Human Lifespans Nearly Constant for 2,000 Years

Live Science ^ | Aug 21, 2009 | Benjamin Radford

[decimon]

The Centers for Disease Control and Prevention, often the harbinger of bad news about e. coli outbreaks and swine flu, recently had some good news: The life expectancy of Americans is higher than ever, at almost 78.

Discussions about life expectancy often involve how it has improved over time. According to the National Center for Health Statistics, life expectancy for men in 1907 was 45.6 years; by 1957 it rose to 66.4; in 2007 it reached 75.5. Unlike the most recent increase in life expectancy (which was attributable largely to a decline in half of the leading causes of death including heart disease, homicide, and influenza), the increase in life expectancy between 1907 and 2007 was largely due to a decreasing infant mortality rate, which was 9.99 percent in 1907; 2.63 percent in 1957; and 0.68 percent in 2007.

But the inclusion of infant mortality rates in calculating life expectancy creates the mistaken impression that earlier generations died at a young age; Americans were not dying en masse at the age of 46 in 1907. The fact is that the maximum human lifespan — a concept often confused with "life expectancy" — has remained more or less the same for thousands of years. The idea that our ancestors routinely died young (say, at age 40) has no basis in scientific fact.

[decimon]

Draining swamps and spraying mosquitoes WAS led by medical science.

Not arguing with your contention but the draining of swamps was done before it was known why that reduced such as malaria.

[Darth Reardon]

Yes, it’s interesting how rarely anyone lives past 120

Interesting maybe, but not surprising. Every time a chromosome is replicated, a little bit of the end of the chromosome is lost. Fortunately, chromosomes come with things at the end called telomeres, which are DNA sequences which (basically) are unused "junk" and serve primarily to protect the "important" DNA.

A telomere is often compred to an aglet (the plastic part of your shoelace which keeps the lace from unravelling), FWIW.

Eventually, you run out of telomere, and chromosomes begin to lose encoding DNA during replication. The body stops making the right stuff, and in some cases makes the wrong stuff, and eventually the wheels on the bus stop going round and round.

At the same time, the longer you live, the slower you move, and the more chances you have to get hit by a bus.

Finally, we have cancer. The body has defenses against cancer (interestingly, the "reason" for telomeres is so that one of the body's defenses against cancer doesn't kill us). IIRC, there are three main ones. Each can be defeated by genetic mutation. Once all three are gone, you're hosed. The longer you live, even if you avoid all of the things that cause high probabilities of said mutations, the higher the odds of eventually hitting the trifecta.

[brytlea]

Yup, I’m a biology teacher, so I know about telomeres and I’m indeed familiar with that. :)

[Flag_This]

"The days of our years are threescore years and ten; and if by reason of strength they be fourscore years, yet is their strength labour and sorrow; for it is soon cut off, and we fly away."
Psalm 90:10

I find this verse interesting re. the topic at hand.

[decimon]

"The days of our years are threescore years and ten; and if by reason of strength they be fourscore years, yet is their strength labour and sorrow; for it is soon cut off, and we fly away." Psalm 90:10

We're doing a bit better than that but not much.

[SampleMan]

Not arguing with your contention but the draining of swamps was done before it was known why that reduced such as malaria.

Sure, but it was coincidental and generally had little impact because it was not done systematically, but rather as a matter of draining useful ground for production. Thus some would be drained and some wouldn't. 18th and early 19th century Amsterdam, Philadelphia, Washington D.C. etc. were plagued with Yellow Fever, despite a strong push to make productive use of the marshes where feasible. The problem was that often it just wasn't feasible from an agricultural economic viewpoint.

The sanitation leaps of the 19th century were absolutely tied to eliminating disease. Many scientists connected the dots of cause and effect, even if they couldn't yet exactly explain the why.

What is worth note though is that I doubt the men of which we speak would have ever thought to divide science into separate pursuits. They were generalists who explored sanitation one day and astronomy the next.

[Flag_This]

"...Amsterdam, Philadelphia, Washington D.C. etc. were plagued with Yellow Fever"

They may have drained the swamp surrounding D.C., but there's a new strain of Yellow Fever that has devastated the GOP.

[SampleMan]

They may have drained the swamp surrounding D.C., but there's a new strain of Yellow Fever that has devastated the GOP.

Indeed.

[Pharmboy]

Don’t forget vaccines; arguably MUCH more important than antibiotics in increasing life expectancy.

[SunkenCiv]

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[rdl6989]

Ask any genealogist. I’ve seen lots of cemetery indexes listing people who died in the 1600’s in the colonies who were in their 70’s or 80’s. At first I thought it was a little odd because “everybody knows” people died young back then.

[the OlLine Rebel]

Read on.

[SunkenCiv]

Yeah, heh... one of my ancestors passed the century mark before she passed over 250 years ago. In the Middle Ages a young man from northern Africa wound up meeting the Pope of that time, converting to Christianity, and (having been born a few years from the end of the previous one) lived to be over 100 years old and saw the entire century. :’)

[ApplegateRanch]

ITMT, the mortality rate has never changed: one death per live birth...with one notable exception.

[ApplegateRanch]

but there's a new strain of Yellow Fever that has devastated the GOP.

Lot of them getting hit by the West de Nile virus, too.

[Free Vulcan]

Just going up my mom’s line - ggrandfather - 91, gg-grandfather - 83, ggg-grandfather 80, his wife’s father - 100, his g-grandfather - 83 born in 1695. That’s one of many just in my family tree.

[aruanan]

Americans were not dying en masse at the age of 46 in 1907. The fact is that the maximum human lifespan — a concept often confused with "life expectancy" — has remained more or less the same for thousands of years. The idea that our ancestors routinely died young (say, at age 40) has no basis in scientific fact.

That "maximum human life span" has remained the same for thousands of years doesn't mean that there aren't conditions under which the majority of the population will fail to reach that maximum. Retirement age for purposes of Social Security was chosen because of the relatively few number of years the retiree would collect after retiring. People now live a lot longer and are far more active now at retirement age than they were at the beginning of the 20th century. This writer really needs to read Robert W. Fogel's Nobel Prize Lecture.

[decimon]

Retirement age for purposes of Social Security was chosen because of the relatively few number of years the retiree would collect after retiring.

A lesser percentage of people reached the elder years.

I think the author made a good point in debunking a popular notion. I think the author misleads in not providing a more complete picture of what he discusses.

[marsh2]

I am assuming they had some way of removing those who died at war. That would load deaths with younger people and skew the average.

[Vermont Lt]

OK....so how do we protect them? Thats the billion dollar mousetrap.