End of the world
Out of context: Reply #24
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Jaline
(Oct 19 05, 06:57)Without natural disasters there would be no people
65 million years ago, the globe was shaken to its core. That much is certain. What the experts don't agree on is what kind of catastrophe really occurred. Was it a meteorite ten, twenty kilometres in diameter that crashed into the Earth? Or was it a series of violent volcanic eruptions that darkened the heavens for a lengthy period? Whatever the reason, the world turned cold and thus pretty inhospitable for the dinosaurs which inhabited it at the time.But the little, warm-blooded mammals, that until then had eked out a wretched existence in the shadow of the giant lizards, were suddenly given their chance. This was the first major geo-historical crossroads that pointed evolution in the direction of the human race. Among the smaller mammals that now came into their own was the tree shrew family. It was from this species that prosimians, apes and, finally, human beings evolved.
Without this cold catastrophe the world might still be ruled by Tyrannosaurus Rex. Frustrated tree shrews would still be choking in the dust thrown up by his feet. Indeed, that is the way things were for a very long time; after all, mammals were already around 220 million years ago. The first true mammal, the eozostrodon, was already in existence when the dinosaurs began their impressive career.
Then, when it went cold and dark, the mammals were able to move into the fast lane. They had a constant body temperature. Their most important sense was that of smell, which they used to find insects at night. Weasel-like creatures were armed and ready for the new climate, while the likes of Tyrannosaurus Rex were in their final throes. Without the global disaster, the evolutionary path that led to homo sapiens would never have been blazed. In this way, drastic environmental changes guide destiny and accelerate evolution.
After this big bang came the tertiary period, the heyday of the mammals. The subsequent Pleistocene epoch then began with a warm period that, on a geological time scale, set in like lightning. The ensuing abundant precipitation brought forth opulent vegetation. In eastern Africa - the birthplace of mankind - yet another natural phenomenon took place: rampant volcanic activity sprayed the region with ash which acted as a fertiliser. Plants, and plant-eaters, multiplied, and the apes left the primaeval forest to partake of the fantastic range of food that the steppe now offered. Now living at ground level, they learned to walk upright and became increasingly intelligent. With his superior brain, our forefather, Australopithecus, was able to hold his own against lions and hyenas. When the next climatic catastrophe caused the temperature to drop again, the humid forests to shrink and the steppe regions to expand, Australopithecus was already ideally suited to the new landscape. As anthropologist Jared Diamond explains, it was interaction with the environment that shaped the course of human evolution. And disasters reshaped the environment time and again.
Primaeval man later emigrated from the African continent in three waves, initially inhabiting only the Old World. If disastrous cold spells during the Pleistocene epoch hadn't covered half of Europe with glaciers, America would have remained untouched by human foot (at least until the arrival of Columbus). Because the swelling of the continental ice sheets dried out the Baring Straight and turned it to tundra. This enabled man to cross from Asia to America by foot 12,000 years ago. And conveniently enough, there were sufficient mammoths on hand to provide him with food and clothing during this trek.