Early human ancestors, hominids, originally gave birth in a similar way that non-human primates do because early obligate quadrupedal individuals would have retained similar skeletal structure to great apes. Most non-human primates today have neonatal heads that are close in size to the mother's birth canal, as evidenced by observing female primates who do not need assistance in birthing, often seeking seclusion away from others of their species. In modern humans, parturition (childbirth) differs greatly from the rest of the primates because of both pelvic shape of the mother and neonatal shape of the infant. Further adaptations evolved to cope with bipedalism and larger craniums were also important such as neonatal rotation of the infant, shorter gestation length, assistance with birth, and a malleable neonatal head.