Social modulation of ageing in termites

As an individual grows older, its bodily functions deteriorate. This phenomenon is known as senescence. Across the tree of life, the rate of senescence varies tremendously. A fruit fly finishes its life cycle within a few weeks, while an elephant can live for several decades. Intriguingly, differences in longevity exist not only among different species but also among different individuals of the same species. So, how and why can some individuals outlive others? I research this big question using small organisms like termites. Plagued by bad press, termites often impress people as “pests” that destroy their favourite books and houses. However, for biologists, termites are excellent model organisms to study the causes of senescence, especially its link with social life. This is because termites live a social life that is characterised by a division of labour, and their queens and kings are able to achieve extraordinary longevities (up to 20 years) in parallel with remarkable reproduction rates (up to 20000 eggs per day). This combination of long life and high reproduction rate is contradicted by classical evolutionary theories of ageing which predict that long life trades off reproduction. In this thesis, I investigate how and why termite queens and kings can live so long and what role social life plays in shaping it.