Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100

created a “pixie dust” with the miraculous power of regrowing tissue. This dust is created not from cells but from the extracellular matrix that exists between cells. This matrix is important because it contains the signals that tell the stem cells to grow in a particular fashion. When this pixie dust is applied to a fingertip that has been cut off, it will stimulate not just the fingertip but also the nail, leaving an almost perfect copy of the original finger. Up to one-third of an inch of tissue and nail has been grown in this fashion. The next goal is to extend this process to see if an entire human limb can be regrown, just like the salamanders’.
    CLONING
    If we can grow various organs of the human body, then can we regrow an entire human being, creating an exact genetic copy, a clone? The answer is yes, in principle, but it has not been done, despite numerous reports to the contrary.
    Clones are a favorite theme in Hollywood movies, but they usually get the science backward. In the movie
The 6th Day,
Arnold Schwarzenegger’s character battles the bad guys who have mastered the art of cloning human beings. More important, they have mastered the art of copying a person’s entire memory and then inserting it into the clone. When Schwarzenegger manages to eliminate one bad guy, a new one rises up with the same personality and memory. Things get messy when he finds out that a clone was made of him without his knowledge. (In reality, when an animal is cloned, the memories are not.)
    The concept of cloning hit the world headlines in 1997, when Ian Wilmut of the Roslin Institute of the University of Edinburgh was able to clone Dolly the sheep. By taking a cell from an adult sheep, extracting the DNA within its nucleus, and then inserting this nucleus into an egg cell, Wilmut was able to accomplish the feat of bringing back a genetic copy of the original. I once asked him if he’d had any idea of the media firestorm that would be ignited by his historic discovery. He said no. He clearly understood the medical importance of his work but underestimated the public’s fascination with his discovery.
    Soon, groups around the world began to duplicate this feat, cloning a wide variety of animals, including mice, goats, cats, pigs, dogs, horses, and cattle. I once went with a BBC camera crew and visited Ron Marquess just outside Dallas, Texas, who has one of the largest cloned-cattle farms in the country. At the ranch, I was amazed to see first-, second-, and even third-generation cloned cattle—clones of clones of clones. Marquess told me that they would have to invent a new vocabulary to keep track of the various generations of cloned cattle.
    One group of cattle caught my eye. There were about eight identical twins, all lined up. They walked, ran, ate, and slept precisely in a row. Although the calves had no conception they were clones of one another, they instinctively banded together and mimicked one another’s motions.
    Marquess told me that cloning cattle was potentially a lucrative business.If you have a bull with superior physical characteristics, then it could fetch a handsome price if it was used for breeding. But if the bull died, then its genetic line would be lost with it unless its sperm had been collected and refrigerated. With cloning, one could keep the genetic line of prized bulls alive forever.
    Although cloning has commercial applications for animals and animal husbandry, the implications for humans are less clear. Although there have been a number of sensational claims that human cloning has been achieved, all of them are probably bogus. So far, no one has successfully cloned a primate, let alone a human. Even cloning animals has proven to be difficult, given that hundreds of defective embryos are created for every one that reaches full term.
    And even if human cloning becomes possible, there are social obstacles. First of all, many religions will oppose human cloning, similar to the way the Catholic Church opposed test tube babies back in 1978, when Louise Brown became the first baby in history to be conceived in a test tube. This means that laws will probably be passed banning the technology, or at least tightly regulating it. Second, the commercial demand for human cloning will be small. At most, probably only a fraction of the human race will be clones, even if it is legal. After all, we already have clones, in the form of identical twins (and triplets), so the novelty of human cloning will