Every mass extinction is different, but two of them, the last and current ones, stand out. The last one, 66 million years ago, started with an Earth collision with an asteroid. A lot of scientists agree that we are experiencing another mass extinction right now. It gets a special name “Sixth extinction”. Its uniqueness lies in the fact that it is caused by our, humankind’s, behavior.
History – Long Time for Mankind and Short for Extinction
The ongoing extinction is called “Holocene extinction” or “Anthropogenic Extinction” or “Sixth Extinction”. When did it start? There is general agreement that it began with the rapid disappearance of big animals, i. e. megafauna. Homo Sapiens were major contributors to that event.
The hunt on big animals spread out along with Sapiens migration from Africa many tens of thousands of years ago. Scientists established that megafauna extinctions linked to humans, not climate change. Of course, at the time Sapiens did not think about biological evolution, environment, and extinctions. Now we have data of how fast and devastative for big animals was this humans’ activity.
You see the pattern in the above graph. Humans came to some continent or big island, and pretty soon, big animals there got extinct.
Of course, we, Sapiens, are animals too. We are predators, and we are not vegetarians. We preserve some big, or small, animals for us to use, as we want, mostly to be killed and eaten by us. Those “preserved” ones, like cows, were modified to fit better our needs. The population of domesticated animals was artificially increased.
What happens with domesticated animals, is a way off the natural biological evolution. In addition, a wide use around the globe of domesticated plants and animals contributed to limiting the size of the natural habitat of wild plants and animals.
Going in And Going Out
There are two basic phases related to any biological extinction. The first one is the extinction itself. The second one is the natural recovery from the extinction. The “simple” question is how much time it takes to go in and to go out. The answer is not simple for many reasons. It depends on our definitions of what is extinction, what is recovery from an extinction, which data we have at our disposal, which measurements we use, and so on.
The most pronounced picture in that regard would be if we just limit the case to mass extinctions. The duration of mass extinction events ranges from tens of thousands of years to tens of million years.
There are many interpretations on how to define recovery after extinction. For example, it could be defined in terms of taxonomy, or ecology, or morphology. It takes around 10 million years for species numbers to fully recover to pre-extinction levels. Christopher M. Lowery, Andrew J. Fraass found that there is some ‘speed limit‘ on recovery after mass extinctions, which results in 10 million years number.
What to Do with Man-made Extinction
Where are we on the way into the sixth extinction?
We started it around 40 or more thousand years ago. Since then, our abilities to impose our will on other biological beings and on an ecological environment on Earth have multiplied. And we use those abilities extensively.
Our population grew from being well below one million to close to 10 billion already. We invented many ways how to suppress biological diversity on our planet.
Here is a shortlist of some of our actions, which are driving the sixth extinction.
- Habitat destruction;
- Oceanic devastation, like overfishing and contamination;
- Modification and destruction of land and river systems around the world;
- Conversion of forests and wetlands into poorer fields and pastures;
- Widespread transmission of infectious diseases spread through livestock and crops;
- The introduction in various regions of non-native species.
Non-obvious Way To Extinction
In the book “The Sixth Extinction: An Unnatural History” by Elizabeth Kolbert there is a vivid example of how the introduction of non-native species drove an extinction of different types of frogs. A certain type of fungi was originally native to Africa. Then it spread out to other continents, where it became a frogs’ killer, causing frogs to get a heart attack. Elizabeth Kolbert noted, “without being loaded by someone onto a boat or a plane, it would have been impossible for a frog carrying Bd to get from Africa to Australia or from North America to Europe.”
On The Path Into Mass Extinction
Could we avoid sixth extinction, or decrease its severity, or mitigate somehow it and its consequences?
Well, humanity as a whole started to do something about it. The number of the problem’ studies is growing. We put endangered species into zoos. We release some of them into the wild.
In 2010 in Japan an environment ministers from around the world adopt a new United Nations strategy. The goal is “to at least halve the loss of natural habitats and expand nature reserves to 17% of the world’s land area by 2020 up from less than 10%” as of 2010. This plan failed so far.
Our current efforts are incomplete and are designed to slow down the slippery into full-blown mass extinction. In other words, we are trying to look at what to do on a way into mass extinction.
No Easy Way Out of Anthropogenic Extinction
The bigger question is if anybody is looking for a way out. We know that recovery from mass extinctions typically lasted around 10 million years. That could happen after the nature on Earth is relieved from the pressure from most factors, which caused the extinction.
The sixth extinction is man-made. We want our civilization to advance and live thousands and millions of years. Will we get rid of our homes, roads, and infrastructure? Should we drop our communication and transportation lines on the ground, in the ocean, and in the air? Could we even plan on dramatically shrinking our population size? Probably, not in thousands, and not in million years.
We could not predict the future. However, right now it seems that humankind will not release its dominant pressure on other life on Earth.
Well, then we would not allow the nature to start its recovery from mass extinction. Which, in turn, will put biological life and the ecological environment out of the natural balance for millions of years. We should not forget that viruses and bacteria are also a part of biological diversity and balance. It is unknown how all that could impact us, the top of the food chain on Earth.
However, we could note this small example. Per the study, the forests of southern China, Myanmar, and Laos in the last 100 years have changed. They change in a way that enhances the habitat favored by bats. That, in turn, increases “the chance that a coronavirus harmful to humans is present, transmitted, or evolves in this area”. Go to Comments on this blog post.
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