he seems to be using DNA as a measure for the amount of irreducible complexity that needs to go into a system that will end up with the complexity of a hum

he seems to be using DNA as a measure for the amount of irreducible complexity that needs to go into a system that will end up with the complexity of a human brain. Before an Irreducible Complexity crackpot uses that argument: this complexity is of course not irreducible. It just takes millions of years and the reproduction of the exact mutations and variations in circumstances to reproduce it exactly. A shorter time period, different mutations and circumstances could lead to something akin to this amount of complexity.