IT wasn’t water on the brain that allowed humans to become the dominant species, but it was the reaction of humans to environmental change, and particularly the availability, that shaped our evolution and took us to the top. So argues Finlayson, and it is hard to disagree with him, for it was our adaptability in the face of climate change and our positive exploitation of water that helped us to prevail over bigger, faster and more ferocious rivals.

It was not exactly sink or swim, but we decided to take the plunge and so we succeeded. It begs the question, however, of whether we can react correctly to current climatic changes and avoid the danger of water wars in the future.