Jeremy Shere

If you could choose, would you rather be smarter and die sooner, or be dumber and live longer?

If you’re a fruit fly, you don’t have a choice–the smarter the fly, the sooner it dies. That’s according to a study done by scientists at the University of Lausanne in Switzerland. In their own words, the scientists found “a negative correlation between an improvement in a fly’s mental capacity and its longevity.”

How do they know? Through a simple experiment. The researchers took two groups of flies and then left one group alone and trained the other group using “Pavlovian methods.” Basically, they claim to have boosted the flies’ intelligence and memory. Then, according to a story on Physorg.com, “over 30 to 40 generations, these methods led to flies which clearly learned better and remembered things for longer.” And it turns out that the smart flies had shorter life spans than their untrained, stupider relations. (The dumb flies lived about 80-85 days, the smart flies lived around 50-60 days).

Why? Because, according to the researchers, larger and more active brains consume more of the body’s resources, leaving the flies more vulnerable.

At least this is what I think the scientists think. It’s not completely clear. It’s also not clear, at least to me, how the scientists define “intelligence.” According to another article about this experiment, the smart flies were bred to “associate a chemical scent with an unpleasant experience–a violent shaking of their test-tube home.” Does this mean that those flies were more intelligent, or were they simply more sensitive to smell? Or are heightened senses a component of intelligence.

I also wonder how, if at all, this finding translates to other species, including humans. In our case, at least over the span of evolutionary time, increased intelligence appears to correlate with increased life span. Prehistoric people had an average lifespan of something like 30 years, give or take. Now, under optimal conditions, people live into their late 70s, on average.

But then again, this could have just as much to do with environmental conditions as with intelligence. Are human necessarily smarter than humans 10,000 years ago? And then there’s the fact that humans are not the longest-lived creatures on the planet. Elephants can live to be over 70. And giant tortoises have been known to live more than 120 years.

Anyhow, the relationship between intelligence and life span is interesting. If you know more about this topic, please enlighten us.