements like, Çatalhöyük in Anatolia (modern day Turkey), by 10,000 years ago. After this moment, the Neolithic rapidly spread into Europe and Asia.

But, for some odd reason, the Neolithic isn’t seen in Africa until much later, about 4,500 years ago. It really doesn’t make sense that we haven’t seen the Neolithic earlier in Africa, given the fact that the Neolithic originated in the Near East which is in close proximity to Africa. Furthermore, the Neolithic is also seen to begin in the Americas at about 4,500 years ago!

A new discovery in Sudan, “the oldest proof of human sacrifice in Africa,” pushes back the date of the Neolithic in Africa to at least 5,500 years ago,

“The tomb of a 5,500-year-old man surrounded by three sacrificed humans, two dogs and exquisite ceramics were exhumed north of Khartoum by Neolithic expert Jacques Reinhold and his 66-year-old Austrian wife.

“This is the oldest proof of human sacrifice in Sudan, in Egypt, in Africa,” Reinhold told reporters next to the remains in El Kadada village, a three-hour drive north of the Sudanese capital.

“I don’t know of another example in Africa at this level… We don’t have anything as strong in other excavations in other countries,” said Reinhold.”

Reinhold also reported on finding “urns, materials used to grind wheat into flour, beeds and bracelets” at the El Kadada site. Tim, of Remote Central, also covered this news too.

To supplement last September’s conclusion that the peopling of the Americas was initiated by a pretty diverse group of people who camped out in Beringia for a long time, long enough to differentiate from their Asian sister-clades, comes this study published in this week’s PLoS One, “A Three-Stage Colonization Model for the Peopling of the Americas.”

The new study offers up perhaps the largest published alignments of Native American mtDNA, spanning all Native American haplogroups. Over 77 full mitochondrial coding genomes were constructed from 812 concatenated mtDNA hypervariable region (HVR) I and II sequences. They took these mitochondrial genomes, aligned them up, and applied the same algorithims, Bayesian skyline plotting, used in a recent paper to estimate prehistoric population sizes. Bayesian skyline plots are a unique approach to the coalescent modeling, that assume a single migration event, and thus test the generally agreed consensus that there was a single migration of people in the Americas.

The dominant model on the peopling of Americas started with the the ice sheets advancing and sea levels falling about 17,000 years ago. It is during this time that people are thought to first migrate across the Eurasian landmass and into the Americas. It was thought that a very small number of people, maybe even as small as 70 or so, who crossed over. Perhaps they were nomadic hunters, following game herds from Siberia across what is today the Bering Strait into Alaska, and then gradually spreading southward. Based upon the distribution of Amerind languages and language families, a movement of tribes along the Rocky Mountain foothills and eastward across the Great Plains to the Atlantic seaboard is assumed to have occurred some 10,000 years ago.

What this new study found doesn’t indicate that the peopling of the Americas happened in one fell swoop. Rather, it supplements the paper I mentioned above, “Beringian Standstill and Spread of Native American Founders,” and offers up an interesting time frame, a three stage colonization event that is effectively illustrated by the authors. I’ve cut out the figure the authors provided, it’s to your left. The first stage began about 40,000 years ago with a gradual ancestral population expansion of people from an East Central Asian gene pool into Beringia. The second stage of ‘proto-American Indians’ was marked by almost no population growth for about 20,000 years, which confirms the previous Beringian standstill conclusion. The last stage started about 16,000 years ago with a massive rush of people, about 5,000 strong, fleeing out of Beringia and into the “ice free, inland corridor between the eastern Laurentide and western Cordilleran Ice Sheets and/or along the Pacific coast.” This challenges the n=70 founding population estimation.

The authors offer up no discussion about a possibility of bidirectional gene flow, which was shown in the September 2007 Beringian Standstill study that I keep referring too. I’m thinking its cause the skyline plots test for single migration events and not backflows.

Either way, it is a very enlightening study especially because other models, such as the Clovis archaeological model, which says the peopling of the Americas happened in 11,000 years, estimate really rapid colonization events. That’s awfully fast. Pushing back first rush of people to 16,000 years ago can help us better explain how the Clovis culture radiated so fast.

Kitchen, A., Miyamoto, M.M., Mulligan, C.J., Harpending, H. (2008). A Three-Stage Colonization Model for the Peopling of the Americas. PLoS ONE, 3(2), e1596. DOI: 10.1371/journal.pone.0001596

The latest and 34th edition of this anthropology blog carnival is brought to us by Our Cultural World, with a slight emphasis this time round on Linguistic Anthropology; there are plenty of other contributions as well, so be sure to head on over and check it all out.

Archaeoporn will be hosting the next Four Stone Hearth on February 27th.

The Pygmy hunter–gatherers of central Africa are an amalgamation of various groups of people that are on average about 4 feet tall. Some genetic and linguistic evidence point to them being direct descendants of hunter-gatherers from the late Stone Age. But that’s about it, there’s not much archaeological evidence to corroborate with this observation.

Most modern day Pygmy populations live in the rain forest alongside Bantu-speaking farmers. It is one of the few places in the world were we see cohabitation of hunter-gatherers with farmers. These two groups have very different lifestyles and a new multidisciplinary study sought to determine to what extent social, cultural and demographic factors have influenced the genetic heritage of these two populations.

The open access paper, “Maternal traces of deep common ancestry and asymmetric gene flow between Pygmy hunter–gatherers and Bantu-speaking farmers,” is published in PNAS. The authors analyzed the variation in mtDNA of 1,404 individuals from 20 Bantu farming populations and 9 Pygmy populations. They were able to identify a sing ancestral and indigenous lineage of mtDNA that was formerly shared by Pygmies and Bantu people. The Pygmy lineage diverged from the ancestral population about 70,000 years ago, at which point they began to be isolated and when the short phenotype began to differentiate. Pygmy variability is much more weak compared to the variability observed in Bantu populations which tells us that modern Pygmies came from a small common ancestor population.

And since they were comparing mtDNA, starting 40,000 years ago, the researchers were able to identify that female Pygmies were reproducing with Bantu males. Subsequently, the mtDNA gene pool of the Pygmies was not enriched by external gene influxes. The Bantu farmer gene pool, however, was enriched during the so-called “Bantu expansions”, an event corresponding to technological, demographic and linguistic advances in the late Stone Age.

The authors write that they wanna expand their study to Y-chromosomal relationships between these two groups and also to study the relationships between the genome and the populations’ vulnerability or resistance to pathogens. Why do they wanna do this? Well, as Razib has written often, the transition into sedentary lifestyle is often accompanied with a shakeup on populations, pathogens, and selection.

Quintana-Murci, L., Quach, H., Harmant, C., Luca, F., Massonnet, B., Patin, E., Sica, L., Mouguiama-Daouda, P., Comas, D., Tzur, S., Balanovsky, O., Kidd, K.K., Kidd, J.R., van der Veen, L., Hombert, J., Gessain, A., Verdu, P., Froment, A., Bahuchet, S., Heyer, E., Dausset, J., Salas, A., Behar, D.M. (2008). Maternal traces of deep common ancestry and asymmetric gene flow between Pygmy hunter-gatherers and Bantu-speaking farmers. Proceedings of the National Academy of Sciences, 105(5), 1596-1601. DOI: 10.1073/pnas.0711467105

The Nazca or Nasca culture is one that fascinates me, especially the massive line art and the mysterious headless burials that are associated with them. The culture flourished before the Inca, for almost 1,100 years, alongside the Moche culture in what is now northern Peru. One of the hallmarks of their society are the intricate underground aqueduct system that still functions.

A recent discovery of a 2,000-year-old mine hematite mine, is documented as being a product of Nasca culture. Hematite is the mineral form of Iron III oxide. Oxidized iron, as you may know, rusts and produces a red color. The discovery is lead by Kevin J. Vaughn, an anthropologist at Purdue University, who published his study in the Journal of the Minerals, Metals & Materials Society. In the paper, “Hematite mining in the ancient Americas: Mina Primavera, A 2,000 year old Peruvian mine,” he and his team write that they think that the Nasca mind the red-pigmented mineral primarily for ceramic paints.

According to Vaughn et al. the mine was hand dug and yielded about 3,710 metric tons or 8,179,066 pounds of ore over about 1,400 years of use! If the pigments on Nascan clay pottery match those produced from this mine, we’ll have a great understanding on about complexity of Nascan culture.

Vaughn, K.J., Grados, M.L., Eerkens, J.W., Edwards, M.J. (2007). Hematite mining in the ancient Americas: Mina Primavera, A 2,000 year old Peruvian mine. JOM, 59(12), 16-20. DOI: 10.1007/s11837-007-0145-x