On Point: Research Shows How Animals Develop the Pointy Parts of Their Body

Monash University's interdisciplinary team uncovered a new fundamental rule of biological development that demonstrates remarkable patterns in the forms of sharp objects around the tree of life, such as teeth, horns, claws, beaks, animal shells, plant thorns, and prickles.

Evolutionary Patterns

Animals and plants often evolve in patterns that obey the golden ratio, such as logarithmic spirals. These patterns are created by very simple processes: a logarithmic spiral is formed as one side of a structure grows faster than the other at a constant ratio. These are known as 'development laws,' and they help to understand why species have such shapes.

The science team illustrates a new rule called the 'control cascade' based on how the form 'cascades' down a tooth following a power law in a new study published today in BMC Biology.

As an elephant tusk grows larger, it widens at a very precise rate, following a 'power law'-a statistical trend in which the logarithm of the tooth's width and length has a straight-line relationship. The magnitudes of earthquakes, the heights of cities, and the stock exchange movement are also examples of control rules.

Wide Variety of Species

This pattern can be seen in many species' teeth, including giant sharks, Tyrannosaurus rex, mammoths, and even humans. Claws, hooves, horns, spider fangs, snail shells, antlers, and the beaks of rodents, reptiles, and dinosaurs all obey this power law. Aside from animals, the team noticed it in a rose bush and lemon tree thorns.

The research team was headed by Associate Professor Alistair Evans of Monash University's School of Biological Sciences.

"The number of animals and plants that follow this rule is astounding," Associate Professor Evans said.

"We were astounded to find it nearly anywhere we searched around the kingdoms of life-in live creatures as well as those that had been extinct for millions of years."

Sir Christopher Wren's Theories

The new pattern builds on Sir Christopher Wren's theories, the polymath anatomist, physicist, and mathematician who designed London's St Paul's Cathedral. Wren proposed in 1659 that a snail shell may be a twisted cone containing a logarithmic spiral. According to a new analysis, the power cascade form (also known as a 'power cone') is used in shells and other shapes such as teeth and horns.

Developing Scientific Law

Associate Professor Evans said, "This new law is the missing piece about a 350-year-old puzzle of how animals and their parts evolve."

"We may use this development pattern to estimate the possible evolution pattern since too many systems match it. When animals develop teeth, horns, or claws, it appears that they would most likely be in this form. It also enables one to anticipate how mythical creatures would appear if they followed the same natural trends."

"Now we can see what Game of Thrones dragons and Harry Potter's fantastic beasts will look like," Associate Professor Evans said.

Also Read: Vertebrate Origin Theory Now Questionable With Discovery of Fossilized Fish Larvae

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Tags evolution, Evolutionary Pattern