Diamond argues that food production is one of the most important factors in human history. It was food production (among other things) that allowed Eurasian societies to get the "guns, germs, and steel" that allowed them to dominate the world.
The most important impact of food production is that it allows for bigger populations with some people who do not have to get their own food. This allows some people to become artisans, government officials, and many other things. A larger population like this makes it possible that some people will start to invent various sorts of technology.
Food production is also important because it helped some populations get the germs that helped them conquer the New World. Epidemic diseases, for the most part, came about because of close contact between humans and domesticated animals.
In this way, food production led to larger populations, to technology, and to the development of epidemic diseases.