A fascinating new paper by the University of Utah’s Kristen Hawkes and colleagues supports the “Grandmother Hypothesis,” which says humans evolved their long postreproductive lifespan, shared only by elephants and killer whales, at least in part due to participation of grandmothers in child rearing.
From a summary here:
The theory says that because a few older women among human ancestors began caring for their grandchildren, their daughters could have more children at shorter intervals, and that women ended up evolving long postmenopausal lifespans, unlike female apes who rarely survive past their childbearing years.
I suspect that evolution of the human appetite for protein was likely optimized through selection pressures for having and raising children, possibly including grandchildren, but not for living past age 60. The Grandmother Hypothesis is consistent with this idea, because once grandchildren become independent, grandmothers have almost no further role in enabling survival of their own genes in later generations. Of course, this assumes no significant participation by great-grandparents in raising great-grandchildren.
protein.md 
This a classic example of how evolution clouds the mind and prevents one from using common sense.
How often do you see elderly animals–male or female–out in the wild, out on the streets, PERIOD? I’ve never seen an elderly tottering pigeon, squirrel, stray cat or dog roaming around as elderly human beings do–HAVE YOU?
That is likely because the weak and the slower get LEFT BEHIND in the animal world. That’s just a harsh reality. Animals do not have the thought processes or physical capabilities that enable them to take care of the elderly or disabled as WE (humans) DO, so they will not have the same access to food and they will be the first to die.
Human beings, on the other hand, not only have the capability to take care of those who cannot care for themselves, but are are often able to care for themselves despite age or other physical challenges. Human beings live in an orderly society where everyone is able to access basic necessities in life. There is no fear of the younger and stronger taking all of the available food resources as is a reality amongst most animals.
So why are there fewer animals of post-reproductive age around? And even fewer older females around? Let me enlighten you. It is because the weaker animals, who will have a harder time competing with for food, water, and shelter than their younger competitors; will be the first to die of malnutrition and exposure. Older females are not only older, they are usually smaller and weaker compared to their male counterparts. They will have the lowest chance of survival. A revelation, isn’t it?
There’s no magic time clock that makes female animals (not on captivity) live shorter lives than their male counterparts. No magic evolutionary NEED that makes women and female animals IN CAPTIVITY often live just as long or longer than their male counterparts–it’s simply about ACCESS TO FOOD AND SHELTER. WOW. I must be a genius to have been able to figure out what’s perplexing scientists right now.
Maybe now they can move on to more pressing issues.