Phylogeny

chimp faces

Figure 1. The imitative responses of the three demonstrated facial gestures. (a) Tongue protrusion, (b) Mouth opening and (c) Lip protrusion (Pal, 2 weeks of age). (Myowa-Yamakoshi, M. 2004)

Studies in related primate species

In order to understand imitative behavior in humans, many studies have been done in similar primate species, namely chimpanzees (one of the human species’ closest living relatives) and rhesus macaques (an Old World monkey species that diverged from humans about 25 million years ago).
Imitation is very similar in all three species, except for the ability to imitate a broad range of whole-body actions or facial expressions (Myowa-Yamakoshi 2004). This is thought to have evolved after the human lineage separated from that of chimpanzees.

phylogeny_tree

Figure 2. An evolotionary tree showing the evolution of different primate species.

Rogers, Jeffrey, and Richard A. Gibbs. Primate Phylogenetic Tree. Digital image. Nature Reviews Genetics. 8 Apr. 2014.

Reasons for the evolution of imitation

Imitation is important for many things, the biggest of which is affiliative bonding, or bonding to kin. Oxytocin-based affiliative bonding, like neonatal (newborn) imitation, is likely to have evolved in mammals to active maternal care and to reinforce the mother-infant bond, as shown in primates as well as rodents. (Curley 2005).

Imitation in non-primate species

While imitation has long been thought to only occur in primate species, recent studies in parrots (Moore 1992), dolphins (Dautenhahn 2002), and dogs (Topal 2006) have shown that this is not the case. However, it’s still not clear whether these non-primate species are simply imitating the result, or whether they are able to imitate intermediate actions.