Kjetil Simonsen made me aware of Sigmund Freud’s highly original view of the origin of (human) civilization, from Civilization and its Discontents (1930). Freud starts off conventionally enough:

If we go back for enough, we find that the first acts of civilization were the use of tools, the gaining of control over fire and the construction of dwellings. Among these, the control over fire stands out as a quite extraordinary and unexampled achievement, 1 […] (p. 37)

However, the real meat is in the accompanying footnote:

1 Psycho-analytic material, incomplete as it is and not susceptible to clear interpretation, nevertheless admits of a conjecture—a fantastic-sounding one— about the origin of this human feat. It is as though primal man had the habit, when he came in contact with fire, of satisfying an infantile desire connected with it, by putting it out with a stream of his urine. The legends that we possess leave no doubt about’ the originally phallic view taken of tongues of flame as they shoot, upwards. Putting out fire by micturating — a theme to which modern giants, Gulliver in Lilliput and Rabelais’ Gargantua, still hark back – was therefore a kind of sexual act with a male, an enjoyment of sexual potency in a homosexual competition. The first person to renounce this desire and spare the fire was able to carry it off with him and subdue it to his own use. By damping down the fire of his own sexual excitation, he had tamed the natural force of fire. This great cultural conquest was thus the reward for his renunciation of instinct. Further, it is as though woman had been appointed guardian of the fire which was held captive on the domestic hearth, because her anatomy made it impossible for her to yield to the temptation of this desire. It is remarkable, too, how regularly analytic experience testifies to the connection between ambition, fire and urethral erotism. (p. 37)

When man stopped (homo-erotically) peeing on fire, civilization rose.