While you may be tempted to believe that bigger individuals have it better, a team of researchers from the University of Glasgow and Norwegian University of Science and Technology have discovered the opposite- that changes in DNA associated with aging and lifespan occur when the body size of an animal gets bigger. Larger animals still tend to live longer than smaller ones, but when looking at sizes within the same species, bigger individuals tend to have a shorter lifespan.

The scientists focused on telomeres, the DNA structures that all animals possess at the end of their chromosomes, in a population of wild house sparrows. The research took place on the island of Leka in Norway.

"The reason why the bigger individuals have shorter telomeres might also be related to increased DNA damage due to growing faster. Being big can have advantages, of course, but this study shows that it can also have costs," Pat Monaghan, who participated in the research, said in a press release.

The team conducted a selective breeding program during the study and found that as the sparrows got bigger, their telomeres became shorter. Short telomeres have been linked to aging, as well as an increased risk of disease such as cancer.

"The results from this study are very exciting and broad reaching," said Thor Ringsby, who participated in the field research. "It is especially interesting that we obtained these results in a natural population. The reduction in telomere size that followed the increase in body size suggests one important mechanism that limits body size evolution in wild animal populations."

The study was published in the Dec. 2 issue of the Proceedings of the Royal Society Biological Sciences.