evolution – Page 13 – Replicated Typo

Phylogenetics, Cultural Evolution and Horizontal Transmission

For some time now, evolutionary biologists have used phylogenetics. It is a well-established, powerful set of tools that allow us to test evolutionary hypotheses. More recently, however, these methods are being imported to analyse linguistic and cultural phenomena. For instance, the use of phylogenetics has led to observations that languages evolve in punctuational bursts, explored the role of population movements, and investigated the descent of Acheulean handaxes. I’ve followed the developments in linguistics with particular interest; after all, tracing the ephemeral nature of language is a daunting task. The first obvious road block is that prior to the invention of writing, the uptake of which is limited in geography and history, language leaves no archaeological record for linguists to examine. One particular note I’d like to make is that when Charles Darwin first formulated his theory of natural selection, he took inspiration from linguistic family trees as the basis for his sketch on the evolutionary tree of life. So it seems rather appropriate that phylogenetic approaches are now being used to inform our knowledge regarding linguistic evolution.

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The Movius Line represents the crossing of a demographic threshold

When examining the dispersal of Pleistocene hominins, one of the more fascinating debates concern the patterns of biological and technological evolution in East Asia and other regions of the Old World. One suggestion emerging from palaeoanthropological research places a demarcation between these two regions in the form of a geographical division known as the Movius Line. Specifically, the suggestions that initially led to the Movius Line were based on observations of differing technological patterns, namely: the lack of Acheulean handaxes and the Levallois core traditions in East Asia.

Since Hallam L. Movius’ initial proposal, the recent discovery of handaxes within East Asia have led to suggestions that the Movius Line is in fact obsolete. Suggesting this may not in fact be the case is a recent paper by Stephen Lycett & Christopher Norton, which highlights three central points coming from a growing body of research: 1) “several morphometric analyses have identified statistically significant differences between the attributes of specific biface assemblages from east and west of the Movius Line”; 2) “The number of sites from which handaxes have been recovered in East Asia tend to be geographically sparse compared with many regions west of the Movius Line”; 3) “‘handaxe’ specimens tend only to comprise a small percentage of the total number of artefacts recovered, a situation that contrasts with many classic Acheulean sites in western portions of the Old World, where bifacial handaxes may dominate assemblages in large numbers”.

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Some links #3

Of my random meanderings around the Internet, I think the coolest thing I’ve seen this past week certainly has to be the Steampunk sequencer:

With that out of the way, here are some links:

In somewhat keeping with the theme from some links 2’s look at primitive writing systems, comes a post from the excellent Not Exactly Rocket Science: An 60,000-year old artistic movement recorded in Ostrich egg shells.
More on topic of writing systems is Kevin Mitchell’s post on Why Johnny can’t read (but Jane can). Essentially, the post is asking: why dyslexia is about twice as common in boys as in girls?
Is synaesthesia a high-level brain power? I’m not sure, but that’s the question being asked over at New Scientist.
Science Daily claims: Simple math explains dramatic beak shape variation in Darwin’s finches. Key paragraph: “Using digitization techniques, the researchers found that 14 distinct beak shapes, that at first glance look unrelated, could be categorized into three broader, group shapes. Despite the striking variety of sizes and shapes, mathematically, the beaks within a particular group only differ by their scales.”
Pamelia Brown has 50 Fascinating Lectures All About Your Brain. I’ve only managed to watch one of the videos (see below), so I’m certain that there is at least one fascinating lecture…
Be sure to check out the Kahn Academy — a not-for-profit organisation that provides some great educational resources. For those of you interested in demographics and the quantitative analysis of movement, then here’s a whole section on differential equations.
Dormivigilia provides a brief overview of a paper examining the neural origins of handedness.
Razib Kahn over at GNXP has an in-depth discussion about the convergent evolution of skin pigmentation: OCA2 makes East Asians white and Europeans blue.
How reliable are fMRI results? Another question I’m not so sure about. However, Prefrontal.org has a full paper on providing something of an answer. The key sentence: “the results from fMRI research may be somewhat less reliable than many researchers implicitly believe.”
Jonah Leher has a lengthy, interesting piece over at the New York Times, asking: Is depression an adaptation? Probably not. But for a more balanced perspective, read Neurocritic’s brilliant analysis of the topic.
Laelaps writes about a paper claiming the discovery a 4,300 year old chimpanzee nut-cracking site: Uncovering the “Chimpanzee Stone Age”.
Lastly, Jeff Elman, UCSD professor of cognitive science and co-director of the Kavli Institute for Brain and Mind, presents a lecture on some of the latest research in our ability to use language and why it is so far removed from other animal communication systems:

Culture and the human genome: a synthesis of genetics and the human sciences

Humans are immersed in culture from birth. It is so fundamental to our experience, and what it means to be human itself, yet we often overlook the consideration that “cultural practices might have transformed the selection pressures acting on humans” (Laland, Odling-Smee & Myles, 2010, pg. 137).

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Cumulative Culture Evolved to Rapidly Coordinate Novel Behaviours

In the deliberations over humanity and its perceived uniqueness, a link is frequently made between our ability to support a rich, diverse culture and the origin of complex human behaviour. Yet what is often overlooked in our view of these two, clearly connected phenomena is the thread that weaves them together: the ability to coordinate behaviour. We need only look at the products of our culture, from language to religion, to see that any variant we may deem successful is contingent on coordinating the behaviour of two or more individuals. Still, what is truly illuminating about this ability is that, far from being a uniquely human feature, the ability to coordinate behaviour is ubiquitous throughout the many organismal kingdoms.

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Guns, Germs and Predictable Reviews

If, like me, you generally like the Guardian’s science features, then please avoid reading Tim Radford‘s book club discussion of Jared Diamond‘s Guns, Germs and Steel. Ever since I noticed this book was on the Guardian’s reading list, it’s been an ongoing curiosity of mine as to how they will tackle the subject. Mainly because Diamond’s book, along with Richard Dawkins’ The Selfish Gene, urged me to move into studying evolution. Sadly, and perhaps not very surprisingly, you get little from the discussion bar an unequivocal acceptance of Diamond’s central thesis: that of environmental determinism.

Nowhere is there a mention of ideas that stand somewhat in opposition to Diamond’s, such as those in the 10,000 Year Explosion. Namely, the consequences of agriculture on recent human evolution, and the growing mountain of evidence supporting the contention that different human populations have adapted to their local environments.

And just to be clear: I think Diamond’s book is a well-written, scholarly account of human history, and it’s influence is not to be understated. But I also think he overlooked a large portion of the argument.

How Culture Shaped The Human Genome

The study of culture, cultural evolution, gene-culture coevolution and niche construction have all received much more attention over the last decade. So it’s nice to see Nature taking on-board a fascinating review by Kevin Laland, John Odling-Smee and Sean Myles about how culture shaped the human genome: bringing genetics and the human sciences together. It’s really worth reading for anyone interested in the interactions between biology and culture. In particular, I was pleased to see them put forward the notion of culture having accelerated recent evolution, contra Stephen J. Gould’s claim that “there’s been no biological change in humans for 40,000 or 50,000 years”. Here’s the abstract:

Researchers from diverse backgrounds are converging on the view that human evolution has been shaped by gene–culture interactions. Theoretical biologists have used population genetic models to demonstrate that cultural processes can have a profound effect on human evolution, and anthropologists are investigating cultural practices that modify current selection. These findings are supported by recent analyses of human genetic variation, which reveal that hundreds of genes have been subject to recent positive selection, often in response to human activities. Here, we collate these data, highlighting the considerable potential for cross-disciplinary exchange to provide novel insights into how culture has shaped the human genome.

Some links #1

Having now returned, I feel a long list of links is needed to kick start things:

The journal Biolinguistics now has a blog. Whether or not this turns out to be interesting will obviously depend on the role they adopt for the blog. At the moment it just seems to be promoting various conferences and a summer school. I’ve added their RSS to google reader, so we shall see if anything worth while pops up.
Peter Frost over at Evo and Proud has written a fascinating article about the late Claude Lévi-Strauss and his view that “cultural differences have, over time, produced biological differences”.
Babel’s Dawn is producing a ridiculous amount of insightful articles. In particular, you should check out: Is anything universal in language? It covers a great paper (click here for a draft copy) by Nicholas Evans and Stephen C. Levinson, which knocks down the perpetuated myth of language universals.
Be sure to check out The Adventures of Auck, a blog by a friend, and fellow Welshman, at Edinburgh University. He’s written two insightful pieces on colour perception in bilinguals. Part one and part two.
Hat tip to Shared Symbolic Storage for directing me towards a review of Michael Tomasello‘s book Why we cooperate? My personal view: it’s a by-product of our ability to coordinate perception and behaviour (but that’s for a future post).
Edge poses the question: How is the internet changing the way you think? Plenty of good responses. Particularly amusing was Andy Clark’s reply: What kind of dumb question is that?

Right, that’s all I’ve got time for at the moment. Laptop battery is dying and my bladder is urging me towards the toilet.

What conclusions can we draw from Neanderthal DNA pt.2

4. Nuclear DNA: Forays into 3 billion base pairs

4.1 Before Vi-80

The Vindija-80 (Vi-80) specimen is an important find for geneticists: it yielded a minimally contaminated sample and provided those first steps into Neanderthal genomics.

Previously, attempts at retrieving ancient nuclear DNA sequences proved to be a notoriously difficult process, plagued with problems of degradation, contamination and chemical damage (Hofreiter et al., 2001). Researchers also need to contend with quantities of nuclear genome available: for every nuclear genome there are approximately several hundred mtDNAs (Green et al., 2008). The severity of these problems, especially contamination, is magnified through Neanderthal genetic similarity with humans (Green et al., 2006). This is troubling because nuclear DNA presents far less variability than mtDNA (Russell, 2002). As a result, huge stretches of nuclear sequences are required to find a significant number of polymorphisms (ibid). Such implications meant that discovering endogenous DNA sequences requires sifting through a large corpus of “[…] more than 70 Neanderthal bone and tooth samples from different sites in Europe and western Asia” (Green et al., 2006, pg. 331).

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What conclusions can we draw from Neanderthal DNA pt.1

In recent times, genetic technology has progressed sufficiently to elucidate upon some of the questions normally preserved for archaeologists. One such question concerns the fate of a group of hominins that roamed Europe and East Asia for at least 250,000 years. During this time, this species adapted and endured some of the harshest environments on offer, all while showing signs of a unique culture. Only for them to suddenly disappear from the fossil record approximately 30,000 years before present (BP) (cf. Barton et al. 2007). So, what happened to our closest evolutionary relatives, the Neanderthals?

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