The Anthropologist concludes that groups of early humans were likely motivated by the benefits of an agriculturist lifestyle when transitioning from a hunter-gatherer lifestyle. Why? Because the transition to agriculture from a hunter-gatherer lifestyle must have been traumatic due to increased incidence of disease, injury, and lack of a nutritious diet.

The statement in the first sentence is a premise offered in support of the Anthropologist’s conclusion. It is also further supported by the next sentence, which provides some examples of traumatic events.