A fascinating fact about limited plant species around the world is that all crops originally arose from them.
Diamond sets out to answer the important question as to how it happened that certain wild plants were eventually turned into crops. This is an especially difficult question to answer, as many of these wild plant species contained elements that were lethal, foul-tasting, or, in some cases, both. And yet, despite this, such plants became the crops that millions of people the world over have consumed for many hundreds of years.
Diamond locates the answer to this question in the domesticating of plants carried out by our cave-dwelling ancestors. Just as they domesticated animals, so they also domesticated wild plant species. This process involved a qualitative genetic change whereby wild plants became edible crops.
Nowadays, the business of crop development is carried out by trained scientists, who invest a lot of time and effort into producing crops. But our primitive ancestors achieved this change unwittingly through the simple process of plant domestication.