Would Life Be Meaningless Without Death?

The other day, I read several articles raging against the commonly repeated notion that ultimately it is death that gives our life meaning. Some of the articles were fairly good while others were mostly pseudo-philosphical nosense. None were anywhere near as succinct as the New U-Station from Borderlands 2.

If any idiot ever tells you that life would be meaningless without death, Hyperion recommends killing them.

Lowered U.S. Life Expectancy, Part 1 – Violence

We know that those of us living in the United States have shorter life expectancy than those living in similar industrialized countries, such as in Europe. We also know that Americans are far more likely to be the victims of homicide than those who live in countries like ours, but how much does that increased risk of homicide impact life expectancy? How much longer would we be likely to live if we didn’t live in such a violent country?

The Associated Press looked at this question in its coverage of a recent report about health discrepancies between the United States and other industrialized nations. The report, U.S. Health in International Perspective: Shorter Lives, Poorer Health is available to read for free online.

First, lets look at just how big those life expectancy discrepancies are. The report looks at life expectancy of men and women in 17 similar countries in 2007. For women, the U.S. life expectancy rate in 2007 was 80.78 years. Japan led the world in life expectancy for women that year at 85.98 years. So U.S. women had a life expectancy 5.2 years lower than Japan.

For men, the U.S. life expectancy rate in 2007 was 75.64 years. Switzerland led the world in life expectancy for men in 2007 with an average of 79.33 years. So American men born in 2007 could expect to die 3.69 years sooner on average than men born in the same year in Switzerland.

The report estimates that homicide and suicide together account for up 25 percent of that disparity for U.S. men. So, compared to Switzerland, American men born in 2007 will on average die a little over 11 months earlier because of the combination of an extremely high homicide rate and relatively high suicide rate.

Differentials in Life Expectancy by Educational Attainment

An interesting study was published in Health Affairs last year finding a fairly stark difference in life expectancy based on years of education (emphasis added).

In this article we update estimates of the impact of race and education on past and present life expectancy, examine trends in disparities from 1990 through 2008, and place observed disparities in the context of a rapidly aging society that is emerging at a time of optimism about the next revolution in longevity. We found that in 2008 US adult men and women with fewer than twelve years of education had life expectancies not much better than those of all adults in the 1950s and 1960s. When race and education are combined, the disparity is even more striking. In 2008 white US men and women with 16 years or more of schooling had life expectancies far greater than black Americans with fewer than 12 years of education—14.2 years more for white men than black men, and 10.3 years more for white women than black women. These gaps have widened over time and have led to at least two “Americas,” if not multiple others, in terms of life expectancy, demarcated by level of education and racial-group membership.

The actual study is behind a stupid paywall, but there doesn’t seem to be any consensus as to what is causing such a large gap. Part of it appears to be down to things like increased smoking rates among people with less education (especially white women) as well as more obvious things like higher levels of education begin correlated with better access to health care.

Census Bureau Report on Centenarians

The U.S. Census Bureau recently released a report (1mb PDF) on American Centenarians — men and women (mostly women) over the age of 100 years old in the United States. According to the report,

. . . in 2010, there were just 53,364 centenarians in the United States, or 1.73 centenar- ians per 10,000 people in the total population. Even among the older population, centenarians are rare. Of those aged 70 and older, only 0.19percent (or 19 per 10,000) were centenarians, while 6.5 percent were in their 90s, 33.6 percent were in their 80s, and 59.6 percent were in their 70s.

The centenarian share of the total population is smaller than that for other developed countries. The U.S. proportion, 1.73 centenarians per 10,000 people, is lower than the proportion in Sweden (1.92 per 10,000), the United Kingdom (1.95 per 10,000), and France (2.70 per 10,000) (Statistics Sweden, 2010; Human Mortality Database, 2012). The U.S. proportion is about half the level found in Japan, 3.43 per 10,000 (Statistics Bureau of Japan, 2011).

One of the interesting things about reaching 100 is that — not surprisingly — reaching that milestone means you’re very close to dying. The life expectancy of someone reaching 100 is only 2.4 years. According to the Census Bureau report, there were only 330 people in the United States 110 years or older, and the report cautions a healthy degree of skepticism about that number “data quality generally declines as age increases within the centenarian age category.”

Gompertz Law of Human Mortality

Gravity and Levity has a concise, informative summary of the Gompertz half of the Gompertz-Makeham Law of Mortality.

In the early part of the 19th century, mathematician Benjamin Gompertz proposed that mortality rates increased exponentially over time. Specifically, any individual’s odds of dying double every 8 years. As Gravity and Levity summarizes it,

For me, a 25-year-old American, the probability of dying during the next year is a fairly miniscule 0.03% — about 1 in 3,000.  When I’m 33 it will be about 1 in 1,500, when I’m 42 it will be about 1 in 750, and so on.  By the time I reach age 100 (and I do plan on it) the probability of living to 101 will only be about 50%.  This is seriously fast growth — my mortality rate is increasing exponentially with age.

And if my mortality rate (the probability of dying during the next year, or during the next second, however you want to phrase it) is rising exponentially, that means that the probability of me surviving to a particular age is falling super-exponentially.

Why would this be the case? There is a longer explanation at Gravity and Levity, but the short version is that the human body simply wasn’t engineered by evolution to survive all that long. Accumulated injuries, disease and other things that impact health eventually exhaust the body’s ability to overcome the damage.

On the one hand, this is a bit depressing to see our odds of surviving decreasing super-exponentially. On the other hand, it means there is something that could potentially be done about it if better technologies are developed to repair or avoid the damage that the body itself cannot repair (for example, a medical advance that all but eliminated breast or colon cancer).

Drug Extends Life Span in Mice

Technology Review has a story on the first drug demonstrated to expand the lifespan of a mammalian species. In this case, rapamycin was administered late in the life of mice and extend lifespan by an average of 9 percent in males and 13 percent in females.

According to TR, rapamycin is already approved in the United States for use as an immunosuppressive drug for organ transplant recipients and is being tested for its potential to treat cancer.

The drug may act as a chemical form of caloric restriction, the only other method known to significantly extend lifespan in mice,

Experts believe it’s possible that rapamycin may tap into one of the same biochemical pathways as calorie restriction, an intervention long known to make mice live longer. While the drug was not as effective as a limited diet initiated early in life, it was far more powerful than a limited diet begun at the same advanced age. In ongoing studies, the researchers are testing different doses across a range of starting ages; an optimal combination may ultimately prove more potent than calorie restriction.

That would certainly be nice.