Apparently, a universal model could describe how teeth, horns, claws, beaks, thorns, and other sharp structures in plants and animals are developed - and researchers have identified what it is.
Both animals and plants usually grow according to understood mathematical and physical patterns, such as ram horns and flower petals following the golden ratio and Fibonacci's sequence. For example, horns grow at a constant ratio, locally called "rules of growth, and help scientists understand and predict certain behavior.
Researchers from Monash University present their findings in a report titled "A universal power law for modeling the growth and form of teeth, claws, horns, thorns, beaks, and shells," published in the latest BMC Biology, March 30.
Power Cascade in Both Plants and Animals
In their paper, researchers explain how one of the major goals of evolutionary developmental biology is to "discover general models and mechanisms" that create organism phenotypes. The new universal model called the "power cascade" follows a power law between the radius and the length of these sharp structures. The pattern indicates a straight relationship between the logarithm of width and length. Aside from sharp structures in animals and plants, these patterns also emerge in other parts of nature, such as earthquakes, human cities, and even the stock market's potential.
For example, when an elephant tusk grows longer, it also grows wider at a particular rate, consistent with the mathematical power law. This is also applicable for the teeth of sharks, mammoths, humans, and even the Tyrannosaurus rex. Additionally, this new universal model also applies to claws, hooves, fangs, horns, shells, and beaks. The same pattern has also been observed in the thorns of the rose bush and lemon tree.
"The diversity of animals, and even plants, that follow this rule is staggering," said associate professor Alistair Evans from the School of Biological Sciences at Monash University, who also led the research team behind the study. "We were quite shocked that we found it almost everywhere we looked across the kingdoms of life-in living animals and those extinct for millions of years."
A New Part of the Biological Puzzle
The press release from Monash University explains how the newly-discovered universal model on power cascade expands on the ideas of Sir Christopher Wren, who was mostly known as the English architect who designed London's St. Paul Cathedral but was also a polymath with expertise as an anatomist, geometer, astronomer, physicist, and mathematician. In 1659, he suggested that a snail's shell could be a cone twisted in a logarithmic spiral pattern. Closely enough, the new study shows that shells and other sharp structures actually follow the "power cascade shape," also known as a power cone.
"This new rule is the missing piece of a 350-year-old puzzle of how animals and their parts grow," Evans noted. He additionally explains that since "so many structures" follow the power cascade pattern, researchers can use this to predict how evolution will proceed in the future. Animal teeth, horns, or claws would most likely adhere to the traits of this universal model. The pattern could also help in better characterizing mythical animals should they follow the same laws of nature.
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