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A bottom-up approach focuses instead on ancient ape fossils that pre-date our last common ancestor, such as those of the genus Nacholapithecus or Sivapithecus.

The ancestral chimpanzee-gorilla-man stock appears to be represented by the Upper Miocene genera Sivapithecus and Dryopithecus, the former more closely allied to, or directly ancestral to, the Hominidæ, the latter to the chimpanzee and gorilla.

Many of the differences that separate man from anthropoids of the Sivapithecus type are retrogressive changes, following the profound change in food habits above noted.