I never confirmed one way or the other, but I'm fairly positive evolution operates by large sudden changes followed by incremental improvements/optimizations -- it's difficult to explain many "weird" traits through incremental improvements, because most of them would get stuck in local maxima's before achieving any real benefit over the prior state.
Like you can't evolve a third arm by slowly iterating towards it, from a lump to a stump to a limb to a functional limb; it'd be entirely a loss until it becomes fully functional. You have to grow a shitty yet complete third arm first, but not so shitty that it doesn't offer benefit, and then iteratively improve it into a pretty nice arm
And these kind of big visible features need more than a few changes in DNA to happen. An arm needs to attach to something, have muscles and arteries and nerves. That can only evolve iteratively from something else. There is a reason that elephant trunks are also a nose.
This is basically the theory of punctuated equilibrium as proposed by Stephen Jay Gould to the commonly held thought at the time of gradualism.