The Evolution of Menopause in Toothed Whales (Nature, 2024)

Tier 2: Professional organization or credentialed expert guidance
Publisher: Nature · Published: March 13, 2024 · Accessed: August 27, 2026

Claims this source supports

Menopause (prolonged female postreproductive life) has evolved in only five toothed-whale species - killer whales, false killer whales, narwhals, belugas, and short-finned pilot whales - plus humans, out of 32 toothed-whale species studied.
The same evolutionary mechanism underlies menopause in humans and toothed whales: older females stop reproducing and instead gain fitness through intergenerational help - improving the survival of offspring and grandoffspring.
In killer whales, post-reproductive older females lead group movement, which is how the pod's knowledge and memory travel - the behavioral expression of the grandmother hypothesis.