The world we see now had nourished many other millions of species before giving place to us, the humanity. It had never been the same before, as this place has witnessed the growth and demise of a large number of species. Putting aside the question if this planet would be our permanent abode for the infinite future, the lives of many other species have become a question mainly due to the way we have started living our lives.
The Earth is 4.532 billion years old, and our scientists have an idea about the number of stars in our sky. But when it comes to the number of species available on Earth, they have certainly no idea as there could be millions of species out there that are yet to be identified. On a average, 15000 species are discovered by scientists every year. Hence, they are also not very sure about the number of species that are getting extinct. But, data says that the extinction rate of species has gone up by 100 times in the 20th century than the previous records mainly due to human intervention and activities.So far, our planet has witnessed five mass extinction events that have wiped off a number of species from the face of our Earth. Mass extinction is not just the disappearance of one life form, but a decrease in the quantity of total number lives on the planet.
The current extinction of species could be counted as the sixth mass extinction event, say scientists caused primarily by Homo sapiens, the species that came to this Earth roughly 200, 000 years ago.
The five mass extinctions:
In 1982, Jack Sepkoski and David M Raup, Palaeontologists from University of Chicago reported five mass extinction events in the history of Earth.
Cretaceous-Paleogene Extinction or K-T Extinction: This is the extinction event during which dinosaurs disappeared from Earth nearly 66 million years ago. This event was responsible for the extinction of around 80% of the species at that time including dinosaurs and marine invertebrate species. Only one member of the dinosaur family, Archosaurs survived the event that became the common ancestor of modern birds and crocodiles.
Triassic-Jurassic Extinction: It is said that this is the event that made dinosaurs become the dominant species on Earth. Occurring between 252 to 201 million years ago, this event put an end to 76% of all species including the marine and terrestrial ones.
Permian-Triassic Extinction: Also known as the Great Dying, this is the most tragic of all the extinctions expounding 705 of terrestrial vertebrates and almost 96% of marine species nearly 252 million years ago. The reason for this extinction event remains unsolved with a lot many speculations including catastrophic events such as volcanism, methane gas eruption, etc. It is also the only known event that resulted in the mass extinction of insects.
Late Devonian Extinction: This event, which included a series of extinctions including Lower Zilchov, Kellwasser, Taghanic, and Hangenberg, happened between 420 and 350 million years ago reducing 80 percent of the total animal species. Scientists say this is the least tragic of all the five extinction events.
Ordovician-Silurian Extinction: This is the second largest extinction -after Permian-Triassic extinction event- that occurred approximately 440 million years ago. This extinction is believed to have happened in different phases. The causes are speculated to be gamma ray burst, volcanism or metal poisoning.What is the situation today?
Worse than the previous five extinction events, scientists say. The rate at which the vertebrate species are becoming extinct due to climate change and loss of habitat is alarmingly higher than that of the five events explained above.
Normally two out of 1000 species will go extinct in a period of 100 years. Since 1900, 447 vertebrates have become extinct, which is a way too higher rate.
The reason for these extinctions cannot be completely a human mistake, but of a need. The rise in population of human beings, which is 1 billion in 1850, 6 billion in 2000 and an estimated 10 billion in 2050, demands more living space and facilities and hence more areas are covered for buildings and workspaces through deforestation and other encroachment of habitats that affects the balance of the biodiversity killing a number of species.Another reason coined by Peter Haff, a Geologist from Duke University is Technosphere. He argues that the advancement in technology for the purpose of our socio-economic activities is creating a separate entity called Technosphere, which acts independently on its own creating more needs and demands. Technology has become indispensable that it has a supremacy over human beings. Hence, it has created its own sphere of influence and has become a part of our biosphere.
The solution is not so impossible, and everything can be managed says the scientific community, before, it gets too late.
Why is it important for me to worry about the extinction of these species, one may ask. Before answering that question, do not forget that we are a part of the species community.
Related Video: The Sixth Extinction
More from readnlove