This news release is available in German.
Ageing inevitably occurs both in humans and in other animals. However, life-span varies widely across species. Researchers of the Max Planck Institute for Ornithology in Seewiesen have now found a possible general mechanism explaining differences in longevity. They investigated life history data of nearly 1400 bird species and found that avian life span varies considerably across the entire Earth, and that much of this variation can be explained by the species' body mass and clutch size and by the local diversity of predator species. With their data the researchers were able to confirm a key prediction of the classical evolutionary theory of ageing that had been proposed more than 50 years ago.
It is well-known that organisms vary widely in life-span. Whereas some fish, turtles or even invertebrates can become hundreds of years old, the neon pygmy goby a small fish - reaches ripe old age at only 60 days. In birds, variation in life-span extends from parrots such as the Sulphur-crested cockatoo that can become more than 100 years old, to the small Allen's hummingbird with a maximum life-span of only 4 years, a 25 fold difference. How can this variation be explained?
The classical evolutionary theory of ageing, first proposed by the famous evolutionary biologist George C. Williams over 50 years ago, gives an answer. The theory predicts that high mortality rates in adult animals due to predation, exposure to parasites and other randomly occurring events will be associated with shorter maximum life-spans. This is because under high external mortality most individuals will already be dead (eaten or succumbed to disease) before natural selection can act on rare mutations that cause healthier ageing.
The theory has since be
|Contact: Dr. Bart Kempenaers|