Anthropology.net

That’s what Timothy Weaver, Charles Roseman and Chris Stringer, asked in a Journal of Human Evolution paper titled, “Were neandertal and modern human cranial differences produced by natural selection or genetic drift?“

It is an interesting question to ask because if you’ve ever spent some time looking at a Neandertal skull and compared it to a modern human’s skull, you probably asked yourself, why the hell are most features in the Neandertal skull so robust? What made it that way? And, if you haven’t had the pleasure of holding and comparing these two heads, no worries… Please use the following image plucked from the article, to ask yourself those questions. On your left is a cast of a Neandertal from La Ferrassie, France and to your right is a modern human skull from Polynesia:

Now, Stringer, Weaver, and Roseman wanted to see if they can explain these differences due to some evolutionary method. They specifically wanted to see if the differences can be attributed due to genetic drift or due to natural selection. But you maybe asking yourself what is the difference between genetic drift and natural selection? I sometimes confuse the definitions, so forgive me if I’m being redundant by sharing with you some common evolutionary theory.

Genetic drift, in the most basic definition is just the probability an allele shows up in a population. The effect of the drift may cause an allele and the biological trait that it confers to become more common or more rare over successive generations. Ultimately, the drift may either remove the allele from the gene pool or remove all other alleles. So that being said, genetic drift is the fundamental tendency of any allele to vary randomly in frequency over time due to statistical variation alone.

It differs from natural selection, because natural selection in the most basic definition is when beneficial alleles become more common over time because they boost the survivability of the organisms and  reciprocally detrimental alleles become less common.

But genetic drift and natural selection aren’t mutually exclusive. In other words, both forces are always at play in a population. However, the degree to which alleles are affected by drift and selection varies according to circumstances such as population size. In a large population, where genetic drift occurs very slowly, a weak selection on an allele will push its frequency upwards or downwards (depending on whether the allele is beneficial or harmful). However, if the population is very small, drift will predominate. In this case, weak selective effects may not be seen at all as the small changes in frequency they would produce are overshadowed by drift.

Before we get deeper into evolutionary theory, I want share with you the answer to the million dollar question asked in the title of the paper, ‘Were neandertal and modern human cranial differences produced by natural selection or genetic drift?’ No, Stringer and crew can’t explain human and Neandertal cranial differences with either evolutionary forces at this time… natural selection can not be supported nor can genetic drift by their measurements and calculations.  Instead, what they conclude is that the differences can be explained as manifestations of only two outcomes pooled from a vast space of random evolutionary possibilities. Which leads me into what Razib brings up. He mentions that,

“[he does] know that human bone structure and teeth have become less robust over the last 10,000 years, perhaps due to agriculture. This might simply be relaxing the selection for more robust physiques.”

Agriculture and other aspects of culture and technology can and does skew defining whether natural selection or genetic drift played a role on our bodies. For example, if one calculated and concluded that Mayan skull modifications were actually due to genetic drift and totally ignored or glanced over modifications being a cultural preference, then a incorrect conclusion would be made. Many cultures select for certain traits in skulls and bodies, which throws a big stick in the wheels of determining the evolutionary force in play. I feel that culture has been a large determining factor in deciding whether or not modern humans had more gracile skulls than robust ones. Take a second and ask yourself how our modern day popular culture is selecting for bodies?

So if I’m right, and culture has a big role, then I don’t know of any statistical method that could discern the effect of culture on traits in the skull. But, I’m thinking that one way where Stringer et al. or someone else can reproduce this work but also integrate measurements from other members of Homo, like H. heidelbergensis or archaic H. sapiens, like Homo sapiens idaltu to see whether or not gracility was selected for in the H. sapiens lineage or if it was a random? It’s a matter of simply expanding the sample size and type… maybe more can be derived or maybe more will be confused.

From time to time, I like to take a moment to ask myself, “Why do I blog?”

I think this is a good time for me to be doing one of these type posts because as most bloggers know, after returning from a hiatus, it is hard to get back into the swing of things. Often you have to remind yourself you are doing this for such and such reasons to the point that it becomes a mantra again. Only when I fall back into the rigors of reading and writing for the blog, do I stop needing to ask and tell myself why I blog.

Jonathan Gitlin‘s post over at his Arstechnica blog Noble Intent reminds me of one of the reasons why I blog, the need to communicate science to the larger public. Far too frequently have I heard the argument from my non-science friends and family that scientists have created a big communication gap between themselves and the rest of the world. I listened to what they said and decided to pick up arms, fight the good fight, and help bring anthropology to the masses. So, to say that I totally agree with Gitlin’s argument that science is inundated with,

“too much use of jargon, and far too many research papers are downright painful to read. All of this puts a barrier between their research and those who want to know what it all means, and that’s bad both for scientists and society at large,”

is a bit of an understatement.

And that’s part of the reason as to why I blog. I know I wanna be in academia in some form or another for the rest of my life, and since I see the discord in communication between science and the rest of the world growing, I feel there’s a strong need to fill that gap. I decided to blog because I knew the rest of my life would be dedicated to reading and writing in some form or another. Also, I don’t consider my writing skills really top notch, so I continue to see and use blogging as an opportunity to spice up my style and structure.

But I digress… In the past, and present, science journalism has been filling the communication gap. Science journalists are trained writers and they have all the tricks under their sleeves to not only pick and choose the new hotness in science but also to translate it. News sources like National Geographic News and EurekAlert are a couple of the science journalist sources that I use to bring new papers and publications to me. I also use them so I can read and understand the gist of a paper before I decide to devote some time to seriously spending time to read and comprehend the first hand account. But as Gitlin points out, I too see that science journalism is becoming as shoddy as the latter form of communication that it tries to translate.

This is where I see blogging intervene. During the two plus year that I’ve been running this site, I’ve seen more and more academics approach blogging as a form of media and news. Even the academics that don’t yet have blogs have directly contacted me because of this blog or better yet commented back to posts I’ve written to clarify or criticize my thoughts on their papers. This is an awesome and remarkable change. I feel like we are seeing a change to the publish and perish mentality that has plagued academia for sometime. A commenter, Norton, to Gitlin’s post writes,

“Publish or perish actually works to make scientists worse at communicating — more more precisely, frequently makes them do it poorly.”

But with an online reputation to track and trace, academics can now easily see how the public feels about their research.

With all that said, I hope more and more scientists and researcher turn to blogging as a form of communication and discussion… especially anthropologists. I know most of ya anthrophiles out there have computers and the internets, but am bewildered as to why we have such a small representation out here on the web.

Anthropology and the internet is like a match made in Heaven, seriously. And, I’m not being entirely naive here… take for example the Hadzabe dilemma that’s been circulating around the anthro-blogosphere. This is a case-in-point situation where blogging is helping facilitate discussion and exchange ideas on how to confront a serious issue facing cultural anthropology and ethnoarchaeology. Already, in our circle of five or so blogs, we have started brainstorming up things to do and drafting up letters of protest to help out the Hadza. I’m pretty sure that this hasn’t been how things we done 10 years ago, and I’m even more sure that this will be more dynamic and fluid in 10 years time… and we’ve got blogging to thank for that!

In late May, I shared with you a paper that introduced us to the hypothesis of bipedalism originating in Orangutans. I thought it was a rather foolish hypothesis to make considering the wealth of comparative anatomical and physiological research done with chimpanzee to human gaits. Chimpanzees have more similar anatomy to us than Orangutans and Gorillas, and they walk bipedally a bit more than Gorillas and Orangutans. I was surprised that Science published it despite these well established facts.

Now, a new paper published in PNAS last week vindicates some of my concerns from the above publication. It is tilted, “Chimpanzee Locomotor Energetics and the Origin of Human Bipedalism” and comes from Herman Pontzer, from Washington University in St. Louis who collaborated with several other colleagues in studying energetics and biomecanics of adult chimpanzees and humans, using treadmills. A similar publication was conducted in 1973, but it was flawed in that it used juvenile chimps, which have a different gait compared to their adults. So this study is significant because it retests the same experiments done before, but under new conditions.

The team also took their analysis a step further, from EurekAlert,

“[they] also examined the early hominin fossil record, which they found to include predicted changes consistent with lower energy cost- longer hind legs compared to body mass and structural changes to the pelvic bone allowing for more upright walking.

Analysis of these features in early fossil hominins, coupled with with analysis of bipedal walking in chimpanzees, indicate that bipedalism in early, ape-like hominins could indeed have been less costly than quadrupedal knucklewalking.”

I’ve plucked one of the more enlightening figures from the PNAS paper, which clearly shows how human bipedalism exerts less tension than the chimpanzee form of bipedalism.

So, I consider this study more analytical than the several orangutans that swayed back and forth in trees. To end this post, if you aren’t convinced on what I’ve been arguing for then the following video should surely convince you:

I don’t know why this is the way it is, but linguistic anthropology seems to make it into my RSS headlines far less than any other sub discipline within anthropology. It is a very active field, with a lot of interesting research available for us to digest and learn from.  So I don’t know why it isn’t all over the press and in our blogs… but maybe I can help change that.

New news has come out about the work of a multidisciplinary team of linguists and scientists at the Santa Fe Institute in New Mexico. I’m hoping it may spark some discussion amongst us. Paraphrased from this USA Today article, these people are working toward finding and reconstructing the mother of all languages.

“Headed by Nobel Laureate physicist Murray Gell-Mann, the international Evolution of Human Languages (EHL) project is developing a freely accessible etymological database of the world’s languages. Where possible, EHL linguists are attempting to reconstruct – and then compare – ancestor languages, moving ever closer to the first human language. Viewed by many linguists as a fringe movement, the project has attracted much criticism. Many linguists say that historical languages cannot be studied beyond an 8,000-year threshold; they change too much, they say. Some take issue with the project’s methods: A few words shared among reconstructed languages doesn’t prove a familial relationship, they insist, especially far back in time.”

I’ve bolded what I consider the heavy hitting clauses. Many languages are organized and categorized by the similarities they have with other languages. This shouldn’t be news to you… I hope we all understand that Latin based languages, like Spanish, Italian, and French share more in common than Spanish to Mandarin.

But what the paragraph addresses is that the rate of change in language is pretty phenomenal. Almost too rapid, dynamic, and organic to track effectively. Don’t believe me? Well, take Ebonics for example. This is a form of speaking derived from English. While the exact date Ebonics originated from haven’t been identified, some say it came from Pigdin during the slave trades in the 16th to 19th centuries, many of us recognize Ebonics fully catalyzed after the emergence of hip-hop and other subcultures in the late 1970′s and 80′s. Whatever the date it originated, many non-Ebonics speaking English speakers cannot understand Ebonics. It has come about far too quickly for culture to adapt too. To them it is like another language… so how can one say languages are related when they are by nature so prone to change?

The EHL has devised a way to discern relations between languages despite the overwhelming amount of change,

“Within languages, linguists think that because certain words – including the pronoun “we” and the number “one” – form the basis of a functional language, they are much less likely to change or be lost. EHL linguists begin by comparing this “basic lexicon.” They include “words that are thoroughly essential and must have been in human language before significant cultural advances were made,” writes EHL team member George Starostin, a linguist at the Russian State University for the Humanities in Moscow, in an e-mail.

Using this method, EHL has grouped all the world’s languages into 12 linguistic superfamilies. They’ve tentatively grouped four of these superfamilies, which include languages of Eurasia, North Africa, and some Pacific islands (and maybe languages of the Americas as well) into one super-superfamily dubbed “Borean.” An ancestor to a large share of today’s languages, Borean was spoken some 16,000 years ago when glaciers covered much of Europe and North America, they say.

EHL linguists use several methods. One – the most controversial, but not the most widely used, says Starostin – involves matching words and meanings across languages. For example, Ruhlen and Bengtson have noticed that a word roughly corresponding to “water,” which they render in proto-sapiens as “AQWA,” appears in many languages. In Latin it’s “aqua”; in Japanese, “aka” means “bilge water”; in Chechen, meanwhile, “aq” means “to suck”; in an African Kung dialect, “kau” means “to rain”; and in Central American Yucatec, “uk” means “to be thirsty.”

Genetic evidence indicates we originated from a population of humans no larger than 1,000 or so in number about 60,000 years ago. And so, the further one moves back in time, the EHL hypothesizes the more related languages should resemble one another… This small founding population may explain how the capacity for language spread so quickly.

The methodology the EHL has deployed has fired up a lot of debates, many say that it is far too common to find words that are similar to one another across languages, and that the EHL is too,

“loose with meanings and sounds, they say. And too many alternate explanations exist: Maybe the word was borrowed from one language and spread to the others. Perhaps it’s onomatopoetic, a word that sounds like what it is. (“Cock-a-doodle-doo” is an onomatopoetic word that appears in similar form in many languages, but that doesn’t prove relation.) Finally, the shorter the word – in some of the languages, just one syllable rather than two or three – the greater the possibility of a chance match.”

But I can’t think of any other way to study language relations and evolution. Can you?

Regardless of their methodology, I think what the EHL is doing is noble and very astute. Just as important as it is for us to identify the genes, archaeology, and fossils that ‘made us human,’ it is equally important to figure out the roots of our language — one of the primary forms of communication and expressions in humans.

I have a podcast I found thru Dr. Hsien-Hsien Lei‘s blog, which actually came originally from Marc Pelletier of Futures in Biotech, that I wanna share withya. The podcast is fairly long, its about 45 minutes long.

Marc interviewed Dr. Svante Pääbo, Director of the Department of Genetics at the Max Planck Institute for Evolutionary Anthropology, and Dr. Thomas Jarvie, Technical Application Manager at 454 Life Sciences, on ancient DNA and the Neandertal Genome Project. Marc discusses with Drs. Pääbo and Jarvie the limitations and benefits of sequencing ancient DNA, such as its heavy fragmentation, and how 454′s sequencing technology is more logical than enzymatic amplification and other methods, such as bacterial cloning.

If this is a topic that interests you, you maybe interested to hear directly from the scientists in charge about what’s going on with their research.

[odeo=http://odeo.com/audio/14453223/view]

UPDATE: I just came across an Ars Technica discussion on evolving tools for ancient DNA, which also discusses the caveats to working with fragments of genomes.

I was actually in Ethiopia when I heard on the national radio of Dr. Yohannes Haile-Selassie‘s new 3.8 million to 3.5 million years ago hominid mandible. I remember it was hot that day, about 116 degrees Fahrenheit or about 47 degrees Celsius, when I heard the news. I was pining over the heat and this news and once it registered in my mind, I was giddy. In fact the entire field team was giddy.

Why?

Well, this mandible is an important specimen because it falls right between Australopithecus anamensis which lived about 4.2 million to 3.9 million years ago, and Australopithecus afarensis—the species to which Lucy belonged—thrived from 3.6 million to 3 million years ago, but it doesn’t quite resemble either. Some paleoanthropologists think that Lucy and others of her species were descendants of A. anamensis—and these new Ethiopian jawbones could end that speculation. Dr. Haile-Selassie told National Geographic News,

“This will help us test this very hypothesis and see if we can falsify it or prove it… We have had isolated teeth and [other skeleton parts] from previous years. What we didn’t have was a complete jaw, which we have now.”

On my last day in Ethiopia, I did get a chance to say hello to Dr. Haile-Selassie and introduce myself but our conversation unfortunately didn’t turn into a chance to really sit down to discuss his findings. Come to think of it, I doubt he would spill all his beans to me since we just met. Regardless, he’s not ready to make any hasty conclusions about the relationship between A. anamensis and A. afarensis. He told National Geographic News,

“Two years down the line we may be able to say something about it.”

So we’re gonna have to sit tight and wait until Dr. Haile-Selassie finishes his research. Until then, I do have this photo of the mandible for us to study and drool over:

UPDATE: I’ve just been reading the site’s backlog and realized Tim has covered this news pretty well. Here’s a link to his post on this news.

The ongoing plight of the Hadzabe in Tanzania has caught the attention of the British mainstream press, in the guise of this article from the Daily Mail, on whose behalf Andrew Malone has filed a report. Although many readers of these pages will already be familiar with this story, it’s important to keep it in the public eye, hence this post.

After a four-day quest covering thousands of miles by light aircraft, Land Rover and, finally, on foot, we knew we were on the brink of an unforgettable experience — the chance to reach back in time and meet our living human ancestors from countless millennia ago. We waited in silence.

Suddenly, shadows of human forms started moving around the bush. The noise of sing-song voices floated towards us. Here, in one of the world’s last untouched wildernesses — the dense bush south of Africa’s Rift Valley where the first humans emerged upright more than two million years ago — a group of men from the mysterious Stone Age tribe were ready to make their introductions.

Draped in animal skins and carrying arrows tipped with poison, two slim, wiry characters walked slowly towards us in the clearing. Time has stood still for these men — two of an estimated 400 remaining survivors of the Hadzabe tribe — whose way of life has scarcely changed since human evolution began.

Malony makes the somewhat ironic point that the Hadza are one of the last hunter-gatherer societies on Earth, and they just happen to live in a part of the world from where some of the earliest traces of our archaic ancestors have been found – the Palaeolithic starts and ends there, so to speak. He describes an encounter with a Hadza tribesman named Gonga… Read the rest of this entry »

My field season in Ethiopia has ended, and it was very successful. I want to share with you a lot more than I’m able to write at the moment, so you’re gonna hafta sit tight until I summarize all my experiences into a more thorough post.

In the meantime, you can busy yourself with the photos I’ve uploaded onto my Flickr account. Please check them out and tell me what you think of them. Here are some of my personal favorites:

I want to thank everyone for helping me out with keeping the site updated and very active, but a special thank you goes out to Tim and Carl who kept posts active and moderated comments.

Here’s a brief report from New Scientist, discussing research by Markus Pfenninger and Klaus Schwenk, of the Goethe-Universitat in Frankfurt, Germany, who have been engaged in a project which aims to ‘barcode’ every living organism on the planet.

Cryptic species – animals that appear identical but are genetically quite distinct – may be much more widespread than previously thought. The findings could have major implications in areas ranging from biodiversity estimates and wildlife management, to our understanding of infectious diseases and evolution.

Scientists had previously speculated that cryptic species were predominantly found in insects and reptiles, and were more likely to occur in tropical rather than temperate regions (see Trends in Ecology and Evolution, vol 22, p 148).

“Species that are seemingly widespread and abundant could in reality be many different cryptic species that have low populations and are highly endangered,” says Pfenninger. Until the genetic information of all species in at least one taxon is thoroughly studied, no one will know just how many cryptic species exist. “It could be as high as 30%,” Pfenninger says. Read the rest of this entry »

One of the realities of humans travelling to Mars is the need to confine as many people as possible into the smallest possible craft, obliged to enjoy or endure each others’ company for months at a time – and to that end, many experiments will be carried out here on Earth, in which it is hoped that problems and frictions that could arise can be spotted here, with possible solutions being found that would help avoid or forestall such concerns on a live mission, before it even blasts off…

More than four-and-a half thousand people have applied to take part in a joint Russian-European venture in which six people will be locked inside a mock spacecraft for 520 days to simulate an expedition to Mars.

Russia’s space agency is sifting through piles of applications from would-be astronauts, including Britons, prepared to suffer extreme privation to test endurance levels for a Mars odyssey.

Successful candidates will be locked inside a cramped barrel-shaped spacecraft in central Moscow for a year and a half: 250 days to Mars, followed by a month on the surface, and 240 days to get back. The craft comprises tiny modules – a claustrophobic 550 cubic metres in total that aims to replicate the psychological pressures of an arduous long-distance space voyage. Read the rest of this entry »