Evolutionary Self-Care

Male Cape ground squirrels are prolific masturbators, and scientists believe they've figured out why: sperm competition.

Researchers observed these African squirrels engaging in self-stimulation to ejaculation, often immediately after mating with a female. This seems counterintuitive — why waste sperm right after sex?

The leading theory is sperm freshness. In Cape ground squirrel society: - Females mate with multiple males - Males can't guard females after mating - Sperm from different males compete to fertilize eggs

By ejaculating after mating, a male clears out his older, potentially damaged sperm. Then when he mates again, he delivers fresh, higher-quality sperm with better motility and fertilization potential.

The researchers found that males masturbated more frequently in situations where: - Sperm competition was likely (multiple males present) - Time between mating opportunities was longer - They had recently mated

This suggests the behavior is a strategic reproductive investment, not just random pleasure-seeking.

The study was published in a peer-reviewed journal and sparked conversations about how common functional masturbation might be across the animal kingdom. Many other rodents and mammals have since been studied with similar questions in mind.