Some worms programmed to die early for sake of colony

Some worms are genetically predisposed to die before reaching old age, which appears to benefit the colony by reducing food demand, finds a new UCL-led study. The modelling study, published in Aging Cell , provides the first evidence of programmed, adaptive death in an animal that has evolved due to the benefits to the community. Lead author Professor David Gems (UCL Institute of Healthy Ageing) said: "According to evolution theory, altruistic death to leave more food to your relatives normally can't evolve. This is because other individuals who live longer would consume resources left behind by altruistic comrades and outcompete them, in what's called a tragedy of the commons. "But it was recently discovered that wild C. elegans roundworms live in colonies of identical worms, which would prevent long-living worms with different genes from taking over." The researchers explain that evolutionary theorists originally believed that ageing evolved to reduce the population in order to increase food availability for the young, but scientists have since shown this cannot be true for most animal species as longer-lived non-altruists would usually be favoured by natural selection. However, certain organisms possess what appear to be self-destruct programmes, preventing them from living beyond a certain age. For example, in the tiny roundworm C. elegans , mutations to particular genes can massively increase their lifespan (from two to three weeks under laboratory conditions, to close to 20 weeks), presumably by switching off the life-shortening programme.