How the cat gets its stripes: It’s genetics, not a folk tale

Folklore is full of stories about the coat patterns of cats: How the tiger got its stripes. How the leopard got its spots. And scientists ask the same questions, although not necessarily about large predators. The research may focus instead on something like the mackerel tabby pattern in domestic shorthairs.

The question of how cat stripes and splotches are made touches on some of the deepest theoretical puzzles of biology. How does a blob of cells organise itself into a fruit fly, or a panda? What tells the bones in a limb to become a hand, or paw, or the ribbing of a leathery wing? What tells some skin cells to grow dark hair and others lighter hair?

A team of geneticists reported Tuesday in the journal Nature Communications that it had identified a gene in domestic cats that plays a key role in creating the traditional tabby stripe pattern, and that the pattern is evident in embryonic tissue even before hair follicles start to grow.

The inheritance of cat coats — how to breed for this or that pattern — is well known. But how patterns emerge in a growing embryo “really has been an unsolved mystery,” said Dr. Gregory S. Barsh, an author of the new report.

“We think this is really the first glimpse into what the molecules might be” that are involved in the process, he added.

The research team included Dr. Barsh, Christopher B. Kaelin and Dr. Kelly A. McGowan, all affiliated with the HudsonAlpha Institute for Biotechnology in Alabama and the Stanford University School of Medicine.

“It’s a very beautiful study,” said Hopi E. Hoekstra, an evolutionary biologist at Harvard University, who has collaborated with Dr. Barsh in the past but was not part of this research.

“It advances our understanding of one of the most fundamental questions in developmental biology: How do patterns form?” Dr. Hoekstra said.

Dr. Barsh said the theoretical basis of the team’s work dated back to a groundbreaking paper by Alan Turing, famous for his work in computer science and code breaking. Turing’s genius was not limited to computers, however. He wrote a paper called “The Chemical Basis of Morphogenesis” in 1952 that “really laid the groundwork for the entire field of mathematical biology,” Dr. Barsh said.

The paper describes what is called a reaction diffusion process in which two chemicals, one that stimulates gene activity and one that inhibits it, can result in regular, alternating patterns. Researchers who study the development of coat patterns have thought that this process could produce stripes in cat coats; Dr. Barsh said the team’s research had confirmed this hypothesis.

The authors emphasise that the patterns they investigated are only a “fraction of the pattern diversity that exists among domestic cat breeds.” In the future, Dr. Barsh said, one target for the team will be to uncover how the tissue pattern translates to color when hair follicles grow. Dr. Hoekstra said the work highlighted the value of domestic animals to science. “Cats are a fantastic model — easier to study than zebras or leopards — that have developed a dazzling array of spots, stripes and everything in between.”