Respuesta :
well not only do humans and animals evolve plants do too.DNA changes over time which changes not only the appearance but the way the plant acts and protects itself .there for the black leave was from a different leave thats DNA changed over time and it reacted to the crops grown by farmers and accelerated the growth hormones in the plant.
Basically, Dyson believes that altering DNA may change the course of the world. If a specific gene is adjusted in a species, the offspring of said species will change to correlate with the mutation. This eventually transforms the species as a whole into something it originally wasn't at the beginning of its existence.