How (and why) did diets change among early humans?

The scientific consensus is that early humans were largely hunter gatherers. The diets changed as humans started farming during the Neolithic period. As early humans started to domesticate some plants through horticulture and domesticate some animals like birds and pigs, the diets for early humans changed substantially eventually becoming-grain based with the advent of more intensive farming.

Explanation:

Being hunter-gatherers means that early humans hunted game for their food and collected other edible food items from surrounding forests like nuts and berries. There is also evidence that coastal peoples ate shellfish they gathered in shallow waters. The advance to farming practices occurred within the Stone Age between the paleolithic and the neolithic eras and is often called the Neolithic Revolution.