Shallow, warm-water tide pools may have provided the ideal conditions for the origins of simple living things. The early Earth was a hostile, lifeless place. Volcanoes poured out red-hot molten rocks and poisonous fumes. Gigantic storms flooded the new land, causing vast clouds of ash, spray and steam. But, over tens of millions of years, conditions cooled. Somewhere, somehow, life began on Earth. It may have first emerged in warm, shallow seas; it may have formed deep in the oceans, close to mineral-rich jets of warm water shooting up through the Earth's crust; or it may even have formed elsewhere in space, with simple organisms arriving on Earth carried on a comet or meteorite.
1. Life forms from
a chemical soup
Scientific studies show that planet Earth formed about 4600 million years ago, from a massive ball of cloud, dust and gases whirling through space. At first, the rocks of Earth were far too hot for life. But gradually they cooled and massive rainstorms lasting many thousands of years filled the lakes, seas and oceans with water.
These seas contained all kinds of salts, minerals and other chemical substances, sometimes described as a “primordial soup”. By chance, some of them may have joined to each other—perhaps helped by the energy of lightning flashes from the storms that raged across the globe. Other chemicals joined around them. These others then broke off to form blobs of their own: the first very simple living things had reproduced. This may have happened as long as 3500 million years ago, possibly hundreds of millions of years earlier. Life stayed as simple microscopic organisms for another 3000 million years.
Classical scholars thought that living things were created out of decaying organic matter. According to ancient Greek philsopher Aristotle, aphids (greenfly) arose from the dew on plants, flies from rotting meat and mice from hay.
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