Human developement

¶ … nonhuman primates and humans can lead to a better understanding of both species has been ongoing for several decades. A variety of academic disciplines including anthropology, psychology, zoology, and biology have spent thousands of hours researching and studying these similarities and drawing conclusions that have added to the vault of human knowledge.

Joining the other disciplines in studying the similarities between nonhuman primates and humans have been scientists in the field of human development. Such scientists have spent considerable time studying neoteny, otherwise referred to as developmental retardation, as an explanation for defining how humans began to develop human-specific features such as brain size and cognitive skills that mark a divergence of humans from nonhuman primates.

Simply stated, neoteny is the process by which the adults of a species retain the traits previously present only in juveniles, that is, the physiological development of the species' adults are slowed or delayed. In the human species evidence of the affects of neoteny can be seen in the form of flattened and broadened faces, a larger brain cavity, decreased body hair, smaller noses, and smaller teeth, decreased jaw size, shortening of arms and elongation of legs, and, most obviously, an extended period of childhood (Bjorklund, 1997).

Neoteny is offered by many scientists as an explanation for the split between nonhuman primates and the human species. They argue that neoteny was actually an adaptive reaction that occurred as part of the evolutionary process that forced humans to prolong their period of youth in order to allow them survive. Unlike other species such as the nonhuman primates, humans could not rely upon their strength and instincts to survive and had to rely upon their wits. Humans are intellectually more complex and diverse than other species and require a prolonged period of adjustment in order to develop the skills necessary to compete in the world. For many experts in the field neoteny explains why this prolonged period of development occurred. By developing a longer period of adjustment from the primates, that is, a virtual period of retardation, human juveniles were provided the benefit of learning more from their parents over a longer period of time which ultimately resulted in a better prepared adult. Oddly, delaying maturation actually served humans as an evolutionary advantage.

Despite humans and primates having split on the evolutionary path but there remain some remarkable developmental similarities between the two species (Boyd, 2009). These similarities are in what are defined as the foetal and juvenile stages. The foetal stage differs in length between the two species but in both species it is the period of development while the young child or primate remains in utero. The juvenile stage in primates and humans is actually quite different in both length and style. In humans the juvenile stage ends with puberty and is followed by a period of adolescent. In primates the juvenile stage is essentially the same but there is no consequent adolescent. An important evolutionary distinction between primates and humans is that puberty and reproduction may begin in primates before the end of the juvenile stage.

Comparison of the developmental stages experienced by both primates and humans has provided invaluable information regarding the evolution of both species. This information has allowed anthropologists and biologists to understand how humans successfully combined the features brought on by neoteny such as extended childhood, delayed reproduction capability, short duration breastfeeding, and adolescent growth spurt to contribute toward their survival.

One of the most obvious similarities between primates and humans is their development of a period of juvenile growth and behavior between infancy and adulthood. Although this period is greatly extended in humans, primates, like most other highly social mammals, such as wolves, dogs, and elephants postpone puberty and insert this juvenile period. Such period provides offspring with additional time to learn life skills from their parents and thereby be better prepared for life as an adult. During this period in both primates and humans, the juveniles are capable of limited self sufficiency but remain dependent on their parents for protection and, on occasion, feeding. In the juvenile period both primates and humans enjoy an acceleration in soft tissue growth. This growth contributes to both species becoming stronger during this period and increasing their agility. One of the divergences that distinguish the two species also occurs at this point as humans also enjoy rapid bone growth while the primate bone growth is much less significant. Primates and humans also demonstrate a pattern of brain growth both before and after birth but after the brain growth continues in humans while it slows down considerably among primates.