Sometimes evolution gets sloppy.
Evolution gone sloppy? This is Sandra Tsing Loh with The Loh Down on Science.
Your genetic code is spelled out with the four-letter DNA alphabet. Each letter – G, C, A, or T – is paired with another.
Only two pairings are stable: G with C, and A with T. If another combination turns up – say, C with A – cellular repair mechanisms quickly change it.
But for some reason – scientists aren't sure why – more mismatches get swapped to GC than AT.
That inequality – "biased gene conversion" – flies in the face of evolution.
Why? Because even when organisms would benefit more from an AT at a given spot, cells favor GC.
It's like always adding extra salt to your recipes – when sometimes sugar would taste better. Obnoxious!
A recent Swedish-American study compared the human genome to genomes of more ancient primates.
One big difference? Humans have lots more unwanted GCs gunking up our genes – each representing a possible misstep along the evolutionary path.
Survival of the fittest? Or just the most insistently wrong? D'oh! It's like American Idol, but for genes!