This article is from WeChat official account:Principle (ID: principle1687), author: Jojo, original title” 18 years of the time gap, hides what secret? “, the head picture comes from: unsplash
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Researching the history of early humans is actually like making a huge puzzle, and not all the puzzle pieces are in your box. Researchers will do their best to collect data from some fossils, artifacts and geological records, and then infer the entire picture, but many problems still exist. For example, one of them is related to the concept of “adaptability”.
On the earth, there are many places with different temperatures, different altitudes, and different landscapes, and in many such places, humans flourish and grow. For a long time, scientists engaged in human origin research have wanted to understand the question, why so many human species have appeared, but in the end only Homo sapiens(Homo sapiens) Stayed? Why can Homo sapiens adapt to all different environments so successfully? How did this adaptability evolve?
In one place in Kenya, some scientists have been studying this problem for decades. There, they discovered archaeological records and fossil records hundreds of thousands of years ago. From those records, they inferred the dramatic changes the environment has experienced. What is the connection between the development of Homo sapiens and environmental changes? This is exactly the content of a study recently published in the journal “Science Advances”.
The research connects everything that happened in the environment at that time, with the transformation of technology and the human species living there, and through analysisAnalyzing the transition from one technology to another, it is concluded that the evolutionary adaptation of Homo sapiens stems from our ability to adapt to environmental changes. Rapid climate and environmental changes can explain the reasons that drove early human innovation.
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In southern Kenya, there is a famous prehistoric site named Olorgesailie. It is located in the Great Rift Valley with active geological activity. There, sediments from lakes and streams accumulate over time, bringing ancient fossils The bones and stone tools are preserved.
Stone hand axes dating back hundreds of thousands of years have been unearthed in these sediments. The general appearance of these hand axes is relatively uniform, all of which are relatively large and oval in shape. These tools span a long period of approximately 700,000 years. During this time, there were Homo erectus (Homo erectus) and Heidelberg People (Homo heidelbergensis) live in East Africa.
However, 500,000 years ago, these tools seemed to disappear mysteriously. The stone tools of the next period that emerged from the sediments began about 320,000 years ago, and these tools that began to appear 320,000 years ago seem to be significantly different from those of the earlier stone tools. They are smaller and easier. Carry, more diversified functions. It is more similar to modern human technology and culture. Archaeology in some other parts of Africa shows that such technology is related to the earliest African Homo sapiens. This means that during the period when there was a gap of 180,000 years in the archaeological record of sediments, there was a certain leap in human technology and culture.
More importantly, the older tools are made from stones that can be found nearby, while the newer tools use sharp obsidian as the raw material. Researchers tracked the source of these obsidians and found them in several distant rock formations in different directions, the furthest of which was 95 kilometers from the Olorgesailie site. These remote sources of obsidian mean that the humans in Olorgesailie had already begun to exchange resources, or “trade” with other groups over a long distance, and this phenomenon had not yet appeared in an earlier period.
In the records of Olorgesailie, there are two types of stone tools from different periods, and there is a record blank of 180,000 years in between. | Image source: Human Origins Program / Smithsonian
Researchers also found in updated records that humans in Olorgesailie had used black and red paint. In the eyes of archaeologists, paint is a symbol of humans’ complex communication. They can use these paints on flags, clothes, or many other places to visually show which ethnic group they belong to. All of this gives a strong impression that people at the time were using the surrounding resources in more complex ways.
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What caused this leap? What happened in the missing 180,000-year time gap? From the archaeological records of Olorgesailie, the researchers did not find a clear transition, which confused them. Until they discovered a new site about 24 kilometers away from Olorgesailie. By extracting sediment cores deep underground there, they pieced together the environmental conditions of the past million years along the timeline. It was discovered that the 180,000-year gap that disappeared was perfectly recorded in the core.
In the cross section of the core, each layer of sedimentary layer provides corresponding clues to the ancient environment. | Image source: LacCore / University of Minnesota
This is a 139-meter-deep core. It shows that many things have happened during the 180,000 years of disappearance. It contains a series of ancient lakes, as well as the habitat and soil around the lakes. All the cores are covered with volcanic layers. It can be determined that these volcanic layers are the most accurate East African environmental records in the past 1 million years. By sampling and analyzing sediments, the researchers found that between 1 million and 500,000 years ago, ecological resources were relatively stable and there were reliable fresh water resources available. Large herbivores, such as zebras, rhinos, baboons, elephants and pigs, have changed the wooded grassland vegetation in this area, forming short and nutritious grasslands.
Starting about 400,000 years ago, a critical environmental change occurred. Crustal tectonic activities split the landforms of East Africa into small basins. The landforms alternate between arid grasslands and fertile woodlands. The ecological resources on which our ancestors and animals depended began to fluctuate. Some large herbivores have gone extinct, replaced by smaller mammals that are smaller, less dependent on water, and have a more diverse diet. These changes in animal communities reflect the advantages of adaptive diets.
At this time, the researchers got inspiration from anthropological research. They noticed that hunter-gatherers now and in modern history will improve technology to deal with periods of resource instability. They will keep in touch with distant ethnic groups to maintain a network of exchanges of resources and information. They developed some symbolic marks to strengthen these social connections and group identities. Does this sound familiar? These behaviors are similar to the way of life of humans who have lived in Olorgesailie since 320,000 years. Therefore, the researchers associate the technological change with the ecological environment.
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In the past two decades, many scientists who have studied the origin of man believe that climate is the main driving force for primitive humans to adapt to evolution. New research shows that the changes in the environment 400,000 years ago did cause great changes in rainfall. However, the topography of this area has also been changed due to tectonic activities and is covered by volcanic ash. And large herbivores are alsoThe vegetation before and after the transition had different effects, leading to a series of ecological changes, including early human life styles.
Therefore, new research believes that all these factors together contributed to this critical evolutionary change. Researchers said that such a conclusion may also give some inspiration to the current human beings: Humanity is now in an era of global environmental uncertainty. In the face of such a situation, whether human ingenuity can be used Social networks, new technologies and reliable sources of information can solve these problems and adapt to future environmental destruction?
Reference source:
[1]https://theconversation.com/turbulent-environment-set-the-stage-for-leaps-in-human-evolution-and-technology-320- 000-years-ago-148381
[2]https://www.sciencenews.org/article/environmental-changes-stone-age-humans-adaptable
[3]https://www.csmonitor.com/Science/2020/1023/Did-prehistoric-climate-change-help-make-us-human?icid= rss
This article is from WeChat official account:Principle (ID: principle1687), Author: Jojo