When investigating aging and longevity through comparing the biology of different species, one place to start is with the few species that are unusually long-lived in comparison to similarly-sized neighboring species. Hence the study of naked mole rats, which live nine times as long as other small rodents. Bats are also of interest, as they live much longer than other small active mammals. Digging into their biochemistry might tell researchers more about how the operation of mammalian metabolism determines longevity and the pace of aging. The results here, for example, may reinforce the role of growth hormone receptor (GHR) in the pace of aging:
Bats are among the most successful groups of animals. They account for ~20% of mammalian species, are the only mammals that have evolved powered flight, and are among the few animals that echolocate. Bats are also among the smallest of mammals, but are unusually long-lived, thus challenging the observed positive correlation between body mass and maximum lifespan. The Brandt's bat (Myotis brandtii) holds the record with regard to lifespan among the bats. Its reported maximal lifespan of at least 41 years also makes it the most extreme mammal with regard to disparity between body mass and longevity.
Here we report sequencing and analysis of the Brandt's bat genome and transcriptome, which suggest adaptations consistent with echolocation and hibernation, as well as altered metabolism, reproduction and visual function. Unique sequence changes in growth hormone and insulin-like growth factor 1 receptors are also observed. The data suggest that an altered growth hormone/insulin-like growth factor 1 axis, which may be common to other long-lived bat species, together with adaptations such as hibernation and low reproductive rate, contribute to the exceptional lifespan of the Brandt's bat.
It is prudent to ask whether the changes in the GHR/IGF1 axis in the Brand's bat contribute to the animal's long lifespan, its small body size or both. Although it is appreciated that other genes have been altered during the ~82 million years of bat evolution, we suggest that the changes observed in GHR and IGF1R contribute to the longevity and dwarfism-like phenotype of the Brandt's bat. Moreover, M. brandtii may mirror GHR dysfunction in mice and humans, and possibly insulin signalling in long-lived nematodes.