A U.S. gerontologist says genetic advantages allow us to outlive our ape ancestors, although we are more susceptible to diseases of aging.
In spite of their genetic similarity to humans, chimpanzees and great apes have maximum life spans rarely exceeding 50 years. The difference, says University of Southern California-Davis Professor Caleb Finch, is as humans evolved, their genes enabled them to better adjust to levels of infection and inflammation and to the high cholesterol levels of meat rich diets.
Finch said such evolutionary genetic advantages, caused by slight differences in DNA sequencing, also make humans uniquely susceptible to diseases of aging, such as cancer and heart disease.
In addition to differences in diets, he said humans evolved unique variants in a cholesterol transporting gene, apolipoprotein E, which also regulates inflammation and many aspects of aging in the brain and arteries.
ApoE3 is unique to humans. But the minor allele, apoE4, when expressed in humans, can impair neuronal development, as well as shorten human lifespan by about four years and increase the risk of heart disease and Alzheimer disease by several-fold, he said.
"The chimpanzee apoE functions more like the "good" apoE3, which contributes to low levels of heart disease and Alzheimer's," Finch said.
He hypothesizes the expression of ApoE4 could be the result of the antagonistic theory of aging, in which genes selected to fight diseases during early life have adverse affects in later life.
The study appears in the early online edition of the Proceedings of the National Academy of Sciences.
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