140
P H V S1C S OF THE IMPOSSIBLE
to refocus the SETI effort. Instead of randomly scanning nearby stars,
astronomers will be able to pinpoint their efforts on a small collection
of stars that may harbor a twin of the Earth.
WHAT DO THEY LOOK LIKE?
Other scientists have tried to use physics, biology, and chemistry to guess
what alien life might look like. Isaac Newton, for example, wondered
why all the animals he could see around him possessed the same bilateral symmetry-two eyes, two arms, and two legs arranged symmetrically. Was this a fortuitous accident or an act of God?
Today biologists believe that during the "Cambrian explosion,"
about half a billion years ago, nature experimented with a vast array
of shapes and forms for tiny, emerging multicellular creatures. Some
had spinal cords shaped like an X, Y, or Z. Some had radial symmetry
like a starfish. By accident one had a spinal cord shaped like an I, with
bilateral symmetry, and it was the ancestor of most mammals on
Earth. So in principle the humanoid shape with bilateral symmetry,
the same shape that Hollywood uses to depict aliens in space, does not
necessarily have to apply to all intelligent life.
Some biologists believe that the reason that diverse life-forms
flourished during the Cambrian explosion is because of an "arms race"
between predator and prey. The emergence of the first multicelled organisms that could devour other organisms forced an accelerated evolution of the two, with each one racing to outmaneuver the other. Like
the arms race between the former Soviet Union and the United States
during the cold war, each side had to hustle to keep ahead of the other.
By examining how life evolved on this planet, one may also make the
following speculations about how intelligent life might have evolved on
Earth. Scientists have concluded that intelligent life probably requires
1. Some sort of eyesight or sensing mechanism to explore its
environment;
P H V S1C S OF THE IMPOSSIBLE
to refocus the SETI effort. Instead of randomly scanning nearby stars,
astronomers will be able to pinpoint their efforts on a small collection
of stars that may harbor a twin of the Earth.
WHAT DO THEY LOOK LIKE?
Other scientists have tried to use physics, biology, and chemistry to guess
what alien life might look like. Isaac Newton, for example, wondered
why all the animals he could see around him possessed the same bilateral symmetry-two eyes, two arms, and two legs arranged symmetrically. Was this a fortuitous accident or an act of God?
Today biologists believe that during the "Cambrian explosion,"
about half a billion years ago, nature experimented with a vast array
of shapes and forms for tiny, emerging multicellular creatures. Some
had spinal cords shaped like an X, Y, or Z. Some had radial symmetry
like a starfish. By accident one had a spinal cord shaped like an I, with
bilateral symmetry, and it was the ancestor of most mammals on
Earth. So in principle the humanoid shape with bilateral symmetry,
the same shape that Hollywood uses to depict aliens in space, does not
necessarily have to apply to all intelligent life.
Some biologists believe that the reason that diverse life-forms
flourished during the Cambrian explosion is because of an "arms race"
between predator and prey. The emergence of the first multicelled organisms that could devour other organisms forced an accelerated evolution of the two, with each one racing to outmaneuver the other. Like
the arms race between the former Soviet Union and the United States
during the cold war, each side had to hustle to keep ahead of the other.
By examining how life evolved on this planet, one may also make the
following speculations about how intelligent life might have evolved on
Earth. Scientists have concluded that intelligent life probably requires
1. Some sort of eyesight or sensing mechanism to explore its
environment;