One-on-one duels favor weapon evolution while chaotic scrambles do not.

Evidence

In animal duels, too, the best fighters usually win, whereas in scrambles they may not. Head-on encounters are relatively predictable and straightforward, without surprises. In these fights it is harder for a poor quality male to usurp a bigger, better male. As with ancient warriors, strength, stamina, and weapon size prevail. … All else being equal, we expect species where males fight each other one-on-one to be more likely to evolve extreme weapons than species where males fight less predictably. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 245

Categorization

• XREF: connects to: Concentrating simultaneous fire disfavors large weapons while duels favor them; Medieval combat structured even battlefield clashes as ritualized one-on-one duels; Symmetrical one-on-one fights are a neglected prerequisite for weapon arms races — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 226 (+7 more)

Related

• Concentrating simultaneous fire disfavors large weapons while duels favor them (similarity 0.92)
• Animal and human fights both hinge on whether duels or gang-ups occur (similarity 0.90)
• Big weapons only pay off when fights are one-on-one duels (similarity 0.89)
• Intense competition without duel structure does not drive weapon evolution. (similarity 0.89)
• Medieval combat structured even battlefield clashes as ritualized one-on-one duels (similarity 0.89)
• Symmetrical one-on-one fights are a neglected prerequisite for weapon arms races (similarity 0.87)
• Specific conditions are required before weapons escalate into an arms race (similarity 0.87)
• Three conditions must align to trigger an animal weapons arms race. (similarity 0.86)
• Dueling plus competition and defensibility is the general rule for extreme weapons (similarity 0.86)
• Tunnel dwellers fight successive duels and evolve weapons; open-ground species scramble without them. (similarity 0.85)
• State arms races mirror single male-male animal contests, not evolutionary turnover (similarity 0.83)
• When balancing selection fails, bigger weapons win every round and escalate the race. (similarity 0.83)
• Pair bonding removes the competitive conditions that drive weapon evolution. (similarity 0.82)
• Weapon evolution needs both competition and economically defensible resources (similarity 0.82)
• Fortification-artillery escalation mirrors predator-prey arms races, not rival contests (similarity 0.81)

Broader Connections

• Intense competition without duel structure does not drive weapon evolution. #corroborates (0.90) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 242
• Burrow-guarding constrains fights to duels and drives weapon evolution #exemplifies (0.75)
• Dueling plus competition and defensibility is the general rule for extreme weapons #expands (0.60) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 266
• Pair bonding removes the competitive conditions that drive weapon evolution. #contradicts (0.50) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 439