This may be what you are driving at, but in case it isn't: The *impression* that...

Crito on April 17, 2015 | parent | context | favorite | on: Female Chimps Seen Making, Wielding Spears

This may be what you are driving at, but in case it isn't: The impression that chimps are suddenly rapidly evolving may simply be a consequence of us watching them closely. We may simply be noticing behaviors that have been present for much longer.