Watchful eyes, thoughtful mind


Extinction 101 October 25, 2008

Filed under: biology,earth,ecology,extinction,nature — Radiance @ 10:31 AM
“The Earth is in the middle of a man-made mass extinction. No species is safe!”, the BBC Four documentary from 2007, The Dodo’s guide to surviving extinction, tells us. This is sixth such mass extinction that the living beings on this planet are facing. The most well-known to us is the last one that took place about 65 million years ago, thought to be due to an asteroid hitting the Earth, that caused about half the species, including dinosaurs, to be wiped out. However, the most severe mass extinction identified by paleontologists happened about 250 million years ago that wiped out about 95% of the living species at that time. This was the largest and longest series of volcanic eruptions (lasting a million years) that has taken place in the history of this planet.
Currently, the sixth mass extinction has begun on its devastating course, aided by the humankind, which is predicted to wipe out 25% mammals, 33% amphibians and 1 in 8 bird species. This is said to be the most rapid mass extinction to the day. The documentary presents the humans as the “murderer convicted by circumstantial evidence“. The extinction of Dodo in Mauritius, that of Passenger pigeon in Americas, the woolly mammoths in Siberia etc. are glaring examples of the capacity of homo sapiens to eradicate other species. There are other various examples cited which hint that the arrival of humans in the area caused rapid decline in population of a particular species. However, the fact that 99% of all species that ever lived in our world are extinct today, does help to take some blame off the homo sapiens and their irreverent behaviour towards nature. Not all have become extinct after their tryst with the humankind. Quite a few met their fate due to natural causes.
Also, factors like where the species is located, their breeding rate, adaptability etc. contribute to the successful (or otherwise) reign. The species living on islands are isolated from rest of the world and hence lose their adaptability, becoming unable to cope with any sudden change (natural or human-made) in environment. Rabbits with very high breeding rate have much better chance of survival than Pandas, who might or might not produce 1 offspring a year. Pandas are also a great example of human race is actually helping a struggling (due to natural reasons) species to survive. The digestive system of Pandas is not suitable for their all-bamboo-diet, which causes lack of nutrition and lethargy. This leads to almost complete absence of urge to mate with other Panda to produce offspring. Now in China, scientists are using IVF (In-vitro fertilisation) technique to breed Pandas with much success!
So all-in-all, this is a very informative documentary that tells us both sides of the extinction-story. It tells homo sapiens what they should stop doing and what they should start doing in order not to be blamed for the sixth mass extinction. The documentary ends with some interesting thoughts………
  • The catastrophe that causes mass extinction gives evolution an opportunity to start new groups and species of life within new environment.
  • ……and with humans out of the way, life could bounce back remarkably…..within a few centuries, the planet will forget about us, and the natural order will restore.
  • There emerged a vast continent in North Atlantic about 35 million years ago. It survived till 10 million years ago and got submerged again as North Atlantic got wider.
  • …..that’s the way Earth will be again, as the nature intended. It might be a lovely place. Just we wont be there to see it. Unless, we change our ways.
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