Rudyard Kipling’s Just So Stories ‘How the leopard got it spots’ tells us that the feline had them painted on so it could blend into the forest ‘full of trees and bushes and stripy, speckly, patchy-blatchy shadows’. While we know that this is not true, he was close in his assumption in that the coat pattern is reflective of the cats primary environment – cats that hunt in open areas and are active mainly during the day, like lions, tend to have plain coats. Ones that dwell and hunt from trees, forested areas or at night, like leopards or jaguars, tend to have dappled, spotted coats, or in the case of tigers stripy coats.
It is known that coat and colors patterns like the leopards evolved for camouflage and, William Allen a researcher at the University of Bristol reinforced this theory after completing a study of coat pattern images from 37 different types of wild cats. The data from the images along with “information concerning the size of each species, its habitat, characteristic behaviors and more, was then plugged into a mathematical model of pattern development. ” It was determined that spots were most common in species that spend greater amounts of time moving in trees, and in those that are active at lower light levels.
Beside environment, there are likely more factors involved which influence the coat patterns of wild cats as they don’t always exactly mirror the animals surroundings. A few anomalies include the cheetah, which prefer open habitats but have retained their spots, this is thought to be the case because they rely mostly on speed, as opposed to camouflage, for hunting. The overall consensus is that coat patterns seem to have evolved to correspond to environments as well as how the wild cats behave within their specific environments.
Allen told BBC News that “When you place cat patterning over the evolutionary tree of cats, you can see that patterning emerges and disappears very frequently within the cat family, which is kind of interesting – it suggests that perhaps particular genetic mechanisms can solve very different appearances of cats.”
The leopards beautiful spots are more than skin deep and the mechanism responsible may have a lot to do with chemistry. Alan Turing a mathematician and founder of computer sciences, proposed that chemistry had a role in forming patterns like those on a leopards coat. In Turings only published paper on chemistry, he put forth a set of equations which attempted to explain the patterns seen on leopards. The elements in this process contained and ‘activator’ whose presence caused cells to produce pigmented black hairs and, an ‘inhibitor’ that would cause cells to create white hairs. If they were strongly different it would enable a pattern to grow. Turing was able to demonstrate mathematically that these “simple components could account for a wide range of patterns and, a subtle tweaking of the parameters could alter the pattern to create spots, stripes, swirls, splodges or other markings.”
Much later on Turing’s theory would be used by biologists to support the hypothesis about other patterned animals. Chemists would eventually recreate an example of Turing’s pattern in a lab using a gel which developed a pattern of “yellow dots on a blue background”. It is now acknowledged that the science of spots has turned out to be more complicated than first presented and researchers admit that it does not fully solve the riddle of how the leopard got its spots, even though the theory is still considered a major contributor to determining how patterns form.
For more on the science of spots I highly recommend taking a listen to the BBC Radio 4 Just So Science episode which talks about the science and math behind the patterns and reading Plus Magazine’s Some Just So Stories of animal patterning.