Once again, apologies for the delay in responding.
I’m going to begin by my response by giving you the written version of what appears in the lectures. There may be some differences; in general, the written version is more extensive than the video version.
“With the striking exception of the Meso-American civilisations, all the major ancient civilisations centred themselves around river valleys. (For a highly readable recent account of these and several other early civilisations–including Shang China, Yoruba and Inka—see Bruce Trigger’s Understanding Early Civilizations. For a different (and amusing perspective) on Egypt, see Kealey 2008, 60ff. For a scholarly, yet accessible, introduction to many aspects of Egyptian civilisation, see the beautifully illustrated volume edited by Schultz & Seidel. For more on Mesopotamia see McIntosh & Twist, 46-57 and Service, 203-204; for more on Egypt see McIntosh & Twist, 82-93 and Service, 225-237. For more on early Meso-American and Peruvian civilisations, see Service, 166-202.) Childe points out that such river-valley communities provided the nascent conditions for coercion. Outside the horizons of the river lies desert or wilderness so those who work the land are geographically circumscribed. Although even the strongest of rulers cannot prevent the raindrops falling on your head, they can restrict your access to irrigation. ‘So when the social will comes to be expressed through a chief or a king, he is invested not merely with moral authority, but with coercive force too; he can apply sanctions against the disobedient.’ [Childe, 109] Those who controlled access to the water also controlled the land and its products. Individual farmers, write Davidson & Rees-Mogg, ‘faced a very high cost for failing to cooperate in maintaining the political structure. Without irrigation, which could be provided only on a large scale, crops would not grow. No crops meant starvation.’ [Davidson & Rees-Mogg, 65]
“Though sharing certain similarities, Egypt and Mesopotamia differed from one another in other respects, Egypt being a territorial state and Mesopotamia a city-state, or rather, a collection of city- states. We often have the impression that the use of the fertile land adjoining the Nile was a simple matter of accepting Nature’s bounty but this was not so. The land on the riverbank would have been a tangle of swamps and reeds that needed to be reclaimed before it could be used and this reclamation was no simple undertaking; in fact, this reclamation was, according to Childe, ‘a stupendous task: the swamps had to be drained by channels, the violence of flood-waters to be restrained by banks, the thickets to be cleared away, the wild beasts lurking in them to be eliminated. No small group could hope to make headway against such obstacles. It needed a strong force capable of acting together to cope with recurrent crises…’ [Childe, 107] Much the same comments could be made about Mesopotamia, the land between the rivers Tigris and Euphrates. There, the land had not just to be cleared but it had to be created more or less ex nihilo. Originally consisting of swamps lying just above the level of the Persian Gulf, the Tigris-Euphrates delta needed to be reclaimed, a dry land created out of a watery chaos. The words of Genesis appear to be particularly applicable to this process: ‘And God said, “Let the water under the sky be gathered to one place, and let dry ground appear.” [Genesis 1: 9] Some of the earliest cities in the region were constructed on platforms of reeds laid out on the alluvial mud. Just as in the case of the Nile communities, so too in Sumeria, reclamation required large-scale social cooperation. The drainage, irrigation and protection of this land gave rise to a centrally controlled economic system. Raw materials were needed and so regular systems of trade had to be created to obtain them, requiring merchants, transport workers, specialist craftsmen, and those willing and able to provide security, people to keep records and, most interesting for our purposes, state officials to reconcile conflicting interests. [see Childe, 141-2]”
Now, to respond to your particular questions. The answer to both is, in effect, the same. Those who controlled the water system/land reclamation were not freely selected. In the main, they would have been those who ran the cities, together with their accompanying military force.
The norm of state governance from the mists of pre-history to the earliest civilisations (and beyond) was some for of kingship, often one in which the king has sacral, as well as civic, functions. In the context of world history, the poleis of Greece and the Roman republic were aberrations.