Wednesday, 2 January 2013

Reviewing the Theory that; ‘Humans 2 Million years ago Doomed Large Carnivores’

Some of the carnivores species to become extinct
 include the saber toothed cat.
So far we have uncovered that there is a huge difficulty in deciding which mechanism was responsible for the extinction of megafauna during the late Pleistocene. An article by Kate Wong (2012) was recently given to me, and in this blog, I will review her ideas as they are highly relevant to the megafaunal debate.

The article immediately determines that humans were not only responsible for recent environmental changes (Anthropocene), but also the extinction of certain carnivores in East Africa, largely due to shifts in technology and diet (Wong 2012). This belief is highly credible as in past blogs we have already seen the impact of sophisticated hunting technology used by Clovis hunters of North America, which may have caused megafaunal extinction on this continent. Therefore, the progression and transformation of basic hunting sticks to stone spears, harpoons and traps suggests that Homo Sapiens had the technology available to kill carnivores.  Alternatively, as human populations grew, it may have caused increased levels of hunting in order to provide enough food to sustain the population. Species that would have been targeted include mega herbivores, and there dramatic decrease in numbers may have caused habitat modifications as well as the decline of carnivores that relied on these food sources. Carnivores that would have suffered include; saber toothed cats, bear sized otters and omnivorous bears. All of these species began dropping precipitously around two million year ago (Wong 2012).

Could more sophisticated technology cause the extinction of Carnivores?
Wong (2012) highlights that climate could not have been the culprit as small carnivores did not become extinct. This is controversial as smaller mammals may have been more resilient to climatic changes and able to find refuge spots enabling their survival. As well as this, climate change would have caused large scale habitat modifications, altering ecosystems. Such changes would have drastically affected larger species that require large amounts of food to survive. This is reinforced by Owen Smith who stated that such habitat changes (as a result of climate change) would have been detrimental to the distribution and abundance of herbivores (1987), which would have affected carnivore populations.

Could climate have caused extinction through habitat modification?
Wong (2012) states that human omnivorous diets may have even caused humans to hunt carnivores for meat; however this theory, in my opinion, is unlikely to have caused the death of all mega carnivores. Other theories are much more realistic causes of extinctions, having more evidence to support them. Lar Werdelin (of the Natural History Museum in Stockholm) states that humans drove carnivores away from kills during scavenging, and this is reinforced by Oakley (1961) who stated that it has been reported that African children have been known to drive lions from their kill. However, whilst this may have occurred, the likelihood of the majority of East African mega carnivores being extinct due to this reason is doubtful.
Humans chasing away scavenging lions. Could starvation
 be the cause of extinction?
 Further evidence with disagrees with the influence of human overkill include the advancement of agriculture which would have provided an alternative food source and consequently reduced hunting practices. Wong (2012) also states of a correlation between the timing of the decline of species and the arrival and expansion of humans. Whilst this may be so, this could be a mere coincidence. Alternately humans may have also caused the arrival of disease (from non-native species) as well as increased fire regimes, both of which have the influence to drastically reduce megafaunal numbers. Consequently the cause of extinction patterns still remains unclear.
Could increased fire regimes be responsible for the extinction of carnivores?
In conclusion, the theory’s put forward by Wong (2012) are intriguing to this debate. Whilst there are many theory’s that can be put forward to explain the decline of East African carnivores, actual reasons for such extinction patterns remain unclear. Whilst the overkill theory has gained much support over the years, there is still an urgent need for improved fossil resolution that would capture more details of past events. Overall I personally have to disagree with the beliefs put forward in Wong’s (2012) argument. I believe that human hunting was a highly influential mechanism in causing some extinction of African carnivores, but I believe that the arrival of humans would have been coupled with the increased fire regimes, as well as disease, which would have contributed to such extinctions. Similarly the combination of human and climate forcing’s providing a stronger  explanation for such large extinction patterns.


  1. Hi Josh,

    Out of interest, has any evidence for possibly human-spread disease been found in East African carnivore fossils? Without fossils with obvious pathologies this must be extremely hard to support.


  2. Hey Harriet,

    Good question! To my knowledge there has been no findings of human spread disease in East African Carnivores. Yes, this theory lack much needed supporting evidence. However, the likelihood of disease being passed to megaherbivores is more probable. If you look at my hyper disease blog, research by Rothschild & Laub (2006)found extinction of a particular type of mammoth through human carried tuberculosis. Evidence of this was found in the disease being present in 52% of the 118 skeletons that were surveyed. Consequently, the removal of mega herbivores would have caused severe detrimental affects to carnivores that rely on this food source. Similarly, it has been found that domesticated dogs transmit Eurasian diseases to new world carnivores, which would have caused a trans-specific epidemic. Therefore there are other (disease related) mechanisms that could have caused the demise of East African Carnivores.

    Hope this is of some help