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Sharks Get Cancer and Other Ways We Can Relate

Being indiscriminate killers isn't one of them.
December 6, 2013, 8:30pm

via faithandmusic/Deviant Art

While I usually find sharks sort of hard to relate to—they live in the ocean, they’ve been around since the time of the dinosaurs, their bones are made of cartilage, etc—there was a lot of research on sharks that was tossed, like so much chum, into the internet waters this week. As I read through it, I found the other-ness I had imposed on sharks softened. Sure, they aren’t dolphins, but we’ve got a lot in common with sharks. And they’ve got a lot in common with us.

If you’ll accept that family ties are really just a matter of shared genetics, our bond with sharks is on a most intimate level. No one has mapped a great white shark genome yet, so when researchers from Cornell and Nova Southeastern University received an illegally-fished great white shark heart, they began laying the groundwork by sequencing the heart’s transcriptome— the messenger molecules produced from the shark’s genome. They discovered that, even though the shark is a fish, the great white shark’s protein arrays that govern metabolism and other functions had more in common with humans than with science's archetypal fish, the zebrafish.

“Although sharks and bony fishes are not closely related, they are nonetheless both fish … [while] mammals have very different anatomies and physiologies,” said study author Michael Stanhope. “Nevertheless, our findings open the possibility that some aspects of white shark metabolism, as well as other aspects of its overall biochemistry, might be more similar to that of a mammal than to that of a bony fish.”

Not only do their proteins closely resemble ours, their maladies do as well. Researchers found that, contrary to assumptions that underlie shark cartilage-based medicine, sharks can get cancer, just like we mammals. In Australia, they found a great white with a great big tumor—a foot long and a foot wide.  This was the first tumor found on a great white shark, but cancer has been found on 23 species of shark.

The belief that shark cartilage cures cancer has not only contributed to decimating wild shark populations, it’s also bad for people. Discovery reports that belief in the healing powers of shark diverts people from actually helpful treatments.

"Sharks get cancer," shark expert David Shiffman told DNews. "Even if they didn't get cancer, eating shark products won't cure cancer any more than me eating Michael Jordan would make me better at basketball."

Just as we all agree you shouldn’t eat Michael Jordan for no reason, you shouldn’t eat an endangered species. A three-year study began this year on whether shark blood carries cancer-fighting antibodies, but wait for the results before you ask for a mako transfusion.

Lemon shark via Wikimedia Commons

Sharks even have a home territory. The luckiest researchers of the bunch spent 17 years watching lemon sharks in the Bahamas and found that the sharks returned to where they were born near the Bimini Islands in order to breed. Granted this is a practice found in other marine animals like salmon and some sea turtles, but if anything it proves that lemon sharks love the Bahamas just like we do, and are capable of “long-term fidelity,” which is a rare thing these days.

In addition to making sharks relatable, the studies have an undercurrent of conservation: Understanding that shark cartilage won’t cure cancer reduces the incentive to fin them. Realizing that they return to the same breeding grounds has implications for conservation in that area.

It’s estimated that 100 million sharks are killed each year and yet shark researchers still have to come to their defense against people who think that shark populations should be culled to prevent already-rare shark attacks.

“Most people's perception of [sharks] comes from films like Jaws,” William Winram, the world free-diving champion and Great White Shark Ambassador told RN Breakfast. “It’s demonization, and it’s not an accurate representation of the animal.”

When you look at the numbers, being out for inter-species blood isn’t a trait that humans and sharks share. It’s a title we have all to ourselves.