The Evolution of Primates (part II)Life in the trees also led to changes in patterns of bearing and raising offspring, making the infant more dependent on its mother.
Lacking a permanent and protected home for raising children, primates were under selective pressure to have one or at most just a few offspring at a time.
And to ensure the survival of these species under such conditions, a large proportion of the offspring must survive.
Whereas a fish may lay thousands of eggs to yield one offspring that survived t0 reproduce, a primate that bears only one baby must take care of it is order to increase its chances of surviving.
Over time this pressure led to greater dependency in primate offspring, both before and after birth.
One way to ensure higher survival rate is to increase the amount of maternal care during pregnancy and after the birth of the child.
One a fish has laid its eggs, it duties are over. Among mammals, the period of care is extended by the fact that the mother must nurse the infant for some time. But in the higher primates the period of dependency becomes even longer.
Yet another change that was brought about by early primate life was greater intelligence. All of the previous changes, such as better eyesight or more nerves in the hands required an increase in the size of the brain.
The reduction on the number of offspring placed a premium on a longer life span and this provided more chances to learn through experience.
Learning as opposed to instinctual response, is clearly a superior means of adapting to the environmental, since it allows the individual to meet changes with new techniques, more important, it allows one to adjust one’s behaviors on the basis of ones experiences (success or failures).
But the greater role of learning, the more pressure there was for increase brain size to allow for the memory of past experience.
The Evolution of Primates (part II)
