Bacteria never became complex because the barrier is structure, not information — they explored genetic space far more thoroughly than eukaryotes and still got stuck.

So they have explored genetic sequence space far more thoroughly than eukaryotes ever did because they’ve had twice as long at least, and they’ve got much larger populations, and they never got around this problem. So why can’t they? It seems as if you can’t solve it with information alone. So what’s the problem? The problem is structure.