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:

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 (, 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.[]

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.