Climate change in the Jomon period around 70,000

Approximately 70,000 years ago, the previously warm climate became colder worldwide, and the Wurm Ice Age, a glacial period, will continue intermittently until approximately 10,000 years ago.

Such an ice age continues for a long time, but from 20,000 years ago, there are signs that it will gradually warm up. In reality, it is said that it was very cold 20,000 to 15,000 years ago because of the "return of cold".

It is said that the average temperature around Japan was -7 degrees Celsius, which was comparable to that of Siberia, and it was only after 15,000 that the temperature felt warming in earnest.

During the Ice Age, there is a lot of ice on land To do. The rise in sea level due to global warming, which we often hear in recent years, is caused by the melting of ice on the surface of the earth and its flow into the sea. The same thing happens when transitioning from past glacial periods to interglacial periods.

It's a bit brute force, but the result of the ice on the ground during the ice age of ancient times melting and flowing into the seawater, and the increased seawater slowly subsided due to its weight, can be said to be the current sea level.

That's why it seems that more than 20,000 years ago, the sea level was more than 100m lower than it is now. People who chased large beasts (mammoths, Naumann elephants, etc.) arrived at the Japanese archipelago after being connected to the Eurasian continent. It is believed that it came from Siberian coastal states to Hokkaido (northern route), from the Korean Peninsula to Kyushu (Korean route), from the Ogasawara Islands to Honshu (South Sea route), from South China (East China route), and from Taiwan and Okinawa (Okinawa route).

Source:wikipedia Last Pleistocene Japan altitude map about 20,000 years ago

At the same time as the signs of warming began to appear, it seems that a culture called the Jomon period began to be seen. It is also believed that this change in temperature caused the large beasts that ate during the Paleolithic era to gradually disappear.

The food acquisition methods that I had relied on until then no longer work, and new cultures have sprung up as needed. It can be said that the new culture is the emergence of the Jomon culture, which is different from the Paleolithic period, such as the use of earthenware and the sedentary life.

At the beginning of the Jomon period, the climate is unstable and cold, but it gradually stabilizes, and about 7,000 to 5,000 years ago, we will enter a period called Hypsithermal (climate optimum period). It overlaps with the heyday of the Jomon period. At that time, the sea level seemed to be a few to four meters higher than it is now.

Source:Flood Maps http://flood.firetree.net/ Created at 4m above sea level

You can see that part of the Kanto Plain, around Nagoya, and around Osaka Prefecture are submerged. The reason why shell mounds where shells that should be collected only around the sea are thrown away are found inland is because the topography is different from now.

By the way, 4000 years ago, the cooling gradually started, and the prosperity of the Jomon period began to fade, and the coastline was no different from the current one. The population was estimated to be about 261,000 seven thousand years ago and was unevenly distributed in eastern Japan, but the population migration from east to west will begin little by little. It seems that this is because the population in eastern Japan has reached the limit of the hunter-gatherer economy.

Meanwhile, in 1159 BC, just before the late Jomon period, a large eruption occurred at Hekla volcano in Iceland, which had an impact on China, and then full-scale and global cooling began. The original cooling has been spurred on.

Yin in mainland China due to the effects of climate change The dynasty is destroyed Zhou You can have a dynasty. This war is particularly big, but various civil wars have occurred even before the Shang dynasty revolution. It seems that people moved from Zhongyuan (plains in the middle and lower reaches of the Yellow River) to the southern part of China to avoid such turmoil, and the people who originally lived crossed the sea and moved to various areas. Of course, there are also people who end up in the Japanese archipelago at this destination.

Those who arrived at the Japanese archipelago were later migrants It is called, and will teach rice farming, metal objects, and the way of thinking about war. At the same time, it seems that diseases peculiar to the continent were brought in, and the population decreased sharply to about 80,000 due to changes in vegetation due to cooling.

If you can't get food due to cooling, you will naturally need to get food in another way. The method taken at this time was rice cultivation brought in by the migrants, and it was an opportunity to move to the Yayoi period.