New Evidence for the Theory of Human Self-Domestication
A new research paper has investigated the link between the BAZ1B gene and self-domestication of humans. The same gene has been found to control much of human facial development and be involved in the domestication of dogs and cats, possibly suggesting that humans are self-domesticated. Domestication is a process of adaptation towards a tamer behaviour also affecting appearance. Findings from the study point to BAZ1B being one of the first genes with hard evidence to be implicated in domestication.
It is easy to recognise domestic animals as they are more sociable towards humans, often have floppy ears and small teeth, and their faces are relatively short in comparison – dogs versus wolves. Likewise, humans also take on a more domesticated appearance when compared with other closely related species such as the Neanderthals, having flatter faces without a prominent brow ridge and being more sociable. With the reasons behind human domestication still not fully understood, scientists suspect that we first domesticated ourselves before we domesticated dogs and cattle.
The BAZ1B gene, a chromatin regulator, lies within a region linked to Williams syndrome and is believed to regulate neural crest development during embryonic development. The embryonic neural crest structure gives rise to most of the peripheral nervous system and other non-neural cell types. The BAZ1B gene plays an important role in the development of the parts of the body affected by domestication. With genetic changes in this region linked to domestication, scientists are searching to see if these same genetic changes are what caused the domestication of dogs and humans.
Williams syndrome is characterised by traits related to domestication with unique personality traits leading to extreme friendliness, reduced reactive aggression, and physical traits such as facial reduction and retraction. The causal deletion of 26-28 genes at the 7q11.23 region are usually not inherited and arise spontaneously in the formation of reproductive cells.
In the study, researchers looked at BAZ1B knockout stem cells and found that the neural crest was slow to form and did not develop properly. 448 genes were found to be affected in the knockout model, suggesting that BAZ1B plays a huge role in regulating genes important to neural crest formation. Some genes affected are CLIP2 and LIMK1, both of which play a role in the development of nerve cells in the brain, and ELN which codes for a component of connective tissues.
In the eyes of evolution, BAZ1B seems to have played a huge role in domestication. Of the genes it regulates, many are already identified to have a major significance in recent evolution. Many different versions of these genes have been found in Neanderthals, and yet theory of human self-domestication remains incomplete.