Three years ago, I wrote a series of blog posts about how scientists at the University of Oregon reconstructed the 450-million-year history of a protein. You can read the posts here, here, and here. What was particularly elegant about the study was how the scientists recreated the ancestral protein as …
This is some very interesting work. Along the way from ancestral to modern, the protein had several amino acid changes that are critical for the new function.
But there were also several mutations that are not critical for function but are also required in some way. Perhaps they stabilize the protein in some way, or alter the folding pathways so that the correct shape is arrived at more rapidly.
So, to go backwards, from modern to ancestral forms, requires a host of changes that have little to do with function. This makes it much harder to natural selection, which uses function for its framework, to really be effective.
The proteins really can not go home again, unless they trace a completely new path.
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