The Game of Life . Although McShea had encountered the concept before in his studies, this time it struck him that the chain's graphic claim of increasing complexity toward the smug human is a hypothesis for which no quantitative proof has ever been established. I'm just naturally skeptical, but I was outraged to read in the evolutionary literature about a claim that was not necessarily false but that was made glibly. There was no clear statement of what is meant by complexity. You can't say progress or perfection anymore.
Complexity is vague, but it has the ring of science.
I'm fighting that vagueness by looking more narrowly for anything that could be used to measure complexity. That is to say, he started counting and measuring. For his dissertation, he examined the spinal vertebrae of animals both extant and extinct. What he's found wherever he's looked so far is that change toward simplicity is as common as change toward complexity in evolution. The vertebrae of a land mammal, for example, may become simpler, more fishlike, if that animal takes to the water.