Our natural life expectancy is only 38 years

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Human beings have a natural life expectancy of only 38 years. However, it has lengthened thanks to advances in medicine and the improvement of our standard of living.

The figure has been given by a group of scientists from the Commonwealth Scientific and Industrial Research Organization (CSIRO) who have discovered a method to calculate the longevity of different species by analyzing their DNA. 

The research, which has been published in Scientific Reports, analyzed how the DNA of different animals changed as they got older. What was found is that the change was not the same in all species and was also related to life expectancy. This is what is known as the genetic clock, the way our DNA changes as we age.

Changes in DNA that predict life expectancy

As we add up years, there are a number of changes in our DNA. The most common modification is methylation, which is the addition of methyl chemical groups in the DNA.

Until now, researchers had been developing DNA clocks using methylation. Studying it, what they were doing was determining the age of an animal. However, they had not ventured to use it to predict its life expectancy. The present investigation has done so.

They used 252 genomes (complete DNA sequences) of different vertebrate species from an online database developed by other researchers and compared them with another known animal life database. Scientists realized that they could estimate the lifespan of these vertebrates by looking at where DNA methylation was produced in 42 particular genes. They could not only predict the life expectancy of living animals, but also of those that have become extinct.

Why you need to know about the useful life of animals

The shelf-life of most animals, that is, those in which biological functions are maintained in perfect condition, is currently unknown. Existing estimates come from a small number of individuals who live in captivity and whose ages at the time of death are known. When it comes to animals with a long life span, it becomes difficult to predict their life expectancy because they can survive researchers. Now, with DNA analysis, researchers can predict both the life expectancy for animals with a long or short life span. 

In the case of extinct animals, the scientists who participated in this study have discovered that the useful life of the Bowhead whale, considered the world’s longest-living mammal, it has a lifespan of over 200 years. They also estimated that the Woolly mammoth had a lifespan of 60 years and Pinta Island tortoise, 120 years. 

Two species which are extinct and closely related to modern human beings are the Neanderthals and the Denisovans. Well, for them, the research group has found a maximum life expectancy of 37.8 years.

In the opinion of researchers, knowing the useful life of wild animals can help manage and conserve them. If they are also endangered species, knowing their life expectancy would help to understand which populations are viable (could survive).

Finally, scientists refer to the fish sector, which can use the life expectancy of animals to determine catch limits.

 

Reference: Mayne, B., Berry, O., Davies, C. et al. A genomic predictor of lifespan in vertebrates. Sci Rep 917866 (2019). DOI: https://doi.org/10.1038/s41598-019-54447-w

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