Human spear-point size is constrained by shaft balance and penetration requirements

Evidence

As early as fifteen thousand years ago, North American hunters began to throw their spears with a throwing stick, or atlatl, and to tip their spears with points flaked from sharp stone. Spears function well only if their tips are balanced with the rest of the shaft, and if the blade is wide enough to create an incision in an animal’s hide sufficiently large for the attached shaft to enter. This puts strict limits on the sizes of tips that will function on particular wooden shafts: bigger shafts require bigger stone points. Large spears are also heavy, hitting their prey with greater force and deeper penetration than smaller ones. Not surprisingly, large spears and points enable the takedown of large prey. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 100

Categorization

• XREF: Parallels the carnivore tooth size tradeoffs discussed earlier in this book’s argument about balancing selection. — connects to: Human spear points shrank as prey species successively dwindled in size — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 103; Early human weapon points shrank rather than grew over time — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 102; Extreme weapon size faces stabilizing, not open-ended, selection in real populations (+4 more)

Related

• Early human weapon points shrank rather than grew over time (similarity 0.92)
• Human spear points shrank as prey species successively dwindled in size (similarity 0.88)
• Predator weapons stay small because larger ones hinder hunting (similarity 0.87)
• Better propulsion technology permitted smaller, deadlier human weapons (similarity 0.86)
• Weapon size in animal species is under stabilizing selection, not open-ended directional selection (similarity 0.85)
• Extreme weapon size faces stabilizing, not open-ended, selection in real populations (similarity 0.84)
• Balanced selection keeps most animal weapons modest rather than extreme. (similarity 0.83)
• Species with huge weapons often show weak current selection on them. (similarity 0.83)
• Natural selection usually favors modest weapon size because cost offsets benefit (similarity 0.83)
• Weapons shrink when predator pressure falls and armor gets costly. (similarity 0.82)
• Each weapon-size increase resets the competitive baseline, ratcheting populations upward (similarity 0.82)
• Bigger weapons usually fail because their costs outweigh their benefits (similarity 0.82)
• Ambush predators evolve large weapons because they strike rather than chase prey (similarity 0.81)
• Variation in animal weapon size is explainable by species ecology and behavior. (similarity 0.81)
• Balancing selection normally curbs weapon size until some lineages escape into runaway arms races (similarity 0.81)

Broader Connections

• Extreme weapon size faces stabilizing, not open-ended, selection in real populations #expands (0.60)
• Agility constraints suppress heavy weapons in airborne insect fighters #exemplifies (0.60) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 729
• Weapon size in animal species is under stabilizing selection, not open-ended directional selection #expands (0.55) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 850
• Animal weapons evolved to extremes far beyond practical size #complicates (0.50) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 2
• Weapons in arms races get so big they impair other bodily functions #contradicts (0.45)