A study by Alfonso Cepeda-Emiliani has revealed that the male G-spot, a part of the penis that is particularly sensitive to stimulation, isn't where textbooks say it is. The primary erogenous zone is the frenular delta, a small triangular area on the underside of the male penis where the head meets the shaft. This discovery could help scientists better understand how circumcision might destroy or decrease sexual pleasure in men. The study was published in the journal Andrology and follows the discovery of the complex nerve network that makes up the clitoris.