The Earth, our home, is around 4.5 billion years old, according to accumulated research from many scientific disciplines, including geology and astronomy. However, While our ancient common ancestors, which we share with chimpanzees and bonobos lived between 8 and 6 million years ago, the modern form of humans (us) only evolved about 200,000 to 350,000 years ago. Interestingly, since separating from our ape cousins humans have lost about 37,000 genes.
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| Ape and Human Evolution Tree |
Today our planet is home to over 7 billion humans. In the year 1800 there were about 1 billion humans and in 1950, about 2.5 billion individuals. In just over a decade's time, the human population of the planet is estimated to go over 12 billion people, which is mind-boggling. And yet, in 70,000 BC, humans as a species almost became extinct.
This severe reduction in human population which occurred around 70,000 years ago is thought by some to be related to the Toba volcanic eruption which occurred about 75,000 years ago at Lake Toba in Sumatra, Indonesia (scientists don't agree about this). This eruption resulted in a global volcanic winter of six to ten years and extreme climate change, which resulted in the homo sapien population, being reduced to about between 1,000 and 10,000 breeding pairs. Other scientists discount the nuclear winter theory, as human populations in India, for example, appeared to recover quickly from the eruption event.
All other archaic human species have become extinct and we Homo Sapiens just narrowly missed out on becoming ancient history ourselves. Homo Erectus became extinct around 70, 000 years ago and Neanderthals about 28,000 years ago. Things changed for our relatives with the development of farming about 12,000 years ago, which allowed a surplus of food and the resulting development of towns and cities and the rapid increase in human populations.
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| A model of the face of an adult female Homo erectus |
Over 99 per cent of all species that ever lived on Earth are estimated to have become extinct. And while we might have dodged a bullet 70,000 years ago, this near extinction of humans had some big effects on our species, resulting in a genetic bottleneck and less genetic variation in the human population, because of the reduced variation in the gene pool and so the ability to adapt to change.
However, analysis of human DNA shows that humans who lived 1 million years ago had greater genetic diversity than we do today. And chimpanzees have about twice the genetic variability of all humans. And yet, the greatest threat to chimpanzees is human encroachment on their habitats and we humans have become the most dominant species on Earth, with our ability to control and manipulate nature.
But our success as a species is now resulting in the destruction of the foundations of the natural world, which is collapsing from the weight of humanity and we can only wonder, what is in our future?
