Episode description

A study finds that Peto’s Paradox, which states that larger animals are no more likely to get cancer than smaller ones, may not hold up. Also, a nearly complete predator skull was found in the Egyptian desert. Its lineage indicates that it was a top carnivore of the age.

If you throw a huge party, there’s more of a chance of problems than if you host a quiet get-together for a couple of friends. The logic is simple: Having more people around means more opportunities for chaos. Similarly, it would seem to make sense that in animals, a bigger species with more cells might have a greater chance of something going wrong with one of those cells, including mutations leading to cancer.

Back in 1977, a British epidemiologist named Richard Peto observed that that didn’t seem to be true. Bigger animals didn’t seem to have a greater risk of cancer than smaller ones. That became known as Peto’s Paradox, and has been a topic of debate among cancer biologists ever since.

Research published this week in the Proceedings of the National Academy of Sciences takes a new look at Peto’s Paradox using an unusual set of data—death reports from zoos around the world. Dr. Sarah Amend of Johns Hopkins Medical School joins Host Flora Lichtman to explain why, in their findings, Peto’s Paradox doesn’t seem to hold up—and what studying animal cancer rates could teach scientists about improving human health.

Once upon a time, some 30 million years ago, what is now Egypt’s Western Desert was a lush forest. Humans had not evolved yet, the nearest relatives being monkey-like creatures. And through those forests stalked Bastetodon syrtos, a newly described apex predator from an extinct lineage known as the Hyaenodonts—one of the top carnivores of the age.

Researchers recently discovered a nearly complete skull of the creature. They reported on the find in the Journal of Vertebrate Paleontology. Host Flora Lichtman talks with Shorouq Al-Ashqar of the Mansoura University Vertebrate Paleontology Center about the discovery, and the picture it helps paint of ancient life.

Transcripts for each segment will be available after the show airs on sciencefriday.com.

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