The role of grandmothers in prolonging the life of great-great-grandchildren
Scientists have proved the importance of grandmothers for anthropogenesis
The work is published in the journal Proceedings of the Royal Society B (Kim et al., Increased longevity evolves from grandmothering), and its summary can be read on the University of Utah website: Grandmas Made Humans Live Longer.
Modeling implied that women could take care of young children starting from the age of 45 and ending at the age of 75. At the same time, the child passed from mother to grandmother not earlier than he turns two years old. One grandmother could only take care of one baby, but it didn't have to be her direct descendant.
The initial average life expectancy of the simulated population was 25 years, about the same as that of modern chimpanzees. However, in one percent of the population, it was increased, which allowed long–lived women to become grandmothers - that is, to take care of offspring. This enabled mothers to have more children, which, in turn, increased the frequency of "longevity" genes.
Modeling has shown that in just 25-60 thousand years of such evolution, the average life expectancy in the population reached 43 years – a value characteristic of modern hunters and gatherers. Interestingly, the developed model did not take into account the size and evolution of the brain in any way – caring for offspring led to an increase in life expectancy independently.
According to scientists, the emergence of the phenomenon of grandmothers in humans and the subsequent increase in life expectancy was associated with climate change. According to them, the ancient people, faced with droughts, were faced with a choice. They could migrate following the shrinking forests, where small (not infants) children are able to feed on fruit on their own. Or go to the savannahs, where the food of minors is completely dependent on adults. In the latter case, this led to the emergence of caring for offspring at a late age and a corresponding increase in life expectancy.
It should be noted that the model provides a mathematical justification for the previously stated evolutionary hypothesis, and does not prove the real role of grandmothers in the history of anthropogenesis. To do this, it would be necessary to determine the change in the average life expectancy of human ancestors over a long time, and scientists do not yet have such data.
Recently, another group of anthropologists conducted a simulation of the nutrition of humans and their closest relatives and showed that before the invention of heat treatment, primates could not afford such a large brain as humans possess.
Portal "Eternal youth" http://vechnayamolodost.ru24.10.2012