Have you ever wondered why humans live a far longer life than the animals around us?
Surely, you must’ve thought about it at one time or another. Why is it that for our animal companions, our dogs or cats, a 20-year lifespan is quite long, but for us, a 50-60 years life is at times considered short?
Well, the simple reason behind that is that humans on average die at around 70-80 years of age. In 2017, the United Nations pegged the estimated global average life expectancy at 72.6 years.
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But why do we have a longer lifespan?
Earlier scientists thought that this had something to do with our body size. Experts suggested that a smaller body size burns up energy quickly, which causes a speedier decline. For example, a mice has an average lifespan of 3.7 years while for a dog it can be anywhere from 10-13 years.
But then, how does a naked mole rat that is only five inches big have pretty much the same lifespan as a giraffe? While a giraffe typically lives for 24 years, the naked mole-rat lives for 25 years.
A new study by the Wellcome Sanger Institute in Cambridge, which was published in the journal Nature suggests that the key to the logic behind the high or low lifespans might be in the rate of genetic decay and DNA mutations.
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The study reports that animals with longer lives successfully slow down their DNA mutations, which contributes to their lengthy lifespans.
Somatic mutations are genetic alterations that occur in all cells and are mostly inconsequential, but some of them can set a cell on the route to cancer or affect normal function.
A report by the Telegraph quotes the study’s lead author saying that: “To find a similar pattern of genetic changes in animals as different from one another as a mouse and a tiger was surprising.
“But the most exciting aspect of the study has to be finding that lifespan is inversely proportional to the somatic mutation rate. This suggests that somatic mutations may play a role in ageing.”
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Going back to the giraffe and naked mole-rat example, the key to their almost similar lifespan lies in the number of genetic mutations; which is 99 for the former and 93 for the latter.
While we humans only face 47 mutations a year, mice which have a very short life span of 3.7 years experience suffer a massive number of 796 mutations every year.
The finding, according to the researchers, opens the door to a better knowledge of the ageing process, as well as the inevitability and timing of death.
(With inputs from agencies)
