The May 4, 2012, issue of the journal Science includes three briefs from the annual meeting of the American Association of Physical Anthropologists, one of which has a few choice words about telomere lengths. In case you hadn’t heard, studying telomere length is all the rage now as it apparently has some correlation to longevity. I don’t know. The whole thing seems fuzzy to me. Remember when neutrinos were going faster than the speed of light? That didn’t last long now did it?
As these creased and dog-eared magazines get passed back and forth at our family dinner table I had my brilliant wife (a real scientist) on hand for questioning.
“So is this telomere stuff for real?” I asked her.
“Mmm-hmm,” she said with a shrug. “It looks that way.” So there you have it, from the seat of authority.
Let’s refer to the Science journalist here:
Telomeres are repetitive sequences of DNA that prevent the ends of chromosomes from unraveling, much like the plastic tops on the ends of shoelaces. As cells divide and replicate, telomeres get shorter and eventually can no longer prevent the fraying of DNA and the decay of aging. Recent studies have found a link between living to 100 and having a hyperactive version of telomerase, an enyzme that keeps telomeres long.
If you’ve got long telomeres on your chromosomes then genetically speaking this is beneficial and improves your chances at living a long life. But what factors determines telomere length?
The results of some very interesting new research (cf. Science vol.336, pg.539) suggest that telomeres in sperm cells are proportional in length to the age of the man. Thus the older the father is at conception, the longer the telomeres of his offspring. The researchers found that this effect extended to grandfathers as well, passing on their telomeres to their son’s children but not their daughter’s children.
This doesn’t necessarily mean that older dads have great genetic advantages. In fact as we age our gametes are more likely to contain mutations, so there are definitely some benefits to having younger parents. But I couldn’t help but be prompted to reflect how reproductive advantages of older men might have had an impact on the organization of society.
Certainly when it comes to mothers, experience pays serious dividends in terms of reproductive fitness. As Sarah Blaffer Hrdy writes in Mother Nature, among primates first time mothers are generally less successful but since mothering is learned behavior this can improve with time. Thus:
Given a choice between two sexually swollen females, male chimps invariably choose the older one. It is interesting to speculate why men in some societies differ from other primates in this respect, placing so much emphasis on youth. One reason, I suspect is that these men are in a position to monopolize access to their mate and to literally possess her long-term. (186)
So human sexuality, as we can observe it today, is always already in the context of patriarchal relations. This may even extend to the cultural valuation placed the beauty of youth, which is desirable not because young people make better parents but because young women yield long term benefits for older men.
On the theme of “interesting to speculate” we might question whether older men hold some benefits in terms of the reproductive fitness of younger women. There is after all this ubiquitous pattern, seen around the world, of older men shacking up with younger women. This is readily observed in the age difference between spouses, with the male partner typically older than the female partner. What is the basis for this? How far back in human history does this pattern extend?
One outcome of this pattern is that from the beginning of the affinal relationship the male is in a privileged position as the elder. Of course, there are other factors that may be more relevant than the age difference of the spouses when it comes to understanding household micropolitics. For example, there are social and cultural reasons why a woman might choose an older man to be her mate. An older man might have command of more economic resources, or he might have more clout and authority in the community — things that can make a big difference when it comes to raising offspring to reproductive maturity.
Now perhaps we can count another “pro” in the advantages of older male spouses: longer telomeres. Because men and women have different reproductive strategies, a man who can sire children well into his maturity can have additional opportunities to enhance his fitness unavailable to his shorter lived peers. And this trait of longevity may be passed down to his offspring, and his son’s offspring.