Michio Kaku on life expectancy
Michio Kaku is currently promoting his new book, Physics of the Future. Today, for the second time, I heard him make an incredible statement about the genetic basis of human longevity. In episode 94 of Dr. Kiki's Science Hour he says:
"We are 98.5 [percent] identical to the chimpanzee, genetically speaking, and yet we live twice as long. So among a handful of genes, a handful of genes, are the genes which doubled our life span since the chimpanzees."
I had immediate doubts when I heard him say this last month on Democracy Now. I agree that there is almost certainly a genetic basis to aging and longevity, but it's not the whole story. The relevant differences between a chimpanzee's life and that of a human being in a developed nation are not wholly attributable to "a handful of genes," as Kaku suggests. If chimpanzees had access to modern plumbing, mountains of food, social services, hospitals and vaccines, I have no doubt that they would live longer.
But is Kaku's statement even correct? After hearing it repeated this morning, I decided to look into it. One study (which I only skimmed) by Jane Goodall and colleagues compared hunter-gatherer societies living today with wild chimps and concluded, "Modern human foragers generally have twice the life expectancy at birth and more than twice the life expectancy once they reach adulthood." But several other sources, like this one, report chimpanzees live to be 40-50 in the wild, which puts them in line with the 47-year life expectancy of humans living in developed countries in 1900. I suspect that some of the discrepancies arise from different definitions of life expectancy. I think we should continue to investigate the genetic and evolutionary roots of longevity, but not without considering other important factors.
"We are 98.5 [percent] identical to the chimpanzee, genetically speaking, and yet we live twice as long. So among a handful of genes, a handful of genes, are the genes which doubled our life span since the chimpanzees."
I had immediate doubts when I heard him say this last month on Democracy Now. I agree that there is almost certainly a genetic basis to aging and longevity, but it's not the whole story. The relevant differences between a chimpanzee's life and that of a human being in a developed nation are not wholly attributable to "a handful of genes," as Kaku suggests. If chimpanzees had access to modern plumbing, mountains of food, social services, hospitals and vaccines, I have no doubt that they would live longer.
But is Kaku's statement even correct? After hearing it repeated this morning, I decided to look into it. One study (which I only skimmed) by Jane Goodall and colleagues compared hunter-gatherer societies living today with wild chimps and concluded, "Modern human foragers generally have twice the life expectancy at birth and more than twice the life expectancy once they reach adulthood." But several other sources, like this one, report chimpanzees live to be 40-50 in the wild, which puts them in line with the 47-year life expectancy of humans living in developed countries in 1900. I suspect that some of the discrepancies arise from different definitions of life expectancy. I think we should continue to investigate the genetic and evolutionary roots of longevity, but not without considering other important factors.