"Trashfish" AKA the Ultimate ‘Living Fossils’ may Advance Human Medicine.

If you could hop into a time machine and travel back 150 million years, the world would have looked very different. The supercontinent Pangaea was just beginning to break up, stegosaurus roamed the Earth, and ichthyosaurs dominated the seas- but if you stuck your head into a stream, you might have spotted a familiar face from our modern age...Gars.






In 1859 Charles Darwin coined the term “living fossil” to describe lineages that have looked the same for tens of millions of years, such as the coelacanth, sturgeon, and horseshoe crab. The term captured the popular imagination, but scientists have struggled to understand whether such species just resemble their long-ago ancestors or have truly evolved little over the eons.

Gars, often dismissed as "trash fish," are toothy, torpedo-shaped fish that have remained relatively unchanged throughout time. These fish are 'living fossils' - among the most primitive animals on Earth for 150 million years. Over this whole time these fish have mostly stayed the same, a rare consistency not even seen in sharks. A new study says that at the molecular level, gars are the most living fossil-y out of all living fossils- and it’s not even close.

Of 481 vertebrate species, researchers—led by Chase Brownstein and Thomas Near of Yale University and Dan MacGuigan of the University of Buffalo—found that gars have the slowest rate of molecular evolution known to science. The team also proposes a mechanism to explain gars’ timelessness to be superb DNA repair machinery. They suggest gars are extremely efficient at repairing DNA after mutations or damage, keeping the animals from evolving even as the continents have shifted around them. This repairing ability has likely kept gar genomes so stable that species and even genera whose last common ancestor lived more than 100 million years ago have diverged very little, and some can still hybridize today to produce viable offspring.

A similar hypothesis has previously been proposed by other researchers for sturgeon, which had the second-lowest substitution rates among vertebrates in the study

The scientists believe this genetic quirk could lead to advances in human medicine- which I find fascinating.

“If we can isolate what that is—and we’ve got some ideas as to what gene that might be—we can then take it to the next step of thinking about implications for human medicine and disease,” says Solomon David, an aquatic ecologist at the University of Minnesota and co-author of the study.David believes that if whatever is correcting those mutations can be replicated in human bodies, it could potentially prevent or counteract diseases such as cancer, the result of shortcomings in DNA repair and cell growth run amok.




Sources:

https://www.nationalgeographic.com/animals/article/living-fossils-gars-fish-evolution

https://www.science.org/content/article/these-gars-are-ultimate-living-fossils