A few people have wondered what Ewan Birney, lead coordinator of ENCODE, would have to say about the Onion Test.
Well, here’s what he had to say on Twitter.
It’s hard to tell from this dodge, but I suppose the suggestions here are that a) the fact that humans have more DNA than pufferfishes is easy to account for because we’re more complex, but b) testing this logic by pointing out that even the smallest salamander genome is 4x larger than ours is silly.
Also, onions (and most salamanders) aren’t polyploid — it’s one of the reasons I chose them for the initial comparison. It didn’t have to be onions, of course. There is no relationship between genome size and organism complexity, which we’ve known for 60 years.
I would still like Birney to answer the question. How is it that humans “need” 100% of their non-coding DNA, but a pufferfish does fine with 1/10 as much whereas a salamander has at least 4x as much? It hardly seems silly to me to ask this very, very basic question about genome evolution.