Not all animals experience aging during their lives. body of some animals Body It doesn’t get worse as we age, but by the time humans reach age 30, their chances of dying doubles about every eight years. So even if you are lucky enough to live to be a centenarian, you will be more likely to die each year. This high mortality rate reflects the many other health problems, such as muscle loss and general weakness, cognitive decline, vision and hearing loss and many other degenerative changes that characterize the human aging process and the longer life span of humans. The reason may be the fact that our ancestors evolved during the time of dinosaurs.
human life is long
Compared to other mammals, humans have a longer life span. We have the longest lifespan of all land-based mammals and of all mammals only whales possibly live longer than us. I say “probably” because you would have to keep animals in captivity to do detailed studies on lifespan, which is almost impossible for whales due to their size and longevity.
Mice and voles age very fast
We know that whale and dolphin species experience menopause and that all mammals experience some form of decline in fertility with age. In fact, physiological aging and increased mortality with age have been observed in all studied mammals, even though some species – such as rats and voles – age much faster than others – such as humans, Whales and elephants, but also many species of reptiles, amphibians and fish, do not show signs of aging. Examples include turtles, salamanders and rockfish.
Turtles live longer than humans
A study of 77 species of reptiles and amphibians, published in Science in 2022, showed that many species of reptiles and amphibians do not show an age-related increase in mortality. It seems as if these animals do not age. Some of these animals, such as turtles, possibly live longer than humans. Perhaps if we study these apparently aging species over a long period of time they will show signs of aging, but if we study animals like the Greenland shark they are estimated to live around 400 years.
Most animals in the forest do not die of old age
For now at least we can say that among reptiles, amphibians and fishes, some species not only live longer than the longest-lived mammals, but also age significantly more slowly. Furthermore, some of these non-aging species continue to grow throughout their lives, meaning that older females lay more eggs, which is the exact opposite of what happens in mammals. These animals mainly die from being eaten by predators and from diseases. In fact, most animals in the wild do not die of old age and until the 20th century, certainly, most people died from infectious diseases. Some reptiles, amphibians and fishes are also known for their ability to regenerate tissue.
pressure on mammals
About 370 million years ago, amphibians evolved from fish, and about 50 million years later, reptiles evolved from amphibians. Mammals evolved from reptiles about 25-30 crore years ago. We are all products of evolution, which we see in vestiges like our tailbone. Our evolutionary history can have a profound impact on modern times. About 200 million years ago, massive volcanic eruptions destroyed 76% of marine and land species. After this, dinosaurs became the dominant predators on land. To survive and avoid being preyed upon by dinosaurs, mammals became smaller, nocturnal, and short-lived.
our ancestors were not like us
Our ancestors of this time were not at all like us. They were like rats and mice, small animals that came out in the dark to catch insects. Under pressure from dinosaurs, ancestral mammals had to reproduce rapidly, just as rats do now, and like rats and shrews, our ancestors also had shorter lifespans.
Mammals often become prey
For 100 million years, during the time of the dinosaurs, mammals were at or near the bottom of the food chain. Mammals were more likely to be prey than predators. During this time, mammals had no reason to maintain processes and genes related to long life, such as DNA repair and tissue regeneration systems. My longevity bottleneck hypothesis proposes that repair and regeneration systems were lost, mutated, or became inactive as early mammals evolved. This imposed biological constraints that dictate how mammals age to this day.
Mammals take over the world
After the dinosaurs disappeared when an asteroid hit Earth 66 million years ago, mammals took over the world. An astonishing diversity of species evolved with a variety of life spans. Some species, like humans, evolved a longer life span, but they may have done so under constraints, remnants of the time of the dinosaurs.
Why did dinosaurs matter?
We can guess by looking at species that did not undergo the same evolutionary pressure as early mammals. For example, the tuatara, a reptile endemic to New Zealand, may look like a lizard, but it diverged from snakes and lizards about 250 million years ago. Because of its slow evolution it is sometimes called a “living fossil”. Tuatara are believed to live more than 100 years and age much more slowly than humans, a 2022 DNA analysis study revealed. Perhaps unlike most long-lived mammals, they have retained their anti-aging genes.