> A virus is much simpler than a human, but even for that simple virus the effects of most of the mutations could not be predicted.

Is this the correct logic? I (very naively) would think that a small mutation of a virus, with the percent change that is being made, would be more of a fundamental change in the nature of the thing, so maybe less predictable. Where poking genes of a human being more of a (possibly strong!) statistical nudge, since most things seem to be spread across many genes, what's being expressed for sometimes environmental reasons, and even influenced by "junk DNA".