NORMAN — From flies to crabs, beetles and elk, every animal has a weapon of sorts. Usually, these weapons are in proportion to the overall size of the animal and provide a balance such that animals may effectively hunt, kill and feed on prey.
However, in some cases, animals are fitted with extreme weapons breaking away from balance. Biologist Doug Emlen, of the University of Montana, discussed his book “Extravagant Weapons” Thursday night and what triggers the evolution of extreme weapons in animals and how this parallels the evolution of human weapons technology.
A part of the University of Oklahoma Sutton Lecture Series, Emlen revealed what three critical prerequisites must be in place for extreme weapons to evolve and an arms race to ensue.
“Most weapons — claws, teeth and talons — stay small because of balance. Big weapons may be critical to killing but may hinder catching prey or eating. Balance allows hunters to do both,” Emlen said. “There are two basic ways balance breaks down: 1) counteracting selection disappears ... and 2) competition over reproduction.”
He said when a predator ambushes his prey, the cost of a big weapon is minimal. Because a female’s turnaround for reproducing takes much longer than a male’s, fewer females are available for mating, resulting in intense competition.
Yet, some species, including birds, effectuate this competition by singing the loudest songs, flashing the brightest colors and having the biggest plumage. Three prerequisites must be in place to push forward the development of extreme weapons in an animal arms race, Elmen said.
Not only must there be intense competition and a limiting/defensible resource, but contests over limited resources must occur in the form of duels and not mere scrambles.
“Scrambles require agility. Extreme weapons are not cost effective as opposed to duels, which are predictable and favor strength, skill and weaponry,” Emlen said.