When we think of evolution, we think of slow, gradual changes in animal and plant species over millions, perhaps even hundreds of millions, of years.

It took humans, for example, an estimated six million years to evolve from an ape-like ancestor.

Over those millions of years, it could be argued we didn’t evolve all that much, as today we still share about 98.8pc of our DNA with chimpanzees.

However, new research into ancient worms, reported in the journal Nature Ecology and Evolution, is upending the idea that evolution must take eons to make its mark.

Aoife McLysaght, professor in genetics in TCD’s school of genetics and microbiology, took part in the research.

“The research reveals that during a critical evolutionary moment, these worms experience what geneticists call a massive genome rearrangement,” ­Professor McLysaght said.

The worms underwent a dramatic “genetic reshuffling”, Prof McLysaght said, after moving from the sea, into freshwater habitats, and then onto the land, some 200 million years ago.

This is not a careful edit of genes to adapt to new conditions – evolution as we know it, but a complete genetic re-write, she said: a “confetti party” where genes are scrambled, thrown in the air, and fall back down randomly.

The chromosomes – the thread-like structures carrying genetic information in the cell’s nucleus – were also re-arranged.

“Imagine taking a carefully organised library and throwing its books into the air, then reassembling them in a completely new order, yet, somehow, the library still functions,” Prof McLysaght said.

Some genes were recombined, creating entirely new genetic configurations

“During a critical evolutionary moment, these worms experienced what geneticists call a massive genome rearrangement.”

Unlike most species, where genetic material remains relatively stable, the worms underwent a radical change that would typically kill an organism.

“Normally such dramatic genome scrambling would be fatal, but in this case it appears to have been a crucial adaptation mechanism,” Prof McLysaght said.

The genetic reshuffling reported by the scientists coincided exactly with the period when the worms shifted from water to terrestrial environments, a move that represented an enormous survival challenge.

“What makes this discovery particularly fascinating is how the worms managed to survive such a dramatic genetic upheaval,” Prof McLysaght added.

“Some genes were recombined, creating entirely new genetic configurations.”

This phenomenon is similar to what is seen in cancer cells, she said, where genomes are shattered and randomly reassembled. If scientists can better figure out how genes in cancer cells undergo rapid, radical change, unharmed, it could have medical implications.

“While typically associated with disease, in this evolutionary context, it appears to be a potential survival strategy.

“Understanding how cells survive and adapt to massive genetic change could provide insights into cancer research, offering new perspectives on how abnormal cells manage to survive and proliferate,” Prof McLysaght said.

Published 21st June ’25 in the Irish Independent