Dinosaurs are responsible for rapid ageing and short lifespans in humans

Dinosaurs are the reason why humans have such short lives, a study has found. According to a University of Birmingham microbiologist named João Pedro de Magalhães, the reproductive cycles in mammals instead sped up to ensure species survival. He has hypothesised that the age of dinosaurs completely shifted the evolutionary track of every mammal on Earth. “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 2023 in BioEssays. He calls this the "longevity bottleneck hypothesis". The absence of regenerative traits in mammals further backs his theory, he says. Mammals lived alongside dinosaurs for over 100 million years, but were "generally small, nocturnal, and short-lived."

Also Read: Jurassic lesson in survival: 180-million-year-old sea predator with 100 teeth gobbled stones to stay alive

When dinosaurs and mammals lived together

Dinosaurs ruled the planet, which triggered evolutionary changes in mammals. de Magalhães claims that every mammal is under genetic constraints dating back to the era of the dinosaurs.

They were under pressure to stay alive, and the environment did not suit a long life. This led to the elimination of the genes for 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 said in a statement. Reptiles and other animals have a much slower biological ageing. He proposed that the evolutionary pressure from the dinosaurs impacted the way humans age.

Mammals also do not have the ability to fix biological damage naturally. de Magalhães says this is because of the loss of enzymes tied to the Mesozoic Era, which limits this feature in mammals. Examples include the loss of enzymes that repair UV-damaged skin, and the fact that—unlike reptiles—mammalian teeth do not grow continuously throughout their lives, he said. But most animals have a remarkable ability for repair and regeneration. However, for mammals, this information was not required as they had the task to save themselves from becoming a certain T. Rex's food.