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The Tree of Life
For thousands of years we have divided all known living things into only two fundamental "kingdoms" -- plants and animals. As science developed, a "tree of life" was drawn placing every living thing on a network of branches stemming from one of these two main boughs. But a new understanding of life on Earth has forced us to redraw this tree of life, pushing plants and animals to one corner of an expanded tree.

Across the planet, life is extremely varied and sometimes exotic. But all life on Earth shares the same mechanism of passing genetic codes to the next generation. These codes include all the instructions needed to create the next generation and preserve the species. These are the genes --constructed from strands of DNA.

Comparing the genes of different life forms can tell us a great deal about how they are related. For example, we share 99% of our genetic code with chimpanzees, but we share very little with bacteria. However, we still possess a few small strands of code in common with even these tiny creatures.

In the ultimate story of life on Earth, we all share the same roots. Tracing back through the genetic history of microbes exposes our own origins. The very first living thing on Earth was most likely a single-celled microbe. The more we know about this ultimate ancestor of all life on Earth, the more we will learn about ourselves.

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