Gibbon–human last common ancestor

A 2014 whole-genome molecular dating analysis indicated that the gibbon lineage diverged from that of great apes (Hominidae) around 17 million years ago (16.8±0.9 Mya), based on certain assumptions about the generation time and mutation rate.

[3] Adaptive divergence associated with chromosomal rearrangements led to rapid radiation of the four genera within the Hylobatidae lineage between about 7 to 5 Mya.

[1][2] Recent coalescent-based analysis of both the coding and noncoding parts of the genome suggests that the most likely sequence of species divergences in the Hylobatidae lineage is (Hylobates, (Nomascus, (Hoolock, Symphalangus))).

This contradicts previous theories that they were the size of chimpanzees and that apes moved to hang and to swing from trees to get off the ground because they were too big.

Also, the Hominidae, which came later, were smaller than their ancestors, which is contrary to normal evolution where animals get larger over their evolutionary development.

Hominoid family tree
Skeletons of members of the ape superfamily, Hominoidea . There are two extant families: Hominidae , the "great apes"; and Hylobatidae , the gibbons, or "lesser apes".