In A Nutshell: The Science of Ageing
By Sarah Holt
"Growing old is mandatory, but growing up is optional"... Walt Disney.
"Age is a matter of mind over matter. If you don't mind it doesn't matter"... Mark Twain.
There's no shortage of famous quotes that try to make light of the concept of aging. The truth is, though, the question of why people grow old and die is one that the human race has been trying to answer for centuries.
In science, biological aging is better known as senescence. The journal and online scientific database Nature defines it specifically as "the process by which cells irreversibly stop dividing and enter a state of permanent growth arrest without undergoing cell death. Senescence can be induced by unrepaired DNA damage or other cellular stresses".
According to charity and open knowledge resource Physiopedia modern biological theories of aging can be split into two categories - programmed and damage or error theories.
It explains: "The programmed theories imply that ageing follows a biological timetable (regulated by changes in gene expression that affect the systems responsible for maintenance, repair and defense responses), and the damage or error theories emphasise environmental assaults to living organisms that induce cumulative damage at various levels as the cause of ageing.
"These two categories of theory are also referred to as non-programmed ageing theories based on evolutionary concepts (where ageing is considered the result of an organism’s inability to better combat natural deteriorative processes), and programmed ageing theories (which consider ageing to ultimately be the result of a biological mechanism or programme that purposely causes or allows deterioration and death in order to obtain a direct evolutionary benefit achieved by limiting lifespan beyond a species-specific optimum lifespan."
These theories, however, focus on the physical elements of aging. They don't explain why the phenomena happens in nature in the first place. A possible answer for this is provided by evolutionary psychologists through The Grandmother Hypothesis.
Psychology Today describes this theory as follows: "The hypothesis, first put forth by anthropologist Kristen Hawkes of the University of Utah, addresses the mystery of why menopause evolved. According to Hawkes, having grandmothers around, especially maternal grandmothers, makes children more likely to survive to adulthood — an adaptive advantage to women who live past their childbearing years, who are able to pass along their longevity genes to the grandchildren’s generation."
The Atlantic explains further: "In the 1980s, Kristen Hawkes and James O'Connell spent time with Hadza hunter-gatherers. They noticed that the older women in the society spent their days collecting tubers and other food for their grandchildren. That was the proverbial fallen apple that sparked Hawkes' interest in the Grandmother Theory, which says that humans evolved to live so long because grandmothers were around to help take care of the young'uns.
"The Grandmother Hypothesis goes further than to establish the importance of grandmas. In our early years as a species, the theory goes, older women helped gather food for their offsprings' offspring.
"In so doing, they were freeing up their daughters to have more children, more quickly. So the most evolutionarily fit grandmothers have the most grandchildren, to whom they pass on their longevity-promoting genes."