Were human-introduced diseases the responsible for Pleistocene-Holocene megafaunal extinctions? First evidence from South America

Diverse hypotheses have been proposed with the aim to explain the extinction of Late Pleistocene/Holocene mammals, including the Megafauna from America. Some authors support that human being was the direct responsible of extinction by means of intensive hunting, as proposed by the "blitzkrieg" or overkilling hypothesis. However, evidence is not conclusive. As is well known by biologists, exotic diseases may play an important role in local extinction of diverse vertebrates. On this basis, some speculated that the arrival of man may also have introduced new diseases that may have played an important role on native mammals, especially megafaunal populations, probably constituting a key factor on their extinction. Recent findings of the parasite Fasciola hepatica in endemic deer from Holocene sites in Patagonia (and also probably from camelids in Peru) previous to Hispanic colonization constitute indirect evidence that may sustain this hypothesis. Because one of the main definite host of this parasite are humans, this potential disease may have been introduced by human populations as hosts and then disperse through the entire continent, as evidenced by the finding of Fasciola hepatica in Patagonia. Its presence in endemic deer and camelids previous to Hispanic colonization, reinforces the proposal that human-related diseases may have played some role in Late Pleistocene extinction of large native mammals.