the other hand, the big penis may have evolved because that’s what possessors wanted – a greater attractant to potential mates and a more visible means of warning off rivals. A big penis also increased the male’s chance of inseminating a female who was having sex with other males, by getting closer to the cervix. There are objections to such theories – not least that other primate males have continued to propagate their species with considerably less at their disposal. As to the theory that the penis grew to assist humankind’s imaginative variety of sexual positions, orang-utans and chimpanzees, particularly the pygmy chimpanzee or bonobo (a separate species, found in the Congo, which has a more upright gait and a more ‘human’ skeleton), are equally imaginative in their coupling – and they can do it swinging from trees while man only talks about doing it swinging from chandeliers.
But if science cannot say definitively why man’s penis is so big, it does have an explanation as to why his testicles are the size that they are.
In the early 1980s the evolutionary psychologist David Buss caused widespread excitement among the ‘ologies’ with the hypothesis (in
The Evolution of Desire
) that the more promiscuous a primate species, the larger the testicles of the males belonging to it – penis size, he surmised, was less relevant in achieving impregnation of a female having sex in rapid sequence with other males than being able to produce the most copious and frequent ejaculate. Subsequently, British scientists weighed the testes of thirty-three primate species, including man, to assess the testicle–promiscuity link. Interestingly, by this measure, the human male, the primate with the biggest penis, was not the king of the swingers: his testicles, together weighing 1.5 ounces, bore no comparison with those of the chimpanzee, which weighed an astounding 4 ounces, a three-times higher testes-to-body-weight ratio than humans. And the mighty gorilla, the primate with the smallest penis? Again he trailed the field, his testicles little more than half the weight of man’s. As Buss pointed out, the gorilla, with his monogamous harem of three to six females, faces no ‘sperm competition’ from other males. On the other hand, the promiscuous common chimp has sex almost daily with different females and the even more promiscuous bonobo has sex several times a day.
Somewhere between gorilla and chimp comes man, neither entirely promiscuous nor entirely monogamous, his penis evolved far beyond those of his distant ancestors but his testicles or at least their firepower probably reduced – his sperm production per gram of tissue is considerably less than either chimps or gorillas, leading to the ‘ological’ view that, as expressed by Lynn Margulis and Dorion Sagan (
Mystery Dance: On the Evolution of Human Sexuality
), he once, when the business of insemination was a contest, had a bigger ‘testicular engine’.
As with all body parts there are racial variations, a subject on which interest focused after Buss’s theory of sperm competition became known and Jared Diamond described it as ‘one of the triumphs of modern physical anthropology’. But measuring testicles was hardly as easy as measuring penises. A finger and thumb appraisal is wildly inaccurate: in the folds of the scrotal sac, testicles skitter out of grasp as easily as a bar of wet soap. Even measurement with an orchidometer (a specialised kind of callipers) is difficult – which is why scientists began to accumulate their data at autopsy. The findings confirmed what had been previously regarded as the case on less systematic analysis: that there is no demonstrable difference between the testicles of blacks and whites but that those of Asians are smaller. The extent of the difference, however, stunned the scientific community. It was more than twofold. As Diamond reported in a paper published in
Nature
magazine, where white and black testicles
But if science cannot say definitively why man’s penis is so big, it does have an explanation as to why his testicles are the size that they are.
In the early 1980s the evolutionary psychologist David Buss caused widespread excitement among the ‘ologies’ with the hypothesis (in
The Evolution of Desire
) that the more promiscuous a primate species, the larger the testicles of the males belonging to it – penis size, he surmised, was less relevant in achieving impregnation of a female having sex in rapid sequence with other males than being able to produce the most copious and frequent ejaculate. Subsequently, British scientists weighed the testes of thirty-three primate species, including man, to assess the testicle–promiscuity link. Interestingly, by this measure, the human male, the primate with the biggest penis, was not the king of the swingers: his testicles, together weighing 1.5 ounces, bore no comparison with those of the chimpanzee, which weighed an astounding 4 ounces, a three-times higher testes-to-body-weight ratio than humans. And the mighty gorilla, the primate with the smallest penis? Again he trailed the field, his testicles little more than half the weight of man’s. As Buss pointed out, the gorilla, with his monogamous harem of three to six females, faces no ‘sperm competition’ from other males. On the other hand, the promiscuous common chimp has sex almost daily with different females and the even more promiscuous bonobo has sex several times a day.
Somewhere between gorilla and chimp comes man, neither entirely promiscuous nor entirely monogamous, his penis evolved far beyond those of his distant ancestors but his testicles or at least their firepower probably reduced – his sperm production per gram of tissue is considerably less than either chimps or gorillas, leading to the ‘ological’ view that, as expressed by Lynn Margulis and Dorion Sagan (
Mystery Dance: On the Evolution of Human Sexuality
), he once, when the business of insemination was a contest, had a bigger ‘testicular engine’.
As with all body parts there are racial variations, a subject on which interest focused after Buss’s theory of sperm competition became known and Jared Diamond described it as ‘one of the triumphs of modern physical anthropology’. But measuring testicles was hardly as easy as measuring penises. A finger and thumb appraisal is wildly inaccurate: in the folds of the scrotal sac, testicles skitter out of grasp as easily as a bar of wet soap. Even measurement with an orchidometer (a specialised kind of callipers) is difficult – which is why scientists began to accumulate their data at autopsy. The findings confirmed what had been previously regarded as the case on less systematic analysis: that there is no demonstrable difference between the testicles of blacks and whites but that those of Asians are smaller. The extent of the difference, however, stunned the scientific community. It was more than twofold. As Diamond reported in a paper published in
Nature
magazine, where white and black testicles
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