I love Carl Zimmer. I think he’s one of those people who just really get it… and not only does he get it, but he explains things in a way that makes other people get it.
Recently, he published an article on the Loom discussing whales and cancer, based around a recent review published in Trends in Ecology and Evolution. The basic premise of cancer works like this:
- Over time, cells make mistakes in DNA replication
- Mistakes accumulate and eventually, mistakes will affect some vital process
- This causes cancer
This stands to reason then, that the more cells you have and the longer you live, the more mistakes you will have, and the higher likelihood that you will have cancer.
But if you looked at blue whales, they’re HUGE. They have a lot of cells and they can live a long time. Indeed, according to calculations, half of all blue whales should have colorectal cancer. By the time they reach middle age, ALL of them should be cancer-ridden. And that’s only one type of cancer!
However, this is not the case. Indeed, across all studied species, including humans with our often-poor health choices, cancer occurs at a rate of about 30%. So mice, with their rapid metabolism and short life spans, get cancer at the same rate as whales, with their much slower metabolism and longer life spans.
This suggests that larger animals have evolved mechanisms against cancer that have held it at the approximately 30% mark – regardless of cell number, age or size, which is contradictory to the current paradigms of cancer as a statistical inevitability. And if that is so, we would be better off studying how larger animals cope with cancer rather than looking at cancer in mice.
That is not to say that we should suddenly be breeding captive whales for laboratory-style research – but so little is known about the health of these animals in the first place, despite the popularity of sea mammals as aquarium entertainment. A well sequenced genome would be the first informative step – The authors suggest studying the genome to look at differences in cancer defenses among related species with a wide range of sizes, such as whales and dolphins. Learning more about their health and biology of these animals may yield interesting new avenues in both human health research and animal veterinary medicine.
Zimmer ends his article eloquently:
“But such an undertaking would have to overcome a lot of inertia in the world of cancer research. Cancer biologists don’t look to big animals as models to study–which is one reason there’s not a single fully-sequenced genome of a whale or a dolphin for scientists to look at. For most cancer researchers, mice are the animals of choice.
But if we want to find inspiration for cancer-fighting medicines, mice are the last animal we’d want to consider. It’s like learning how to play baseball from a bench-cooler at a Little League game, when Willie Mays is waiting to dispense his wisdom.”
Again, find the original article at The Loom.
AlbinoMouse 