Variation and signatures of selection on the human face.

There has been much debate about why humans throughout the world differ in facial form. Previous studies of human skull morphology found levels of among-population differentiation that were comparable to those of neutral genetic markers, suggesting that genetic drift (neutral processes) played an important role in influencing facial differentiation. However, variation in soft-tissue morphology has not been studied in detail. In this study, we analyzed high-resolution 3D images of soft-tissue facial form in four Eurasian populations: Han Chinese, Tibetans, Uyghur and Europeans. A novel method was used to establish a high-density alignment across all of the faces, allowing facial diversity to be examined at an unprecedented resolution. These data exhibit signatures of population structure and history. However, among-population differentiation was higher for soft-tissue facial form than for genome-wide genetic loci, and high-resolution analyses reveal that the nose, brow area and cheekbones exhibit particularly strong signals of differentiation (Qst estimates: 0.3-0.8) between Europeans and Han Chinese. Our results suggest that local adaptation and/or sexual selection have been important in shaping human soft-tissue facial morphology.

A new interpretation on the homology of the teleostean telencephalon based on hodology and a new eversion model.

Various hypotheses regarding the homology of the teleostean telencephalon with that of other vertebrates have been proposed to date. However, a firm conclusion on this issue has yet to be drawn. We propose here a new hypothesis with a new eversion model. Our hodological data and the analysis of dorsal telencephalic organization in adult cyprinids suggest that: (1) the area dorsalis pars posterior corresponds to the lateral pallium; (2) ventral region of area dorsalis pars lateralis to the medial pallium; (3) pars medialis, dorsal region of pars lateralis, pars dorsalis, and pars centralis of the area dorsalis to the dorsal pallium, and (4) nucleus taenia to the ventral pallium. We propose in a three dimensional model that the eversion process occurs not only dorsolaterally but also caudolaterally. We consider that the caudally directed component dominates for ventral zones of the pallium, or the lateral and ventral pallia; and the periventricular surface of these zones shift caudally, laterally, and then rostrally in teleosts with pronounced telencephalic eversion. This new model fits well with the putative homology based on hodology and the organization of telencephalic divisions in the adult brain.