Some anthropologists argue that the human species could not have survived prehistoric times if the species had not evolved the ability to cope with diverse natural environments. However, there is considerable evidence that Australopithecus afarensis, a prehistoric species related to early humans, also thrived in a diverse array of environments, but became extinct. Hence, the anthropologists' claim is false. The reasoning in the argument is most vulnerable to criticism on the grounds that the argument ["confuses a condition's being required for a given result to occur in one case with the condition's being sufficient for such a result to occur in a similar case", 'fails to consider the possibility that, even if a condition caused a result to occur in one case, it was not necessary to cause the result to occur in a similar case', 'generalizes, from the fact that one species with a certain characteristic survived certain conditions, that all related species with the same characteristic must have survived exactly the same conditions', 'fails to consider the possibility that Australopithecus afarensis had one or more characteristics that lessened its chances of surviving prehistoric times']