Rather than stretch out the thread on Evolution: Backward Reasoning? any farther, I’m taking this question to a new post.
Can anyone explain to me, in three paragraphs or less, exactly what cladistics is? This is as far as I understand the concept:
The famous system of bilogical classification first developed by Linnaeus is based on anatomical observation, and strongly implies that all living things are related to each other in a hierarchal organization. For example, apes and dogs are similar enough to each other that it makes sense to say that they’re both “mammals”. Mammals and birds are similar enough to each other that it makes sense to call them both “Vertebrates”; and so on.
Darwin’s theory of Evolution by Natural Selection proposes a plausible mechanism for how this could have come about: by variation from common ancestors.
Supposedly, there’s a problem with this. Evolution is supposed from anatomical observation. But if you presume evolution, and then use that to infer relationships between organisms (i.e., “anatomical feature in speciman A evolved from anatomical feature of speciman B”, then you have circular reasoning.
Supposedly, cladistics is a system of using certain objective(?) criteria for determining evolutionary relationships. But I couldn’t follow the reasoning in what I’ve read about it. Any “Cladistics for Dummies” authors out there?