I thought natural selection was responsible for changing the way organisms are, but in the Comparing DNA workshop, we learned that natural selection keeps things the same. Which is it?
Well, it’s both, actually. Think of natural selection like a ‘justice system’ of sorts. If a mutation happens and it’s better than the original version for survival, then that mutation gets rewarded by getting passed on to more individuals in the next generation. This is one major way that organisms evolve, or change, over time. But natural selection also punishes mutations that are worse for survival. Those mutations disappear quickly, leaving the original version as the dominant one. In this way, its sort of an “if it isnt broken, don’t fix it” kind of system. And lots of our DNA hasn’t been substantially improved upon since single-celled life forms emerged on the planet.
