How did agriculture take hold? Piecemeal seems to be the answer, at first supplementing hunter-gatherers‘ food, then in favourable conditions replacing it. Those conditions were most favourable in the Fertile Crescent, where crops came to provide much of humans’ needs. That is to say, subsistence needs; the evidence also points to a marked decline in health and lifespan during this period.
So, how did agriculture start? By chance initially. We selected optimum sources of nutrition and unwittingly spread them, in a natural symbiotic process. Other creatures have done the same since the beginning of life. We had the advantage of observation and reflection and thus the deliberate promulgation of species useful to us. In many cases this meant mutations of species that were incapable of spreading themselves otherwise.
Jared Diamond goes on to observe how Eurasian peoples later managed to dominate the rest of the planet. This brings in the second of our food sources – animals. Large African and European mammals grew up with homo sapiens (where the sapiens is ironic of course) and learned wariness and hence survival. Those in the Americas and Australasia were suddenly confronted by humans and were easy prey. So easy that we wiped them out and they weren’t available to feed, and just as important, power civilisations in those places.
Diamond doesn’t so well explain the how of animal domestication unless that too were simply inevitable among all the trial and error. The implication here is that we’re not likely to domesticate any others. We have been around long enough to have settled on the suitable ones.
This is the same conclusion he draws for our plants and is a crippler for those hoping to find some panacea for our ills in the rainforest, for example. They somehow think technology will unlock secrets that thousands of generations of humanity couldn’t. Such is the hubris of modern society.
This search is often used as motivation for not wiping out species in such places. The more convincing argument lies with the utility already noted about large mammals.
As for germs, they seem to have hitched a ride on the back of domestication. Most of our interesting killers jumped from livestock to us. People who had a head start on building immunity could then, unwittingly in most cases, carry a sort of viral warfare before them.
So, perhaps the book should have been called crops, germs and mammals but that doesn’t have the same ring. And guns and steel do seem to be the inevitable sharp end arising from civilisation’s bedrock of crops and mammals.