Jan. 14 (UPI) -- Even insects grow old before they die.
Among mammals, birds, reptiles and even fish, the signs of aging are easily observed. The aging process is less visible among insects. But new research confirms even short-lived species, like field crickets, experience physical decline before they die.
Scientists have previously observed aging among insects in the lab, but some researchers surmised their protection from the dangers of life in the wild allowed signs of senescence to surface. For the latest study -- published this week in the journal Evolution -- scientists observed field crickets in their natural environs, in the fields.
Using more than 130 video cameras, researchers recorded and analyzed the movements and behaviors of several generations of field crickets over the course of their lifetimes, which last just a few weeks. The scientists found crickets exhibit evidence of physical decline as they get older.
"Though we didn't find evidence of 'live fast, die young' in this species, those that put more energy into reproduction early in life showed some signs of faster decline as they aged," Rolando Rodríguez-Muñoz, researcher at the University of Exeter's Center for Ecology and Conservation, said in a news release.
Over the course of a decade, researchers tracked correlations between reproductive effort, aging and survival among field crickets. While scientists did uncover a link between reproductive effort and aging, they found no correlation between reproductive effort and survival.
Researchers classified chirping less and losing more fights as signs of senescence.
"There's a big question in biology about why we fall apart as we get old," said Exeter researcher Tom Tregenza. "In the past, it was thought that there was something inevitable about declining with age. But there has been a shift towards believing this is something we have evolved to do."
The latest research supports the idea that aging is at least partially evolutionary decision, the result of investing energy in reproduction instead of physiological maintenance and repair.