Humans can be described as ecosystem engineers because since we have arrived, we have made many changes. In fact, the Palaeolithic era, which occurred 2.6 million years ago, are linked to major megafauna extinctions. It is unclear whether humans were responsible or if it was climate induced. According to an interesting journal, A D Barnosky et al. Science 2004, only rarely have island megafaune been demonstrated to go extinct because of environmental change without human interaction. Overkill of slow breeding pret is more likely when hunter populations become large. Another study by Flannery in 1989 also claims that there is a strong correlation between the arrival of humans in Australia and the extinction of megafauna in the Late Pleistocene.
On the other hand, in J L Gill et al. Science 2009, there is a link made regarding climate change causing major megafaunal extinction. Pollen can be used as a proxy for climate change as it is extremely resistent to decay. This study uses a fungus called 'Sporomiella' and found that they were scarce in the the Holocene era and coincided roughly with the Bolling Allerod period. This means that the decline in megafaunal could have been caused by the warming of the earth. An article in The Guardian raises awareness of how 'Scientists have 'limited knowledge' of how climate change causes extinction'.
In fact, its interesting that recent studies including, Hopper et al. 2012, reveals that biodiversity loss is a major driver of eco system change. However, before we must identify what actually causes extinction to resolve this never ending debate!
Interesting article. I believe that humans are responsible for the extinction of certain organisms but only to a certain extent. Take for example African Forest Elephants that have been hunted for ivory and meat and are now endangered. However evolution justifies the changes that occur in organisms. Some species evolve to become better and others cannot adapt quickly enough. Dinosaurs for example became extinct not due to human intervention but simply because the environment around them changed and they did not evolve in sync with it. None the less we are accountable for climate change today but not completely responsible for organisms becoming endangered or extinct.
ReplyDeleteThere are many theories regarding how dinosaurs became extinct. Dinosaurs tracks are found all around the world, which makes it difficult to understand how they all became extinct and whether they all became extinct at once. I agree with you, that humans did not cause dinosaur extinction, but ever since humans have come into existence, they have led to many megafauna extinctions.
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