One of Kipling’s Just-So Stories is “How the Leopard Got His Spots.” In the fanciful tale for children, the sandy-colored leopard and the Ethiopian make an arrangement to share features so that they can camouflage themselves in the forest. Spots and stripes are widespread in the living world, but how do they come about? Surely science can come up with a better explanation than Kipling’s. Just so, a recent scientific paper suggests that understanding the process is still a long way off.
Since Science Daily mentioned zebras, we’ll start with them. The article suggested the answer is simple. In Kipling fashion, the headline read, “How the Zebra Gets Its Stripes: A Simple Genetic Circuit.” Referring to the paper in Science by Liu et al.,1 they implied that the genetic mechanisms behind stripes and spots on animals is finally coming to light. “Now a team of scientists has designed a simple genetic circuit that creates a striped pattern that they can control by tweaking a single gene,” the article (actually just a self-promoting press release from UC San Diego, home of one of the researchers). The suggestion from the headline is that this goes a long way toward understanding zebra stripes and other patterns on animals and plants.
Strangely, though, the authors of the original paper (mostly from China) said nothing about zebras or any particular animal:
Periodic stripe patterns are ubiquitous in living organisms, yet the underlying developmental processes are complex and difficult to disentangle…. Living organisms display an amazing array of regular spatial patterns. Traditionally, elucidation of their developmental mechanisms has been pursued through forward or reverse genetics. However, essential components required for pattern formation and control are often buried in the overwhelmingly complex physiological context.
In addition, the others did their research on colonies of bacteria – not zebras or any other multicellular animal. Their findings were quite modest. By tweaking a gene for switching E. coli flagella from swimming to tumbling mode, they got them to form waves of pile-ups, like regular traffic jams caused by poorly coordinated signal lights….
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