DURHAM, N.C. — The genetic code of chimpanzees is just under 99% identical to that of human beings. And yet, us humans enjoy much longer lives than our closely related (and hairier) genetic cousins. Now, a team of researchers from Duke University and George Washington University believe they’ve uncovered why this is the case.
On average, chimpanzees rarely live to see their 50th birthday. Meanwhile, humans regularly live well into their 70s, 80s, and beyond. While it’s certainly true that the human lifespan has steadily improved in unison with medical breakthroughs and medicinal discoveries, researchers say the reason for humanity’s longer lifespan can be traced much farther back than the 20th century.
The authors theorize that a series of chemical changes along the DNA within our cells dating back seven or eight million years were the catalyst for our long lifespans and diminished rate of aging. So, these changes seem to have taken place right around the time our early-human ancestors broke away from chimps in general.
How aging affects our cells
Over the past decade, scientists have discovered that certain chemical marks on the human genome actually appear to change over time and as an individual grows older. These marks can influence gene activity without actually changing DNA sequences.
On a more detailed level, prior research has shown that specific areas of one’s DNA can “gain or lose” groupings of a certain type of chemical tag known as methyl groups. These tags follow a patterned sequence that appears to track the passing of time — almost like a metronome. Almost unbelievably, these changes are often so regular and consistent that scientists say they can be used to correctly estimate a person’s age within a roughly four year window.
This time around, researchers investigated the very same age-related DNA changes among chimpanzees. In total, 850,000 of these DNA sites were analyzed via blood samples collected from 83 chimps (aged one to 59 years old).
The ensuing findings were illuminating. Just like in humans, aging also leaves a genetic mark on chimpanzees. Over 65,000 examined DNA sites showed age-related changes.
“A lot of their genome shows an age-related pattern,” lead study author Elaine Guevara, an assistant research professor of evolutionary anthropology at Duke, says in a release.
Chimps’ cells age faster than humans
The chimps’ age patterns were so reliable that the research team was able to correctly guess each primate’s age using the markings within a 2.5 year range. Next, upon comparing the chimps’ age-related DNA changes to recorded markings in humans, the research team quickly noted that the chimps’ epigenetic aging clock is ticking at a much faster pace.
As of now, however, the study’s authors aren’t sure if these changes are simply keeping track of the chimps’ aging process, or actively jumpstarting/adding to it.
These findings are groundbreaking for a number of reasons. Besides just offering new information on what separates us from other animals, these discoveries may one day prove invaluable for the treatment and prevention of age-related diseases – in both chimpanzees and humans.
The study is published in Philosophical Transactions of the Royal Society B.