Wonder why you live longer than a chimp?:
Hawkes and colleagues of hers have long sought to advance their theory of grandmothering, which goes roughly like this. In the remote past, the common ancestral mothers of humans and great apes couldn't generally move on to have another child until their most recent nipper was no longer breast-feeding (breast feeding acts as a contraceptive, in order to prevent a mother being overburdened with children she can't support).
This could take quite a long time, much longer than it now does, as the infants need to be quite old before they can feed themselves and generally in an ape-man tribe nobody else was going to get hold of suitable food - for instance by digging up suitable root veg etc - and feed it to them.
Back then, female apes would generally die once they were past childbearing age: but naturally a few genetically different individuals might live on for longer. According to Hawkes and her colleagues, these older ape ladies in many cases would get hold of suitable infant food and pitch in to help feed their descendants. The nippers would thus be weaned earlier, allowing their mothers to have another child sooner, so spreading the grandma's unusual long-life genes faster and conferring an evolutionary advantage.
'via Blog this'


