Doba volcano eruption might be overestimated, modern people may not have originated in Africa
Our reporter Lu Chengkuan
Where do humans come from?
Since the 20th century, people have been searching for the scientific answer to this question.
The origin of modern people has always been a hot topic of debate in academia.
The "complete replacement hypothesis" is an important hypothesis in the field of the origin of modern man.
The Toba volcanic eruption about 74,000 years ago is a very important evidence of the "complete replacement hypothesis". The event was once believed to have caused global climate cooling and environmental degradation, and eventually led to areas outside tropical Africa. The demise of the crowd.
At the end of August, the international journal International Quaternary published online the latest research progress of Dr. Ge Yong and Gao Xing from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences on the origin of modern humans.
The study believes that the eruption of Mount Doba did not lead to global cooling and human extinction, and the eruption of Mount Doba cannot be used to support the "complete replacement hypothesis."
So, what is the "complete substitution hypothesis"?
In addition to the eruption of Mount Doba, what other evidence supports this hypothesis?
In addition to the "complete replacement hypothesis", what other hypotheses about the origin of modern man?
Has the ancient Chinese population ever gone extinct?
To this end, a reporter from Science and Technology Daily interviewed relevant experts on October 19.
The "complete replacement hypothesis" holds that Africans are the direct ancestors of other populations
The so-called modern man refers to the ancient man who is anatomically consistent with the living population, which means that modern man is our direct ancestor.
Regarding the origin of modern people, there are currently two mainstream hypotheses, namely the "complete replacement hypothesis" and the "regional evolution hypothesis".
The main difference between these two hypotheses is whether there is an event that "humans outside tropical Africa have been extinct".
The "complete replacement hypothesis" believes that there is an event of "human extinction outside tropical Africa", which means that the African population is the direct ancestor of the population in other regions.
"There are two main theoretical foundations for this hypothesis: First, there are few ancient human fossils that have been discovered between 100,000 and 50,000 years ago, which has become the basis of the'complete replacement hypothesis'; second, through molecular biology , That is, the DNA study of the living population found that there was a process in which the African population replaced the population in other regions. After inference, scientists believe that this event occurred between 60,000 and 50,000 years ago.” Ge Yong told reporters.
Due to the evidence of molecular biology, the "complete replacement hypothesis" has prevailed for a period of time.
However, the "complete replacement hypothesis" itself does not explain why an event such as "humans outside tropical Africa was extinct" occurred. At this time, the research on Mount Doba just gave a perfect explanation for the "complete replacement hypothesis". .
The Doba volcanic eruption is the largest known volcanic eruption in nearly 2 million years.
For a long time, this event has been regarded as important evidence for the "complete replacement hypothesis" of the origin of modern people.
The time of the Doba volcano eruption is approaching the global climate transition period. About 70,000 years ago, the earth's climate changed from the warm MIS 5 (the fifth stage of deep-sea oxygen isotope) to the cold MIS 4 (the fourth stage of deep-sea oxygen isotope).
By analogy with the effects of large-scale volcanic eruptions in history and combined with nuclear winter theory, researchers believe that the eruption of Doba volcano has caused the earth to be cold for a long time, and this result can correspond to the 60,000 years of the "complete replacement hypothesis" The "human extinction outside tropical Africa" event 50,000 years ago.
"Therefore, the eruption of Toba volcano is considered to be the cause of the event of'human extinction outside tropical Africa', and the event of'human extinction outside tropical Africa' is the result of the eruption of Toba volcano." Ge Yong It is emphasized that after researchers have established such a causal relationship, the "complete replacement hypothesis" has become the mainstream theory for a long time.
Molecular biology evidence shows that human activities outside Africa have not stopped
In order to clarify the impact of this volcanic eruption, researchers such as Ge Yong, Gao Xing and others collected global high-resolution geological records covering the eruption period of the Toba volcano, such as ice cores, stalagmites and lake sediments, as well as Europe, Asia and Asia. Archaeological records of Africa to comprehensively assess the impact of Mount Doba on the earth's environment and ancient humans.
Through a comprehensive analysis of various records, the researchers found that the Dopa volcano eruption about 74,000 years ago did not cause global climate cooling and environmental degradation, and that human activities in areas outside tropical Africa have not stopped.
"Therefore, there is no event of global cooling and human extinction caused by the eruption of Mount Doba, and the eruption of Mount Doba cannot be used to support the'complete replacement hypothesis'." Ge Yong said that the origin of modern humans is an important issue. The scientific issues of China should be treated more carefully and discussed in depth.
At the same time, with the development of paleoenvironment, archaeology and molecular biology and the accumulation of related evidence, more and more evidences show that the eruption of Mount Toba did not cause catastrophic global climate change, that is to say, There is no long-term climate cold due to the eruption of Mount Toba.
At the same time, human activities in areas outside tropical Africa have not ceased, and Neanderthal and Denisovan genes are also present in the living population.
Neanderthals and Denisovans were all races that were extinct between 20,000 and 30,000 years ago. In the past, it was thought that these ancient humans did not contribute to the living population.
"So, judging from the various evidences now, the eruption of Mount Toba did not have the ability to cause the'human extinction outside tropical Africa', and whether the event of'human extinction outside tropical Africa' truly exists is worth renewing Consider, that is to say, the theory of the'complete substitution hypothesis' may be biased." Ge Yong said that when discussing the origin of modern humans, supporters of the two hypotheses need to find more strong evidence instead of using the Doba volcano. The eruption was used as a tool to resolve disputes.
There is no evolutionary interruption and substitution for modern people in East Asia
Regarding the origin of modern man, in addition to the "complete replacement hypothesis", there is also a "regional evolution hypothesis".
The "regional evolution hypothesis" believes that there is no such thing as "humanity extinction outside tropical Africa".
In other words, the native populations in various regions have never been extinct, and there may be hybridization with African populations.
"The main basis for this hypothesis lies in various archeological evidence, such as the spread and inheritance of stone tool technology, the continuation of human activities, etc." Ge Yong said.
Regarding the origin of modern people in East Asia, Gao Xing once said that since the discovery of "Beijing people", especially since the German anatomist and physical anthropologist Wei Dunrui put forward the hypothesis of "multi-regional evolution", the East Asian population has been in a long time. The inner is considered to be a continuous evolution, from Homo erectus to early Homo sapiens, late Homo sapiens, to the living population, there is no interruption and replacement of evolution.
Xujiayao-Houjiayao, Beiyao, Dadiwan, Xujiacheng, Sarawusu, Ulan Mulun, Zhijidong, Qinling Sites, Jingshuiwan, Huanglong Cave and other sites of the stratigraphic and dating data show There is no material gap between 100,000 and 40,000 years ago in China, and the chain of human evolution has not been interrupted during this period.
This makes the "complete replacement hypothesis" supporters' claim that there is a "blank period" of materials self-defeating.
"Through the characteristics of the raw materials of stone products and the methods of development and utilization, the technology of stone tools, the types, forms and combinations of stone products, and the evolution of regional cultural traditions and other cultural factors, it can be seen that the Paleolithic culture of China and even East Asia is in the same line. The ancient population of China is constantly evolving," Gao Xing said.
However, the eruption of Toba volcano has led to the "human extinction outside tropical Africa". The impact is very far-reaching, not only in scientific debates, but also in many film and television works and popular science lectures.
Ge Yong said that now, this view obviously should not continue to exist.
Although the eruption of Toba volcano is very large, it has not caused drastic changes in the earth's climate system and environment. It may have caused a short-term devastating impact on nearby areas, but it does not have the ability to cause global human extinction.