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Sharks are at the top of the marine food chain for a reason. Their massive size along with a dazzling row of extra-sharp teeth make them the fiercest hunters in our oceans. But it turns out that the shark’s aquatic dominance reaches down into its very DNA, and through its mutations, sharks could teach us how to fight our most deadly affliction—cancer.

This isn’t the first evidence that mutations can prove beneficial for disease resistance and long-term survival. High bone density, a hemoglobin that boosts malaria resistance, and a third retinal cone that improves color vision are some human examples. But new gene mapping conducted by scientists at the Save Our Seas Foundation Shark Research Center at Florida’s Nova Southeastern University, the Guy Harvey Research Institute, and the Cornell University College of Veterinary Medicine shows that sharks have developed genomic adaptations that repair damaged DNA, effectively protecting them against cancer and other diseases.

According to the study led by Nicholas Marra and published in BMC Genomics, two shark genes in particular—legumain and Bag1—have been refined through evolutionary adaptation to become agents of disease resistance. Strangely enough, humans carry counterparts of these genes, but in our case, they are indicators of cancer risk.

This might have something to do with the size of shark genetic code, which is one-and-a-half times larger than human DNA. A BBC report covering the research article suggests that there are adaptations coded into this large, highly evolved shark DNA that are not coded into human DNA. The proteins produced by legumain and Bag1 have been modified in sharks to the extent that they actually protect the animals from the disease instead of exposing them to it. Such genetic defense mechanisms have preserved the integrity of the genome over millennia and help explain the uncommon resilience and longevity of the species.

“Not only were there a surprisingly high number of genome stability genes that contained these adaptive changes,” said Mahmood Shivji, Ph.D., co-leader of the study, “but there was also an enrichment of several of these genes, highlighting the importance of this genetic fine-tuning.”

The DNA mapping also revealed that the four species of sharks and ray examined in the study have a high proportion of genes related to infection immunity, wound healing, and blood clotting—not a surprise given their well-documented ability to heal from severe injuries. Naturally, scientists wonder whether these genetic defenses could somehow benefit us.

“There’s still tons to be learned from these evolutionary marvels,” said Shivaji, “including information that will potentially be useful to fight cancer and age-related diseases, and improve wound healing treatments in humans, as we uncover how these animals do it.”

So improving humanity’s chances against cancer could go hand-in-hand with deepening our appreciation of these long-lived, genetically advanced creatures who’ve roamed our oceans for 400 million years.

Excerpted from https://www.popularmechanics.com/science/animals/a26474764/shark-dna-cancer/