Final answer:
Jared Diamond suggests that to find a time when there was equality among human societies, we must go back to the hunter-gatherer societies that existed for the first 190,000 years of human existence, before the Neolithic Revolution, where societies began developing hierarchies with the advent of farming.
Step-by-step explanation:
To answer the question of how far back Jared Diamond had to go to find a time when there was equality among human societies, one would need to look at the early stages of human existence. Human civilization is roughly 10,000 years old, but for the first 190,000 years of human existence, societies can be said to have been more egalitarian. Studies of archaeology and modern hunter-gatherer societies indicate these ancient societies were relatively egalitarian due to their small size, lack of accumulated wealth, and nomadic lifestyle, although some hierarchies did exist.
As societies developed and agriculture emerged, stratifications began to form, and with the advent of civilization, marked inequalities became more pronounced. This trend continued and is reflected through various historical periods and social issues such as slavery, gender inequality, and race relations. A profound change in hunter-gatherer equalities would have occurred with the Neolithic Revolution, when humans started farming, which enabled the accumulation of surplus resources and contributed to the development of social hierarchies and structured inequalities.