It’s hard not to notice a tortoiseshell cat. Their appearance is striking, with distinctively colored fur. No two cats are alike, and genetics controls the differences. The majority are also female, which adds to their mystique. The pattern is more prevalent in some breeds, but tortoiseshell is not a breed; it only describes the color pattern.
The term describes animals that are spotted with patches of orange and not orange. They can be black or some variation, from ginger to chocolate to cream. Calicos are the same color, with the addition of white, making it a tri-colored variant of the tortoiseshell cat. However, the Tortoiseshell Cat only has black and orange markings.
The Earliest Records of the Tortoiseshell Cat in History
It is not clear when the first tortoiseshell cats appeared, but ancient records suggest that they were mentioned by the Celts and Khmers of Southeast Asia. When the tortoiseshell variant occurs in female cats, it is simply a manifestation of a sex-linked dominant trait.
The gene that controls its physical expression is located on the X chromosome. Each parent contributes one copy or one allele of the two they possess to each of their offspring. A kitten must inherit only one copy of the trait to be seen.
A recessive trait appears only if both alleles are the same copy. For example, if the alleles an offspring receives from their parents are OO or Yes, the dominant trait is present. The capital O is shorthand for the dominant tortoiseshell variant, and the lowercase letter is the recessive. The only way to not see tortoiseshell is if both alleles are yes, making the cat brown or black and not orange.
A Genetic Explanation
However, that fact raises another question. If this color trait is dominant, why aren’t all female tortoiseshell cats orange? If he is YES or Yes for the trait, you would expect the cat to be orange without any black coloring. The answer lies in the role of evolution in survival.
Remarkably, researchers have identified more than 1,000 genes on the X chromosome. Men’s Y chromosomes don’t have nearly as many. However, that does not mean that X-linked traits are viable or necessary for survival. Some are harmful and potentially fatal. How did evolution deal with this battle?
Natural selection suppresses the expression of certain X-linked traits through a process known as X-chromosome inactivation (XCI). That is, some O alleles are suppressed, leading to the mottled patchwork we call tortoiseshell, with orange and black present. XCI does not occur in male cats. If the animal inherits an O dominant allele, the cat is orange or black, not both.
The incident of the tortoiseshell male cat has another genetic twist. Early scientists concluded that it must be sex-related simply because of the inheritance pattern and animal sex.1 The only way a male animal can have this pattern is if they have two X chromosomes, which allow orange and black to be seen, making them XXY. This can happen if the cat has inherited Klinefelter syndrome.2
This condition also exists in humans. It’s not surprising since we share 90% of our DNA with cats.3 Unfortunately, Klinefelter’s syndrome carries many risks, including an increased risk of cardiovascular disease, certain cancers, and autism. This random genetic mutation also causes sterility in males. This explains its rarity in male cats and its prevalence in females.
Why the Tortoise Color Appeared in the First Place
The domestic cat is a descendant of the African Wild Cat (Lybian wild cat). This cat is strikingly sand colored to match their arid habitat and provide camouflage. Why do our pets have so many color variations, like tortoiseshells? An animal with this type will stand out and probably won’t survive. The answer lies in domestication.
Charles Darwin theorized that selective breeding had a major impact on the genetics and phenotype or physical appearance of animals. Later, scientists observed relative depigmentation and other traits associated with breeding animals to be tame. The term domestication syndrome describes these changes that humans cause in the animals they domesticate.
The beautiful color, like tortoiseshell and other characteristics we like, are the result of human efforts for selective breeding. This process occurs much faster than natural selection. What would take Nature thousands of years happens in a few generations with human intervention. Of course, evolution also had something to say.
How the Tortoiseshell Cat Gained Popularity
Although the earliest records are unclear, it is likely that tortoiseshell has been in the gene pool of the domestic cat since ancient times. The folklore of many cultures contains stories about this beautiful but mysterious cat, with explanations of the animal’s appearance and supposed meaning. Stories exist from the United Kingdom to Japan and the United States about the strange tortoiseshell coat.
The beauty of the tortoiseshell pattern is undoubtedly a factor in its popularity. The animal’s appearance is distinctive, often with distinctive markings. Keep in mind that formal cat breeds are a relatively recent phenomenon. Fanciers may have tried to selectively breed cats to increase their spread. The emergence of males is random, with no guarantee of tortoiseshell children.
Formal Identification of the Tortoiseshell Cat
The formal recognition of the tortoiseshell cat depends on the breeds in which it is allowed to color. The Persian is an ancient breed, with tortoiseshell in its many accepted colors. Other breeds with similar standards include the following:
Tortoiseshell color is not allowed in breed standards where appearance is important to the conformation of the animal. Chartreux and Russian Blue are two classic examples, with only one color and its variants allowed. Note that parent clubs that approve of tortoiseshells also include calico by its very definition, the latter being three-colored as opposed to the two-colored tortoiseshell.
Top 4 Unique Facts About Tortoiseshell Cat
1. Turtle Diversity is a Rare Phenomenon.
Scientists estimate that this only occurs in approximately 1 in 3,000 male cats. The prevalence of sterility in these animals is a mitigating factor in its scarcity.
2. Variations of the Tortoiseshell Pattern exist.
Although every cat is different, several well-known tortoiseshell color variations exist, including the tortoiseshell tabby and bridled cat.
3. A Small Study Hypothesized Gene Stability as an Explanation for Tortoise Color.
Researchers have identified two fertile males with this color variant. Animals have the normal 38 chromosomes without XXY in cats with Klinefelter’s syndrome. They determined that all things being equal, gene stability was the only explanation for the color and fertility of cats.
4. Another More Spectacular and Rare Explanation Involving Chimerism.
Chimerism refers to an organism that has cells from two sources. In this case, the second organism is the reabsorbed DNA of a dead twin embryo. Scientists have identified what they believe is the first case of a fertile tortoiseshell male cat exhibiting chimerism.
Do Tortoiseshell Cats Make Good Pets?
Tortoiseshell would make a delightful pet, regardless of breed. Much depends on the care and protection of the animal. We hope that the unique appearance of the kitten can get more attention and pampering. One of the most critical considerations is providing adequate mental stimulation and enrichment for your pet.
Cats are intelligent and need stimulation for their mental health. You can meet this need through regular interaction with your pet and interactive toys that challenge them. Understanding the financial and time commitment of inviting a cat into your life is important for their well-being and well-being.
Conclusion
The tortoiseshell cat is not a breed but a recognized color variation accepted by many parent clubs. Its appearance is the result of eons of evolution that shaped the animal’s DNA and improved its fitness for survival. The feature has attracted many enthusiasts who have admired the cat’s beauty along the way. The tortoiseshell pattern is also a genetics lesson because it is an X-linked trait.
Featured Image Credit: Tinka Mach, Shutterstock
