Monday, May 21, 2012
Cancer: The call of the wild
Cells in your multi-cellular body are in a very odd, almost "un-natural" state -- they aren't reproducing as fast as they could. In fact, sometimes they even kill themselves. From an evolutionary perspective, this is very, very odd.
We multi-cellular creatures are both new and rare in the grand scheme of things. Almost all life on Earth is and was single-celled and, leaving aside the complexities of living in colonies, the typical cell simply makes copies of itself as fast as it possibly can limited only by its ability to acquire food. Holding back or, even more radically, killing oneself is completely anathema to a cell. If cells were politicians, "reproduce as fast as possible" would be their only platform.
The evolution of multi-cellularity required that collections of cells work together and this implies that some of them give up the right to reproduce in favor of others. That is, a random cell in your body, say on your finger, is giving up the right to produce descendants but by doing so it "hopes" that it is increasing the chance that its nearly identical cousin cell (your sperm or egg) will reproduce. As implied above, that is no small request of a cell. Everything in a cell's history prepares it to, indeed demands, that it make copies of itself as fast as possible. Yet, in multicellular creatures such as we, all the cells except a lucky few are being asked to halt that directive. In a sense they have signed a contract: "I forgo the right to reproduce so that my nearly identical cousin will survive." The vast majority of the time the contract is upheld. Until it isn't. And when cells don't respect the contract anymore, we call that cancer.
In other words, cancer is the call of the wild. A cancerous cell is reverting back to what its ancestors have always done -- reproduce. A cancerous cell is, in effect, saying: "To hell with the contract, I'm reverting to what worked for my ancestors. It worked for them it will work for me." Of course, they're wrong, but they don't know that, they're just "stupid" cells after all.
It's a miracle that we strange multi-cellular creatures are here at all -- multicellularity requires the most incredible yet tenuous compromise in the history of the world.