selection – Page 5 – Replicated Typo

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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The arcuate fasciculus within the dual stream model pt.2

3.1 What is the dual stream model?

Given these separate anatomical accounts, attributing a function(s) to the arcuate is not clear cut, and any current account is far from the authoritative statement on the matter. Nonetheless, a vast majority of literature does place the arcuate as part of the dual stream model[1] of speech processing, although its exact role within these neural networks is still being disputed – and largely depends on which anatomical account you prescribe to.

The basic assumption of dual stream accounts is that phonological networks interact with both conceptual-semantic and motor-articulatory systems, leading to a distinction between the neural networks that process this speech information. These separate interactions are summarised under two processing streams: the dorsal stream and the ventral stream (Hickok and Poeppel, 2007). Connecting phonological networks with conceptual-semantic systems, using structures in the superior and middle portions of the temporal lobe, is the ventral stream. Meanwhile, the dorsal stream is linked via structures in the posterior frontal lobe to the posterior temporal lobe and parietal operculum, which connects phonological networks with motor-articulatory systems (ibid).

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Olfactory communication and mate choice

From the regulation and reproduction in bacteria colonies (Bassler, 2002) to complex smell and taste systems of humans (Van Toller & Dodd, 1988), the ability of sensing chemical stimuli, known as chemosensation, is believed to be the most basic and ubiquitous of senses (Bhutta, 2007). One strain of thought places chemosensation as merely an evolved ability to detect dangerous and volatile substances – such as putrefied food (see Bhutta, 2007). Still, the notion that this ability to detect chemical stimuli, particularly in the domain of smell, serves a purpose in communication is not necessarily a contemporary concept (Wyatt, 2009).

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Iterated Learning and Language Evolution

If we accept that language is not only a conveyer of cultural information, but it is itself a socially learned and culturally transmitted system, then an individual’s linguistic knowledge is the result of observing the linguistic behaviour of others. This well attested process of language acquisition is often termed Iterated Learning, and it opens up a new avenue to investigate the design features of language: that cultural, as opposed to biological, evolution is fundamental in understanding these features.

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Language as a complex adaptive system

A prominent idea in linguistics is that humans have an array of specialised organs geared towards the production, reception and comprehension of language. For some features, particularly the physical capacity to produce and receive multiple vocalizations, there is ample evidence for specialisation: a descended larynx (Lieberman, 2003), thoracic breathing (MacLarnon & Hewitt, 1999), and several distinct hearing organs (Hawks, in press). Given that these features are firmly in the domain of biology, it makes intuitive sense to apply the theory of natural selection to solve the problem: humans are specially adapted to the production and reception of multiple vocalizations.

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Cultaptation Conference

Earlier this year I went along to the Cultaptation Conference at St Andrews. Despite being a fascinating event, there appears to nothing on the blogsphere pertaining to the speakers and their talks. In fact, this generally holds true for cultural evolution: there are no dedicated blogs reporting what is undoubtedly a serious scientific endeavour. As a remedy I’m going to dedicate several future blog posts to the conference. Until then, here are the talk abstracts for some of my personal highlights:

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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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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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Current Issues in Language Evolution

As part of my assessment this term I’m to write four mock peer-reviewed items for a module called Current Issues in Language Evolution. It’s a great module run by Simon Kirby, examining some of the best food for thought in the field. Alone this is an interesting endeavour, after all we’re right in the middle of a language evolution renaissance, however, even cooler are the lectures, where students get to do their own presentations on a particular paper. I already did my presentation at the start of this term, on Dediu and Ladd’s paper, which went rather well, even if one of my slip ups did not go unnoticed (hint: always label the graphs). So, over the next few weeks, in amongst additional posts covering some of the presentations in class, I’ll hopefully be writing articles on these four five papers:

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