18 February, 2015
When animals fight for mates, food and territory, they use the weapons they were born with: teeth and claws, horns and hooves. Human animals can use their hands and feet, but they also fight with knives, guns and bombs.
A new book looks at the comparisons between human weapons and that of the animal world. It tells about some weapons that reduce the likelihood of battle. And other weaponry that, if uncontrolled, could end the arms race for everyone.
Insects fill the night with a low continuous sound as two male stag beetles prepare to fight. They are competing for the interest of a female beetle. They battle with their mandibles, mouth parts that are pointy and sharp like the antlers of a deer. The stag beetle's mandibles can extend to half their body length.
Doug Emlen is a scientist at University of Montana. He says that while animal weapons are common, extreme weapons, like the beetle's, are not, and for good reason.
"Just about every animal out there has some kind of a weapon. You can look at cats in your house or dogs have claws and eagles have talons. But when you look across animals most of the time, these weapons are pretty small. They're light weight, they're portable. They don't slow you down, they're not very expensive to produce. But here and there, every now and then, we find these animal lineages where something has changed. And in these special species, the weapons start to get really big."
Doug Emlen explores these extremes in his new book, "Animal Weapons: The Evolution of Battle." He says animals always evolve for a reason, such as ambushing – or a surprise attack – on their prey.
Mr. Emlen says the ancient saber tooth cat is an example. It had long, curved teeth that came to a sharp point well below the animal's lower jaw. The huge, heavy fangs made the cat slow and clumsy. So instead of chasing prey, it probably hid in trees to wait for prey. Then the cat would jump on the back of its victim and sink its fangs in for the kill.
"These animals experience a very different pattern of selection. For them, it's not the overall running speed of their body or flying speed or swimming speed that matters, because they sit and they wait."
Another place where extreme weapons have developed is in termite colonies. Among these insects, the worker termites are small and quick. The soldier termites that guard the colony have very powerful jaws.
"There are soldiers in these guys that can slice through a pencil."
Doug Emlen says most of these extreme weapons are on the male of the species. He adds that the most common driver of their development is battle. Like the elks that crash, head to head, with their huge antlers.
"These are things that look like they should tip over, trip, or get tangled up in branches."
Another animal that packs an extreme weapon is the very small fiddler crab. There can be thousands of them running around a single beach. Most of the males do so while waving a huge claw in the air.
"Fiddler crabs actually are, as far as we know, the most extreme animal weapon anywhere. In some of the most extreme cases, the biggest males of these fiddler crab populations produce a claw that is literally the entire weight of the rest of the body of the male."
The crab with the biggest "claw" almost always wins. Doug Emlen says the main point of the claw is communication to avoid battle, not win battle.
"The males can go right up to an opponent, they wave their claws, they size each other up, and the smaller male walks away. And so this odd sort of paradox that arises in these animal species with these huge weapons is a lot of times, they hardly ever fight."
Doug Emlen says that, in some ways, humans are no different. Size of weapons counts a lot in military services like the U.S. Navy.
"Our aircraft carriers absolutely work as deterrents. There aren't any other countries that have navies as big as the one the United States has for example today and we use those aircraft carriers as deterrents."
Doug Emlen says this is when human behavior moves in a very dangerous direction. He says our most powerful weapons are now widely available. He adds, if everyone has a nuclear bomb, how can enemies measure each other's strength and know when to surrender?
"The cost of the weapons of mass destruction actually went down. They started making smaller and smaller warheads that could be packaged on smaller and lighter missiles."
Mr. Emlen says the number of warheads grew hugely. Now he says the problem is keeping watch on all of them.
The biologist says there is no comparison in the animal kingdom for weapons of mass destruction. And those could destroy the world. So, Doug Emlen says, he hopes all nations will learn from the natural world.
I'm Marsha James.
Shelley Schlender reported this story from Boulder, Colorado. Marsha James wrote it for Learning English. Caty Weaver was the editor.
Words in This Story
mate – n. either one of a pair of animals that are reproduction partners
evolve – v. to change or develop slowly often into a better, more complex, or more advanced state; to develop by a process of evolution
prey – n. an animal that is hunted or killed by another animal for food
fangs – n. a long, sharp tooth
clumsy – adj. badly or awkwardly made or done
beach – n. an area covered with sand or small rocks that is next to an ocean or lake
deterrent – n. something that makes someone decide not to do something
warhead – n. the part of a missile that contains the explosive