

For proteins, evolution can't go backwards  - prat
http://www.newscientist.com/article/dn17841-for-proteins-evolution-cant-go-backwards.html?DCMP=OTC-rss&nsref=genetics

======
prat
There is a problem with observing changes in a single protein and reversing
them to see if it all fits again. Evolution doesn't necessarily changes single
proteins - it changes whole pathways (that define a biological function) -
that include a number of different proteins expressed from different genes. If
scientists had changed all these proteins back to where they were in addition
to reversing the 5 changes in glucocorticoid receptor, the old function would
surely be restored.

