[sissyFuss]

Well, I tend to think of the repititions in two ways, each with its own context. One is allele frequency, such that gaps of funtional utility are created with ineffective codons, to create timing effects and distance oriented partitioning of productive segments as enzymes crawl the unzipped, live genome.

The other is more about radiation hardening, and those are full, bulk duplicates of chromosome sets, like the hexaploid grain genome that was recently being discussed last week.

But I wonder when that sort of radiation hardening aspect was selected for? Millions of years ago? Billions of years ago? Or was it all just an accident, never selected for or even put to use? If we, as humans, only have a set from each parent, I’d estimate that bulk duplication doesn’t seem to offer real benefits in the radiation hardened sense, or everything would have more copies for billions of years.