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Stephen Hawking gave an introductory speech
for the EyeforPharma
Europe 2000 conference
You
might wonder why I'm talking at this conference about the future
evolution of the human race. I am not a geneticist or an expert
on DNA and I have only a lay person's knowledge of biology. On
the other hand, I have thought quite a lot about the origin of
the universe and the significance of the fact that it led to
complex structures that evolved to intelligent life. By
intelligent life, I don't just mean DNA based humanoid life like
you see in Star Trek. On the basis of its behavior, I wouldn't
put the human race very high in the intelligence stakes.
I think the range of possible life forms in the universe is
much wider and includes electronic systems like computers.
Biologists are expert on the DNA tree of life, but maybe it
takes someone outside biology to see the wider forest. I can
also say things about genetic engineering that those in the
field may think but wouldn't dare utter publicly because they
feel under attack. It is in this complexity that I think the
most important developments of the future will be. By far the
most complex systems that we have are our own bodies.
Life seems to have originated in the primordial oceans
that covered the Earth four billion years ago. How this
happened, we don't know. It may be that random collisions
between atoms built up matter or molecules that could reproduce
themselves and assemble themselves into more complicated
structures. What we do know is that by three and a half billion
years ago, the highly complicated molecule, DNA, had emerged.
DNA is the basis for all life on Earth but there is nothing
inevitable about it. There are probably other chemical
structures that can encode genetic information and reproduce it.
They may be realized in life forms on other planets. As you
know, DNA has a double helix structure, like a spiral staircase,
which was discovered by Francis Crick and James Watson in the
Cavendish Lab at Cambridge in
1953. The two strands of the double helix are linked by pairs of
nicolic acids like the treads in a spiral staircase. The order
in which the different nicolic acids occur along the spiral
staircase carries the genetic information that enables the DNA
molecule to assemble an organism around it and reproduce itself.
As the DNA made copies of itself, there would have been
occasional errors in the order of the nicolic acids along the
spiral. In most cases, the mistakes in copying would have made
the DNA unable to reproduce itself. Such genetic errors or
mutations would die out. But in a few cases, the error mutation
would increase the chances of the DNA surviving and reproducing.
Thus the information content in the sequence of nicolic acids
would gradually evolve and increase in complexity because
biological evolution is basically a random walk in the space of
all genetic possibilities, it has been very slow. The
complexity, or number of bits of information that are coded in
DNA, is roughly the number of nicolic acids in the molecule.
For the first two billion years or so, the rate of
increase in complexity must have been of the order of one bit of
information every hundred years. The rate of increase of DNA
complexity gradually rose to about one bit a year over the last
few million years. But then a major new development occurred
about six or eight thousand years ago. We developed written
language. This meant that information could be passed from one
generation to the next without having to wait for the very slow
process of random mutations and natural selection to code them
into the DNA sequence. The amount of complexity increased
enormously. A single paperback romance could hold as much
information as the difference in DNA between apes and humans,
and a 30-volume encyclopedia could describe the entire sequence
of human DNA. Even more important, the information in books can
be updated rapidly.
The current rate at which human DNA is being updated by
biological evolution is about one bit a year. But there are
200,000 new books published each year, a new information rate of
over a million bits a second. Of course, most of this
information is garbage but even if only one bit in a million is
useful, that is still a hundred thousand times faster than
biological evolution. This transmission of data through
external, non-biological means has led the human race to
dominate the world and have an exponentially increasing
population.
But now we are at the beginning of a new era in which we
will be able to increase the complexity of our internal record,
the DNA, without having to wait for the slow process of
biological evolution. There has been no significant change in
human DNA in the last ten thousand years but it is likely that
we will be able to completely redesign it in the next thousand.
Of course, many people will say that genetic engineering on
humans should be banned, but I rather doubt if they will be able
to prevent it. Genetic engineering on plants and animals will be
allowed for economic reasons and someone is bound to try it on
humans. Unless we have a totalitarian world order, someone will
design improved humans somewhere.
Will this increase of human capabilities go on forever or
is there a natural limit? Up to now, the limit on human
intelligence has been set by the size of the brain that will
pass through the birth canal. Having watched my three children
being born, I know how difficult it is to get the head out. But
within the next hundred years, I expect we will be able to grow
babies outside the human body so this limitation will be
removed. But ultimately increases in the size of the human brain
through genetic engineering will come up against a problem that
mechanical messages responsible for our mental activity are
relatively slow moving. So further increases in the complexity
of the brain will be at the expense of speed. We can be quick
witted or very intelligent, but not both.
Assuming we don't destroy ourselves in the next hundred
years, I expect we will spread out first to the planets in the
solar system and then to the nearby stars. But it won't be like
Star Trek or Battle in
Five with a new race of nearly human beings in almost every
stellar system. The human race has been in its present form for
only two million years out of the fifteen billion years or so
since the Big Bang. So even if life develops in other stellar
systems, the chances of catching it at a recognizably human
stage are very small. Any alien life we encounter will either be
much more primitive or much more advanced. And if it is more
advanced, why hasn't it spread through the galaxy and visited
Earth. Some people claim there is a government conspiracy to
hush up UFOs, but I think it would have been obvious if aliens
had come here. More like Independence Day, than ET.
So how does one account for our lack of extraterrestrial
visitors? It could be that there is an advanced race out there
which is aware of our existence but is leaving us to stew in our
own primitive juices. However, I doubt they would be so
considerate to a lower life form. A more reasonable explanation
is that there is a very low probability either of life
developing on a planet or of that life developing intelligence.
Because we claim to be intelligent, though maybe without much
ground, we tend to see intelligence as an inevitable consequence
of evolution. But I would like to question that. It is not clear
that intelligence has much survival value. Bacteria do very well
without it and will survive us if our so-called intelligence
causes us to wipe ourselves out in a nuclear war. So, as we
explore the galaxy, we may find primitive life, but not beings
like us.
گروه فارسی
س. پی. اچ
فرستنده محمد رضا حسینی
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