The Science of Spots

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.

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Connect the spots – Image – M-H JeevesChemistry World

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.

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©Tori-Ellen Dileo – It’s all about genetics. Every leopard has a different pattern – female South Luangwa NP, Zambia

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.”

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Image ©Tori-Ellen Dileo – Clever cats at home in trees and perfectly camouflaged in low, shady light – Male Leopard South Luangwa NP, Zambia

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.

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Leopards in High Places

Many of the big cats are known for climbing trees to escape the heat, flies, to watch for prey or to escape other predators. It is not uncommon to see them taking to heights and, in Africa leopards are commonly seen hanging out in tall trees. Although lions have been known to do the same in certain places they are not exactly designed for tree climbing and come across a little more awkward compared to the fluid and graceful leopard who is naturally at home in the heights where they will stash kills, eat and happily sleep.

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©Tori-Ellen Dileo – Salt Pan female hangs out and catches a breeze in a large tree – South Luangwa NP. Zambia

During my trip to Africa last year I was fortunate to have many wonderful leopard sightings both on the ground and up high, in fact over a few days all I had to do was look up to see these dappled beauties looking down at me. Of course, that’s when they weren’t busy enjoying a siesta or post-meal nap.

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©Tori-Ellen Dileo – Kataba the one-eyed legend – Puku Ridge South Luangwa NP, Zambia

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©Tori-Ellen Dileo – Kataba sleeping with a full belly – Puku Ridge South Luangwa NP, Zambia

While leopards are able to climb some very tall trees you might be surprised to know that at least one had made it all the way to the top of Africa’s highest mountain to take in a view that perhaps no other has. In 1926 on Tanzania’s Mount Kilimanjaro, a frozen leopard carcass was found along the volcanoes crater rim by Pastor Richard Reusch, a Missionary for the Lutheran Church. The Pastor was supposedly the first to discover the leopard which would later inspire, and be immortalized in, Hemingway’s book The Snows of Kilimanjaro. The Pastor made sure to get proof of his find and cut off an ear as souvenir on a subsequent climb the following year, afterwards the leopards remains were reported to have mysteriously disappeared. No reason was given as to why the leopard would have been that high, approximately 18,500 feet (or 5638.8 meters), close to the western summit at a place that would be christened Leopard point, but Pastor Reusch had hypothesized that the cat had been chasing a goat since he also found the remains of one not far from where the leopard lay. Since there were no remains and no radiocarbon dating, the leopards age along with length of time it remained locked in the once famous snows of Kilimanjaro will also remain a mystery.

Interestingly, there is a reference that notes the first report of a leopard carcass on Kilimanjaro was in 1889 by a German Geologist and Geographer named Hans Meyer who had seen one not far from where Reusch would later spot his. Among some of the theories included the possibility that the leopard could have come from the Kilimanjaro Mountain  Forest Reserve and took a wrong turn, or that the leopard was pursued up to high elevations by local hunters as Meyer had seen a hunting camp nearby. Officially though, nothing has ever been confirmed and to this day there has been no explanation for either Meyer’s or Reusch’s leopard.

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Kilimanjaro stands 5,895 meters high, the leopard was found at about 5638.8 meters – Image – John Reader/Science Photo Library via Earth Touch News

It does seems that leopards had an affinity for the mountains and in 1997 another leopard carcass was discovered on Africa’s second highest mountain, near Tyndall Glacier, Mount Kenya. In this case there were remains, although very decomposed, which turned out to be enough for radiocarbon dating placing the animal at about 900 years old.

There are opportunities to see wildlife during the early stages of a Kilimanjaro climb at lower elevations, but those still hoping to spot a leopard on higher slopes shouldn’t hold their breath. The high altitudes that are reached during climbs are not ones that most wild animals can survive at and if there are any, most will do their best to steer clear of humans.

If you are set on a chance to glimpse a leopard in high places it is probably best to keep your eyes on the trees and maybe, you will be lucky enough to have one of these beautiful cats reveal themselves and all their spotted splendor.