Although It has taken h*** sapiens several million years to evolve from the apes, the useful information in our DNA, has probably changed by only a few million bits. So the rate of
biological evolution in humans, Stephen Hawking points out in his Life in the Universe lecture, is about a bit a year.
"By contrast," Hawking says, "there are about 50,000 new books published in the English language each year, containing of the order of a hundred
billion bits of information. Of course, the great majority of this
information is garbage, and no use to any form of life. But, even so,
the rate at which useful information can be added is millions, if not
billions, higher than with DNA."
This means Hawking says that we have entered a new phase of evolution. "At first, evolution proceeded by natural selection, from random mutations.
This Darwinian phase, lasted about three and a half billion years, and
produced us, beings who developed language, to exchange information."
But what distinguishes us from our cave man ancestors is the knowledge that we have accumulated over the last ten thousand years, and particularly,
Hawking points out, over the last three hundred.
"I think it is legitimate to take a broader view, and include externally transmitted information, as well as DNA, in the evolution of the human
race," Hawking said.
In the last ten thousand years the human species has been in what Hawking calls, "an external transmission phase," where the internal record of
information, handed down to succeeding generations in DNA, has not
changed significantly. "But the external record, in books, and other
long lasting forms of storage," Hawking says, "has grown enormously.
Some people would use the term, evolution, only for the internally
transmitted genetic material, and would object to it being applied to
information handed down externally. But I think that is too narrow a
view. We are more than just our genes."
The time scale for evolution, in the external transmission period, has collapsed to about 50 years, or less.
Meanwhile, Hawking observes, our human brains "with which we process this information have evolved only on the Darwinian time scale, of hundreds
of thousands of years. This is beginning to cause problems. In the 18th
century, there was said to be a man who had read every book written.
But nowadays, if you read one book a day, it would take you about
15,000 years to read through the books in a national Library. By which
time, many more books would have been written."
But we are now entering a new phase, of what Hawking calls "self designed evolution," in which we will be able to change and improve our DNA. "At
first," he continues "these changes will be confined to the repair of
genetic defects, like cystic fibrosis, and muscular dystrophy. These
are controlled by single genes, and so are fairly easy to identify, and
correct. Other qualities, such as intelligence, are probably controlled
by a large number of genes. It will be much more difficult to find
them, and work out the relations between them. Nevertheless, I am sure
that during the next century, people will discover how to modify both
intelligence, and instincts like aggression."
If the human race manages to redesign itself, to reduce or eliminate the risk of self-destruction, we will probably reach out to the stars and
colonize other planets. But this will be done, Hawking believes, with
intelligent machines based on mechanical and electronic components,
rather than macromolecules, which could eventually replace DNA based
life, just as DNA may have replaced an earlier form of life.