Intelligent people live longer—the correlation is as strong as that between smoking and premature death. But the reason is not fully understood. Beyond simply making wiser choices in life, these people also may have biology working in their favor. Now research in honeybees offers evidence that learning ability is indeed linked with a general capacity to withstand one of the rigors of aging—namely, oxidative stress.
Ian Deary, a psychologist at the University of Edinburgh, has proposed the term “system integrity” for the possible biological link between intelligence and long life: in his conception, a well-wired system not only performs better on mental tests but is less susceptible to environmental onslaughts. Gro Amdam of Arizona State University and the Norwegian University of Life Sciences was intrigued by the idea and last year devised a way to test it in bees.
Honeybees are frequently used as a neurobiological model for learning—they can be trained, using positive or negative reinforcement, to retain information. In Amdam’s experiment, individual bees were strapped into a straw, where they learned to associate an odor with a food reward in a classic Pavlovian conditioning scenario. After only one or two trials, many bees learned to stick out their tonguelike proboscis in anticipation of a sugary droplet. Some bees took a little longer—as in humans, there are quick learners and slower ones.
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To simulate aging, the same bees were then placed in plastic tubes and exposed to a high-oxygen environment, a metabolic stress test. All animals need oxygen to breathe, but an overload drives cells to churn out damaging free radicals that break down cell membranes and cause cells to commit suicide, triggering premature aging. The better learners tended to live longer during this ordeal—an average of 58.8 hours, as opposed to the poor learners’ average of 54.6—suggesting they have a more robust antioxidant system, which mops up destructive free radicals.
Amdam suspects that general stress resilience may explain why the quick learners lived longer. In the learning trials, the bees that could stand the stress of being in the straw were able to learn faster that the odor signaled a treat, and the same resilience allowed these bees to better withstand the stress of being in a high-oxygen environment.
For people, too, Amdam hypothesizes that the ability to handle stress could be a component of system integrity; better overall stress resilience may contribute to both higher IQ scores and longer life. And if scientists can unravel what underlies these biological differences, they might be able to alleviate inborn disparities. “There is an opportunity to help everyone live longer,” Amdam says.
