GMAT Critical Reasoning (CR) | Re: In order to comprehend how prehistoric human societies

In order to comprehend how prehistoric human societies were organized and how interactions between people took place at that time, scientists are studying modern societies in specific contexts (such as troops during Vietnam War, hippie communities in the 70’s and religious brotherhoods). A flaw pointed in this approach is that though they are still talking of humans, evolution has made comparisons rather meaningless.
Which of the following, if true, would most weaken the criticism made above