Natural Frequencies in Sexual Pelvic Thrusting

Area of Science:

• Evolutionary Biology
• Biomechanics
• Animal Behavior

Background:

• Most mammals use repeated pelvic thrusting for copulation, despite sperm transfer requiring only one intromission.
• The evolutionary drivers behind the prevalence of thrusting remain unclear.

Purpose of the Study:

• To investigate the relationship between mammalian body size and the rate of pelvic thrusting during sexual intercourse.
• To explore the biomechanical principles underlying sexual thrusting frequencies.

Main Methods:

• Analysis of video recordings of mammalian copulation across a range of species, from mice to elephants.
• Comparison of observed sexual thrusting frequencies with known resonant frequencies of musculoskeletal systems during locomotion.

Main Results:

• A significant inverse correlation was found between body size and pelvic thrusting rate.
• Thrusting frequency decreases with increasing body size, from 6 Hz in pocket mice to 1.3-1.8 Hz in humans, with no thrusting in rhinos and elephants.
• Sexual thrusting frequencies align with the natural resonant frequencies of mammalian locomotion, suggesting shared biomechanical constraints.

Conclusions:

• The rate of sexual pelvic thrusting is constrained by the resonant frequencies of the musculoskeletal system, similar to locomotion.
• Understanding these biomechanical principles could lead to advancements in treating human sexual dysfunction and enhancing mammalian breeding programs.