June 20, 2013 | News

Congratulations!

On June 19, Boris Kramer from the Laboratory of Evolutionary Biodemography successfully defended his dissertation at the University of Mainz. His PhD research focused on the lifespan of eusocial insects. Their length of life varies significantly depending on the tasks they have been allocated to perform in the state.

The individual maximum lifespan of most animal species and of Homo sapiens does not deviate much from the average. It is thus reasonable to assume that life expectancy is in some way heritable.  But there are exceptions.

Such exceptions are eusocial insects, among others, bees and ants. These so-called hymenopterans have queens, a few males, and a large body of female workers. A queen ant can live up to 28 years, female workers of the same species, by contrast, have a maximum lifespan of 3 years; this notwithstanding the fact that there are no genetic differences between them.

Is this just a whim of nature? An exception that proves the rule? Not at all, says biologist Boris Kramer. In his dissertation, he studied the evolution of lifespan and colony size in various eusocial insects. Among other things, he was able to show that life-expectancy variation between workers and queen can be attributed to colony size and that these differences can contribute to the fitness of the colony.

Boris Kramer is convinced that this apparent special case in eusocial insects is not just a coincidence. This is because the behavior of these insects makes sense evolutionary and it is plausible when a different perspective is taken — a perspective that does not consider every individual insect as such but rather the colony they form as kind of an a superorganism that must be considered in its entirety.