Al Fin, You Sexy Thing!

14 June 2012

Older Men and Younger Babes: For the Good of the Species

New research published in PNAS reveals that the sperm of older men tends to have longer telomeres, conferring an advantage in longevity to offspring.
Dr Dan Eisenberg and colleagues from the Department of Anthropology at Northwestern University studied telomere inheritance in a group of young people living in the Philippines.

Telomeres, measured in blood samples, were longer in individuals whose fathers were older when they were born.

The telomere lengthening seen with each year that the men delayed fatherhood was equal to the yearly shortening of telomere length that occurs in middle-aged adults.

Telomere lengthening was even greater if the child's paternal grandfather had also been older when he became a father.

...Inheriting longer telomeres will be particularly beneficial for tissues and biological functions that involve rapid cell growth and turnover - such as the immune system, gut and skin - the scientists believe.

And it could have significant implications for general population health.

"As paternal ancestors delay reproduction, longer telomere length will be passed to offspring, which could allow lifespan to be extended as populations survive to reproduce at older ages." _BBC

Here's more from an earlier Stanford study:
It turns out that older men chasing younger women contributes to human longevity and the survival of the species, according to new findings by researchers at Stanford and the University of California-Santa Barbara.

Evolutionary theory says that individuals should die of old age when their reproductive lives are complete, generally by age 55 in humans, according to demographer Cedric Puleston, a doctoral candidate in biological sciences at Stanford. But the fatherhood of a small number of older men is enough to postpone the date with death because natural selection fights life-shortening mutations until the species is finished reproducing. _Stanford

This makes a certain amount of evolutionary sense. If humans stop reproducing around the age of 40 or 45, there is no particular reason that longevity-promoting genes would be passed on to future generations at a higher rate than anti-longevity genes.

We know that women lose fertility fairly rapidly after the age of 30 or 35. A woman's overall energy levels and ability to keep up with a young child also decline with age.

Women in their twenties have a good chance of becoming pregnant as a result of a relatively greater number of eggs in their ovaries. Additionally, a larger percentage of those eggs are normal genetically. Since a woman is born with all of the eggs that they will have in their lifetime, the older she gets the fewer eggs are left. In addition, as women age the percentage of genetically normal eggs remaining decreases. This is why women have a decreasing fertility rate, increased miscarriage rate and increased chance of birth defects like Down syndrome as they age. _Female Age and Fertility

The scientists learned that in more traditional hunter-gatherer societies, the older man / younger woman pairing was most common, with a typical age difference of up to 15 years.

Older men capable of attracting younger women are more likely to be able to provide an economic advantage to offspring, in addition to the pro-longevity advantages. A more affluent mate can provide more assistance and reassurance, which a young mother often needs. The relative maturity and greater experience of the older man compared to the younger woman can provide a longer time perspective for the family as well.

Eventually, scientists will be able to select both sperm and eggs which confer life extending advantages to offspring. Until then, it might be best to follow the best evolutionary path. At least, Donald Trump and a large number of other men seem to think so. ;-)

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  • At Friday, July 13, 2012 11:30:00 AM , Anonymous Anonymous said...

    It would be interesting to know if ova also show this effect, and whether more moderate aging would balance telomere lengthening with less other damage to the DNA.

    Parenthood at 30 rather than 20 might deliver two sets of moderately long telomered chromosomes, rather than a single set with very long ones, and the other set with short telomeres.

    Alternately, one old set for longevity and one short set for minimal age damage might be the more advantageous combination.


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