Each advance in weapon metallurgy forced a corresponding advance in protective armor

Evidence

The first manufactured weapons were sharp, fire-hardened pointed sticks and spears tipped with flint blades. Knapped flint could slice flesh, but blades shattered easily—stiffened leather provided adequate protection against flint for thousands of years. Metallurgy brought with it tougher weapons—first bronze, which was soft and dulled quickly, and later iron—and against these weapons, leather armor was not as effective. Armorers began attaching metal rings or scales to the outsides of leather garments to block against the stabbing or slicing blows of metal-tipped pikes and swords. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 59

Categorization

• XREF: The offense-defense arms race described for sticklebacks earlier in the book maps directly onto human technological escalation. — connects to: Cheap weapons let untrained commoners overcome heavily armored elites; An inexpensive weapon made elaborate armor a deadly liability rather than protection. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 430; Fortification style evolved in direct response to artillery effectiveness — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 972

Related

• Armor evolution tracks a benefit-cost trade-off identical to that shaping animal weaponry (similarity 0.85)
• Human fortifications and artillery evolve via the same arms-race logic as animal weapons (similarity 0.84)
• Fortification style evolved in direct response to artillery effectiveness (similarity 0.84)
• Bombers evolved like castles, adding all-around defenses against attackers (similarity 0.82)
• An inexpensive weapon made elaborate armor a deadly liability rather than protection. (similarity 0.82)
• Weapons shrink when predator pressure falls and armor gets costly. (similarity 0.80)
• Fortification-artillery escalation mirrors predator-prey arms races, not rival contests (similarity 0.80)
• Cheap long-range weapons eroded the battlefield value of expensive armor. (similarity 0.80)
• Comparisons of animal and human weapons have a long scholarly tradition. (similarity 0.79)
• Rising predator pressure quickly enlarged lake stickleback armor (similarity 0.79)
• Identical circumstances trigger and collapse arms races in animals and humans. (similarity 0.79)
• Markets and battlefields select among rifle designs like natural selection acts on weapons (similarity 0.78)
• Weapon evolution is judged by competition among designs, not human survival (similarity 0.78)
• Human and animal arms races follow parallel evolutionary dynamics (similarity 0.78)
• Cheap weapons let untrained commoners overcome heavily armored elites (similarity 0.78)

Broader Connections

• Fortification style evolved in direct response to artillery effectiveness #expands (0.80) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 972