Tool Module: What
People have always
been trying to explain the origin and profusion of the forms of life on Earth.
Over the centuries, many explanations have been offered. One was fixism: the doctrine
that the species living on Earth have always been the same and have not evolved
since their creation. Another was Lamarck's theory of the transmission of acquired
characteristics, based on the idea that populations are gradually transformed
as the direct result of the environmental constraints they face.
For nearly two centuries now, so many confirming observations have been accumulating that we can now state that evolution is a phenomenon that has in fact occurred and continues to occur today. All the evidence, from disciplines as diverse as paleontology, genetics, anatomy, chemistry, and geography, converges to confirm the existence of evolution.
Scientists have now discovered that natural selection was not the only
mechanism of this evolution. But they can state that all living species are the
product of evolution and are derived from common distant ancestors.
On the time scale of a human life, to design a complex machine, someone
must first decide on its function, then draw up plans for a mechanism that can
perform that function, and then manufacture that mechanism. But that is not how
the process of evolution produced the human brain. Evolution built on top of what
it already had to work with, rather than starting from zero. On the scale of a
human life, this approach is totally inefficient; it would be like trying to build
a car by modifying a wheelbarrow. But on the geologic time scales on which life
evolves, it works just fine.
In fact, when you consider how the activities of some groups of humans are threatening the planet Earth today, you may well wonder whether the advent of our species was really such a great idea on evolution's part.
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