According to Wikipedia, "An extinction event is a widespread and rapid decrease in the biodiversity on Earth".
Our Earth has witnessed 5 mass extinctions over the course of its history, is it about to see it’s sixth? Some may call it Omnicide, others call it an Anthropogenic hazard. The way I see it, we are slowly killing ourselves in a manner that I feel really displays our true human characteristics - not doing enough about it! Our planet has indeed endured enough pain because of our faults, but are we making it better or worse? How quickly will the next extinction come? What will be the cause of our demise? What organisms are the heirs to this planet?
As a species, I think it’s fair to say that the homo sapiens have done a great deal of damage to this planet. Although, this was done to better the functionality and sanity of our kind, such as the use of cars and diesel reliant vehicles, the production of amazing furniture and the exploitation of fossil fuels for daily needs. Despite the fact that our lives wouldn’t be the same without these things, we have accelerated the trajectory of our extinction of our kind by doing so…
If and when we do go extinct, what do you think will be the most likely cause? I think the main extinction theories with some validity include:
The cancellation of the Simpsons/Dr. Phil Show – let’s not go down that road please
Nuclear warfare – things will have to go really South for this to happen. Political disputes between countries may lead to this in the distant future causing loss of innocent lives.
Global warming – this may take some time to achieve, but at the current rate, it will happen sooner or later.
Carbon Emissions – detrimental effects on the biodiversity in all ecosystems
Asteroid collision – asteroids larger than 5km in diameter definitely have a chance of mass extinction (like the Chicxulub Impact). They occur every 50-100 million years and have a 70% chance of hitting water, but still having a cataclysmic effect.
Running out of fossil fuels (oil, natural gas) – if we run out of these bad boys then we lose the significance of everyday uses like cars and airplanes and we lose a hell of a lot of energy. The world goes into shock and we all die of confusion.
Ocean acidification and pollution – caused by an increase in Carbon Dioxide and global temperature. The most diversity is present in our oceans.
Global Pandemic – now where have I heard this before?
These extinction theories are bound to change as we as humans can display unpredictable behaviour; one day we are friends, the next we want to nuke each other! But we must change our habits to save this planet! It is imperative to our survival at this very moment. Although I have spoken about the physical damage being done to the Earth, what about mental warfare? The mental damage that is being done everyday? What I mean by this, is that there is hate in many people’s minds about those of different genders, sexes, ages, creeds, religions and races. Ultimately, this can’t be removed as I think it’s just IN our nature to judge people based on social norms. Judging leads to hate leads to crime and sometimes even terrorism and war. This is therefore a threat to life, which in extreme conditions can wreak havoc amongst our kind. However, this may or may not lead to mass extinction even in the worst of cases, but really depends on the situation at hand and its gravity.
Five Mass Extinctions
In terms of our beloved planet, there have been 5 mass extinctions in its history. The Ordovician with 85% of marine life eliminated, the Devonian with 80%, the Permo-Triassic with a whopping 96% of marine life and 70% of terrestrial, the Triassic-Jurassic with over 50% and finally the K-Pg extinction with almost 75% of all life gone! The trends seen here imply that the environment that has suffered the most are the oceans, by for example losing 96% of marine life in the Permo-Triassic. This Extinction took place over a period of 60,000 years, which is not a long time in geological terms. This suggests that “any future mass extinction is going to happen really fast” (Dr. Jahandar Ramezani, MIT) with the level of damage brought about by human activity. This is just great! Although, the cause of the Permian extinction involves factors such as high volcanic activity, reduction in marine oxygen concentration and the alteration of “atmospheric chemistry”. The issue here is, we are doing the EXACT SAME THING!
How are we altering the atmospheric chemistry you ask? Carbon emissions from industrial use and vehicle use. Deforestation means less vegetation to suck the CO2 out of the atmosphere.
How are we reducing marine oxygen concentration you ask? Ocean acidification due to the dissolving of CO2 into sea water, forming carbonic acid, reducing the seawater’s pH. “Since the beginning of the industrial era, the ocean has absorbed some 525 billion tons of CO2 from the atmosphere, presently around 22 million tons per day.”
More CO2 in the atmosphere means more is dissolved into the water and so increased photosynthesis of algae. Once the algal life cycle is complete, they die, attracting bacteria to eat them, respire and use more oxygen in the ocean. This reduces the oxygen concentration underwater, which means others can’t respire and they die (a eutrophication type situation).This model however is a little over-exaggerated as it would take a lot of algae and indeed CO2 to reduce the marine oxygen levels on such a macro scale.
After analysing the history of extinctions here on Earth, I think that the most likely extinction theory for the Anthropocene is the theory of Carbon emissions. As I have shown you, the carbon emissions change the atmospheric chemistry, which in turn affects the functionality of a multitude of organisms above and below our seas by reducing oxygen levels and heating our atmosphere beyond a point of return.
If you ask me, our planet is like a zit. There are large magnitudes of pressure involved, it is full of liquid and it is just ready to pop (and I mean explode).
Life After Humans
Well folks, the only explosion I want to be talking about right now is the explosion of life and what animals will be the heirs to the throne of Earth (we weren’t really ruling, we all know it was the West Highland White Terriers). Well, to explain this, I have constructed a cladogram-type diagram, illustrating the 5 mass extinctions and the animals that came directly after them. I have observed some trends in my diagram.
Animals are shown to have transitioned onto land – this is visible from morphological changes such as the growth of individual digits and evolution into tetrapods from fish (adapting to the increase in proportion of terrestrial plants to marine plants).
Those terrestrial animals become more erect – from low lying Tiktaaliks to upright Ornithomimids and eventually us (although we are not reptiles)! Can we evolve to an even more upright position?
Size is not a variable to be considered – as time increases, size unfortunately DOESN’T. This can be shown by the 18-metre-long apex predator Carcharadon Megalodon compared to the Nebrius Ferrugeneus, as well as the mighty Tyrannosaurus Rex compared to the cute little Gallus Gallus. Size matters not (Master Yoda) as different organisms evolve differently and adapt themselves to various ecological niches, despite existing along the same or a nearby phylogenetic bracket.
There is no way to predict what’s next – Most animals that have evolved after every extinction are different to the last, as Oxygen concentration is different and temperature is too, this has been proven to cause obvious and not so obvious physiological changes, like the recent article depicting the fact that crocodiles increased their size to prevent freezing.
What this tells me is that hypothesising the next rulers of Earth will be VERY difficult as it’s quite hard to predict future environments, atmospheric chemistry and volatility of the plate tectonics too. However, what we could do is use homologous and analogous scenarios, for instance, what new environments could emerge after each extinction, what animals could explode and diversify after us? I think by asking these questions, we can really start to explore the possibilities of a new organism or an improved version of an extant organism after us.
Another point, is that some organisms like tardigrades that evolved in the Cambrian 500 mya (million years ago) are still around today even after all 5 extinctions and other major changes in the geology, chemistry and biology of the Earth. It may be the case that they evolve further to adapt to new Earthly environments and become the dominating species.
Wow, it must be so brave!
As you can see on the diagram, I have put a lovely picture of a West Highland White Terrier. Yes, that’s right! They are going to take over… Maybe they will teach us a lesson about how to really live life, like in Marley and Me.
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