Evolutionary biologists at the universities in Bielefeld and Uppsala (Sweden) found that the descendants of these insects mostly inherit their lifespan from their own sex: male descendants will very probably live about as long as their fathers; female descendants, about as long as their mothers.
The study proceeded from the assumption that the average life expectancy of women and men differs -this may be for genetic reasons but also due to different lifestyles. The German-Swedish research team wanted to find out how far this sex difference in the lifespan depends on the genetic make-up.
To carry out their experiments, the researchers intervened in the heredity of fruit flies by cross-breeding them with special fly mutants. This enabled them to breed 50 hemi-clones; that is, groups of individuals in whom one-half of the genetic make-up is absolutely identical, whereas the other half is completely unrelated.
From each hemi-clone, the researchers determined the lifespan of 400 females and 400 males.
The authors then used the data from the hemi-cloned fruit flies to read off how similar the individuals in a hemi-clone are and how far females and males from one hemi-clone share the same lifespan.
Results showed that the lifespan was very similar within sexes, whereas the calculated relation between sexes was only slight. Hence, Methuselah genes in the father exert only a limited influence on female descendants - at least in fruit flies.
The study has been published in the journal 'American Naturalist.'