New research shows that children of men who fathered them later in life may be able to expect to live longer than those of us whose fathers were young. But don't run into a nursing home with your pants around your ankles and arms outstretched just yet — the "older dad, longer life" principle only seems to apply to fathersstarted having children later and who spent their youths taking good care of their bodies and not being accidentally maimed in industrial accidents. In other words, it's a reflection of a society that fosters long life rather than genetic strength derived from individual choice. Clear as mud, right?

Researchers at Northwestern University found that men who start their babymaking later tend to live in the sort of social environment that sees men routinely live to middle age. The study's lead author Dan Eisenberg wrote in a news release,

If your father and grandfather were able to live and reproduce at a later age, this might predict that you yourself live in an environment that is somewhat similar — an environment with less accidental deaths or in which men are only able to find a partner at later ages. In such an environment, investing more in a body capable of reaching these late ages could be an adaptive strategy from an evolutionary perspective.

That seems kind of obvious, but what's most interesting about the study is the impact that older fathers have on successive generations. If men wait until later in life to bear children, their offspring are born with longer telomeres, the parts of DNA that keep chromosomes from deteriorating. Longer telomeres mean slower aging, which means that kids with older parents may age more slowly because their genes "think" that it probably won't be babymakin' time for awhile.

This complicates the question of the "male biological clock," as other research into old dudes who try to have kids has found that as men age, the quality of their sperm deteriorates, increasing the risk of certain genetic abnormalities.