Lifespan is random

I'm very surprised. The data from human and animal studies seems very strong. Lifespan is pretty random and not clearly related to genetics. The article also implies it's not clearly related to behavior either ...

Live Long? Die Young? Answer Isn't Just in Genes - New York Times:

...A woman whose sister lived to be 100 has a 4 percent chance of living that long, Dr. Christensen says. That is better than the 1 percent chance for women in general, but still not very great because the absolute numbers, 1 out of 100 or 4 out of 100, are still so small. For men, the odds are much lower. A man whose sister lived to be 100 has just a 0.4 percent chance of living that long. In comparison, men in general have a 0.1 percent chance of reaching 100.

Those data fit well with animal studies, says Caleb Finch, a researcher on aging at the University of Southern California. Genetically identical animals — from worms to flies to mice — living in the same environments die at different times...

...Matt McGue, a psychology professor at the University of Minnesota who studies twins, contrasts life spans with personality, which, he says, is about 50 percent heritable, or attention-deficit hyperactivity disorder, which is 70 to 80 percent heritable, or body weight, which is 70 percent heritable.

“I’ve been in this business for a long while, and life span is probably one of the most weakly heritable traits I’ve ever studied,” Dr. McGue said.

Random. That's weird. Nothing like I'd expected.

Incidentally, ADHD is incredibly hereditable and men don't live that long.

Update 9/1/06: This article continues to puzzle me. Although the researchers note that animal studies show limited hereditability of lifespan, that's not true of dogs. Different breeds have very different lifespans -- from the 4-6 years of Great Danes to the 18+ years of one Australian mid-sized breed. Could it be that we're deceived by the relative genetic homogeneity of humans, who, after all, went through that 10,000 person evolutionary bottleneck less than 200K years ago? They do mention some families do show an exception to this rule ...

One practical implication of the data is that it suggests persons with long lived families should not stint on life insurance policies ... And that life insurers can make a bundle by charging more to persons with short lived families. These folks will pay more for life insurance, thinking that it's more likely to be needed, but in fact their lifespans are not all that predictable.

Update 9/8/06: Still chewing this one over. I think the aging rate/cancer tradeoff plays a role ...