Scientists looked at how cultural influences like easy access to contraception and medical advances reducing infant mortality, effects natural selection in modern human populations. (sciencedaily.com)
The authors of the study, an international team from Portuguese, Spanish, Catalonian, German, Austrian and Italian research institutions, say their findings suggest that the process of modern human populations absorbing Neanderthal populations through interbreeding was not a regular, gradual wave - of - advance but a «stop - and - go, punctuated, geographically uneven history.» (sciencedaily.com)
But the need for pigment to provide this extra protection waned as modern human populations migrated northward over the past 60,000 years or so, while the need to absorb UVB light became greater, particularly for those humans who migrated to the far North behind retreating glaciers less than 10,000 years ago. (sciencedaily.com)