Is Human Overkill Responsible for Megafauna Extinction?

There is much controversy as to the cause of megafauna collapse in the late Pleistocene. Whilst there is much evidence to support the influence of climate and disease, I will discuss the importance of human overkill in driving widespread extinction.

About 12,000 years ago one of the great scientific mysteries occurred. Up until that time, during the first 2 million years of the Pleistocene, species rarely went extinct (Bulte et al 2006). But then, around 12,000 years ago megafauna such as Deinotherium and mammoths disappeared. Evidence of this disappearance is stated by Bulte et al (2006) who states that the Americas lost 57 large mammals, including three genera of elephants, an average of one every thirty years. Many believe that overkill was responsible for such extinction, with hunters preying on large mammals leading to their demise. Growing support for the overkill hypothesis is due to extinction events in North America and Eurasia coinciding with the arrival of Homo Sapians. Similarly, evidence to support the overkill hypothesis is mentioned by Roberts et al (2001) who found that extinction in Australia did not coincide with extreme climatic events. It is important to note two theories within the overkill hypothesis. Blitzkrieg theory suggests that hunting occurred over intense periods, whilst Protracted Overkill states that extinction (from hunting) happened over longer timescales. Another factor which corroborates the over kill hypothesis is findings of advanced tools/weapons such as spears, harpoons and nets. Such tools provide evidence that Homo Sapiens had the ability to cause the extinction of megafauna. In contrast, some reject this hypothesis, stating that sophisticated technology might have caused primitive man to vary his diet, eating other forms of food such as fish and shellfish (Hoffecker 2005), and thus reduced hunting of megafauna.

Poor quality fossil data sets make it exceptionally hard to discover whether it was climate or primitive man that caused mega fauna collapse. Similarly, the lack of found 'kill sites' weakens this theory. Alternative hypotheses questions whether humans had access to an alternative food source (most likely from agriculture). Had man not obtained another food source wouldn't the extinction of megafauna would have caused humans to die out? Furthermore, if a substitute food source was available, this would have required a large amount of time and labor to sustain, thus limiting hunting time. Others reject this hypothesis as they believe the advancement of agriculture would have caused human populations to grow faster, which in turn may have increased hunting. Bulte et al(2006) proposes an alternative theory in which the rapid hunting of “mini-fauna” e.g. deer and hares would have increased chance encounters with mega fauna, leading to their eventual extinction. Humans can also cause extinction through habitat alteration (through the use of fire), introducing non-native species which act as predators on megafauna and by spreading pathogens (Barnowsky et al 2011)

Therefore, evidence suggests man had a huge impact on mega fauna during the late Pleistocene. Whether such influence was enough to cause the extinction of mega fauna is still unknown. Whist evidence from palaeontology, climatology archaeology, and ecology now supports the idea that humans contributed to extinction on some continents, human hunting was not solely responsible for extinction everywhere (Barnosky et al 2004). In my next blogs I will explore alternative hypothesis such as the role of climate, disease, and the possible impact of an extra-terrestrial event (12,900 years ago), which are all plausible explanations for the extinction of mega fauna during the Pleistocene.

An insight into the life of a hunter gatherer during the Pleistocene era:

The hunt is on: famous 10,000 BC clip of a mammoth hunt: Enjoy!