Humans in the Universe 13 Billion – 200,000 Years Ago Scientists offer a different explanation, based on evidence gathered from sources on earth and in space. Here’s what they might say: Long ago, there was no time...There was no space...But 13 billion years ago...things changed. Where there had been nothing, now there was everything. The whole universe – tiny, and fantastically hot. For an instant, it expanded faster than the speed of light. Then it slowed down but kept expanding, as it still is. As the universe cooled down, clouds of hydrogen and helium gas began to gather together, their centers getting hotter and hotter. And when they were hot enough, the hydrogen atoms began to fuse together with the power of millions of hydrogen bombs. STARS WERE BORN! They clustered together in vast galaxies, each containing billions of these new stars. Four and a half billion years ago – when the universe was already two-thirds as old as it is today – a star was born near the edge of a galaxy we call the Milky Way: OUR SUN! Around the sun, wisps of matter were drawn together by the forces of gravity to create the planets of our solar system… …Including the third rock from the sun: OUR EARTH! The early earth was incredibly HOT. Heavier metals melted and sank to the center, lighter metals rose to the surface, and gases bubbled up to make the earth’s first atmosphere. By four billion years ago, the earth had cooled enough for water to condense into oceans. And so the earth turned blue. The surface hardened into thin “plates” floating on the molten materials underneath. Those “plates” float on the surface to this day, constantly changing the landscapes and weather patterns on the earth’s surface. Where the plates collided, great mountains were formed and where they tore apart, melted rock poured out from under the surface. Deep within the newly formed oceans, complex chemicals were created using volcanic heat for energy. Some of these chemicals became so highly organized that they formed cells – the first LIFE ON EARTH! Living organisms changed the atmosphere, adding oxygen. Cells developed that could “breathe” oxygen and, about 600 million years ago, the first multi-cellular organisms arose in the earth’s oceans. The first animals appeared not too long after! After a while, some animals moved out of the oceans and onto the land. Dinosaurs were the most successful of the early land animals but about 65 million years ago, a giant meteor came crashing down to earth and the dinosaurs were no more! This left a new class of animals dominant on the land. MAMMALS! Over time, a particular group of mammals emerged that lived in trees. To survive in that environment, these mammals needed 3D vision and large brains to process visual information. They also needed hands that could grip with precision. (Imagine living in a tree without any of these. You’d fall out!) These mammals were the first PRIMATES. Then, about 7 million years ago in Africa, a branch of those primates became the first to stand upright. These were the first HOMINIDS. Different hominids lived on earth over the next 7 million years, some at the same time as others, but only one survives to this day...US!!! The earliest hominids lived in small, family-sized groups. They gathered plants, insects, and small animals, and they occasionally scavenged the meat of larger animals killed by predators. The first hominids had brains about the size of a modern chimp’s. Over time, new species developed ever-larger brains, and they began to make more and more complex tools. The Australopithecines likely used sharp sticks to dig for food while Homo habilis hominids, a later species, were able to make stone tools. They chipped ‘flakes’ of stone from large rocks and used those flakes as knives. They also used the leftover ‘core’ to scrape out hides and do other jobs. Homo erectus hominids, which lived on Earth for almost two million years, were probably the first ones who could control and use fire. They were also the first to leave Africa. Their fossils have been found as far away as China and Java (in modern Indonesia). Social relationships among our ancestors were complex. Like modern chimpanzees, early hominids must have been quite clever, with a great deal of social cooperation and group politics. They cared for each other, especially their children. Well, in some ways that’s true – but this species was different in many other respects from our species. We have no evidence, for example, that they had art, religion, or language.