Another article about self-domestication:The Incredible Shrinking Brain
This article gives an overview of a book called THE DOMESTICATED BRAIN, which ranges over many fields such as evolution, childhood development, genetics, neuroscience, and social psychology in an exploration of what makes us human. In domesticating ourselves, we became able to live together in groups, with all the benefits of that lifestyle. As a result, we became more dependent on each other.
One intriguing feature of domestication is that it tends to make animals' brains smaller. That trend applies to human brains, too. Several hypotheses are suggested to explain this phenomenon, but no definite answer is given. It does seem to have some connection with our development into highly social creatures. For one thing, lower levels of aggression mean less testosterone, which is linked to smaller brains.
I wonder whether a reduction in typical brain size might have something to do with our developing a corporate memory. We don't have to rely on our own knowledge for survival. We can draw upon facts and lore known by our neighbors, handed down from our ancestors through tribal traditions, or (once writing is invented) recorded in fixed form to be available to everybody theoretically forever. We don't need to grow our brains to ever-larger size because we have access to an external mind of potentially unlimited scope.
The linked page comprises the preface to the book, THE DOMESTICATED BRAIN, which looks interesting enough that I ordered a copy. It seems to be out of print, but Amazon lists multiple used copies.
When we encounter alien species, will we discover that living in social groups is a prerequisite for advanced intelligence in any species (at least, any humanoid or mammalian creatures)?
Margaret L. CarterCarter's Crypt