Why are only cats born red? - briefly
The color of newborn kittens is determined by their genetics and the amount of melanin in their fur. Most cats are born with a light-colored coat that darkens as they age due to increased melanin production, but some breeds like the Siamese retain their lighter coloring.
Why are only cats born red? - in detail
The phenomenon of red-haired cats is not as common as one might think, but it does occur in certain breeds and genetic circumstances. To understand why some cats are born with red fur, we must delve into the science of genetics and pigmentation.
Firstly, it's important to clarify that the term "red" is a bit of a misnomer when referring to cat fur. The color typically described as red in cats is more accurately an orange or ginger hue. This color is determined by a specific gene known as the orange gene (O). Cats can inherit two copies of this gene, one copy, or no copies at all. When a cat inherits two copies of the orange gene (OO), it results in a red or ginger coat.
The orange gene is sex-linked and located on the X chromosome. Since female cats have two X chromosomes (XX) and male cats have one X and one Y chromosome (XY), females can be homozygous for the orange gene (OO), heterozygous (Oo), or lack it altogether (oo). Males, on the other hand, can only inherit the orange gene from their mother, as they receive their single X chromosome from her. Therefore, a male cat with the orange gene will always express it, resulting in a red coat.
Additionally, the intensity and variation of the red color can be influenced by other genes. For example, the dilution gene (D) can modify the red pigment, creating lighter shades such as cream or apricot. The agouti gene (A) affects the distribution pattern of the pigment, leading to variations like mackerel tabby or classic tabby patterns in ginger cats.
In conclusion, the appearance of red-haired cats is a fascinating result of genetic inheritance and expression. While not all cats are born with this distinctive coat color, those that do carry the orange gene exhibit a unique and striking visual characteristic.