Being smart helps you live longer, and that applies to humans and lemurs


The Grey Mouse Lemur has a tiny brain. But it's still pretty useful sometimes. Photo: Getty
The grey mouse lemur has the smallest brain of any primate. It weighs about two grams. That’s about half a teaspoon of sugar.
This might suggest that it lacks smarts – but researchers have found that some are smarter than others.
Smarter lemurs live longer.
And if you follow Charles Darwin’s survival of the fittest theory, smarter lemurs – by surviving longer than their dumbo relatives – enables the species to evolve as a smarter one over time.
That’s what researchers from the Leibniz Institute for Primate Research in Gottingen, Germany, were hoping to see happen in a new study:
“Only if smarter individuals enjoy better survival and have higher reproductive rates than their conspecifics [individuals of the same species], improved cognitive abilities can evolve.”
The plan
The scientists travelled to the Kirindy Forest is in western Madagascar.
There they caught 198 wild gray mouse lemurs and subjected them to four cognitive and two personality tests. They were then weighed and released.
They were marked – to indicate their level of smartness and personality – so they could be identified when recaptured. This meant their survival could be monitored and assessed.
How to test a lemur’s intelligence
The cognition tests assessed:
- Problem-solving (reaching food by manipulating a slider).
- Spatial memory (remembering the location of hidden food).
- Inhibitory control (taking a detour to access food).
- And causal understanding (retrieving food by pulling a string).
The first personality test evaluated exploratory behaviour.
The second measured curiosity through the animals’ reactions to unfamiliar objects.
The results
The scientists found that being smart led to a longer life. But it wasn’t the only route to longevity.
Being particularly explorative – willing to get out and search for food in unknown territory – also led to a longer life, although this was a strategy that presumably carried risks (of being caught and eaten). This seems to have been reflected in the fact that lemurs that did better on the cognitive tests were less inclined to be exploratory.
However, the more explorative individuals were heavier because they found more food. In human terms, they were chancers – and chancers can do very well indeed. Until their luck runs out.

Einstein was smart, but still silly enough to smoke. Photo: Getty
“These results suggest that being either smart or exhibiting good physical condition and exploratory behaviour are likely to be different strategies that can lead to a longer lifespan,” said Dr Claudia Fichtel, first author of the study and a scientist at the German Primate Centre.
“In future studies, we aim to investigate how cognitive abilities translate into behavioural strategies to find food or mating partner.”
What about people?
It’s not only smart lemurs who live longer. At least 20 longitudinal studies have shown a strong link between IQ and mortality: higher intelligence tends to deliver a longer life.
According to a piece in Scientific American, the Scottish government in 1932 administered an IQ test to nearly all 11-year old children who were attending school on a particular day.
In 1997, 65 years later, University of Edinburgh scientists went looking for those children who were now old people. They wanted to know who was still alive at 76 years of age.
They found that “a 15-point IQ advantage translated into a 21 per cent greater chance of survival”.
For example, “a person with an IQ of 115 was 21 per cent more likely to be alive at age 76 than a person with an IQ of 100” (which is the average for the general population).
One of the scientists was Professor Ian Dreary, a differential psychologist. He published a similarly big population study in 2017. Again, a high IQ delivered a long life.
“The increased risk of dying earlier from many different causes is not just about low versus high IQ scores,” said he told STAT.
Ian Deary, a psychologist at the University of Edinburgh and the senior author of the paper, puts it this way: “The slight benefit to longevity from higher intelligence seems to increase all the way up the intelligence scale, so that very smart people live longer than smart people, who live longer than averagely intelligent people, and so on.”
Albert Einstein, by the way, lived to 76. Which was pretty good for his time. But he was a smoker, and might have lived longer if he’d given up the pipe. Not so smart after all.