Did Scientists Actually Discover The Average Lifespan Of A Woolly Mammoth?

With people talking about de-extincting animals lately, it's no wonder that mammoths have been in the news. But despite our ambitions to bring mammoths back to the world of the living — and the fact that they were thriving relatively recently on geological time scales — there's not really a lot that we know about them. One thing we think we know, however, is about how long mammoths lived for: around 60 years.

This bit of esoteric knowledge comes to us from a team of scientists based in Australia. The researchers wanted to find a genetic basis for lifespan (and they had a rough idea of where to look), so they compared the DNA of over 250 different vertebrate species looking for specific markers. After fine tuning their model, and looking at the entire genome of the mammoth, they settled on a result of 60 years.

But the Australian team didn't stop with estimating the longevity of prehistoric pachyderms. Also included in its research was the passenger pigeon. Sadly, the passenger pigeon went extinct over 100 years ago, but the last one died at around 29 years old, lining up neatly with the predicted lifespan of 28 years. The team's method isn't perfect, however. When it looked at the human genome it predicted a lifespan of just 38 years.

In order to make their predictions, the researchers — whose work is published in Scientific Reports — needed to look at specific parts of the animals' DNA called cytosine-phosphate-guanine (CpG) sites. Cytosine, one of the four nucleobases, is the only spot on DNA where methylation can occur, and methylation (the addition of a methane-like CH₃ molecule) is known to play a significant role in aging. Specifically, the researchers looked at the density of CpG in particular parts of the genomes called CpG islands. They found that the denser the CpG in these clusters, the longer the maximum lifespan of the animal.

The researchers' prediction model was accurate for around 75% of the more than 250 genomes they tested. That's pretty good, but there are some limitations to the study and the lifespan model it outlines. The big one is it only seems to work with vertebrates. When they turned their model on the common fruit fly, it predicted a lifespan of around 16 years, a far cry from the actual lifespan of around 60 days.

Complicating matters is the recent retraction of two papers by the lead author of the study, Benjamin Mayne. Both of the retracted studies were related to DNA methylation and age estimation, but so far, no concerns have been raised over the paper expounding lifespan estimation, nor any of the many other papers he has co-authored in the last five years.