The Polyvagal Theory offers a clear explanation of why mammals are able to affiliate
Mammals have unique reproductive patterns unlike most every other family of species on our planet. The way we invest in raising our young is unique (with birds making a curious exception). Evolutionary biologists call this, “Parental Investment” (wikipedia) and the Polyvagal theory explains why this process of affiliation is found only in mammals.
Once again, it comes to the fact that the mammalian autonomic nervous system has a 3rd subsystem, the Ventral Vagal complex, which helps mediate internal visceral state and simultaneously allow for dynamic engagement with the environment and others.
In social species like ours this allows us to stay in close proximity with others without feeling unduly threatened by them – at least when the reading of neuroception is accurate.
Below is an 8 minute excerpted piece from one of my previous talks on the Polyvagal Theory.