26.01.2022: Adaptation to a human living environment permanently altered behavior, appearance, and anatomy of domesticated animals. Domestic and wild mammals can be easily distinguished from one another by characteristic features such as white fur patches and tame behavior (lower stress response to humans). However, to understand the mechanisms underlying domestication, it is also necessary to investigate less conspicuous features, such as changes to the skull and brain. This recent study showed that a reduction in brain volume has occurred during cat domestication: domestic cats have smaller brains than their wild progenitors, the African wildcat. This confirms earlier research, using a new data sample, and also looked at hybrid wild/domestic cat brain sizes.

Raffaela Lesch (Institute of Animal Welfare Science, University of Veterinary Medicine Vienna), Kurt Kotrschal and W. Tecumseh Fitch (Department of Behavioral and Cognitive Biology, University of Vienna), with Georg Hantke and Andrew C. Kitchener of the National Museums Scotland, investigated how snout length and cranial volume have changed in domestic cats compared to their wild ancestors. Snout length and cranial volume are two parameters for evaluating changes to skull shape and provide insight into changes in brain and behavior during domestication.

A 1972 publication compared brain volumes across wild and domestic cats and showed that domestic cats have smaller brains than their ancestors (North African wildcat). Many current hypotheses in domestication research are partially based on the results of this now 50-year-old study. Therefore a replication of the finding that cats have experienced a reduction in brain volume during domestication was necessary.

One of the hypotheses closely linked to changes in brain volume and snout length is the neural crest/domestication syndrome hypothesis of Wilkins, Wrangham and Fitch. This hypothesis proposes that during domestication, selection for tame animals resulted in decreases in the division and migration of neural crest cells. These cells are essential components of embryonic development and are responsible, among other things, for pigmentation, stress responses, and skull and jaw development. This mild deficit in neural crest cells could therefore lead both to changes in behavior and in skull anatomy. This hypothesis predicted both a shortening in snout length and a reduction in brain volume in domestic cats.

Domestic cats have smaller brains

Data on brain volume and snout length were measured and analyzed from over 100 cat skulls from the National Museums Scotland collection. The study confirmed that domestic cats have smaller brain volumes than their wild ancestors, but a shortening of the snout was not detected.