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>evolution certainly works at the species level (in the sense that population genetics is a thing). That's not at the species level. That's, at the very best,

>evolution certainly works at the species level (in the sense that population genetics is a thing). That's not at the species level. That's, at the very best, at the level of a very small group. And most of those theories have generally been discredited - it only works if the beneficial effect on the group is sufficiently large, see http://lesswrong.com/lw/kw/the_tragedy_of_group_selectionism/ http://lesswrong.com/lw/kw/the_tragedy_of_group_selectionism... >there are genes preventing cancer (tumor suppressors), and those genes are under active selection. That doesn't contradict what I said. Those genes work well enough to prevent cancer in young organisms, but they are clearly not enough to stop all cancer. Why hasn't evolution evolved away all cancer? Because even if there was a gene that could decrease cancer risk by an additional 1%, it wouldn't actually increase fitness that much. A 1% decrease in risk is small on it's own, and then it only affects the 1% of organisms that haven't already died of other things. Preventing cancer is just not in evolution's priorities - at least not past a certain point.

dekhn 10y ago
I concede I was probably inaccurate in my statement about evolution and the species level; note, however, that I disagree with people who believe that the gene is the unit of evolutionary selection (I would refine it to say "functional region" rather than gene because I believe that mutations in enhancers and other transcriptional activators play a bigger role in evolution that mainstream science). On to your second reply: I basically agree. We're mostly arguing about where that certain point is. Problem is: cancer is a disease that is closely tied to many necessary functional parts of multicellular organisms. In a sense cancer is what gets people who weren't got by something more acute earlier, and probably evolution is addressing the more acute issues with a higher priority.

dekhn 10y ago

I concede I was probably inaccurate in my statement about evolution and the species level; note, however, that I disagree with people who believe that the gene is the unit of evolutionary selection (I would refine it to say "functional region" rather than gene because I believe that mutations in enhancers and other transcriptional activators play a bigger role in evolution that mainstream science). On to your second reply: I basically agree. We're mostly arguing about where that certain point is. Problem is: cancer is a disease that is closely tied to many necessary functional parts of multicellular organisms. In a sense cancer is what gets people who weren't got by something more acute earlier, and probably evolution is addressing the more acute issues with a higher priority.