Direct dating of human fossils
During human birth, because of the variation in size of the pelvic region, the fetal head must be in a transverse position (compared to the mother) during entry into the birth canal and rotate about 90 degrees upon exit.
The smaller birth canal became a limiting factor to brain size increases in early humans and prompted a shorter gestation period leading to the relative immaturity of human offspring, who are unable to walk much before 12 months and have greater neoteny, compared to other primates, who are mobile at a much earlier age.
The foramen magnum migrated under the skull and more anterior.
The most significant changes occurred in the pelvic region, where the long downward facing iliac blade was shortened and widened as a requirement for keeping the center of gravity stable while walking; bipedal hominids have a shorter but broader, bowl-like pelvis due to this.
The practical difficulty of this approach is whether there are actually any old samples that conform to the D-A model.
Human evolution is the evolutionary process that led to the emergence of anatomically modern humans, beginning with the evolutionary history of primates – in particular genus Homo – and leading to the emergence of Homo sapiens as a distinct species of the hominid family, the great apes.
Grun, Rainer; Aubert, Maxime; Hellstrom, John Charles; Duval, Mathieu This paper reviews the possible approaches for dating of human bones and teeth, older than 500,000. Skeletal tissues can, in principle, be dated with an open-system U-series approach, which requires that the Th/U activity ratio is still below equilibrium.
This indicates that the sample experienced continuing U-uptake.
In the feet the big toe moved into alignment with the other toes to help in forward locomotion.
The arms and forearms shortened relative to the legs making it easier to run.
Within the Hominoidea (apes) superfamily, the Hominidae family diverged from the Hylobatidae (gibbon) family some 15–20 million years ago; African great apes (subfamily Homininae) diverged from orangutans (Ponginae) about Human evolution from its first separation from the last common ancestor of humans and chimpanzees is characterized by a number of morphological, developmental, physiological, and behavioral changes.