Significance: The frequency of the human-specificEDAR V370Aisoform is highly elevated in North and East Asian populations. The gene is known to have several pleiotropic effects, among which are sweat gland density and ductal branching in the mammary gland. The former has led some geneticists to argue that the near-fixation of this allele was caused by selection for modulation of thermoregulatory sweating. We provide an alternative hypothesis, that selection instead acted on the allele’s effect of increasing ductal branching in the mammary gland, thereby amplifying the transfer of critical nutrients to infants via mother’s milk. This is likely to have occurred during the Last Glacial Maximum when a human population was genetically isolated in the high-latitude environment of the Beringia.

Significance: Experimental research on mice has yielded tremendous biological insight. However, the ∼140 million y of evolution that separate mice from humans pose a hurdle to direct application of this knowledge to humans. We report here that considerable progress for identifying genetically patterned skeletal phenotypes beyond the mouse model is possible through transdisciplinary approaches that include the anatomical sciences. Indeed, anatomy and paleontology offer unique opportunities through which to develop and test hypotheses about the underlying genetic mechanisms of the skeleton for taxa that are not well suited to experimental manipulation, such as ourselves.

Thousands of vertebrate specimens were systematically collected from the stratigraphic interval containing Ardipithecus ramidus . The carcasses of larger mammals were heavily ravaged by carnivores. Nearly 10,000 small-mammal remains appear to be derived primarily from decomposed owl pellets. The rich avifauna includes at least 29 species, mostly nonaquatic forms. Modern analogs of the most abundant birds and of a variety of rodents are associated with mesic woodland environments distant from large water bodies. These findings support inferences from associated geological, isotopic, invertebrate, and large-vertebrate assemblages. The combined results suggest that Ar. ramidus occupied a wooded Pliocene habitat.