Are Sharks Truly Immune to Cancer? Unraveling the Myths
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The Fascinating World of Sharks
Sharks have roamed the Earth for over 450 million years, predating dinosaurs by a significant margin. As ancient creatures, they embody a sense of awe and fear, largely fueled by their portrayal in media, from classics like "Jaws" to campy films like "Sharknado." This fascination has led to a plethora of myths and questions about their biology.
For instance, do sharks need to swim continuously to survive? The answer is nuanced; some species can pump water over their gills while stationary, while others must keep moving to breathe. Furthermore, due to the absence of a swim bladder, stopping could cause them to sink.
Can they really detect a drop of blood in the ocean? While it’s a common belief, the truth is they can sense blood at a concentration of just one part per million, akin to detecting a single drop in a swimming pool—a remarkable feat nonetheless.
Then, there’s the myth that sharks frequently attack humans. In reality, the statistics suggest that there are approximately 1,000 drowning incidents for every shark attack reported in the United States.
But what about the claim that "sharks don’t get cancer"?
The Myth of Shark Immunity
This assertion gained popularity following the 1992 release of Dr. I. William Lane and Linda Comac's book, "Sharks Don’t Get Cancer." The title alone suggests a definitive conclusion.
The authors followed up four years later with "Sharks Still Don’t Get Cancer," reinforcing their stance.
Is it possible that sharks are genuinely immune to cancer? To explore this, let’s consider Dr. Lane, the book's author. Born in 1922 and a proponent of "natural medicine," he also wrote works such as "The Skin Cancer Answer."
However, his recommendations regarding shark cartilage as a cancer treatment raise flags, especially since the company promoting these products was linked to his family, creating a conflict of interest. The FTC intervened in 2000, fining his son’s company for false advertising and stating that their claims lacked clinical validation.
The Truth About Sharks and Cancer
Despite the sensational claims, the reality is that sharks are not immune to cancer. Historical evidence reveals the first tumor found in a shark dates back to 1908, with numerous other cases documented since.
While it is true that sharks tend to have a lower incidence of cancer, they are not exempt from it. This phenomenon has prompted scientific investigation into their unique biology. Sharks possess cartilage instead of bones, which plays a role in their immune response. Their immune cells are generated in the spleen and thymus and circulate quickly, potentially allowing them to respond more rapidly to tumors.
Research into cartilage suggests it may inhibit tumor growth by preventing blood vessel formation, yet this does not imply that consuming cartilage will yield similar results in humans. Just as one wouldn’t treat sunburn by eating aloe vera, expecting cartilage to combat tumors is misguided.
Conservation Concerns
Two dangerous myths persist regarding sharks: first, the false belief that they don’t get cancer, and second, the notion that shark cartilage can cure or prevent cancer in humans. Sadly, these misconceptions contribute to the endangered status of several shark species, as they are often hunted for so-called "alternative medicine" or shark fin soup. Approximately 73 million sharks are killed each year, which poses a significant threat to their populations.
Clinical trials have repeatedly shown that cartilage products do not provide any benefits in cancer treatment. While sharks may experience a lower rate of cancer, they are not immune, highlighting the importance of their conservation.
In summary, while sharks are captivating creatures that have survived for millions of years, they face threats from both human activities and misconceptions. For more insights into scientific myths and questions, stay tuned to Sharing Science!
Chapter 2: Understanding Shark Cancer Research
This video titled "Can sharks get cancer? | Natural History Museum" explores the truth about shark cancer immunity and the myths surrounding it.
In "Scientists work to unlock sharks' cancer-fighting secret," researchers delve into the biological properties of sharks that may contribute to their cancer resistance.