When we cast a broad light, the evolution of any species is considered either by chance and/or by choice. The evolution of weapons, however, is often misinterpreted as the outcome of chance events. In the previous parts, we have seen the factors point to choices that vary across different species. Both options are feasible, often working in tandem, provided the effective cost of change is not significantly high.

Once the arms race is triggered, weapons start getting sizable and more sophisticated. In animals, as long as the selection pressure is applied, natural or artificial, the rate of development varies with the required application. In the book, the author demonstrated the evolution of weapons in rhinoceros beetles in an artificial setting to study the variation in cost and size. It is important to note that for an animal species, the primary loss is bodily changes affecting its life cycle. Since the life cycle of the beetles is short, it is possible to observe salient evolutionary changes in a short span of time. The author conducted his research for two and a half years.  The results of the research were clear. There was a significant increase in the size of the horns. However, since the availability of internal resources was limited, deficit spending resulted in unsustainable growth. The eyes of the beetles were shunted, along with affected wings and genitalia. In comparison, horn growth was three times as sensitive to wings and limbs.

Reliable signals and Deterrence

The affordability of a weapon is dependent on the resource pool of animal species. Similar to humans, family and bloodline play a major role in how capable the new generation can be. Weapons get bigger when the rest of the body turns fully grown. What propels the race is the opportunity cost. Whenever an opportunity to invest in weapons development leads to viable returns, animal species can create a discretionary pool to further the size. This is because weapons act as reliable signals to all parties, favoring females as well as rival males. For both battle purposes and protection, weapons advertise honest proofs of investment, and information like health status and fighting ability. This allows rivals to assess each other before engaging in dangerous battles. Avoidance is the best option for those not close to the top of the ladder as they live to fight another day.

For those who are stronger, the deterrence alone is enough. Weapons in animals are vastly more variable than other bodily elements. The dominant ones in a species need to fight with rivals of comparable strength and full attention. Small battles can cause minor injuries, which may later result in risks of distraction and exposure to predation. This is visible in the case of fiddler crabs with huge claspers. Most of the time, fiddlers employ their claws as warnings rather than instruments of battle. They use them as an agent of deterrence for weaker crabs. They do use them for intense fights, but only for a few minutes. After they spend hours waving up and down. This also acts as a welcoming signal for female crabs that are far away from fights as not all fights end well.  Normally, crabs are well protected from one another, since their exoskeletons are like armor, but in the heat of a battle, crabs get distracted and become easy targets for gulls and grackles.^[1]

Deterrence acts as an integral stage in an arms race. The evolutionary increase in size keeps up with the rate of extreme possessors. As signals, weapons become more honest by pushing the evolution of deterrence to avoid deadly confrontations. Fight costs saved by deterrence boost the already-fulfilled gains for males with the largest weapons. For example, the total horn length of male ibexes, a wild goat species, is ~20 cm for up to 3 years, whereas for individuals ≥10 years, the average lies between 60 and 80 cm.^[2] In a typical challenge, Ibex rams size each other up, comparing weapon sizes; most confrontations end without escalating to battle.

This cycle fuels the race to keep getting faster. To quote the author: Arms races and deterrence push each other forward, escalating in an evolutionary spiral. Nowadays, the odds of war on the sea are extremely low. It was different not so long ago. The size of the fleet was the measure of a country’s fighting ability—the perfect signal for deterrence.  The research underscores that certainty plays a more significant role in deterrence than severity.^[3] Warships used to chase down rivals of comparable size while medium-sized ones focused on escapes. Smaller ships used to either get destroyed or shied away. These elongated battles were too expensive for states to afford. For naval battles, state-of-the-art weapons are still too expensive. As a result, warships are close to being extinct, rather, aircraft carriers serve as the new agents of deterrence.

Sneaks and Cheats/End of the Race

When fighting doesn't ensure a victory, you need to opt for plan B. Strong monopolies incentivize individuals to evolve their way of fighting. Many animals chose alternative ways to infiltrate rival territories for the sake of mating. In the case of dung beetles, males with big horns are often deceived when a weaker rival male reaches the guarded female through a tunnel from a different end, avoiding the confrontation altogether. That's why males are observed doing guarding duty in rounds, but the infiltrators with far smaller weapons are quick and agile. In animals like Bighorn sheep, the strategy to disguise is fairly common as sneaky males are found almost in every species. Since most eminent males are bigger in size and weapons compared to females, smaller males can effectively sneak past the guards and camouflage in the herd. 

Similar courses of action are visible when talking about human conflicts and warfare. The definition of cheating becomes irrelevant in an active war when one military force cannot stand a chance against a larger one. Non-combatants and spies blend inside rival warring states as sneak forces. They stay in the game just by surviving in disguise. The surprise element can dismantle large tanks by slipping IEDs (improvised explosive devices) and disabling deadly weapons, making the bulk of conventional forces a liability. Guerilla warfare, a paragon of sneak tactics, is the foremost way of battle in a majority of small countries with poor economies.^[4] Even the conflicts between large nations are heavily dependent on sneaky submarines capable of knocking down aircraft carriers positioned in relatively safer territory.

The biggest cheat of the current era comes in the form of cyberattacks. Getting access to rival weapons can cripple the entire military force to a scary extent. A compromised security system is the worst nightmare for a warring nation as it may pose an existential risk to the population. In these Zero-day attacks, codes are deeply embedded until the day they are needed. Once active, hackers can gain control of everything from missile guidance systems to navigation and handling of submarines, to aircraft and aircraft carriers.

With the advent of such high risks in handling the deadliest of weapons, the end of the weapons race becomes the only option.

In the case of animals, the evolution of weapons is bound to reach an equilibrium stage. Bigger weapons in animals start losing their advantage, stalling the arms race, and the population settles on a new size. The relative benefit of weapon growth often fails to keep up with the associated cost, especially when the resources to sustain deplete in the surroundings. These circumstances are further exploited by others leading to the extinction of the entire species (for ex.  Sabertooth, Mammoth).

Human civilization is surrounded by a realm of costs, resources, expenses, payoffs, etc., at different points.  Enrichment of cheats is primarily backed by innovation and the trigger for change. When horse-mount soldiers were investing in shiny-bulky armor and engraved swords, foot soldiers invented the crossbow and longbows that pierced through centuries of investment in battle gear. As long-range weapons became more sophisticated and effective, we saw the birth of guns that collapsed the race for melee weapons. In such cases, even after the race ends, the weapons linger in various parts of society because of their low cost and considerable payoffs at the time.

In the final part, we'll see the extension of the parallels we have seen in the first three parts to the current state of human technologies, how it affects war in our time, and some important distinctions...