A leading hypothesis for morphogenesis (pattern formation, such as tiger stripes) has been shown to be oversimplified. Whatever gave a tiger its stripes is more complicated than developmental biologists thought.
Live Science reported that the morphogen theory – the idea that protein gradients control pattern formation – is insufficient to account for the evidence:
A decades-old explanation for how tigers get their stripes has come into question as researchers challenge what’s called the morphogen theory. The research does not nix the theory, but science may now have a hypothetical tiger by the tail as they try to figure out this aspect of how Nature works.
The morphogen theory dates back to the 1950s and 60s from the work of Alan Turing and Lewis Wolpert. Researchers at New York University though, studying pattern development in fruit flies, found that simple protein gradients are not enough. There must be multiple competing gradients involved:
In other words, contrary to Turing’s theory, a single gradient of proteins does not have sufficient power to form the same body plan in each member of a species; however, if there are multiple gradients that work against each other, then the system becomes robust enough for normal development.
The team doesn’t believe their work has falsified the morphogen theory, but “suggested it needed some additional refinement.”
Here is a scientific phenomenon that should be easily studied in lab conditions, and they cannot explain it. An old theory taken for granted for some 50 years is not sufficient to explain pattern development in simple fruit flies, easily cultured and genetically altered in thousands of labs around the world. If the explanation of fruit fly patterns eludes scientists, how much less can they explain the tiger’s stripes, or the amazingly intricate patterns in birds, butterflies and many mammals! It’s not that it isn’t worth trying to understand genetically and developmentally how patterns form in embryos. The point is that if a phenomenon this accessible to observational science evades their grasp, how much less can they know about the unobservable past, and the origin of complex organs? Remember this when you hear the next science article claiming birds evolved from dinosaurs.