Genes may be freely shared around, but where did they come from is the first place?
“A coming revolution in biology, may go so far as to unseat Darwinian evolution as the key explanatory process in biology.
The evidence for this radical turnabout has been accruing at an accelerating pace. A fair fraction of most bacterial genomes have been acquired not solely through inheritance from earlier generations, but also through horizontal gene transfer. DNA flows readily between bacterial chromosomes and the external world.
Such gene flow exerts an enormous influence on evolutionary dynamics. This was first suspected when a number of bacteria around the world rapidly gained resistance to multiple antibiotic drugs. Such resistance spread too fast to have been ‘invented’ independently by distinct species, but clearly seemed to have spread from one species to another.
The clear impact of horizontal gene transfer on bacterial evolution has been established only fairly recently.
Horizontal gene exchange may have been the dominant force in an earlier era of evolution. The conjecture is that horizontal gene transfer was indeed required for the present genetic code to take the form it has.
Exploring that point in greater detail will be a task for a new kind of biology, one that breaks with many of the presuppositions of traditional evolutionary thinking.”