Recent evolution in dogs and people show "striking parallelism," researchers led by Chung-I Wu and Ya-ping Zhang from the Chinese Academy of Sciences report in Nature Communications. Wu, Zhang, and their team performed whole-genome sequencing of four grey wolves, three Chinese indigenous dogs, and three modern dog breeds.
From subsequent analyses, the researchers traced the split between wolves and indigenous dogs back to about 32,000 years ago — earlier than previous estimates of domestication. Additionally, they identified 311 genes that appear to be under positive selection, and those genes are enriched in reproduction, metabolic, and neurologic pathways. Wu, Zhang, and their team note that their list of genes contains many genes that are under selection in humans. For example, ABCG5 and ABCG8, both part of the TP-binding cassette transporters superfamily appear to be under positive selection in both people and dogs as does SLC6A4, an integral membrane protein involved in serotonin transmission.
"As domestication is often associated with large increases in population density and crowded living conditions, these 'unfavorable' environments might be the selective pressure that drove the rewiring of both species," the researchers write. "Positive selection in neurological pathways, in particular the serotonin system, could be associated with the constant need for reduced aggression stemming from the crowded living environment."
The researchers also suggest that, based on the high genetic diversity they observed in Chinese indigenous dogs, that dogs may have originated in Southeast Asia. As National Geographic points out, other studies have indicated a Middle Eastern origin for dogs.