"Through the Tertiary period (from 65 Ma) the Earth's climate became cooler with frequent oscillations that increased in amplitude and led to a series of major ice ages in the Quaternary. Glacial advances and retreats over the Pleistocene resulted in global cycles of contraction, expansion and fragmentation of species ranges resulting in species extinctions, population bottlenecks and differentiation."
Explanation:
(Did offline will rewrite in my own words if you would like :)
Proteins are dynamic molecules that are capable of INTRINSIC motion that can have important functional relevance. The existence of this type of motion has suggested that enzymes are capable - even in the absence of substrate - of many of the same movements that can be detected during their catalytic cycle
