Background: In Nigeria, especially among the Igbo tribe, there is a well-held belief that a man's penile size can be predicted from his physique and the size of his buttocks, with people of small physique and flat buttocks likely to have long penile lengths.
Study design: A prospective study to test the scientific veracity of this traditional and apparently mythical belief. Stretched penile length was measured in 115 men between the ages of 30-65 years and its correlation with the body-mass index and the circumference of the hip as measured around the most prominent points on their buttocks, was statistically determined.
Result: The mean age of the subjects was 42.30 years (SD = 9.67), with a median of 40 years and a range of 30-65 years. The mean penile length was 13.37 cm with a median of 13 cm and a range of 7.5-19.5 cm. The mean circumference of the body around the buttocks was 96.46 cm (SD = 10.91), median 98 cm, and range 73-122 cm. The body-mass index ranged 17.34-44.44, with the mean at 26.87 (SD = 5.86), and the median 25.53. Linear regression statistics showed no statistically significant correlation between stretched penile length and body-mass index, thus physique. There was a significant direct correlation between penile length and gluteal size.
Conclusion: The supposed relationship between penile length and gluteal size may have a scientific basis, but contrary to belief, large buttocks is more predictive of longer penile length than small buttocks. Penile length has no relationship to physique.