Chromosomal Clarity

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Researchers unearthed a groundbreaking discovery in the frozen remains of a woolly mammoth that died 52,000 years ago in Siberian permafrost.

The very well-preserved chromosomes offer an unprecedented look at the genetic makeup of this extinct species, scientists wrote in their study published in the journal Cell.

Preserved in a glass-like state induced by cooling and dehydration, the chromosomes appeared structurally intact “down to the nanometer scale” for tens of millennia.

The team used a special procedure to map sections of DNA in contact with each other to reconstruct the three-dimensional structure of the mammoth’s chromosomes.

“Recently, experiments along with theory have made it possible to study the detailed structures of modern chromosomes,” co-author Vinicius Contessoto said. “But this is the first time that we have been able to turn back the clock, as it were, and look at chromosomes of extinct species in full 3D.”

The mammoth had 28 pairs of chromosomes, which is the same number as modern elephants and underscores the close genetic relationship between the species.

They compared the extinct creature’s chromosomes with those of their modern relatives and identified a number of genetic differences that showed how the woolly creatures adapted to frigid environments.

For instance, the EGFR gene is inactive in mammoths but active in Asian elephants. Previous research has shown that suppressing this gene in humans or sheep causes them to grow unruly hair, Scientific American noted.

The condition of the remains suggests that other well-preserved ancient DNA samples might be just waiting to be found, some of which could date back two million years.

The authors noted that such discoveries could significantly enhance our understanding of ancient genomes and the evolutionary history of other extinct species.

“Fossil chromosomes are a game-changer,” Olga Dudchenko, another study author, said. “Knowing the shape of an organism’s chromosomes allows us to assemble the entire DNA sequence of extinct creatures, enabling insights that were previously impossible.”