Having less number of children and that too, later in life, may help you live longer, a new study on birds has found. New research into ageing processes, based on modern genetic techniques, confirms theoretical expectations about the correlation between reproduction and lifespan. According to the study on birds by The University of Gothenburg, Sweden, those that have offspring later in life and have fewer broods live longer. And the decisive factor is telomeres. Telomeres are the protective caps at the end of chromosomes. The length of telomeres influences how long an individual lives, researchers said. Telomeres start off at a certain length, become shorter each time a cell divides, decline as the years pass by until the telomeres can no longer protect the chromosomes, and the cell dies. However, the length of telomeres varies significantly among individuals of the same age. This is partly due to the length of the telomeres that has been inherited from the parents, and partly due to the amount of stress an individual is exposed to. "This is important, not least for our own species, as we are all having to deal with increased stress," said researcher Angela Pauliny in a statement. Researchers studied barnacle geese, which are long-lived birds, the oldest in the study being 22 years old. The results show that geese, compared to short-lived bird species, have a better ability to preserve the length of their telomeres.
The explanation is probably that species with a longer lifespan invest more in maintaining bodily functions than, for example, reproduction. "There is a clear correlation between reproduction and ageing in the animal world. Take elephants, which have a long lifespan but few offspring, while mice, for example, live for a short time but produce a lot of offspring each time they try," said Pauliny. "The study revealed that telomeres were best-preserved in males. Among barnacle geese, the telomeres thus shorten more quickly in females, which in birds is the sex with two different gender chromosomes. Interestingly, it is the exactly opposite in humans," said Pauliny. The study was published in the journal BMC Evolutionary Biology.