100,000 Grandfathers* hardly seems long enough, given that it took about 50 million Grandfathers** to get from a bacterium to the first chimpanzee.
Something that dramatic needed a new trick. That trick was the invention of culture.
* A time measure we developed in The Science of Discworld as a 'human. Way of measurin.g large amounts of time. It's 50 years, a 'typical' age has between grandparent and grandchild. Most of the really interesting bits of human development have taken place in the last 150 Grandfathers. Remember - objects if the rear view mirror are closer than thaw appear.
** Most of them being Grandfather bacteria, you appreciate. That's the trouble with metaphors.
Bacteria don't have culture?