Individual identity signaling in humans

Interesting-looking poster title:

Michael Sheehan Morphological and population genomic evidence of selection for individual identity signaling in human faces

There's no abstract, but one area where I suspect selection of this sort may turn out to be relevant (at least more relevant than Peter Frost-style sexual selection) is in explaining European hair and eye color variation.

"Traits signaling identity should be highly variable, often display polymodal distributions, not be condition dependent (i.e., be cheap to produce and/or maintain), not be associated with fitness differences, exhibit independent assortment of component characters, and often occur as fixed phenotypes with a high degree of genetic determination."

"Is human facial distinctiveness an adaptive signal of individual identity? From a sociobiological perspective, humans seem to have the ‘perfect storm’ of selection pressures that might favor recognizability. We are extremely social, interacting repeatedly with large numbers of individuals, each with varying roles in our lives. We are extremely cooperative, and we make complex decisions about whether and how much to cooperate based on kinship, friendship and social reputation [39,78]."

"Tracing the Indo-Europeans" conference videos

David Anthony, Wheeled vehicles, horses, and Indo-European origins (link)

Paper presented at the seminar "Tracing the Indo-Europeans: Origin and migration", organized by Roots of Europe - Language, Culture, and Migrations, University of Copenhagen, 12-14 December 2012

Kristian Kristiansen, Trade, travels and the transmission of cultural change in the Bronze Age (link)

See the playlist or Polako's blog for links to more talks.

Friendship and natural selection

NRNB Symposium on Network Biology 2012, Gladstone institutes, San Francisco: James Fowler presents Friendship and Natural Selection (link)

Friendship and Natural Selection

Nicholas A. Christakis, James H. Fowler

More than any other species, humans form social ties to individuals who are neither kin nor mates, and these ties tend to be with similar people. Here, we show that this similarity extends to genotypes. Across the whole genome, friends' genotypes at the SNP level tend to be positively correlated (homophilic); however, certain genotypes are negatively correlated (heterophilic). A focused gene set analysis suggests that some of the overall correlation can be explained by specific systems; for example, an olfactory gene set is homophilic and an immune system gene set is heterophilic. Finally, homophilic genotypes exhibit significantly higher measures of positive selection, suggesting that, on average, they may yield a synergistic fitness advantage that has been helping to drive recent human evolution.

Modeling European demographic history using neutral genomic regions

Neutral genomic regions refine models of recent rapid human population growth

In this study, we introduce targeted sequencing data for studying recent human history with minimal confounding by natural selection. We sequenced putatively neutral loci that are very far from genes and that meet a wide array of additional criteria. [. . .]

The best-fit model points to Europeans having experienced recent growth from an effective population size of about 4-7 thousand individuals as recently as 120--160 generations (3000--4000 years) ago. Growth over the last 3000-4000 years is estimated at an average rate of about 2--5% per generation, resulting in an overall increase in effective population size of two orders of magnitude.