Tuesday 11 April 2017

Humans, the agents of destruction : The story of the 6th mass extinction

(image courtesy : www.greenpeace.org)

Before I start with this post, I would like to mention right now that I will try to keep safe distance from the moral aspect as much as possible in this post. I am no one to comment on what is right, what should be done and what should have been. This post is about looking at everything from the impartial eyes of nature and its evolutionary process.

Now that the disclaimer is out of the way, let us start with a term everyone is familiar with... 'Extinction'. In simple terms, it is a dying out or termination of a species with no remaining living members. The dinosaurs, the dodo, the woolly mammoth and the likes are prime examples of this phenomenon. Can you add a few more to the list? 10, or maybe 5? Unless you are a biology buff and are thorough with the topic, I'm sure you'll struggle to find too many more names. But guess what? Since life started on earth, roughly 40 billion species have become extinct, which is around 99% of all the species which ever existed.

Why does extinction take place really? The reasons are many. But consider this. The earth is 4.5 billion years old. It has undergone numerous changes in terms of geology, climate, atmospheric composition etc, and continues to do so to this day. In order to adapt to the changing environment, some of them evolve, most of them die, because that is how nature works. And because life is so much about co-existing, the extinction of one species might lead to drastic changes in the entire ecosystem. Sometimes, species are wiped out if some other species out-competes them. Mutations and natural selection are also reasons why extinctions might occur. These processes are fairly gradual, when we look at it in the time-frame of thousands or millions of years. But sometimes, certain events wipe out a major chunk of all the living species, much 'quicker' in the geological time frame, when more than 50% of all species go extinct. These events are called mass extinctions.

There have been 5 major mass extinctions that we know of.

ORDOVICIAN-SILURIAN : Occurred about 450 million years ago, when more than 60% of all living beings were extinct 
over a period of about 10 million years. This probably took place due to the formation of gigantic glaciers and dramatic worldwide fall in sea levels, which in turn might have been caused by a gamma ray burst, which again in turn might have been caused by a hypernova explosion (basically an explosion much larger than a supernova). The cause is actually all speculation at this moment, but the proof of the massive die-off lies in the various strata of rocks, which shows absence of fossils in the layers formed during those times.

THE LATE DEVONIAN : Around 365 million years ago, more than 70% of all species got extinct over a period of maybe 20-25 million years in a series of mass extinction events. It probably happened due to global cooling, which might have been caused by an asteroid strike, or a massive volcanic eruption. Simultaneously, the ocean levels fell and its oxygen levels depleted (or ocean anoxia). One of the theories also suggests that plants, which were taking a strong hold on land, absorbed so much carbon dioxide from the atmosphere, that it caused global cooling.

PERMIAN TRIASSIC (THE GREAT DYING) : This is the worst known mass extinction event, where about 95% of all species got extinct about 250 million years ago. The cause was most probably a series of volcanic eruptions in an area called the Siberian traps (its area roughly the size of western Europe), which lasted a million years. It directly resulted in an increase in global temperatures by 5-10 degrees Fahrenheit. The release of gases in the sea floor lead to periods of too much oxygen in the oceans (hyperoxia), and later, too less oxygen (anoxia), and marine life suffered greatly due to this.

: About 200 million years ago, the super-continent Pangaea started to break up, which lead to volcanic eruptions in many parts of the world. The sudden release of methane and carbon dioxide lead to a large scale global warming. Scientists know less about this event than the others, but it seems that ocean life was hit much harder than plants and land animals. This event hence, paved the way for the age of the dinosaurs, which would last around 135 million years.

CRETACEOUS-TERTIARY (K-T) : Probably due to a massive asteroid/comet strike 65 million years ago in the Yucatan peninsula off the coast of Mexico (as evident from the Chicxulub crater), about 75% of all species got extinct (including the dinosaurs), paving the way for the age of mammals and birds. A lesser known theory also suggests that a massive volcanic eruption in India could have been the cause too.

'THE CURRENT ONE' : The previous mass extinctions were either due to hypernovae, volcanic eruptions, change in tectonic plates, or asteroid collisions. This time it is us.
The impact that human beings have had on our planet is unprecedented. Ocean acidification, rise in global temperatures, and mass extinctions itself have happened before. But the current events are unique in many ways. Never before has a single species taken over such a significant percentage of the world's primary production. There has never been so much habitat destruction, and the introduction of non-native and invasive species the world over, as we see today. There also has never been any species which have had such an impact on evolution itself. Even though the term hasn't been officially coined yet, scientists think that because of the changes in the environment due to human intervention, a period, either from the onset of Industrial revolution in the 18th century, or from the 1950's, marks a beginning of a new epoch, and many call it the 'ANTHROPOCENE'.

If it all seems like an over-exaggerated fairy tale, such as 'Climate change' is (*sarcasm), let me give you a little reality check.

As I've mentioned before, extinction is a natural phenomenon. In normal conditions, there is usually a constant rate of extinction. For example, it is estimated that in case of mammals, 1 species get extinct every 700 years or so. Want to take a guess as to where we stand according to the current extinction rates? Would you say 5? Maybe 10? 100? 200? No, the current rate of extinctions are at 1000 mammal extinctions per 700 years! Sea life? Well, the acidification of oceans is at the highest in more than 800,000 years, and at this current trend, by the end of this century alone, more than one-third of the species will go extinct. Let's go a little further. Invertebrates, which make up about 97% of all living beings, have declined by 45% in the last 40 years alone. Amphibians, many of whom have survived multiple mass extinctions for the past 350 million years or so, seem to have been hit very badly too. At a normal rate, 1 species of amphibians go extinct in a 1000 years. Current rate? 45,000 extinctions in a thousand! Another fact is that the numbers which I have given above, are conservative estimates, as we are yet to find out more data. So in all probability, things are much worse.

The 5 major mass extinction events probably occurred over millions of years. The Anthropocene started just around 70-200 years ago, and already, the current extinction rates are higher than the K-T extinction. So the peak of the 'Anthropocene' might be closer than we expect.

Will the humans survive the extinction? Probably, but maybe barely. We might have made great progress in science and technology, but what we forget is that the key word here is 'co-existence'. While it seems that the changes in the environment are only affecting the plants and animals, it will come bite us back one day. For example, we are not directly affected by global warming yet, because we have AC's to keep us cool. But it has an effect on the animals and plants outside too, who do not have the luxury of AC's. Eventually, they will die if the increase in temperature is unbearable. So if the corns and the cucumbers die off, we will eventually be hit by famines and droughts, which might lead to an all-out war, as history has seen many times over. What then? Nature has its own ways to balance everything out. If not famines, then diseases might wipe half of us out. The rising ocean levels are no longer a myth; many parts of Bangladesh, Phillipines, USA, India, you name it, might be swallowed up by the sea within this century alone. There is also something called the 'Thermohaline circulation' (also know as 'ocean conveyor belt'), which has a huge impact on the global climate. I would love to explain that too, but I feel my post is already too long, so click here to read it up on Wikipedia. Basically, if the Thermohaline circulation stops, there will be mass extinctions in the seas, the climate will change drastically (how though, nobody can predict), and it will lead to a massive increase in anaerobic bacteria, which emits one of the most toxic of gases, hydrogen sulfide.

These are but just a few possibilities out of so many others. Frankly, I am very positive about a lot of things, but for the future of mankind, not so much. My intention behind writing this post is to make people aware about what our impact on the world is, because everyone knows we are a threat to our planet, our very home itself, but not many know to what degree. In my opinion, leaving aside good or bad, right or wrong, humans are indeed the agents of destruction. We are a very strange and mysterious entity, unlike anything ever seen on earth. Our instinct is not to live with nature, but to control it to favour our way of life. But, unlike asteroids and volcanic eruptions, we do have a conscience. Because things are still not out of hand at this moment, and if we want to put a stop to it, we still have time. Humans might be the problem for all this, but the only answer to all this is also, humans.

"When we try to pick out anything by itself, we find it hitched to everything else in the universe"

- John Muir

References : 

https://www.theguardian.com/environment/radical-conservation/2015/oct/20/the-four-horsemen-of-the-sixth-mass-extinction by Jeremy Hance


  1. A very informative post. And a sad one. It gets even sadder considering I don't have an AC to keep me cook :) But seriously speaking, it's pretty obvious most of our problems are caused by massive human overpopulation. The planet can't take our impact not only because of careless attitude, but simply because there are so many of us. As you said, nature has its own ways to balance things out, and, unfortunately, diseases, natural disasters and wars are inevitable. There is a peaceful way to solve the problem, I suppose - for that families in every next generations will have to have only one child. But most probably it will never happen - they tried this system in China and as a result there is a huge gender imbalance.

    1. Solutions are many, but every one of them is ideal, with loads of practical problems attached to each of them. Just like you mentioned, there is a huge gender imbalance in China due to the one child policy. A sudden halt in the rate of population leads to a boom of aging population at some point, as we can see in countries such as Japan and Italy. As per some data, the world population is going to increase from the current 7.3 billion to about 9.6 billion by 2050, and to 11.2 billion by 2100. The earth technically, can still accommodate everyone's needs even then, but not their wants. Anyway, my point is that as Nietzsche had said "Earth has a skin, and it has diseases. Humanity is one of them", we are a plague, and we have affected the earth like nothing ever has. We will probably be the reason for the next mass extinction. But I also feel, there might be a time much later, millions of years into the future, that the earth and its beings will adapt to us, and we might be looked at as the biggest boon of the earth. Only time will tell, and you and I won't be there to witness it, so speculation is all we can do.