It is often said that 9 out of 10 orange cats are overweight, and many people associate orange cats with being particularly large. One common explanation is that most orange cats are male. Research shows that about 80% of orange cats are indeed male. But why does this interesting phenomenon occur?
Recent studies reveal that the reason lies in the genetic differences between male and female cats' X chromosomes. According to a report by USA Today, on May 15, geneticists from Stanford University and Japan independently published two studies explaining the orange coloration in cats. Both studies identified that the orange fur results from a deletion in a small segment of DNA near the gene ARHGAP36, which encodes a Rho GTPase activating protein involved in pigment production.
Stanford geneticist Gregory Barsh, a co-author of the research, explained that when this DNA segment is deleted, the activity of ARHGAP36 increases tenfold, producing more red, orange, or yellow pigments, which makes the cat's coat more orange in appearance.
Importantly, ARHGAP36 is located on the X chromosome. Female cats have two X chromosomes, while males have one X and one Y chromosome. For a female cat to be fully orange, this mutation must occur on both of her X chromosomes, which is statistically less likely. In contrast, male cats only need the mutation on their single X chromosome to express the orange coat. This genetic mechanism explains why most orange cats are male.
Barsh also noted that although the two studies were conducted independently, the researchers maintained communication over the past year and decided to publish their findings simultaneously in the same journal.
