Anthropology.net

Despite the fact that I’ve seen some really impactful primate related research lately, I’ve completely neglected updating Primatology.net with it. I can’t believe it has been almost three months since I’ve posted there! I should really resume posting there. Actually, I was considering putting up this following blog post over there, since it has to do with differences in neuroanatomy of the primate brain… but because these comparative studies are in the context of identifying specific architectural differences in the human brain related to language, I think posting it here is more fitting.

If you’re a reader of Neurophilosophy, you may have an idea of what research I’m referring too, the new Nature Neuroscience paper from James Rilling and team. Before I jump into this paper, “The evolution of the arcuate fasciculus revealed with comparative DTI,” please let me share another recent paper that gives some introduction about what I’m gonna talk about.

See earlier this month, Current Biology published a paper, “Communicative Signaling Activates ‘Broca’s’ Homolog in Chimpanzees,” where researchers not only confirmed that the Broca’s area as an important area of the human brain for language comprehension, but also chimpanzees have similar activity in the homologous area of their brains when communicative signals are produced or heard. The Broca’s area has long been thought to be one of the specialized functional areas of the brain for language comprehension. In fact was discovered almost 150 years ago by a physician named Pierre Paul Broca, who conducted an autopsy of patient with a speech deficit. Broca was able to determine the patient had a syphilitic lesion in the left cerebral hemisphere and identified this area as his namesake.

If you’ve heard anything about Broca’s area, it larger in the left hemisphere of the brain. Comparing activity levels between the two hemisphere, during language-related tasks, have shown the left hemisphere Broca’s area is more active. That’s due to the lateralization of the brain, which I’m sure you’ve heard of.

Anyways, the results of this study have important implications in figuring out the functional and structural differences of the human and chimpanzee brain. Why? Well, for starters, the linguistic abilities of humans have been thought to be unique to us for a while. This is a really big misconception because research on signing apes and other communicating animals, have begun to show us that we’re not alone in our abilities to symbolize information and exchange it by way of complex sound and gesture.

In order to investigate the differences of the activity between Broca’s areas in humans and related structure in chimpanzees, Taglialatela et al., put three chimpanzee subjects in PET and fMRI machines and stimulated to vocalize by putting treats just out of their reach. They then recorded the activity of the subjects would vocalize in frustration. They were able to see the very same the neuroanatomical structures associated with the production of communicative behaviors in humans, fire in chimpanzees.

Now, of course that doesn’t mean chimpanzees are gonna be reciting Shakespeare anytime soon. This leads me to the first paper I mentioned today, the one from Rilling and crew. Rilling et al., did a comparative anatomical study on the structure of arcuate fasciculus, a large white matter tract, in humans, chimpanzees and macaques. The arcuate fasciculus functions as a linker between Broca’s area and another language associated area of the brain, Wernicke’s area. The researchers used diffusion tensor imaging (DTI), a type of noninvasive medical imaging that’s a lot like MRI but it compares and contrasts the local characteristics of water diffusion within tissues.

While the arcuate fasiculus of the rhesus macaque, the chimpanzee, and the human linked up to the frontal cortex — including with Broca’s area, it was observed that the human arcuate fasiculus is much larger. It more spreads deep into the middle temporal lobe, leaving the classical Wernicke’s area. In chimps, the arcuate fasciculus made very superficial connections to the temporal cortex regions homologous to Wernicke’s area. Macaques showed a much lower extend of this integration. Rilling commented,

“We know from previous functional imaging studies that the middle temporal lobe is involved with analyzing the meanings of words. In humans, it seems the brain not only evolved larger language regions but also a network of fibers to connect those regions, which supports humans’ superior language capabilities.”

This following diagram was published in Rilling et al.’s paper and illustrates their results:

So from these two papers, the evolution of specialized language areas maybe active in both chimpanzee and human brains but as the human brain diverged from other primate counterparts, major re-wiring at the arcuate fasciculus accompanied the massive expansion of brain size. Ultimately the area that is associated with understanding word meaning, Wernicke’s area, has been strongly connected with Broca’s area.

Rilling, J.K., Glasser, M.F., Preuss, T.M., Ma, X., Zhao, T., Hu, X., Behrens, T.E. (2008). The evolution of the arcuate fasciculus revealed with comparative DTI. Nature Neuroscience DOI: 10.1038/nn2072

TAGLIALATELA, J., RUSSELL, J., SCHAEFFER, J., HOPKINS, W. (2008). Communicative Signaling Activates ‘Broca’s’ Homolog in Chimpanzees. Current Biology, 18(5), 343-348. DOI: 10.1016/j.cub.2008.01.049

The question answering (QA) research group at Carnegie Mellon University has recently released an open source version of their Ephyra Question and Answer System. The software utilizes the internet to answer linguistic questions as well as recognize syntax, word ordering, and tone, using a series of algorithms to produce the most context-appropriate and statistically correct responses. The group hopes to get feedback and evaluations from researchers, so the code is currently being made available to the public.

Ephyra retrieves answers to natural language questions from the Web and other sources. The open source version – OpenEphyra – is almost identical to the system that has been evaluated in the TREC question answering track (http://trec.nist.gov/), except that we had to exclude some 3rd party tools and code with specific hardware requirements. The result is a system that is platform-independent, easy to use, and that can be run on a standard desktop computer and evaluated on questions from the TREC 8-15 evaluations.

While possible applications of the software may span the entirety of Social and Behavioral Sciences, it appears particularly useful to Anthropology and Linguistics as a reconstruction experiment: building the necessary systems of cognition from the inside out. Understanding the subsystems of language in the context of efficiency and necessity may be a useful instrument to developing an understanding of our own language acquisition mechanisms. Furthermore, it may help us further discern differences between animal communication and modern human language.

To supplement last week’s discussion on language evolution, I stumbled upon an Indo-European language tree posted on Jonathan Beaton’s blog. Neither Jonathan nor I know where it was published, nor what data was used to construct the tree and its relationships. So it may not be completely accurate… but it is a nifty illustration.

Just cause I’m curious on how accurate the tree is, I’ve compared to Ethnologue’s report on Indo-European languages. The general trend on language relationships are accurate but many languages are left out.

Fellow blogger, Simon Greenhill of HENRY, and co-authors published a cool paper evaluating language evolution that just came out in today’s issue of Science. The premise behind the paper, “Languages Evolve in Punctuational Bursts,” is simple to follow. By comparing related versions, or homologs, of common words between the following language families: Indo-European, Bantu, and Austronesian, changes in languages can be tracked through the fate of certain words, just as mutations in key genes can tell a species’ history.

The team selected the homologous words from a Swadesh list, one of several linguistic lists of vocabulary where the words have “basic.” Swadesh lists are used is used in lexicostatistics, a way of quantitative language relatedness assessment as well as glottochronology, a method to assess and date language divergence dating. Swadesh lists were used in this study because they are changed very little over time and are rarely borrowed, making them good clues about how one language relates to another.

In my own head, I’ve built my own set of Swadesh lists and compared them to languages I’ve come across. I wish I thought about making some sort of formal study out of my observations. I guess Simon et al. beat me to the punch! Here’s a couple of examples from a cross Indo-European language family comparison that I’ve conjured up…. The words for father and mother in English, Spanish padre and madre, Farsi (Persian) pedar and madar. Despite many borrowings, English the much younger languages is much phonetically different from Latin languages in this example, and even more derived from the Farsi homologs.

Using this sort of comparative vocabulary data, Simon et al. were able to construct phylogenetic trees to show how new languages sprouted from root languages. Furthermore, applying the same mathematical models that showed that biological speciation can occur in bursts, to language to conclude that lineages with many “nodes,” or offshoots, change faster over time than language families that have few offshoots. And most of this acceleration occurs right around time the new languages separated from their ancestral lines.

I love these sorts of comparisons, especially because punctuated equilibria is fresh on my mind. As recent as last week has there been an explosion of discussion on punctuated equilibrium on Sandwalk, the Loom and Greg Laden’s blog. But anyways, I must hand it to Simon Greenhill and his coauthors who gracefully integrated an evolutionary biological concept into a linguistic anthropological scope. It really doesn’t matter whether the replicators are genes or words, the same approaches can be used to analyze the data and explain the model.

One last thing, do read Simon’s blog post describing his project and involvement as well as the Nature News coverage on the paper.

Atkinson, Q.D., Meade, A., Venditti, C., Greenhill, S.J., Pagel, M. (2008). Languages Evolve in Punctuational Bursts. Science, 319(5863), 588-588. DOI: 10.1126/science.1149683

If you don’t know already, I’m of Iranian decent. I was born in Tehran, but because of persistent socio-political instability in that region of the world, my family and I immigrated out of the country about 20 years ago. But just cause I live somewhere else doesn’t mean I’m not interested in my background. I’ve always been curious and inquisitive about my heritage. I’ve come to understand my mother’s and father’s lineage come from very different cultural backgrounds.

My mother’s family have been established Tehranians for quite sometime and because of the nature of big city life, their heritage has been mixed and lost. But if you look at members of my mother’s family, they are fair skinned and have blond hair with green or blue eyes. Often, they get mistaken for Europeans, which leads me to think they have a different heritage from my father’s side of the family. I’ve sequenced a short bit of my mtDNA and can only figure out that my maternal lineage has the haplotype H4 signature, which is very frequent in middle eastern populations, and not enough of a resolving feature to really make make any strong conclusions about where that half of me comes from.

What we know of my father’s family differs greatly. My dad’s parents hauled out of Lorestan and into Tehran. Lorestan is a western Iranian province smack dab in the Zagros Mountains. It is sometimes home to the Bakhtiari, a nomadic pastoralist group that you may have been introduced in your cultural anthropology learnings. The Bakhtiari regularly speak Luri, a language that’s classified as Indo-Iranian. Indo-Iranian languages are distinct from languages spoken by Semitic peoples, such as Arabic and Hebrew, if you want more information about this distinction check out Ethnologue.com.

Suffice to say, I got really interested to stumble upon an early online release paper from the Annals of Human Genetics, which investigates the, “Close Genetic Relationship Between Semitic-speaking and Indo-European-speaking Groups in Iran,” because it has tangents to at least half of my known heritage. Academics from the Max Planck Powerhouse of Evolutionary Anthropology and Tehran University collaborated on figuring out who the Bakhtiari are related to.

In order to carry out the study 99 people were sampled from a different province, Khuzestan, with almost 50 to 50 ratio of people from both ethnicities. The authors honed in on comparing the mtDNA HV1 sequences, eleven Y chromosome bi-allelic markers, and 9 Y-STR loci. STRs are a class of polymorphisms that, like microsatellites, consist of a repeated pattern of two or more nucleotides. The repeats are directly adjacent to each other and can range in length from 2 to 10 base pairs. They usually exist in the non-coding introns of genes.

Anyways, all these different loci show that the Iranian-Arabs share close relatedness of to the Bakhtiari as well as with neighboring geographic groups, irrespective of the language spoken. Haplogroups J2 and G are especially intriguing because they are found in really high frequencies in Bakhtiari and Iranian-Arab populations. Like I mentioned above, the Bakhtiari are a distinctly different cultural group that speak a Indo-Iranian language which does not belong to the Afro-Asiatic linguistic family that classify Semitic speaking Iranian-Arabs. Many cultural barriers have been formed to keep the Bakhtiari way of life unique, and one of them is language. So it doesn’t make sense that these two linguistically separate groups share two haplogroup signatures in such a disproportionally high frequency.

A comparison of Iranian-Arabs to other Semitic speaking groups showed that Semitic-speaking North African groups are way more distant genetically from Semitic-speaking groups from the Near East and Iran. The above illustration documents this. Haplogroup L is almost nonexistent east of Iraq, despite the fact there are Semitic speaking populations in foothills of the Zagros mountains in Iran.

Now, I said that was surprising because often language is a big barrier, as recently expressed by Razib with the Slavs as an example. In Iran however, a different situation exists. There is a lack of significant differentiation between west Asian Semitic-speaking and Indo-European-speaking groups indicates that language has not been a substantial barrier to gene flow in this part of the world. But this leads me to wonder about the origins of Iranian-Arabs, if they are genetically less similar to other Semitic speakers, doesn’t that imply they were ‘cultural converts’?

P.S., If you do read the paper, take note of the disclaimer the authors put about inscribing identity.

FOXP2 is thought to be a language gene. It is highly conserved in most mammals but in humans there are two unique mutations in the protein caused by nucleotide substitutions at positions 911 and 977 of exon 7. It is thought to be a language gene because humans who have one FOXP2 copy have speech impediments and deficiencies in orofacial movement.

Now with all the progress in sequencing the genome of Neandertals, it seems like some anthropologists and biologists from Max Planck and institutions in France and Spain got curious about finding out the whether or not Neandertals have the same two mutuations as modern humans do in their FOXP2 gene.

Their work has been published today, in Current Biology under the following title, “The Derived FOXP2 Variant of Modern Humans Was Shared with Neandertals.” Thanks to one of our readers, Hugo, who sent me this paper I’ve had a chance to read this outstanding paper. Now, if you’ve been keeping track of the Neandertal genome project, I know what you’re thinking, “What about the inconsistencies with Neandertal sequences!?!”

Well the authors, Johannes Krause and team, were very careful about this from the beginning. They made sure the two bones from El Sidrón cave in Asturias were extracted under sterile condition. They also amplified the FOXP2 gene using Neandertal specific primers. That was done so that little to no modern human genes shoulda been targeted for amplification.

After a whole lot of cycles, sequencing, and alignment, the team found out that the Neandertals carried FOXP2 that was identical to that of present-day humans in the only two positions that differ between human and chimpanzee. Speicifcally, at position 911 on exon 7 of the Neandertal FOXP2, threonine is swapped for aspartic acid just like humans and also at position 977 of the Neandertal FOXP2, arginine replaces serine… just like in humans. Sending the samples to other lab to reproduce the experiments yielded the same results.

While the authors are a bit cautious, saying that the whole genome of the Neandertal will provide much more resolution in comparing FOXP2 genes, I do want to point out that this new finding messes up the results of Pääbo, who showed that the mutations in FOXP2 in modern humans were very recent, maybe less than 200,000 years ago in 2002. The authors kinda sorta challenge Pääbo’s conclusion,

“Leaving out the unlikely scenario of gene flow [between the two lineages], this establishes that these changes were present in the common ancestor of modern humans and Neandertals. The date of the emergence of these genetic changes therefore must be older than that estimated with only extant human diversity data, thus demonstrating the utility of direct evidence from Neandertal DNA sequences for understanding recent modern human evolution.”

So the common ancestor of Neandertals had this unique allele of FOXP2. Does that mean they had language capabilities? Does this mean Neandertals had language capabilities… I’d sure hope so because at this point in human evolution, erectines like Neandertals and their culture were widespread. Their ability to communicate in some higher form or another was crucial for their ubiquity in Europe and Asia.

According to the the New York Times and National Geographic, there is an alarming report on the rate of extinction of languages,

“Every 14 days a language dies. By 2100, more than half of the more than 7,000 languages spoken on Earth—many of them never yet recorded—will likely disappear, taking with them a wealth of knowledge about history, culture, the natural environment, and how the human brain works.”

The news is all base off of research conducted by the National Geographic Society and the Living Tongues Institute for Endangered Languages. David Harrison and David Anderson lead the project. What they found are five hotspots where languages are vanishing faster than other regions.

• Northern Australia
• Central South America
• North America’s upper Pacific coastal zone
• Eastern Siberia
• Oklahoma and the southwestern United States

The map to below better documents the hotspots and you can explore the interactive map by clicking it to goto languagehotspots.org.

Here are some interesting facts:

• In the last 500 years, an estimated half of the world’s languages, from Etruscan to Tasmanian, have become extinct.
• More than 500 languages may be spoken by fewer than ten people.
• Of the 50 native languages remaining in California, none is taught to schoolchildren today.

Also there is an interesting video clip of Anderson and Harrison’s work, where they find the only known speaker of a language long thought to be extinct. The video will air in its entirity on PBS’ “Wild Chronicles.”

For linguistic anthropology, the study of human languages throughout time and place, this news is devastating. The quote above, the one which talks about the wealth of knowledge on human history and culture locked away in the languages around the world barely captures the severity of this situation. As the world becomes more globalized, and more cultures become assimilated and this seems like an inevitable consequence.