title: Anthropological considerations relevant to the maturation of the immune response in humans.
abstract: OBJECTIVE
  The reason for the postnatal maturation of the immune response in humans was explored from the anthropological standpoint in order to gain some insight into how development in modern humans evolved and how it might have affected the immune system.
  
  
  METHODS
  The estimation of the length of gestation in modern humans if it had followed the same developmental pattern as in the other hominids and the higher primates was calculated by extrapolation from the lengths of gestation and the physical characteristics of these other primates compared to those of modern humans.
  
  
  RESULTS
  These calculations show that the gestation time of modern humans would be 3-18 months longer than the 9 months that it is if modern humans had followed a linear evolutionary development comparable to that of the other primates. The key difference between modern humans and the other primates is the rapid and extensive development of the brain that occurs in utero and in the first 12-18 months postnatally in modern humans.
  
  
  CONCLUSIONS
  The first 12-18 months postnatally in humans follows the embryonic/fetal pattern of development, whereas that of other primates does not. The maturation of the immune response in humans occurs during both the intrauterine and extrauterine phases of the embryonic/fetal pattern of development.
authors.affiliation: Department of Pathology, University of Pittsburgh, School of Medicine, PA 15261, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Gill
mesh_terms: D000818:Animals; D000883:Anthropology; D005075:Biological Evolution; D001921:Brain / Q000196:embryology / Q000254:growth & development; D005314:Embryonic and Fetal Development / Q000502:physiology; D005260:Female; D015186:Hominidae / Q000254:growth & development* / Q000276:immunology*; D006801:Humans; D007107:Immune System / Q000196:embryology / Q000254:growth & development*; D007231:Infant, Newborn / Q000502:physiology*; D011247:Pregnancy; D011323:Primates / Q000254:growth & development*; D013997:Time Factors