Answer: Wealth

From the NY Times:

People of Valentin Keller's era [mid 19th century], like those before and after them,
expected to develop chronic diseases by their 40's or 50's. Keller's
descendants had lung problems, they had heart problems, they had liver
problems. They died in their 50's or 60's.

Now, though, life has changed. The family's baby boomers are reaching middle age and beyond and are doing fine.

"I feel good," says Keller's great-great-great-grandson Craig Keller.
At 45, Mr. Keller says he has no health problems, nor does his
45-year-old wife, Sandy.

The Keller family illustrates what may
prove to be one of the most striking shifts in human existence "” a
change from small, relatively weak and sickly people to humans who are
so big and robust that their ancestors seem almost unrecognizable.

Scientists are looking for the explanation of a generation of humans so much stronger and healthier than those who preceded them.  Hypotheses seem to center on pre-natal maternal health and early life nutrition.  But I can give the bigger picture answer:  wealth.  Not Bill Gates wealth, but the generally enormous increase in wealth, even among the poorest Americans.  I discussed this issue along with other related ones in this article on wealth creation.  And this cartoon seems relevant.  Also makes you wonder about whether the obsession with obesity nowadays makes much sense.

The biggest surprise emerging from the new studies is that many chronic ailments like heart disease,
lung disease and arthritis are occurring an average of 10 to 25 years
later than they used to. There is also less disability among older
people today, according to a federal study that directly measures it.
And that is not just because medical treatments like cataract surgery
keep people functioning. Human bodies are simply not breaking down the
way they did before.

Even the human mind seems improved. The
average I.Q. has been increasing for decades, and at least one study
found that a person's chances of having dementia in old age appeared to
have fallen in recent years....

People
even look different today. American men, for example, are nearly three
inches taller than they were 100 years ago and about 50 pounds heavier.

A nice perspective to maintain during modern media-fed health panics.

Update:  Brian Doherty makes a similar observation.

  • http://genericconfusion.blogspot.com Greg

    That reminds me of the complaints about today's overweight and obese kids. I observe that today's 22 year olds are taller than last generation's 22 year olds. Why is that? I'm wondering if the kids of the 50's were actually undernourished, and they were thin but also stunted in growth.