The power of microbes
The popular theory about the extinction of dinosaurs 65 million years
ago is that they died off after the Earth was hit by a huge meteorite.
There are, however, several other theories that try to explain what
happened to the dinosaurs. Despite its popularity even among the
ordinary public, this is not the only ‘extinction event’ in the history
of Life on Earth. There have been several such instances.
Apart from the dinosaur event, another well known extinction event
took place 252 million years ago when many species were wiped out.
Various theories were put forward to explain this event as well.
However, scientists at the Massachusetts Institute of Technology (MIT)
have forwarded an intriguing new theory.
The mass extinction 252 million years ago may have been the work of a
tiny microbe, according to new research from the MIT. Daniel Rothman and
Gregory Fournier of MIT lead research into the role the microbe may have
played in the Great Dying. This study of the “root causes of the
Permian-Triassic extinction” was published in the Proceedings of the
National Academy of Sciences of the United States of America.
The Permian-Triassic extinction event caused 90 percent of all
species living on Earth to die off in a short period of time. The ‘Great
Dying’ was the worst of five great extinctions in the history of our
planet. Marine invertebrates were particularly affected, especially
species with shells.
Scientists have argued for decades over the cause of this global
Extinction Level Event (ELE). Scientists earlier thought that volcanoes
could have been responsible for the extinction.
According to the latest theory, the culprit may have been a microbe
called Methanosarcina. Research has found that these microscopic life
forms saw a population explosion and emitted tremendous quantities of
methane into the waters and atmosphere of the Earth. This radically
changed the chemistry of the air and oceans to the point where most life
could not continue in the new environment. Indeed, the methane theory
has been enunciated to explain the vanishing of the dinosaurs as well,
by other scientists.
But before you count out the volcanoes altogether, there is an
interesting link: Volcanoes erupted more often around the time of the
Permian-Triassic extinction event and this volcanism may have introduced
more nickel to the oceans. Nickel is essential for the growth of
The researchers knew there was a build-up of carbon dioxide in the
oceans, which formed the carbon needed for the microbe to grow and
multiply. Carbon dioxide was shown to build up over time, which
disproves the idea that volcanoes were responsible. In that case, it
should have been a sudden build-up.
Unfortunately for the other living beings, Methanosarcina developed
the ability to turn carbon into methane in large quantities. Nickel
released from volcanoes acted as a catalyst, aiding even greater
proliferation of the gas. Moreover, the tiny organism carried out a gene
transfer with a type of Clostridia bacteria, speeding the process.
The most interesting part is that as methane levels rose in the air,
so did the concentration of carbon dioxide in the ocean. This led to an
increase in the concentration of carbon dioxide, which wasn’t good news
for most marine and land species.
Earth and its flora and fauna apparently took more than 10 million
years to recover from this disastrous event. The scary part is that this
organism is still alive and well everywhere on Earth - even in our
intestines. Thus there is a distinct possibility that such an event
could occur again. The only difference this time is that there are
people - or more precisely, humans, on the planet who may be able to
stem the tide in their favour.
There are many other ways in which Man and other creatures could be
wiped out from the Earth. An asteroid/planetary body impact is still one
of the most feared possibilities.
Scientists are tracking such objects 24/7 to avert just such a
disaster. From time to time, some celestial objects manage to come very
close to Earth (in cosmic terms). Scientists are devising various
high-tech means and ways of deflecting such objects, including nuclear
strikes, to avoid a massive and disastrous collision with Earth -
Armageddon or Deep Impact style.
Another possibility is a disease which turns into a virulent
epidemic, killing off most of the world’s population. Yes, the Earth
itself would not be affected, but the human population and/or some other
animal populations would be effectively wiped out.
We have seen several close calls in recent times - SARS, bird flu,
H1N1 - which can all potentially turn deadly on a massive scale.
Scientists are racing to find cures and vaccinations to these
afflictions before they can cause harm on such a global scale.
Many movies depict a post-apocalypse Earth with little or no human
presence - it is an eerie thought, albeit a probable one.
Mankind may also be eventually responsible for its own downfall and
the destruction of the Earth. Our activities have caused climatic
changes which led to a rise in Carbon Dioxide levels, just as in the
extinction event outlined earlier. Nuclear war among even just two
States can destroy much of the world.
The resulting radioactive ash cloud will prevent the sun’s rays from
penetrating to the ground which will hasten the demise of plants and
animals in that order. (Without ample sunshine, plants will not be able
to engage in photosynthesis, their preferred method of energy
We are still learning about our planet. The Earth has survived so far
for nearly 4.5 billion years and can go on at least for another 4.5
billion years (as long as the Sun lasts). The only exception will be an
event, natural or man-made, that fundamentally alters it.
However, long before that, intrepid humans will have explored other
worlds beyond our Solar System and established colonies that will also
be inhabited by selected flora and fauna. The Earth will live on by
other means, even if it is destroyed physically.