Human epidemiological data exhibits a web of correlations between intelligence, education, wealth, lifestyle choices, social status, and longevity. Correlations are simple enough to discover, but determining causal relationships is much harder, particularly when pulling in the possible role of biological mechanisms. Nonetheless, there is an intriguing thread of research suggesting that there is some biological contribution to the correlation between intelligence and longevity. It may be that some aspects of the natural variation between individuals in physical robustness, or in resilience to age-related cell and tissue damage, can contribute to both intelligence and longevity.
As today’s open access paper makes clear, the measurement of intelligence is a tricky business. One can argue about the merits of the various approaches taken in humans, but an entirely different set of issues arises when trying to measure intelligence in lower species. The paper is an addition to the body of knowledge regarding the correlation between intelligence and longevity in flies, but there is room to argue that the assessment used may not be a measure of intelligence per se, or at least not in a way that is easily related to the way we measure intelligence in humans. Flies are presented with a left or right choice in a simple T maze and there is food in one direction that can be sensed by smell. Are flies that head towards the food actually more intelligent, or is this instead a measure of drive, olfactory capability, or some other line item? One sees the challenge. Since the successful flies lived longer, there is clearly some interesting biology here relating to robustness in cell function, but it is far from clear that intelligence is involved.
Genetic association of intelligence with longevity in Drosophila melanogaster
Epidemiological studies in different populations, in different countries, and in different epochs consistently showed that high intelligence is positively correlated with longevity. The link between high intelligence and longevity has remained unknown, only to be assumed as a consequence of the socioeconomic difference associated with intelligence in human population.
Here, we report that genome stability contributes both to lifespan and intelligence in Drosophila melanogaster. The intelligence of the genetically heterogenous flies was determined by T-maze olfactory memory assay, and the flies moving to the right direction defined as intelligent flies (INT) were separated from the flies moving to the wrong direction defined as non-intelligent flies (NINT). INT male and female lived 26.40% and 21.35% longer than NINT male and female, respectively, suggesting a possible genetic linkage between intelligence and longevity.
The bidirectional selective breeding based on intelligence extended lifespans gradually generation by generation in INT breeding contrast to the reversed pattern in NINT breeding. INT of F12 generation lived longer than NINT of F12 generation, 63.91% for male and 67.88% for female, as a result from slower aging. The whole-genome transcriptome analysis showed the activation of the genes in ribosome and autophagy in INT and the pathways of genome stability and immune reaction in NINT. Especially, the genetic pathway associated with genome stability was most noticeable, indicating that genome stability contributes both to lifespan and intelligence in D. melanogaster.
