On Facebook recently, my brother asked why, if “macroevolution” is real, there aren’t more variety “in between” the species that exist today. I thought the answer to that question might be worth posting here.

The context of the question, was as comments to a tweet in which I thanked Richard Dawkins, citing his The Selfish Gene and The Ancestors Tales as having been instrumental in my scientific re-education, coming from a creationist homeschooler’s background (which my brother shares).

Among other things, all those in-between species did exist, and we’ve found scads and scads and scads of their fossiles. Most didn’t survive to today (except as fossils), because they were far less fit to compete with both descendents and cousins who were much better suited to their respective environments than today. Evolutionary jumps tend to happen when something in the environment or situation changes in a way that effects survival rates. This tends to provide strong death rates in the members that are poorly suited to deal with the change, providing a huge opportunity for members who are even just slightly better-suited to reproduce exponentially. Every small variation that is introduced that provides any sort of benefit in the new environment, reproduces quickly, because of its usefulness.

But the biggest evidence is in our genes. Continue reading →