Jorge Avaria-Llautureo, Thomas A Püschel, Andrew Meade, Joanna Baker, Samuel L Nicholson, Chris Venditti

The most influential hypothesis about euprimate evolution postulates that their origin, radiation, and major dispersals, were associated with the exceptional warmer conditions of the planet in the tropical forests of higher latitudes. However, this notion has proven difficult to test given the overall uncertainty about the geographic locations and palaeoclimates of ancestral species. By the resolution of both challenges, we reveal that early euprimates dispersed and radiated in higher latitudes and through diverse climates defined by the Köppen-Geiger classification system, including cold, arid, and temperate. Contrary to expectations of the hypothesis, historical global temperature had no effect on dispersal distance or speciation rate. But how much the local temperature and precipitation changed substantially predicted geographic and species diversity. Our results set a new perspective on euprimate origins and evolution. They suggest that non-tropical and changeable environments exerted strong selective pressures on euprimates with higher dispersal ability which promoted this group’s radiation and subsequent colonisation of tropical climates millions of years after their origin.