Tuesday, 4 June 2013

Synaptic scaffold evolution generated components of vertebrate components of vertebrate cognitive complexity

Scientists have discovered for the first time how humans -- and other mammals -- have evolved to have intelligence. Researchers have identified the moment in history when the genes that enabled us to think and reason evolved. This point 500 million years ago provided our ability to learn complex skills, analyse situations and have flexibility in the way in which we think. Professor Seth Grant, of the University of Edinburgh, who led the research, said: "One of the greatest scientific problems is to explain how intelligence and complex behaviours arose during evolution."

The research, which is detailed in two papers in Nature Neuroscience, also shows a direct link between the evolution of complex cognition and behaviour and the origins of brain diseases. Scientists believe that the same genes that improved our mental capacity are also responsible for a number of brain disorders. "This ground breaking work has implications for how we understand the emergence of psychiatric disorders and will offer new avenues for the development of new treatments," said John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, one of the study funders. The study shows that intelligence in humans developed as the result of an increase in the number of brain genes in our evolutionary ancestors. The researchers suggest that a simple invertebrate animal living in the sea 500 million years ago experienced a 'genetic accident', which resulted in extra copies of these genes being made. This animal's descendants benefited from these extra genes, leading to behaviourally sophisticated vertebrates -- including humans.

The research team studied the mental abilities of mice and humans, using comparative tasks that involved identifying objects on touch-screen computers. Researchers then combined results of these behavioural tests with information from the genetic codes of various species to work out when different behaviours evolved.
They found that higher mental functions in humans and mice were controlled by the same genes. The study also showed that when these genes were mutated or damaged, they impaired higher mental functions. "Our work shows that the price of higher intelligence and more complex behaviours is more mental illness," said Professor Grant. The researchers had previously shown that more than 100 childhood and adult brain diseases are caused by gene mutations. "We can now apply genetics and behavioural testing to help patients with these diseases," said Dr Tim Bussey from Cambridge University, which was also involved in the study.

A Science Daily summary of the work can be found here: http://www.sciencedaily.com/releases/2012/12/121202164325.htm

The full-length pdf article can be found here:

Wednesday, 13 February 2013

Genetic identification of C fibres that detect massage-like stroking of hairy skin in vivo

In this recent Nature article, biologists at CalTech identified a rare group of sensory neurons in mice that respond specifically to stroking, but not other types of touch, such as pinching or poking. The team used florescent markers that illuminated when the neurons were active. Moreover, the mice seemed to demonstrate preferential affinity to specific spatial cues - associated with being placed in a particular box partition - when the stroking neurons were artificially stimulated via specific chemicals. 

This led the researchers to conclude the stroking neurons produced a pleasurable sensation when activated (and why they preferred a particular box partition associated with the stimulation over the alternative). The experiment demonstrated that stroking is positively reinforcing which might explain why animals enjoy social grooming. The researchers speculated that a variety of hairy mammals, including humans, are likely to have similar sensory neurons that respond during social stroking. 

An interesting summary video clip of the research can be found here: http://www.youtube.com/watch?v=OFCRvjle2o8

The full-length pdf article can be found here:

Tuesday, 29 January 2013

Modeling Neanderthal clothing using ethnographic analogues

Wales, N., 2012. Modeling Neanderthal clothing using ethnographic analogues. J. Hum. Evol. 63, 781-795.

This study used a large sample of recent human hunter-gatherers and climatic data to predict the percentage of the body that Neanderthals and AMH would have needed to cover and whether they would have required shoes and head coverings when living at known archeological sites under prevailing climatic conditions.  The model predicts that although Neanderthals would have had to cover >70% of their bodies including their head and feet, they need not have worn complex tailored clothing.

Wednesday, 5 December 2012

Bateman gradient and operational sex ratio, unite!

Yet one more Kokko paper on sexual selection which immediately reads like a classic.
Unifying cornerstones of sexual selection: operational sex ratio, Bateman gradient and the scope for competitive investment (Ecology Letters) 

challenges the common assumption that a male-biased sex ratio always leads to stronger sexual selection on men, point out ambiguity in the use of the term competition ("The sex that experiences stronger competition /in the mating pool/ does not invariably invest more in competitive traits, because more profitable routes to fitness than increased mating success can differ between the sexes" - for instance, males may invest more  in providing for offspring and less in mate competition if the chance of ever mating again is small), and elegantly introduce the "scope for competitive investment" for assessing when and how traits that improve mating rates are affected by the OSR. Add to this the literary qualities of the subtitles, and enjoy.

Wednesday, 28 November 2012

Linking brains and brawn: exercise and the evolution of human neurobiology.

Raichlen, D.A., Polk, J.D., 2013. Linking brains and brawn: exercise and the evolution of human neurobiology. Proceedings of the Royal Society B: Biological Sciences 280.

This paper argues that hominin encephalisation may have arisen through the action of neurotrophins and growth factors, which are known to be positively related to brain growth and enhanced cognition within and across a range of species.  The authors argue that these were upregulated during hominin evolution in association with increased endurance locomotion.

Tuesday, 27 November 2012

Evidence for Early Hafted Hunting Technology.

Wilkins, J., Schoville, B.J., Brown, K.S., Chazan, M., 2012. Evidence for Early Hafted Hunting Technology. Science 338, 942-946.

This paper reports ~500ky old stone spear tips from Kathu Pan 1 in South Africa, which suggests that the common ancestor of Neanderthals and Anatomically Modern Humans was manufacturing hafted spears much earlier than previously thought.  Comparison with experimental and archeological stone artifacts indicated that fracture types, wear, base modification and symmetry are consistent with functioning as hafted thrusting spears but not with cutting or scraping.

An early and enduring advanced technology originating 71,000 years ago in South Africa

Brown, K.S., Marean, C.W., Jacobs, Z., Schoville, B.J., Oestmo, S., Fisher, E.C., Bernatchez, J., Karkanas, P., Matthews, T., 2012. An early and enduring advanced technology originating 71,000 years ago in South Africa. Nature advance online publication.

The earliest microliths found so far, thought be hafted in arrows, these finds bring the complex technological indicators of the emergence of modern human behavior further back towards the anatomical appearance of Homo sapiens.  The authors argue for a complex manufacturing process, including heat treating.  


Monday, 26 November 2012

Signaling Theory, Strategic Interaction, and Symbolic Capital

This article is a few years old, but in my view, represents one of the most cutting-edge and comprehensive articles to date on honest (costly) signaling theory. The article presents a fairly broad argument for the application of animal signaling theory to a wide variety of human cultural phenomena. Published in Current Anthropology, it further contains reviewer commentary of six academics and their occasionally critical opinions of the article (actually very similar in format to a BBS article). Overall, however, the article seems to be warmly received by the reviewers and essentially constitutes a very thorough theoretical outline for further rigorous empirical research in the field of signaling theory- everything from altruism, prestige, subsistence production, hunting, and perhaps more controversially, artistic display, symbolic behavior, and semiotics, as well as an intriguing argument for it's application to the evolution of human language.

Here is a link: http://www.ceacb.ucl.ac.uk/cultureclub/files/CC2005-12-13-Bliege-Bird_and_Smith.pdf

A lack of men boost women's careers in the US

One of the very few studies looking at operational sex ratios today and their social consequences. (Kristina Durante has many other interesting articles, among the most popular is, for some peculiar reason, "Why do the wrong men feel so right?")

Sex Ratio and Women's Career Choice: Does a Scarcity of Men Lead Women to Choose Briefcase Over Baby?.
DOI: 10.1037/a0027949
Durante, Kristina M. 1; Griskevicius, Vladas 2; Simpson, Jeffry A. 3; Cantu, Stephanie M. 3; Tybur, Joshua M. 4

"Although the ratio of males to females in a population is known to influence behavior in nonhuman animals, little is known about how sex ratio influences human behavior. We propose that sex ratio affects women’s family planning and career choices. Using both historical data and experiments, we examined how sex ratio influences women’s career aspirations. Findings showed that a scarcity of men led women to seek high-paying careers and to delay starting a family. This effect was driven by how sex ratio altered the mating market, not just the job market. Sex ratios involving a scarcity of men led women to seek lucrative careers because of the difficulty women have in finding an investing, long-term mate under such circumstances. Accordingly, this low-male sex ratio produced the strongest desire for lucrative careers in women who are least able to secure a mate. These findings demonstrate that sex ratio has far-reaching effects in humans, including whether women choose briefcase over baby."

Evolution of Cooperation Among Carnivores

An important paper in Current Anthropology on the evolution of cooperation in carnivores. When we look at at the origins of cooperation in humans, we tend to focus on primates (not surprisingly) or we look at Everything (a.k.a. evolution of society), including bacteria, insects etc.

Here is s fascinating view of another, non-primate branch of the tree, a branch which is not that far, and might have much more to do with human evolution (and the effect of hunting and intergroup conflict) that we might have expected.

Here is the paper:

Smith, J. E., Swanson, E. M., Reed, D., & Holekamp, K. E. (2012). Evolution of Cooperation among Mammalian Carnivores and Its Relevance to Hominin Evolution. Current Anthropology

Monday, 19 November 2012

Don't fool yourself - it's less funny

Triver's work on self deception continues with this neat study, where subjects rating higher in self deception laughed less when watching a comedian (and also themselves reported having less fun). The authors point out that "humor deals with the absurdities of life. The less you are in tune with reality the less likely you are to see the absurdities".
Robert F. Lynch & Robert L. Trivers: Self-deception inhibits laughter
Personality and Individual Differences 53: 4, September 2012, p 491–495

The same number of PID has a Special Issue on Behavioral genetic contributions to research on individual differences, with eg twin studies on the genetic underpinnings of personality and IQ, or parenting styles.

Thursday, 15 November 2012

False-Positive Psychology

Simmons JP, Nelson LD, Simonsohn U. (2011) False-positive psychology: undisclosed flexibility in data collection and analysis allows presenting anything as significant. Psychological Science. 2011 Nov;22(11):1359-66. Epub 2011 Oct 17.

This article addresses the elephant in the room of statistical analysis in the social sciences - how perfectly legitimate analysis decisions made by researchers can lead to ever increasing chances of making Type I errors (finding significance where none exists). Using basic modelling techniques, it was shown that simple analysis decisions can very quickly increase the chances of making a Type I error from 5% to over 60%. In a follow up paper (http://www.ssrn.com/abstract=2160588), the authors suggest a simple solution - adding, and acting on, 21  words to every methods section "We report how we determined our sample size, all data exclusions (if any), all manipulations, and all measures in the study." 

Wednesday, 14 November 2012

John Odling-Smee: The ENCODE project seminar

Hi all- here are links to copies of the two articles discussed this morning by John Odling-Smee if anyone's interested:

Environment sensitive epigentics and the heritability of complex diseases


An integrated encyclopedia of DNA elements in the human genome (full article)


Tuesday, 6 November 2012

Immortality of the Soul as Intuitive Idea

Pereira, Vera, Luis Faísca and Rodrigo de Sá-Saraiva (2012).  "Immortality of the Soul as an Intuitive Idea: Towards a Psychological Explanation of Afterlife Beliefs."  Journal of Cognition and Culture 12: 101-127.[http://www.ingentaconnect.com/content/brill/jocc/2012/]

In this paper, the authors investigate the intutions that enter into the representation of the state of being dead.  On the basis of questionaire results, they argue that the dead self is imagined as being largely continuous with the living self, in that various epistemic, perceptual and boulomaic states are attributed to the dead subject.  Crucially, they also argue that learned religious and cultural beliefs impact on the representation of the dead self.

Though offering much useful material for speculation, it would have been interesting to see the paper incorporate a discussion of Bering's work on the supernatural role of punitive agents, especially given that Bering's work features so prominently otherwise.  This would have been especially useful in the discussion of the persistent attribution of hearing and sight (primary sensory modalities for vigilance) to the dead self.

Wednesday, 31 October 2012

Infection Breeds Reticence: The Effects of Disease Salience on Self-Perceptions of Personality and Behavioral Avoidance Tendencies

Chad R. Mortensen, D. Vaughn Becker, Joshua M. Ackerman, Steven L. Neuberg, and Douglas T. Kenrick, (2010) Psychological Science 21(3) 440–447

Past research has shown that humans seem to have evolved behavioural mechanisms for reducing risk of infection form communicable disease. This paper looks to examine this experimentally. Undergraduate students exposed to a disease prime led participants to rate themselves as less extroverted than did exposure to a control prime, and those who thought they were particularly vulnerable to disease also rated themselves as less agreeable and less open to new experiences. Behavioural differences were also found. Past research also suggests that this kind of avoidance, as well as ethnocentrism and various in-group out group behaviours, are also triggered by observing people with other types of physical abnormalities, even when there is no infectious  disease or parasite involved - such as when confronted with physically disabled or obese individuals. Could the recent staggering rise in obesity in the developed world, particularly in the US, partly explain increased prevalence of attitudes and political beliefs tending towards ethnocentrism, illiberal attitudes and the rise of the conservative right?  Hmmm . . .

Radiocarbon dates from the Grotte du Renne and Saint-Césaire support a Neandertal origin for the Châtelperronian.

Hublin, J.-J., Talamo, S., Julien, M., David, F., Connet, N., Bodu, P., Vandermeersch, B., Richards, M.P., 2012. PNAS.

The Chatelperronian is a so-called ‘transitional industry’ between Middle Palaeolithic (MP: definitely associated with Neanderthals) and Upper Palaeolithic (UP: almost definitely associated with anatomically modern humans (AMH)) industries in Central/Southwestern France and Northern Spain.  Châtelperronian artefacts have been found in direct association with a Neanderthal fossil at St Césaire. 
However, it has been argued that stratigraphic mixing has created associations between Neanderthal skeletal material, Châtelperronian tools and body ornaments by chance. 
This paper reports new radiocarbon dates from bone for late Mousterian (MP), Châtelperronian and Protoaurignacian (UP) layers at Grotte du Renne and shows that the dates are inconsistent with strata mixing (admixture), contrary to previous work (Higham et al 2011 PNAS).  They also directly date St Césaire (41-95 – 40.66ky calBP).  Their dates place the Châtelperronian body ornaments (~41ky calBP) as post-dating AMH dispersals into adjacent areas (e.g. 43–42kyr cal bp in Kent: Higham et al 2011, Nature) and therefore argue that this ‘innovation’ could be the result of acculturation (cultural diffusion from AMH) rather than independent innovation.  However, the two apparent 50ky-old pigmented shell ornaments from Spain pre-date the current earliest dates for AMH in Europe (http://www.pnas.org/content/early/2010/01/06/0914088107.abstract). 

Thursday, 25 October 2012

The Date of Interbreeding between Neandertals and Modern Humans.

Sankararaman, S., Patterson, N., Li, H., Pääbo, S., Reich, D., 2012. PLoS Genet 8, e1002947.

The authors use the extent of linkage disequilibrium (the association between two or more loci – the distance of DNA that hasn’t been broken up by recombination, which is reduced over time) in modern humans to test between two models (i) Neanderthal (or their close kin)-AMH interbreeding (Neanderthal gene flow) versus (ii) ancient sub-structuring in the ancestral population in Africa.  They find evidence for the former and date the last gene flow from Neanderthals to AMH to 37-986kyaBP.  Taking the possibility of both ancient sub-structuring and gene flow into account yields dates of 47-65kya.