Ginger cats are the result of a bizarre genetic mutation that doesn’t occur in any other species – at least, as far as scientists know.
That’s according to a study, recently published in Current Biology, which found orangeness occurred because of the rogue expression of a gene called Arhgap36 – a gene that had never before been connected to making mammals ginger.
Interestingly, this gene is located on the X chromosome, which explains why orange cats are predominantly male.
Like most male animals (including humans), cats have one X and one Y chromosome. Since the gene for orange fur lives on the X chromosome, if a male inherits an X with the orange gene, he’ll be fully orange – there’s no second X to mix things up.
However, female cats have two X chromosomes. To be completely orange, they need to get the orange gene on both of their Xs. If they only get it on one, the other X likely carries a non-orange gene.
As a result, their fur ends up a mix of colours – like the patchy orange, black, and white patterns seen in calico or tortoiseshell cats.
While orangeness in cats is linked to their sex, this doesn’t seem to be the case with other orange mammals, like tigers, orangutans and red-headed humans.
Mutations for orangeness in those animals occur in one of two genes, explained Dr Christopher Kaelin – a senior scientist in genetics at Stanford Medicine and the study’s lead author – but neither of those genes is linked to sex.
Orange cats seem to be “a genetic exception,” he said.
While this study confirms ginger cats are genetic anomalies, the jury’s still out on whether this genetic weirdness is responsible for their reputation as fluffy bundles of chaos.
To find out if the Arhgap36 mutation affects more than just fur colour, scientists examined various organs – like the kidney, heart, brain, and adrenal glands – in both orange and non-orange cats. They found no significant differences.
Kaelin said: “I don’t think we can exclude the possibility that there is altered expression of the gene in some tissue we haven’t tested that might affect behaviour.”
He added that the apparent tendency of orange cats to wreak havoc on the world might be mainly due to the fact that they are mostly male, and noted that there are not many scientific studies on the personality of orange cats.
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