Big Animals, Big Cancer Risk

Scientists have long thought that bigger animals should get more cancer. The idea is simple: more cells mean more chances for something to go wrong. So, elephants and whales should be cancer hotspots, right? Well, not so fast. For a long time, this idea didn't add up. Some small animals, like budgies, get cancer a lot, while larger ones, like roe deer, don't. This puzzle is known as Peto's paradox. It was first noticed in 1977 and has been a mystery ever since. The paradox is that bigger, longer-lived species should have more cancer, but they don't. Some scientists thought that larger species must have special defenses against cancer. For example, Asian elephants have extra copies of a gene that helps prevent tumors. But this doesn't explain everything. A new study looked at cancer in over 260 species of amphibians, birds, mammals, and reptiles. They used fancy statistical tools to compare cancer rates. Guess what they found? Bigger species do have more cancer. This is true for all four major groups of vertebrates. So, the old idea about Peto's paradox doesn't hold up. But here's where it gets interesting. There's another idea called Cope's rule. It says that evolution favors bigger body sizes because they have advantages, like better predation and resilience. But if bigger sizes mean more cancer, why would evolution push for that? This new study doesn't solve that mystery, but it does give us a new angle to think about. The study also found that faster evolution rates can reduce cancer risk. This means that animals that evolve quickly might have better cancer defenses. It's like they're one step ahead of the game. But this is just one piece of the puzzle. There's still a lot we don't know about cancer and how it works in different animals. So, what does this all mean? Well, it's a reminder that nature is full of surprises. And it shows that we still have a lot to learn about cancer and how it affects different species. Maybe one day, we'll find a way to use this knowledge to help both animals and humans.