Mammals may struggle to attain long life thanks to dinosaurs. According to University of Birmingham microbiologist João Pedro de Magalhães, the age of dinosaur dominance completely shifted the evolutionary track of virtually every mammal on Earth, refocusing evolutionary efforts on rapid reproduction instead of long life.
You see, there was no point in trying to live for a long time when a dinosaur would just eat you anyway. To keep a species alive, rapid reproduction proved way more useful.
“My hypothesis is that such a long evolutionary pressure on early mammals for rapid reproduction led to the loss or inactivation of genes and pathways associated with long life,” de Magalhães wrote in a paper published in BioEssays. “I call this the ‘longevity bottleneck hypothesis,’ which is further supported by the absence in mammals of regenerative traits.”
While noting that humans (along with elephants and whales) theoretically have the potential to live longer than most other mammals, de Magalhães said that every mammal is still living under genetic constraints dating back to the era of the dinosaurs.
“Evolving during the rule of the dinosaurs left a lasting legacy in mammals,” de Magalhães wrote. “For over 100 million years when dinosaurs were the dominant predators, mammals were generally small, nocturnal, and short-lived.”
The pressure to stay alive eliminated the genes needed for long life. Citing reptiles and other animals with a much slower biological aging process than mammals, de Magalhães hypothesizes that during the Mesozoic Era, mammals either lost or deactivated genes associated with long life.
“Some of the earliest mammals were forced to live toward the bottom of the food chain and have likely spent 100 million years during the age of the dinosaurs evolving to survive through rapid reproduction,” de Magalhães wrote in a statement. “That long period of evolutionary pressure has, I propose, an impact on the way that we humans age.”
