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Thursday, Sept. 6, 2001
THE SPEED OF GENETIC CHANGE
Evolution: Who's responsible?
By ROWAN HOOPER
The human impact on earth has been well-documented: There's climate change, environmental destruction and pollution. Today an American scientist says that humans are driving another, more subtle change that may have consequences that are just as damaging: Evolution in other species is speeding up, and we're to blame.
Coincidentally, a few days ago an English scientist recommended that increasing the rate of human evolution by genetic engineering is the only way for us to stay ahead of artificial intelligence. Whichever way you look at it, the speed of evolution is under human control. The implications for the future are not trivial.
The American first. Humans are now the dominant driving force behind evolution, because of the massive impact of technology. This is most clearly seen in the speed of the evolution of bacterial resistance to antibiotics. No sooner are new antibiotics deployed than a new strain of resistant disease turns up. It's the same with insecticides and pest species. But, says Stephen Palumbi, an evolutionary biologist at Harvard University's department of organismic and evolutionary biology, the danger goes further than that.
"Human ecological impact can greatly accelerate evolutionary change in the species around us," he says in today's issue of Science. "The importance of human-induced evolutionary change can be measured economically and is frequently seen in the exposure of societies to uncontrollable disease or pest outbreaks."
Palumbi's paper aims to draw attention to the danger of accelerated evolution, which he estimates is costing the United States $30 billion to $50 billion a year.
Penicillin was first widely used in 1943 to great effect in World War II. By 1946, however, resistance was reported. The Swiss scientist Paul Muller discovered in 1939 that DDT killed insects. By the time he was awarded the Nobel Prize in 1948 for his research, house flies had already evolved resistance.
Bacteria like E. coli and Staphylococcus, with their much shorter generation times, can evolve resistance even faster than insects. Viruses are faster still. HIV, the virus that causes AIDS, evolves so quickly that there can be thousands of quasi-species in a single infected person.
High-speed evolution occurs in food species, too. Fish have been found to grow more slowly when they are under heavy fishing pressure, with thinner bodies that let them pass through fishing nets.
"I hope that people begin to realize the power of rapid evolution -- and instead of waiting for it to happen, begin taking actions ahead of time," said Palumbi, who outlines possible solutions in his paper.
To put the brakes on rapid evolution, he says, we have to attack the three factors that make evolution by natural selection possible. We should: 1) reduce variation in fitness traits (e.g., slow the mutation rate of HIV); 2) reduce directional selection (e.g., make the gaps in fishing nets bigger, reduce fishing pressure); and 3) reduce the heritability of the fitness trait (ensure that favorable mutations are not passed on).
"Overuse of antibiotics has been one of the main problems," said Palumbi, who recommends withholding the most powerful new drugs, and thus reducing the selection pressure on bacteria to develop resistance. "Countries with over-the-counter antibiotic availability have a higher incidence of resistance than those like the U.S. that require prescriptions."
Meanwhile, on the other side of the Atlantic, in Cambridge, England, the physicist Stephen Hawking has fanned the flames of the debate over genetic engineering by advising that humans increase the rate of our own evolution by judicious genetic manipulation so as to boost our health and intelligence.
Speaking to the German magazine Focus, Hawking said that there is a real danger that computer intelligence will surpass that of humans -- with the worrying implication that computer intelligence will take over the world. The Issac Newton professor of mathematics, who has suffered from Lou Gehrig's disease since his 20s, said, "We should follow this road [to genetic manipulation] if we want biological systems to remain superior to electronic ones."
Decrease the speed of evolution of other organisms, but increase that of humans. Should we follow this road?
"I agree that there might be a problem," said Palumbi, "but professor Hawking's solution creates even more. Increasing the complexity of human DNA is not necessary -- the current genome is 10 times larger than needed -- or ethical. But the problem of machine evolution is a real one for the future, one we should anticipate and perhaps guard against."
Hawking is describing how he sees the future but is also advocating extensive genetic engineering. He predicts that during this century, we will discover how to modify complex traits like intelligence and eliminate or reduce undesirable traits such as aggression. These "cave man" traits are handicaps now, said Hawking, which, combined with modern technology, result in a real danger of self-destruction. For a current example, see the Texan president and his missile defense plans.
Hawking has a penchant for airing radical views of the future. In his public lecture "Life in the Universe," he said: "Laws will be passed against genetic engineering with humans. But some people won't be able to resist the temptation to improve human characteristics, such as the size of memory, resistance to disease and length of life. Once such super humans appear, there will be major political problems with the unimproved humans, who won't be able to compete. Presumably, they will die out, or become unimportant."
E-mail Rowan Hooper at email@example.com