genetics – Page 3 – Replicated Typo

Reading Round Up

Here’s some stuff I’ve been reading over the last month or so:

Babel’s Dawn discusses Michael Arbib’s paper, Invention and Community in the Emergence of Language: Insights from New Sign Languages.
Over at Neurophilosophy there is an overview of a fascinating paper on the Universal Grammar of birdsong (also check out my comment, it’s the first one under JW).
John Hawks talks about some of my favourite topics: learning, population size, and modern human behaviour.
The recent resurgence of the Sapir-Whorf hypothesis and Lera Boroditsky are the topics of discussion over at Mind Hacks.
Deric Bownds’ MindBlog mentions the “origins of altruism toward one’s own social group and the emergence of cultural complexity“.
Evolution can occur in less than 10 years… In guppy fish.
Researchers at Brown find: “A front portion of the brain that handles tasks like decision-making also helps decipher different phonetic sounds“.
And lastly, Dienekes’ anthropology blog discusses a paper that investigates the role of drift and selection in the shaping of human skulls, concluding “that neutral processes have been much more important than climate in shaping the human cranium”.

Okay, so that brings you up to date with my reading from May through to July. Next round up will cover August. How fascinating :-/

Continuity or Discontinuity: are our minds purely shaped by natural selection?

The debate concerning the origin of our minds stems back to the diverging opinions of Darwin (1871) and Wallace (1870). When Charles Darwin first discussed the evolution of our seemingly unique cognitive faculties, he proposed that there is “no fundamental difference between man and the higher mammals in their mental faculties.” (Darwin, 1871, pg. 66). Conversely, Wallace was suspicious of whether natural selection alone could have shaped the human mind, writing: “[…] that the same law which appears to have sufficed for the development of animals, has been alone the cause of man’s superior mental nature, […] will, I have no doubt, be overruled and explained away. But I venture to think they will nevertheless maintain their ground, and that they can only be met by the discovery of new facts or new laws, of a nature very different from any yet known to us.” In the intervening years, the debate surrounding the degree of continuity between animal and human minds still rages on in contemporary discussions (Bolhuis & Wynne, 2009; Penn, Holyoak & Povinelli, 2009).

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How do biology and culture interact?

In the year of Darwin, I’m not too surprised at the number of articles being published on the interactions between cultural change and biological evolution — this synthesis, if achieved, will certainly be a crucial step in explaining how humans evolved. Still, it’s unlikely we’re going to see the Darwin of culture in 2009, given we’re still disputing some of the fundamentals surrounding these two modes of evolution. One of these key arguments is whether or not culture inhibits biological evolution. That we’re seeing accelerated changes in the human genome seems to suggest (for some) that culture is one of these evolutionary selection pressures, as John Hawks explains:
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Neanderthal Genome Published

…Well, 60% of the genome at least. Not much has been said yet in regards to the nitty gritty aspects of Svante and colleagues’ findings. No doubt John Hawks and many others will offer their own perspectives over the next couple of days. If you’re interested in the immediate gist then here’s a link to the press release. Also, here is a quote from the BBC offering a succinct summary:
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Toadflax flowers are cool

Other than sound like a character from Bucky O’Hare, Toadflax (Linaria vulgaris) are fascinating plants for several reasons. Taking centre stage though is how this plant potentially offers another method of inheritance beyond genes. We’re now entering the slightly confusing world of epigenetics.

See, a particular species of these toadflax plants come in two distinct flavours: one consists of white, symmetrically arranged petals, whilst the other form is yellow and has five-pointed stars. Interestingly, this variation is not directly due to their DNA. Rather, these observed differences, which by the way are inherited by the offspring, are due to molecular caps attached to their DNA. As Carl Zimmer explains in his brilliant essay for the New York times:
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Neanderthal genome unveiling to coincide with Darwin's birthday

February 12th — keep this date in mind and prepare your browser on automatic refresh because the Neanderthal genome is to be unveiled. And just to make it extra special, the date on which we’ll dip into the three billion base pairs of our extinct relative is the 200th anniversary of Charles Darwin‘s birth. Here’s a little extract from the Nature article just to peak your interest:

Comparisons with the human genome may uncover evidence of interbreeding between Neanderthals and humans, the genomes of which overlap by more than 99%. They certainly had enough time for fraternization — Homo sapiens emerged as a separate species by about 400,000 years ago, and Neanderthals became extinct just 30,000 years ago. Their last common ancestor lived about 660,000 years ago, give or take 140,000 years.

I can’t think why we wouldn’t have interbred with Neanderthals. Language of course is one possible reason, acting as a symbolic marker of group boundaries to such an extent that even cultural differences within humans would minimise gene flow (assuming language, or even a protolanguage, was around then). That said, even contemporary humans are quite willing to fuck goats (and god knows what else). So why not the Neanderthals?

N.B. If you’re not familiar with they dynamics surrounding the possibility of Neanderthals having contributed some genes to modern humans, then I strongly suggest you read John Hawks’ Neanderthal FAQ. Also, check out his sections on adaptive introgression.

ASPM, Microcephalin and Tone

Disclaimer: I know this post is on a paper released over a year ago; however, I’m still going to write about it for three reasons: 1) I did a presentation about it earlier this week (20/01/08); 2) I think it relates to a recent buzz around gene-culture co-evolution; and, 3) It’s a bloody awesome paper.

So, what is the paper called? Okay, once you read this title, do not yawn, go to another website or… Linguistic tone is related to the population frequency of the adaptive haplogroups of the two brain size genes, ASPM and Mircocephalin. See, now we’ve got the hard part out of the way, I can begin to discuss exactly what the authors, Dan Dediu and Robert ‘Bob’ Ladd, found and why it’s important to our understanding of linguistics, genetics and evolution. It’s really interesting, honestly.
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