Will humanity go extinct? Many people seem to get this question out of their minds because they think this is impossible. But in the history of evolution, mankind has experienced population crises that have left humanity on the brink of extinction. Biologist Gould once said: “If history repeats itself, the probability of human being is almost zero.”
When it comes to the concept of race, we may think of the division by color, but actually this is not a completely correct biological structure because it only reflects geographical differences and climate through external traits.
In fact, it only takes a few thousand years for a person’s skin color to change. Scientists have speculated that racial differences have followed the pace of population flow and trends in marriage today that are no longer clearly divided.
As of April 2019, the world population has surpassed 7.7 billion. In terms of numbers, mankind is at the top of the list when compared to large mice.
However, from a genetic perspective, the biodiversity of mankind is not high, in other words, we are all genetically similar.
Our bodies are made up of 3 billion base pairs, but only a tiny fraction of them are unique to us. By random comparison of two passers-by, they had a genetic similarity of 99.9%.
Compared to other primates, modern humans are more similar at the genetic level, although their traits (appearance) look very different. It is estimated that only a small group of chimpanzees has more genetic diversity than all of humanity today.
Such low genetic diversity also means that the vast number of humankind today can actually be traced back to an extremely small number of humans in the evolutionary history of mankind. In other words, 7.7 billion people in the world today actually come from the few survivors of evolutionary history.
Regarding how many of these survivors, scientists have also made some estimates based on the genetic differences in humans today. Studies show that only 500 to 3,000 Homo sapiens women can have children. Studies also show that only 40 to 600 Homo sapiens women survive and have the ability to inherit the next generation.
And that means that in history human history has been on the verge of extinction with the number not exceeding a small town today.
With such a small amount, it only takes a pandemic or a natural disaster, environmental conflicts can completely eradicate humanity on Earth.
Along with the lack of modern medicine at the time, the life expectancy of people was only 30 to 40 years, but in some “miraculous” way, people were able to quickly recover the population thanks to on special advantages compared to other animals, and with just a small group of survivors, they have become the ancestors of nearly 8 billion people on our planet today.
However, even if the population increases, there will be serious loss of human genetic diversity. This is also known as the “bottleneck effect”, which refers to the death of a large number of individuals and the serious loss of genetic variation in the population due to many reasons.
Even if the population is filtered by a “bottleneck” and expands to its original size or even exceeds its original size, the level of genetic variation of the population will not improve, thus we still cannot recover the genetically exhausted that has been severely depleted in the past.
So what exactly did our ancestors at the time lead to very few survivors? In the conjecture of scientists, perhaps the theory of the Toba disaster is arguably the most convincing. The Toba disaster is considered to be the longest and most powerful volcanic eruption in history, it is considered the eruption that led to the global disaster.
The Toba disaster or Toba super eruption is a super volcanic eruption that happened at what is today Toba Lake in Sumatra, Indonesia, between 69 and 77 thousand years ago. This is one of the largest known eruptions of the earth, and is the most well-studied super volcanic eruption.
The Toba Catastrophe hypothesis states that this event caused a global volcanic winter about 6-10 years long and possibly followed by a 1,000-year long temperature decline.
It is speculated that the volcanic eruption erupted to 2,800 cubic kilometers of hot lava and volcanic ash in a short period of time, with the mass equivalent to 19 million of the Empire State Building.
This eruption is 100 times larger than the volume of the largest volcanic eruption in recent history, the Tambora eruption in Indonesia in 1815, the eruption that made 1816 a “year without a season.” summer “in the Northern Hemisphere.
This hypothesis believes that volcanic ash has covered the sky and prevented a large amount of solar radiation from reaching Earth, causing a “volcanic winter” and plunging the Earth into a temperature decline for thousands of years. . Human ancestors at that time experienced a dramatic decline in population size during this environmental disaster.
However, a lot of evidence then refutes the Toba disaster theory. Archaeological evidence also indicates that hunting and gathering in human settlements in India were not much affected by volcanic eruptions.
The sediments of Lake Alawi in East Africa also showed that the Earth did not drop too sharply at that time. Therefore, it is difficult to confirm that the Toba volcanic eruption made humanity stand on the brink of extinction.
But judging by the difference in genetics, this giant bottleneck still exists and our ancestors actually had only a very small number at the time. And perhaps what has caused such a dramatic decline in human populations in the past could be due to disease or conflict between humans and animals, or war between people and humans, or all of them.