10 – Page 6 – Replicated Typo

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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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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Inconsistent, yes… But here are some links.

Okay, I promised a post a day and failed miserably. But it does say in my profile that I’m inconsistent. So it’s probably best to not believe everything I write, even if there is one valuable lesson in my broken promises: avoid targets. Anyway, I just thought I’d do a quick post on some articles that have caught my attention over the past few days:

Pop over to read the hairy nipple of the angry walrus — quite possibly the only other blog written by a “humanistic evolutionary linguist from Wales”. In fact, the blogger in question is a PhD student in my former department at Edinburgh. In keeping with this Welsh theme, you should check out his post concerning common misconceptions about the Welsh language: http://garics.blogspot.com/2009/10/silly-things-people-say-about-welsh-ii.html
Next on the agenda is a massive deviation from my comfort zone of cognition, evolution and linguistics into the entangled world of quantum physics, and how through “linking the electrical currents of two superconductors large enough to be seen with the naked eye, researchers have extended the domain of observable quantum effects.“
Babel’s Dawn discusses Prof. Jim Hurford‘s (my former lecturer) presentation at the Torun Proto-language conference about the word-sentence continuum.
And lastly, thanks to her mentioning my article on Broca’s area, I’ve discovered a new cognitive science blog: Nou Stuff. A wealth of information on this website; plus, she’s got some really cool links, one of which I’m about to start watching — Life Without Memory: The Case of Clive Wearing.

Discerning the role of the arcuate fasciculus in speech processing pt.1

Originally identified by Reil (1809) and subsequently named by Burdach (1819), the arcuate fasciculus is a white-matter, neural pathway that intersects with both the lateral temporal cortex and frontal cortex via a “dorsal projection that arches around the Sylvain fissure.” (Rilling et al., 2008, pg. 426). Classical hypotheses saw this pathway as a critical component in connecting two centres of language: Broca’s area (speech production) and Wernicke’s area (speech comprehension) (Catani and Mesulam, 2008).

Much of these assumptions were based on a tentative relationship between language-impairment and damaged portions of the brain. Notably, damage to the arcuate fasciculus is implicated in a syndrome known as conduction aphasia, where an individual has difficulty in speech repetition. Often characterised by errors in spontaneous speech, an individual with conduction aphasia will be fully aware of their mistake, retaining well-preserved auditory comprehension and speech production while also being syntactically and grammatically correct (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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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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Negative Interest Rates

I just read this article in BBC news about negative interest rates:

If the Bank of England cuts interest rates on Thursday could the interest paid on our savings fall below zero?

Negative interest rates, where the bank charges us to look after our savings, have been seen before.

In the 1970s Swiss banks charged foreign customers rather than paying them interest to hold their money.

I don’t think we’ll see negative interest rates in the UK, although it is technically possible, and has happened before. To use the hypothetical example offered by the BBC: if you place £10,000 in the bank, and the negative interest rate is at -1%, then at the end of the year you’d get a return of just £9,900 — essentially a £100 charge for the pleasure of banking. Great.

A word of warning if this does happen: Northern Rock will, to quote one comment from the Guardian website, look like “a 6 year old emptying his piggy bank“.

Orangutans – probably more interesting than you

In the past few years there has been a recent spate of articles concerning orangutan intelligence. So, as I’m fairly bored, and in need of a break from university work, I’ve decided to write a bit of an essay on some of these finds.

Orangutans… They’re orange, right?

Correct; but Pongo pygmaeus abelii are so much more than just some arboreal orange ape that eats a lot of fruit. In fact, these great apes, the last surviving members of the genus Pongo, are highly resourceful and intelligent creatures, as evident in their ability to make and use tools, perform calculated reciprocity and even whistle a tune.

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