Aristotle's Problems

...sutures on the heads, as if they were certain bands by which the hemispheres, so to speak, of the head are bound. In those, therefore, where those passages were wider, they change moisture for dryness; and thus they turn gray more slowly, but are not without baldness. If, therefore, dryness causes baldness, and you said the posterior parts of the head were drier, why do we never see a bald occiput? He replied: the dryness of the occiput is not from a defect, but from nature; therefore, the occiputs of all are dry. But from that dryness baldness is born which happens through an ill temperament, which the Greeks are accustomed to call acrasia. Whence those with curly hair, who are so tempered that they have a drier head, turn gray slowly but quickly pass into baldness. On the contrary, those who have thinner hair are not so easily denuded of it, because the humor called phlegm nourishes it; but for these, grayness is early: for gray hairs are white because they imitate the color of the humor by which they are nourished. If, therefore, in the elderly an abundance of humor dyes the hair into grayness, why has old age received the reputation of exact dryness? Because, he said, when natural heat is extinguished through age, old age becomes cold, and from that cold, chilly and superfluous humors are born. For the rest, the vital liquor of a long life has been dried out; hence old age is dry and unexpectedly [destitute] of natural humor. It is moist by an abundance of the vicious humor created from cold. Hence it is that from wakefulness age is made more heavy: because sleep, which happens mostly from humor, is born from non-natural humor: just as it is great in infancy, which is moist by an abundance, not of superfluous, but of natural humor. The same reason is that which does not allow childhood to turn gray, though it is most moist, because it is not moist from cold-born phlegm, but is nourished by that vital and natural humor. For that humor, which is born either from the cold of age, or is contracted by the occasion of any viciousness, is as superfluous as it is harmful; we see this in women where it is voided in the brain, threatening the extremities. This in eunuchs brings weakness to the shins, which bones, as if always swimming in superfluous humor, have lacked natural strength: and therefore they are easily twisted while they can almost not bear the weight of the underlying body, just as a reed is bent when a weight is placed upon it.

Macrobius:

Why do they have the same voice.

Why are the voices of eunuchs so acute that often, unless you see them, you would not know whether a woman or a eunuch is speaking; he replied that the abundance of superfluous humor also does this. For the artery itself, through which the sound of the voice ascends, being made thicker, the passage of the voice is narrowed: and therefore the voice is acute in either women or eunuchs: but deep in men, for whom the transition of the voice has a free and entirely open passage. But that there is born in eunuchs and in women, from equal cold, an almost equal abundance of troublesome humor, is also clear from this: that both bodies often grow fat. Certainly, the breasts of both grow large in nearly the same way.

...just as they are vexed by gout and other diseases, the hairs being brought out by kinds. Also, while warming, they turn gray from fennel-like and redundant [humors]. Finally, gray hairs are white since they imitate pituita, which produces a color of this sort. Sometimes they are also tawny when yellowish pituita has been mixed in.

Why are the elderly redundant and wakeful? They are redundant because, on account of age, they are colder and weaker and, concocting less, they drive many superfluities to the pores. But they are dry because they have obtained solid bodies, and on account of this, they are wakeful. Infants, however, have moist pores and solid bodies.

Why do children, since they are moist and redundant, not produce gray hair? Because they are moist and hot; and pituita is moist and cold. Moreover, they have the skulls of the head filmy and with open pores which also lead out superfluities; and as age matures, it hardens and turns to bone and becomes denser; wherefore nature provided for the future a solution for emitting the superfluities to be exhaled there, from the temperament and the craftsmanship of bodies.

Why do women and eunuchs turn gray quickly? Women, indeed, as they are naturally cold, also collect many superfluities from leisure: especially when the menses fail. Eunuchs, furthermore, because they no longer return semen. Nevertheless, they have the superfluity that generates semen, poured back into the blood through the whole body: which is certainly pituitous.

Why are the same also smooth [hairless]? Women, indeed, as they are cold, have dense pores of the body: for cold checks and constricts: and so the hair has no access to come out. Eunuchs, furthermore, as they are moist and greatly redundant. For for this reason, even places submerged in too much moisture by no means sprout grass: nor likewise those that are moderately dry and rocky, which are most similar to the bald.

Why are the feet of eunuchs for the most part turned out? Because, on account of the much moisture of which we spoke, they have limbs irrigated by humor and soft: and on account of this, also weaker. Thus, since the legs cannot sustain the weight of the body, they are turned out: almost as a reed is bent when a weight is placed upon it. And yet that which is hard and dry is also strong and resists action upon itself more. But the moist and soft is weak and yields easily in movement; surely wood and skins and ropes indicate this. Men also indicate it: for from baths and many drinks they are rendered weaker for doing anything. On the contrary, having attained a moderate dryness from moderation, they approach much more perfectly to action. Hence eunuchs are indeed effeminate and weak, and not without reason also given to wine, as they are more pituitous; because they have been made colder, on the contrary, they desire to be driven in the opposite direction; wine, certainly, is hot by nature. But Ethiopians, as they are drier, have twisted hair and thin muscles?