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Home | The Puzzle
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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