Amotz Zahavi

Amotz Zahavi (1938–2017) was an Israeli evolutionary biologist and ornithologist whose 1975 proposal of the handicap principle transformed the study of animal communication and sexual selection. Zahavi argued that extravagant ornaments like the peacock's tail are honest signals precisely because they impose severe costs that only high-quality individuals can bear. His proposal was initially dismissed as paradoxical, but subsequent formalization through ESS analysis and signaling games vindicated the logic, establishing costly signaling as a foundational framework in behavioral ecology.

Zahavi's broader contribution was to insist that communication cannot be understood independently of the strategic conflict between sender and receiver interests. His decades of fieldwork on the Arabian babbler — a cooperatively breeding bird in which dominant individuals perform costly acts of vigilance and sentinel behavior — provided empirical support for the view that signals are competitive acts rather than cooperative exchanges of information.