Scientist Says ‘No’ to Human Cloning
“I’ve never met a human worth cloning,” says cloning expert Mark Westhusin from his lab at Texas A&M University. “It’s a stupid endeavor.”
That’s an interesting choice of adjective, coming from a man who has spent millions of dollars trying to clone a 13-year-old dog named Missy. So far, he and his team have not succeeded, though they have cloned two cows and a cat.
They just might succeed in cloning Missy soon — or perhaps not for another five years.
Westhusin's experience with cloning animals leaves him upset by all this talk of human cloning. In three years of work on the Missy project, using hundreds upon hundreds of dog's eggs, the A&M team has produced only a dozen or so embryos carrying Missy's DNA. None have survived the transfer to a surrogate（代孕的）mother. The wastage of eggs and the many spontaneously aborted(流产，发育不全) fetuses（胎）may be acceptable when you're dealing with cats or bulls, he argues, but not with humans. “Cloning is incredibly inefficient, and also dangerous,” he says.
Even so, dog cloning is a commercial opportunity, with a nice research payoff. Ever since Dolly the sheep was cloned in 1997, Westhusin's phone has been ringing with people calling in hopes of duplicating their cats and dogs, cattle and horses. “A lot of people want to clone pets, especially if the price is right,” says Westhusin. Cost is no obstacle for Missy's mysterious billionaire owner; he's put up $3.7 million so far to fund A&M's research.
Contrary to some media reports, Missy is not dead. The owner wants a twin to carry on Missy's fine qualities after she does die. The prototype（原型；雏形）is, by all accounts, athletic, good-natured and supersmart. Missy's master does not expect an exact copy of her. He knows her clone may not have her temperament（气质、性情）. In a statement of purpose, Missy's owner and the A&M team say they are “both looking forward to studying the ways that her clones differ from Missy.”
Besides cloning a great dog, the project may contribute insight into the old question of nature vs. nurture. It could also lead to the cloning of special rescue dogs and many endangered animals.
However, Westhusin is cautious about his work. He knows that even if he gets a dog pregnant, the offspring, should they survive, will face the problems shown at birth by other cloned animals: abnormalities like immature lungs and heart and weight problems~ “Why would you ever want to clone humans,” Westhusin asks, “when we're not even close to getting it worked out in animals yet?”
小题1:By “stupid endeavor”, Westhusin means to say that ________.
A．human cloning is a foolish undertaking
B．animal cloning is absolutely impractical
C．human cloning should be done selectively
D．animal cloning is not worth the effort at all小题2:What does the first paragraph tell us about Westhusin's dog cloning project?
A．Its success is already in sight.
B．It is progressing smoothly.
C．It is doomed to utter failure.
D．Its outcome remains uncertain.小题3:By cloning Missy, Mark Westhusin hopes to ________.
A．study the possibility of cloning humans
B．search for ways to modify its temperament
C．find out the differences between Missy and its clones
D．examine the reproductive system of the dog species小题4:We learn from the passage that animal clones are likely to have ________.
A．a bad temper
B．defective（有缺陷的、有毛病的）organs
C．immune deficiency
D．an abnormal shape
原子核在中子的轰击下发生裂变反应，一种可能的裂变方程为
，则下列说法正确的是[ ]
是天然放射性元素，半衰期约为7亿年，随着地球环境的不断变化，半衰期可能变短也可能变长