Human supercentenarians share at least one thing in common--over 95
percent are women. Scientists have long observed differences between the
sexes when it comes to aging, but there is no clear explanation for why
females live longer. In a discussion of what we know about stem cell
behavior and sex, researchers argue that it's time to look at
differences in regenerative decline between men and women. This line of
research could open up new explanations for how the sex hormones
estrogen and testosterone
, or other factors, modify lifespan.
, or other factors, modify lifespan. 
It's known that estrogen has direct effects on stem cell populations
in female mice, from increasing the number of blood stem cells (which is
very helpful during pregnancy) to enhancing the regenerative capacity
of brain stem cells at the height of estrus. Whether these changes have a
direct impact on lifespan is what's yet to be explored. Recent studies
have already found that estrogen supplements increase the lifespan of
male mice, and that human eunuchs live about 14 years longer than
non-castrated males.
More work is also needed to understand how genetics impacts stem cell
aging between the sexes. Scientists have seen that knocking out
different genes in mice can add longevity benefits to one sex but not
the other, and that males in twin studies have shorter telomeres--a sign
of shorter cellular lifespan--compared to females.
"It is likely that sex plays a role in defining both lifespan and
healthspan, and the effects of sex may not be identical for these two
variables," the authors write. "As the search continues for ways to
ameliorate the aging process and maintain the regenerative capacity of
stem cells, let us not forget one of the most effective aging modifiers:
sex."
This story is taken from Science Daily
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