Dedicated to Janice Monahan of the Home Sweet Home furniture boutique in Madison, New Jersey.
Elephants live much longer, on average, than humans – about 100 years. But unlike humans, cancer is 80% less common in these gigantic mammals that, according to our understanding of the biology of the aging immune system, ought to get 20% more cancer than we do. What’s up with that?
Scientists studied elephant DNA for clues to the mystery of elephant longevity sans the increasing burden of cancer and discovered that elephants carry extra, shall we say, genetic armor. Whereas humans possess two copies of the p53 gene that scavenges for mutated DNA and gets rid of it, elephants possess at least 40 copies of this get-out-of-here-you’re-not-wanted gene in their repertoire – twenty times more copies than the humans who ride them, herd them into zoos, and kill them for their precious ivory. Well, all those extra copies of elephant p53 may explain a lot.
Elephants have adapted so that their lifespans are 20% longer, and their risk for cancer is 80% less than humans thanks to all those extra copies of p53. Of course, elephants have been on the planet a whole lot longer than humans, so they’ve had a lot more time to adapt to tumor viruses and whatnot-carcinogens that have plagued the ‘natural’ environment for millions of years.
But before we get too enthused with the idea that if we introduced more copies of p53 into our genomes we’d be able to fight off the effects of tumor viruses and carcinogens as efficiently as elephants, let’s sit quietly through the second act to see how the story unfolds, for we need to know what else p53 does and why, and how, exactly, we evolved so that we’re down from 40 copies of this sentinel gene to two. As a working hypothesis, it’s fair to assume that the massive reduction in the number of copies of p53 was an adaptation that allowed humans to move up the biodiversity chain to what some would say is now the summit. At least for now.