THE secret to a long life has been sought in the strangest of places, and latest on the list is the finch family. Some of these songbirds live an unusually long time for their size, and now Hagai Rottenberg of New Hope Biomedical R&D in New Hope, Pennsylvania, has a clue as to why. He has found they have a peculiarly high rate of evolution of a protein called cytochrome b.
Larger animals generally live longer than small ones. This is thought to be because their size allows them to conserve energy and so have a slower metabolism, which in turn produces fewer cell-damaging free radicals. But many animals, including the small yet long-lived finches, don鈥檛 fit this pattern.
Rottenberg has compared the gene sequences, lifespan and mass of birds in 122 genera and found that of all the finches the canaries have the most rapidly evolving cytochrome b, and that the changes cluster in a region that may inhibit the production of free radicals (The Journal of Experimental Biology, vol 210, p 2170). Cytochrome b helps generate energy in the mitochondria, the powerhouses of cells, and versions of the protein that do this without producing an excess of free radicals will be favoured by evolution.
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Selection for reduced production of free radicals may help prolong life, and may boost brainpower too, Rottenberg says. Free radicals are thought to interfere with cognitive functions such as long-term memory. 鈥淭he groups with the fastest cytochrome b evolution and the longest life, like primates, elephants and dolphins, also share exceptional cognitive ability and sociality,鈥� he says. Canaries, with their need to learn and memorise complex tunes, are similar in this regard.
鈥淲hether there is a link between cytochrome b, longevity and cognitive function in individual humans remains to be seen鈥�
Aubrey de Grey of the SENS Institute in Cambridge, UK, sees the work in terms of longevity explaining intelligence. 鈥淎 long lifespan creates pressure to protect neurons from free radicals which may help advanced cognition to evolve.鈥�
Smart animals may also be under pressure to further increase their lifespan, Rottenberg points out: 鈥淭hey need extra time to learn, memorise and exchange all the complex information their brains can process.鈥�
Whether there is a link between cytochrome b, longevity and cognitive function in individual humans remains to be seen. 鈥淪ome mitochondrial gene mutations are linked with exceptional longevity and I have seen results suggesting that smart people live longer,鈥� says Jo茫o Magalh茫es of Harvard University. 鈥淏ut this may simply be due to a healthier lifestyle.鈥�
