Extinction is defined as the process whereby a species of animal or plant completely dies out to the point that not one individual remains alive. Once a species has gone extinct, it is forever lost and never to return, unless by future technologies utilizing the animal’s (or plant’s) DNA. As long as life on our planet has existed, extinction has been a part of nature.
Through his ground-breaking book, On the Origin of Species, Charles Darwin taught us that the species that are most fit and most able to adapt, are the species that will survive, thrive and evolve in nature, and those that are not, eventually become extinct. Over the course of the history of our planet more animals and plants have become extinct than are alive today.
Extinction can be a natural process often caused by competition between species with similar diets and similar habitats, although recently, during the Anthropocene, human activities have become a greater factor. Human caused climate change and more significantly, habitat destruction, have caused many species of animal to go extinct.
The do-do bird, a native of the remote Mauritius Island near Madagascar is the de-facto mascot of extinction. When something goes extinct or missing it is said to have ‘gone the way of the do-do bird.’ This clumsy, flightless bird was, unfortunately, ripe to suffer the irreversible fate of extinction. There are several reasons for this; first of all, do-dos existed only on Mauritius Island. There were no do-dos anywhere else in the world, so there was no back up population once the last individual was killed. Secondly, the do-do evolved without ever coming into contact with humans. This left them completely unprepared for the assault they were destined to face once humans arrived on the island. They were simply too friendly and had no idea that they should flee from these strange beings. In addition to this, they had no built-in defense that would frighten a person or allow the bird to flee. No sharp beak, no ability to fly or run fast, no ability to fight. Moreover, like the turkey, they were just perfectly built for a human feast, making them a very popular delicacy while they lasted. Ultimately, the do-do never stood a chance.
It’s hard to imagine the people that arrived on Mauritius killing these birds and not making an effort to breed them once they realized the population was depleted and heading toward extinction. However, it seems, they made no effort.
An animal that couldn’t be more different than the do-do, but is suffering the same fate is the northern white rhinoceros. This rhino is not extinct yet, but is destined for extinction as only two individuals remain and unfortunately, they are both the same sex, female. There is a small glimmer of hope that the species could be saved by human intervention. The last male member of the species donated to the northern white rhinoceros sperm bank before he died leaving us with the hope that one or both of the females may one day become impregnated.
Ten thousand years ago the plains of North America were teeming with huge animals that have all gone extinct. Woolly mammoths, mastodons, woolly rhinoceros, sabre tooth cats, giant sloths, giant beavers, giant wolves, North American lions, cheetahs and many more. All extinct. How? We don’t know for sure, but the evidence points directly at us. When our ancestors arrived in North America from Asia, travelling across the Bearing land bridge between what is now eastern Russia and western Alaska, all of these animals quickly went extinct. The timing is too close to be coincidental. There seems to be little doubt that early humans, with their refined hunting skills played a major role in the demise of all of these animals.
In the history of life on Earth there have been 5 mass extinction events. Each of these 5 mass extinctions caused the majority of animal species on earth at the time to disappear. The plight of the North American mammals did not qualify as a mass extinction because there were millions more species at that time that did not die off. In order to qualify as a mass extinction, 75% of species on Earth have to die off in a reasonably condensed time frame.
The most famous mass extinction event is the most recent, the event that wiped out the dinosaurs 65 million years ago. The dinosaurs and many other animals met their fate when a ten kilometer in diameter asteroid struck the Earth, kicking up enough dust to block out the sun around the entire planet for several years. The lack of sunlight first killed the plants, then the herbivores that ate the plants, then the carnivores that ate the herbivores. Within a few short years, the mass extinction was complete and the Earth was changed dramatically.
Mass extinctions do not necessarily happen quickly. The first 4 were slow to occur, taking many thousands of years to transpire. However, when viewed through the lens of hindsight, visible only in the fossil records, they appear as a condensed event relative to the long history of life on the planet.
The first 4 mass extinctions were each caused by climate change (heating or cooling), ocean acidification, or some combination. Over the course of time the planet has experienced wide swings in average temperature caused by various natural circumstances. A small fluctuation in temperature up or down, can cause many animal species to suffer and then die off as they are not able to adapt to their new surroundings.
Today, as a result of human activity, it is doubtless we are living through a 6th mass extinction. This one is happening as a result of human-caused climate change and habitat destruction. We have not yet lost 75% of our species, not even close, but if we continue unabated, we will get there.
After a mass extinction has occurred there is new opportunity for the adaptable species that survived the new conditions. 65 million years ago, with the dinosaurs no longer roaming the Earth, the planet became free for smaller animals to take over. In the intervening years, evolution selected a line of small mammals, slowly changed them into primates, then apes, then somewhere between 5 and 7 million years ago, a group of these apes walked away from their family group, possibly to seek out greener pastures beyond the next hill, and they never returned – and thus the human species was launched.
The human species has existed on Earth for a mere blip of time (5 – 7 million years) relative to the 4.5 billion-year-history of our planet. Many animals have lived for a much longer period of time. Sharks and turtles for example have both existed since before the time of the dinosaurs. They have persevered, largely unchanged, for around 300 million years. Dinosaurs, themselves existed for 200+ million years. We often think of our species as infallible, but if dinosaurs were capable of thinking, one would expect they would have thought of themselves as infallible too. There is nothing to guarantee that we couldn’t suffer the same fate as the dinosaurs.
The purpose of this essay is to explain extinction and then to imagine the possibility of an event that could cause the extinction of the human race – a morbid topic, I know, but a real one.
For us to go extinct it would not require a mass extinction, as we might be the only species to be affected, but it certainly would require a tragedy of mass proportions. There are 8 billion people on Earth and we are very good at adapting to our surroundings. To cause the extinction of the human race would require a catastrophe the likes of which has never been experienced in our planet’s history. It would need to not only be lethal to 8 billion people, but it would have to hit all corners of the earth. If even one remote island escaped the impact, there would likely be a small group of people that would escape to that island and survive to replenish the population.
The event would not have to kill everybody at once (and if it did, nobody would be left to record it), it could happen over time, creating an environment where we can’t survive for long or where we can’t have children.
Below I list the events that I believe are capable of causing the extinction of the human race. Of course, there could be some that I haven’t considered. In order to make this list, an event must satisfy two criteria. First it must be plausible, there must be known existing conditions that could allow it to occur. I am not including alien invasion, for example, because we have no proof of the existence of aliens, and if they did exist and visit us, would they kill all of us? One would think such an advanced species would want to study us, not eliminate us. Secondly, the event must be severe enough that it could either wipe out the entire human race, or create an environment where the existing humans cannot survive and/or replenish the population and then, when the last human dies, extinction occurs.
Here is the list.
- Asteroid Strike
There are asteroids and comets of all different sizes flying through space. Fortunately, space is immense and the odds of one colliding with Earth are slim. The asteroid that struck the Earth 65 million years ago was very large, but not nearly large enough to hurt Mother Earth permanently. It landed in what is today the Gulf of Mexico off the coast of the Yucatan Peninsula. Its crater is still there under the water. Any animal within miles of this asteroid strike would have perished immediately, however it is the planet-wide dust cloud that killed the dinosaurs in the far corners of the Earth. Only small animals, such as various mammals, reptiles and birds, survived. Fish and other animals living in the sea were largely able to avoid extinction although they certainly would have been impacted.
Could we survive an asteroid strike of this magnitude? Our technology today would surely allow us to find a way to grow food without the requisite sunlight for a few years until the dust cloud subsided. However, there is no limit to the size of an asteroid flying through space. An asteroid of sufficient size could conceivably cause greater damage, knock the earth’s orbit off kilter, or even destroy the planet completely. There is no question the human race would not survive that scenario.
- Climate Change
Climate change could be the greatest threat to our existence today. Of all of the listed possible causes of human extinction, this is the one that is already in process. If the average temperature of the Earth continues to rise unabated, there is certainly a point where extinction of the human race would become plausible. All one has to do is look at one of our two closest neighbours in the solar system to see what happens to a planet with runaway climate change. Venus is the most uninhabitable planet we know of. It is surrounded by thick clouds which combine with the hot sun to create a green house effect causing a surface temperature roughly equivalent to the inside of a pottery kiln. No life as we know it could survive in these conditions.
- Nuclear War
Similar to the asteroid strike, the war itself would kill millions of people in the near vicinity, but it’s the after effects that could cause extinction. The destruction that would result if even a small fraction of the existing nuclear weapons were detonated could cause extinction through a combination of the immediate radiation, nuclear fallout, nuclear winter, and if you survived all of these you would probably starve to death because the world food supplies would also be destroyed.
- Pandemic
We have just lived through one of the worst pandemics in history. There isn’t much I could say that isn’t already well known. Imagine, however, a pandemic with no cure and with a much higher fatality rate than Covid 19.
It’s truly hard to imagine a pandemic causing extinction. Even the Bubonic Plague only wiped out around half of the population of Europe in the 14th century. Nevertheless, pandemic makes the list because of the unlimited potential for the destruction of life.
- Oxygen Depletion
The oxygen level on Earth was established millions of years ago when the planet was dominated by huge ferns and other massive plants that manufactured oxygen at an impressive rate. Today that level remains very stable despite all of the environmental degradation we have inflicted. It seems unlikely that this would be our undoing, but it certainly is a possibility when one considers the rate at which we can raze a forest and, more to the point, the way we can raze a forest and not bat an eye.
- Artificial Intelligence
Stephen Hawking is on record as warning us that A.I. is one of the greatest threats to human existence. As dire as this seems, there is little question we have only scratched the surface of this technology which would have, seemingly, no limit. The simplest way to look at it is this: if we build machines that are capable of killing people on their own agenda, they will kill people on their own agenda.
- Super Nova
An exploding star far off in space is one of nature’s most spectacular events. The remnants of an exploding star, or super nova, fill vast voids of space with gases and debris which are visible here on Earth, with the help of a telescope. If/ when this happens to a star close enough to us or, God forbid, our own sun, life on our planet could be extinguished. The sun will, one day, a few billion years from now, expand into a red giant and engulf the Earth, burning it to an ember, but this event is so far off in the future it is unlikely there will still be human life to extinguish. If there is, we likely will have occupied other planets by that time.
- Mass Reproductive Failure
If an environmental disaster of epic proportions were to occur which worked its way into the body of every person or most people on Earth, especially people in their reproductive years; and the result of this tragedy were to be destruction of the reproductive system, perhaps sperm growth for example, the result could be the extinction of the human race by the slow and gradual method – waiting more than a century for the last person to die.
This completes my exhaustive list of potential causes of human extinction. And it also completes this lovely topic. Rather than squirm at the thought of this we should revel in the fact that we are living at a time when can do something to ward off any one of these except #1 and #7, which are extremely unlikely.
If you have any ideas that are both plausible and capable of causing human extinction. Please contact me and I will consider adding them to this list. Thank you.
BT
