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The Ice Age and Human History
Surviving the Ice Age
During the Ice Age, glaciers covered the earth, but not quite all of it. The traditionally warmer, jungle, or desert areas were spared the massive sheets of ice that extinguished human settlements within range of the polar ice caps. No one knows exactly why the temperature dropped, just as today there are debates over whether humans are causing the undeniable global warming taking place.
Twenty thousand years ago there was maximum spread of glaciers, evidence in core samples of existing ice that's remained frozen for hundreds of thousands of years tell scientists. But an earlier glacial period or Ice Age occurred about 140 thousand years ago, and another about 260 thousand years ago, and still another about 330 thousand years ago. (http://en.wikipedia.org/wiki/Ice_age)
There isn't much history of human civilization available except for the period reaching back only to around ten thousand years ago.
Scientists guess that all the Ice Ages are only relatively recent in the history of the physical earth itself, having begun within the last two to three million years. In fact, this whole period often is called the one and only true "ice age," in which individual periods of glacial spreading occurred regularly. Before that two to three-million year period, the theory is that the earth was very hot, and there wasn't any glacial or ice age activity. But isn't it possible that humans existed even back then, to say nothing of the relatively recent Ice Age that reached its maximum severity 20,000 years ago?
Graphs indicate that in all the glacial periods of the Ice Ages or individual glacial spreading over the past 400,000 years, the temperature on Earth suddenly shoots upward right after the coldest temperatures are reached during glacial spreading periods, or individual ice ages that have occurred repeatedly, roughly every 100,000 years or so. Since the most recent maximum coldness was reached 20,000 years ago, and since the temperature has climbed steadily since then, this would explain why the global warming of today is normal and in keeping with sudden increases in temperature after each little Ice Age. It's almost as if the sun might have a heart beat that pulsates once every 100,000 years to increase the temperature of the planet. Possibly the Earth makes different orbits around the Sun every so often.
Much of the evidence of the Ice Ages comes from the study of geology, however, rather than astronomy. There are many theories about Ice Ages.
Life During the Glacial Spreading
Human Beings Lived Through Glacial Periods
What of the ancient history of humanity, however pathetically recent that may be in the broad scope of things? Until recently in history, it was assumed the earth couldn't be much older than 10,000 years. Now the estimate is in the billions or even a trillion. (http://en.wikibooks.org/wiki/Ancient_History/Human_Evolution/Neolithic_Age)
It would be logical to assume that in the advancing glacial period, human settlements would move not upward to the mountains, because of the increased cold, but rather would gravitate toward the Equator in search of more direct overhead sunlight and warmth. With a limited amount of space in which to live, it unfortunately would be logical to assume wars and violence erupted throughout these periods. But an Ice Age or individual advancement of glaciers comes on slowly, over the course of tens of thousands of years as indicated by scientific evidence of core samples of enduring ice near the poles.
Even the Ice Age or glacial spreading period itself will last thousands of years. Therefore, the change is not rapid, except that once the coldness has ended, the global temperature seems to increase very rapidly.
Theories exist as to how humans survived before, during, and after the glaciers. While it is possible that humans lived in civilized cities, such as the movie "Planet of the Apes" theorized, most scientists at present believe ancient mankind was primitive. People would hunt animals or collect berries and seeds. They would live in caves. Scientists call them "hunter-gatherers."
While most tribes of people must have moved slowly but surely in the direction of the Equator, it's possible that some of the tougher ones would have stayed in the frozen climate and endured. They could have survived much the same as today's Eskimos.
But after the Ice Age, as the earth warmed at a very rapid pace compared to the gradual coming of the glacial period, there has been, as real history shows, a movement in the direction of civilization. First, people started to control crops and animals. They became ranchers and farmers. This was a step up from being sporadic, disorganized hunter-gatherers.
Next, cities evolved in which urban residents depended on the agrarian people to supply them with food, grain, meat, and milk. What did the urban residents do with their time? They developed culture, philosophy, systems of government, and became civilized even more than humans before them. History provides evidence of this in China, India, and Egypt, and other places on earth that developed urban lifestyles.
But the crude nature of humanity, its violence and wars of conquest, continued to exist as evidenced in ancient writings, even the Bible itself.
Most of today's world was not covered in ice. But temperatures must have been colder everywhere. Only Northern Europe and Northern United States were covered. Africa and most of South America were not under glaciers. And yet, there's sparse evidence of cities from before the glacial period or during it. This is why scientists and historians generally assume humans were nomadic before and during the glacial period of 20,000 years ago, which receded significantly by 10,000 years ago, which is when ancient history seems to begin. Ancient men and women needed all the hair growth and tough nails and teeth that they were born with, in order to survive.
But the estimated age of the planet Earth is so great that all sorts of imaginative theories are in existence, many of them highly respected. The latest estimate is about four and one-half billion years. (http://en.wikipedia.org/wiki/Age_of_the_Earth) This takes in not only earth but samples from the moon, which seems directly connected to the planet. Within the rocks are found fossils indicating that animals existed millions of years ago, possibly humans as well.
No one seems to know how far back human beings existed. There are conservative estimates of twenty to eighty thousand years. Some fossils from Africa support an estimate of two hundred thousand years. This would mean that humanity has endured more than one glacial period.
No matter how old humanity is, it's obvious that humans are adaptable creatures who can become tough and survive an Ice Age if necessary. As for history, human nature seems to have existed in all the ancient civilizations. It's logical to believe it was the same even before, during, and directly after the most recent advance of the glaciers. Emotions like love and hate must have been the same driving forces in antiquity as they are today.