The surface of our planet is populated by living things—curious, intricately
organized chemical factories that take in matter from their surroundings and
use these raw materials to generate copies of themselves.
The living organisms
appear extraordinarily...
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The surface of our planet is populated by living things—curious, intricately
organized chemical factories that take in matter from their surroundings and
use these raw materials to generate copies of themselves.
The living organisms
appear extraordinarily diverse.
What could be more different than a tiger and a
piece of seaweed, or a bacterium and a tree? Yet our ancestors, knowing nothing
of cells or DNA, saw that all these things had something in common.
They called
that something “life,” marveled at it, struggled to define it, and despaired of
explaining what it was or how it worked in terms that relate to nonliving matter.
The discoveries of the past century have not diminished the marvel—quite
the contrary.
But they have lifted away the mystery as to the nature of life.
We can
now see that all living things are made of cells, and that these units of living matter all share the same machinery for their most basic functions.
Living things,
though infinitely varied when viewed
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