Tracing the tumultuous natural history of the brutal yet beautiful "extreme weapon."

This book examines the principles of diverse struggles in the biological world through the 'evolution of weapons.'
Douglas Emlyn, a biology professor at the University of Montana, travels through rainforests and beaches, taking readers on a journey through the world of remarkable animals to uncover the mysteries of animal weapons.
The author, who has been pursuing dung beetles across Africa, Australia, and Central and South America for the past 20 years, has doggedly studied the development and evolution of their weapons. He has broadened his interests to encompass the entire biosphere and presents a fascinating account of the evolution of animal weapons.


What stands out in this book is the 'extreme weapon'.
From the mastodon's formidable tusks to the long, chopstick-like forelimbs of the scorpionfish and the deadly pincers of the crayfish, the massive and impressive weapons immediately grab your attention.
While the grandeur of such a weapon may be awe-inspiring, the truth is that possessing such a large weapon comes at a great cost.
But why do so many animals engage in arms races, investing enormous amounts of energy in evolving "ultimate weapons"?

The author weaves together the biology of the arms race, starting with small things like thorns and teeth and progressing to increasingly larger weapons like horns and tusks.
The author's analysis encompasses approaches such as behavioral ecology, genetics, systematics, and developmental biology, drawing on the work of scientists around the world.
The story begins with biology and moves on to discuss all the weapons in the world, looking back at the arms race in the human world that is heading towards “unbridled all-out war.”
This is a masterpiece that weaves together a grand story of survival, evolution, and even human history through the prism of extreme weapons.

The animals' massive weapons look too bizarre to have been favored by natural selection.
It is impossible not to recognize such a sight.
Big weapons are 'really' ugly, and most entities can't get along with them.
For most weapons in most animal species, natural selection favors moderate size and moderate cost.

--- p.
26

Predators that sit and wait, soon to ambush, evolve towards larger and more extreme weapons.
The saber-toothed creature would lie in ambush, then jump down from a tree branch and plunge its greatsword into the prey's neck.
Like piranhas, ambush predators do not pursue their prey to get their kill.
In fact, most of them are terrible at running or swimming.
Instead, it is good at staying still and ambush, often blending in surprisingly well with the background, as befitting a hunter who waits for prey to approach.
When unlucky prey accidentally approaches, these predators leap from their hiding places and incapacitate their prey with a bite or a swipe with their legs.
--- p.
72

After a two-year gestation period, female elephants give birth to their calves, and nurse and protect them for another two years.
Females can only conceive in a very short period of five days.
So, modification is only possible for 1,460 days, or 5 days in 4 years.
This means that the period of modification is less than 0.5 percent of the lifespan.
As a result, there are only a few females capable of breeding at any given time, while there are far too many males.
Because of this rarity of fertile females, males engage in fierce duels with their dangerous fangs to mate.
--- p.
96

A second strategy adopted by many dung beetles is burrowing.
Females of this species fly to the dung site and immediately begin digging a burrow in the soil beneath the dung.
After digging a burrow deep enough—between 30 centimeters and a meter—they drag pieces of dung into the burrow, collecting food secretly from competitors above.
The female climbs up and down more than 50 times to gather food for one egg.
And then she lays a new egg and repeats the process.
While the females do this arduous work, the males fight over ownership of the den.
The victorious male guards the entrance to the burrow.
Not only to keep food away from other species, but also to keep rival males of the same species away from females.
In the den, males mate with females several times, sometimes being driven out by larger intruder males.
Males of the burrowing species usually have horns.

--- p.
125~126

When all is said and done, the cost to these males of their horns appears to be comparable to the cost to females of reproduction.
The cost of producing and using horns, in terms of energy and nutrients, was equivalent to the cost of raising two calves to weaning.
Horn growth dramatically reduces other bone mass, making males weaker and much more prone to bone fractures.
Essentially, the fact that bones grow when an animal engages in the most physically demanding and riskiest activity of its life means that it is at risk for seasonal osteoporosis.
…seasonal osteoporosis due to bone growth is certainly part of the reason why many large deer species suffer serious injuries during fights.
Moose males have a high incidence of rib and scapula fractures.
In red deer, one-quarter of all breeding males suffer injuries such as fractures during mating duels, and 6 percent suffer irreparable injuries each year.
--- p.
174

Deterrence arises from the arms race, but it also accelerates the evolution of weapons.
The moment weapons begin to function as signals of combat power, an entirely new motivation arises that triggers extreme size.
Now the male with the largest weapon raises the dog for two reasons.
Firstly, because it allows you to defeat your rivals in battle, and secondly, because it allows you to defeat your enemies without fighting.
The male with the largest weapon is already greatly rewarded, and thanks to its deterrent effect, he is rewarded with the additional benefit of saving money on fighting costs.

--- p.
206~207

When access to breeding is dominated by a small number of dominant males, the remaining males are strongly motivated to break the rules.
If you play a game that you can't win normally, there are bound to be males who use tricks.
This is true for populations of almost all animal species.
Bighorn sheep keep harems nestled on the steep slopes of the Rocky Mountains.
The largest and oldest males have the largest horns, and these males invariably win and lead the harems.
However, 40 percent of bighorn sheep are sired by smaller males.
These so-called "coursers", males who engage in sexual intercourse, enter a territory for only a few seconds at a time and quickly mate with females before being mauled by the dominant male.
--- p.
216~217

One species of stag beetle, freed from the need to fight over sap and able to forage abundantly in the spacious interiors of hollow trees, reduced the size of its mandibles, freeing it from the need to defend its resources economically.
Similarly, in three other stag beetle species, two of the three elements of the arms race disappeared when males formed long-term, stable bonds with a single female and helped each other raise their young.
So now not only do males not fight over where the sap flows, they don't fight at all.
The time required for male and female reproduction was similar, so there was no competition.
Today, their tongs are tiny.
--- p.
231

As with farming, there are mandatory costs that a nation must pay before it can devote resources to weapons.
A crab is made up of millions of cells that provide nutrients and need protection.
When cells die, the crabs die too.
Most of the mandatory costs are used to keep the cells alive.
A nation is made up of people, and it costs money to feed and shelter these people.
For example, the costs of education, welfare, police forces, highways, etc.
Only when there is a surplus after paying mandatory expenses can a country invest in luxuries such as armaments and weapons.

The wealthiest few nations have vast resources at their disposal to invest in weapons development, technological development, ships, aircraft, military equipment, training, and human resources.
Most countries have far fewer resources at their disposal.
If a country with no resources spends money on military spending, it will seriously erode the resources necessary for survival.
Nations invest in their militaries within their capabilities, but the size of the military varies from country to country.
As with beetle horns, North American caribou antlers, and fiddler crab claws, the relative size of a nation's military is an honest signal of its fighting power.
The size of the military is the perfect tool for deterrence of war.

--- p.
287~288

Only the two richest superpowers possessed nuclear weapons.
But as competition progressed, nuclear warheads became cheaper.
While the cost of conventional weapons, such as submarines, fighter jets, and aircraft carriers, has risen, nuclear warheads themselves have become smaller and cheaper.
Soon after, Britain and France tested nuclear warheads, followed by China and South Africa.
In the 1970s, India also successfully tested a nuclear warhead, and in the 1990s, Pakistan did the same.
Now Israel and North Korea also have nuclear weapons.
The most important prerequisite for deterrence is thus disappearing.

--- p.
287~288