Human Lifespan May Have Shortened Due to Dinosaurs' Dominance Millions of Years Ago [Study]

Humans evolved to survive, and while we did not exist during the dinosaurs' era, they may have influenced lifespans. A microbiologist presented a "longevity bottleneck" hypothesis linking dinos to why humans aged fast.

Dinosaurs Influenced Human Lifespan?

The rate at which several species of reptiles, amphibians, and mammals, including ourselves, age varies. One scientist suggests that this discrepancy might be the dominance of dinosaurs during a pivotal epoch in the history of mammals millions of years ago.

In a recently published study, microbiologist João Pedro de Magalhães of the University of Birmingham in the UK outlines his "longevity bottleneck" theory. He claimed that because the dinosaurs dominated Earth, the genes for longer lifespans may have been lost as evolution moved forward since the much smaller mammals needed to breed quickly to survive.

"Some of the earliest mammals were forced to live towards 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 explained. "That long period of evolutionary pressure has, I propose, an impact on the way that we humans age."

Enzymes that repair UV radiation damage appear to have been lost by our very old ancestors in the Eutherian mammal lineage sometime around the time of the dinosaurs. It's interesting to note that none of the three UV-repair enzymes, or photolyases, is present in marsupials or monotremes. It's hard to say whether this has anything to do with their comparatively shorter lifespans.

One theory is that the loss occurred because mammals evolved to become more nocturnal to stay safe. Millions of years later, we're compensating for this by using sunscreen. It illustrates a mechanism for restoration and repair we would have otherwise possessed.

Other indicators include teeth. The expert noted that certain reptiles, like alligators, can keep growing their teeth throughout their lifetime, which humans don't. He suggests this is due to genetic selection dating back hundreds of millennia.

"We see examples in the animal world of truly remarkable repair and regeneration," de Magalhães explained. "That genetic information would have been unnecessary for early mammals that were lucky to not end up as T. rex food."

Fighting age-related illnesses like dementia and stroke always benefits from a deeper understanding of the aging process, and the genetics underlying the "longevity bottleneck" may have more to teach us in this regard.

ALSO READ: Do Short People Live Longer? Here's the Impact of Height on Life Span

Lifespan

Lifespan is the maximum age that any member of a certain population (or species) can achieve. The average human lifespan was previously 120-125 years, but the figures have since dropped.

The average number of years that individuals of a population (or species) live is known as life expectancy. The World Health Organization (WHO) (2016) reported that the average life expectancy at birth in 2015 was 71.4 years, 73.8 years for women and 69.1 years for men.

Everywhere in the world, women outlive men, and this disparity hasn't changed since 1990. The WHO African Region's overall life expectancy was 60.0 years, whereas the WHO European Region's was 76.8 years.

Between 2000 and 2015, the average life expectancy rose by five years worldwide, with the WHO African Region experiencing the most rise of 9.4 years. This was mainly brought about by increases in child survival and accessibility to HIV treatment-related antiretroviral drugs. In terms of life expectancy, the United States came in at number 43 in the world in 2016, according to the Central Intelligence Agency.

In the United States, the CDC's National Center for Health Statistics (NCHS) released fresh provisional data showing an almost one-year fall in life expectancy at birth between 2020 and 2021. The drop in life expectancy from 77.0 to 76.1 years at birth was the lowest since 1996 in the United States.

The most recent report revealed that men's life expectancy is 73.2 years, compared with women's 79.1.