Submission + - Human penis size influences female attraction and male assessment of rivals (phys.org)
Females rated male figures that were taller, had a higher shoulder-to-hip ratio (indicating a more V-shaped body) and a larger penis as being more attractive. However, beyond a certain point, further increases in penis size, height and shoulder breadth had diminishing benefits.
Males also rated taller figures that had a more V-shaped body and a larger penis as being more intimidating as sexual rivals and fighting opponents. But, in contrast to female participants, they consistently ranked males with more exaggerated traits as more of a sexual threat, suggesting that males tend to overestimate the importance of these characteristics for attracting females.