Hand of whether the three digits of the bird hand involved the same homologous loss of two digits as in the dinosaur hand. The human hand normally has five digits: four fingers plus one thumb; these are often referred to collectively as five fingers, however, whereby the thumb is included as one of the fingers. It has 27 bones, not including the sesamoid bone, the number of which varies between people, 14 of which are the phalanges (proximal, intermediate and distal) of the fingers and thumb. The metacarpal bones connect the fingers and the carpal bones of the wrist. Each human
Who We Are and How We Got Here its uneven style of progress as old theories (like the idea that modern humans arose in several regions, popular until the early 1990s) are abandoned. He notes Reich's "restraint" in saying little about how human diversity arose: scientists simply do not yet know, but natural selection acted on many genes and phenotypes: it was not a matter of creating "behavioral modernity" with any large mutation. An open letter "by a group of 67 scientists and researchers" including anthropologists, sociologists, historians, and others takes Reich to task for his book, under the heading "How Not To Talk About Race And Genetics".