There are scientists out there trying to bring the dead back to life. They're not mad, but they are dedicated, because they believe it will happen, sooner or later. It might not occur on a cold stone slab, there probably won't be lightning flashing between huge electrodes, and it definitely won't take place in a gothic German castle. But it will happen. Somewhere, scientists will revive the dead--and not just an individual, but an entire species.
Most scientists believe that any animal could be cloned, given enough time.
Species have been going extinct since the beginnings of life. Although millions of creatures have lived and thrived on this planet for more than 3 billion years, more than 99 percent of them are gone. It's a natural part of evolution. Like death and taxes, extinction is practically a sure thing. It's also permanent. Once the last living member of a species succumbs, it's all over.
But in 1997, a team led by Ian Wilmut at the Rosland Research Institute in Scotland made headlines with the announcement that they had successfully cloned a female sheep, the now famous "Dolly." The breakthrough surprised many, and immediately started discussion about the future of cloning and its impact on the world. In the midst of this swirling debate, wheels began to spin in the minds of several scientists. If living animals could be cloned, they thought, why not extinct species?
Cloning 101
In spite of the excitement surrounding the Dolly experiment, scientists urged people not to get too worked up about the possibilities. The reason is that, in spite of this success, cloning is really hard. Cloners compare it to assembling a one-million-piece puzzle where all the pieces are the same color. Of course, nature makes genetic duplicates all the time. We refer to them as identical twins. But twins grow according to the DNA code from developmental cells--cells that are supposed to divide and grow into complete adult beings. Cloning attempts to get the DNA from adult cells to do the same thing.
Unlike developmental cells, adult cells have gone through a process called differentiation. This process allows them to specialize into the muscle, bone, skin, and many other types of cells that make up an entire animal. But this specialization also causes the cells to lose their ability to grow into other types. Skin cells can only make more skin cells, and muscle cells can only make more muscle cells. They just can't do anything else.
Cloners attempt to overcome this cellular specialization by using only the DNA from cells in specific locations of the body. In the case of Dolly, after countless earlier attempts had failed, scientists used DNA from female mammary glands. They chose these cells because the cells had entered a state called quiescence. Quiescent cells no longer replicate themselves, which would seem to make them poor candidates for clonal development. But actually, they're just what Dr. Frankenstein ordered. The DNA in the nucleus of these cells is in its least active state, and that makes it most suitable for transfer. Because it's not busy doing anything at the moment, it seems to be more amenable to becoming a clone.
The next step is to find a suitable host cell from another animal to put the quiescent DNA into. As with donor cells, scientists need to choose host cells from just the right location. With Dolly, they used female oocytes, the cells that go on to form the egg cells used in reproduction. Of course, most cells already have a perfectly good set of DNA residing in their nucleus. Cloners must remove all of this DNA before they can insert the new set. They use a tiny glass tube to carefully suck the old nucleus out and put the new one in, hoping all the while that the rest of the cell doesn't notice. Seen through a microscope, the maneuver looks like trying to pierce a soap bubble with a turkey baster without bursting it.
Even after successful implantation of a new nucleus, which doesn't happen very often, the vast majority of these cells fail to grow into healthy adult organisms. The host oocyte and the new nucleus with the donor DNA in it need to cooperate with each other. The DNA from the donor has all the information needed to grow the cell into a complete adult being, but it needs the host oocyte to give it a biochemical "incentive" to do so. Even though oocytes are reproductive cells, supposed to grow into complete adults eventually, this doesn't always work. Scientists aren't sure why exactly, but a variety of genetic conditions inside the nucleus as well as biochemical conditions inside the host cell need to be just right for proper growth to occur. If any one of these conditions is missing or off just a bit, the cell fails--and failure is indeed what happens most of the time.
If the cell does start to divide, growing into the tiny ball of cells that marks embryonic development, cloners face the next hurdle: getting an adoptive mother to accept the embryo. Success at this important stage requires the mother to have a specific set of hormonal conditions--conditions which must synchronize with those in the developing embryo for it to properly implant itself in the mother's uterus and grow. The timing has to be just right, and as anyone trying to get pregnant can tell you, it usually isn't.
The end result is a success rate of less than 1 percent. Even Dr. Frankenstein had a better average than that. But scientists are learning more about the conditions necessary for successful cloning, and refinements to the original Dolly experiments promise to make the success rate increase in coming years. Confidence is high enough now that most scientists believe that any animal could be cloned given enough time--any living animal, at least.
Clone This!
If cloning a living animal is like trying to assemble a one-million-piece puzzle where all the pieces are the same color, then cloning an extinct animal is like doing the same thing with most of the pieces missing. Once an animal dies, there are no living cells from which to gather a complete set of genes, and fragile DNA quickly degrades. Only in a few, very rare circumstances are conditions after death conducive to preserving even small amounts of DNA. Consequently, scientists say that the hardest challenge in cloning an extinct creature would be gathering enough of the elusive genetic stuff to make a complete genome.
The most common remains of extinct animals are in the form of skeletal fossils, but they are poor candidates for harvesting DNA. Millions of years of weathering and biological activity have long since scoured the bones of any soft tissue, to the point where even a few molecules of organic matter are hard to find. A well-preserved fossil may yield a few bits of recoverable DNA, but nowhere near enough to reconstruct a complete genome.
Another target for the would-be Frankenstein lies in amber, the hardened and fossilized resin of ancient tree sap. Many chunks of amber have been found with well-preserved animals, mostly insects, trapped inside. The amber coating protects the animal's carcass from the ravages of nature over time. But in spite of what the celluloid scientists in Jurassic Park might have done, amber is not a perfect preservative, and only limited amounts of DNA have ever been successfully extracted from amber-encased animals.
One potential DNA source that scientists are exploring is based on a secret that restaurateurs have known for years: that ice makes a nice preservative. At the end of the most recent Ice Age (about 10,000 years ago), a few arctic animals were frozen in large blocks of ice, preserved in death until thawed out by modern explorers. The most notable of these animals, and the most compelling to the imagination, is the woolly mammoth. A relative of modern elephants, the last mammoths went extinct more than 4,000 years ago, victims of the Earth's warming climate and the spread of early humans. Well-preserved mammoth specimens have been recovered from the ancient glaciers of northern Russia. Complete with remains of skin, hair, and possibly even internal organs, these mammoth carcasses could be better preserved than last week's tuna casserole.
In 2000, an international team of scientists attempted to recover a 23,000-year-old specimen from the Taimyr Peninsula in Siberia. After the remains were carved out of the ice and taken back to the lab, the extracted mammoth DNA was found to be heavily damaged by ultraviolet radiation and the freezing and thawing of the ice. In spite of the sophisticated methods used to recover the tissue samples, only small fragments of DNA were recovered. Scientists now doubt that a complete genome could be put together anytime soon, if ever.
That leaves one last option: alcohol. Scientists have been using alcohol and similar compounds to preserve specimens for centuries. It sterilizes the tissues placed inside, preventing bacteria and other organisms from consuming them and slowing down decay. It is in such a jar of alcohol that perhaps the best hope for raising the dead exists.
Pickled Tiger, Ethical Pickle
In the 1930s, the Hobart Zoo in Tasmania housed a variety of animals. Like many zoos around the world, Hobart's star attractions were its predators. But compared to the lions, bears, and other exotic mammals brought in from the far corners of the world, Tasmania's local predator was decidedly unimpressive. Zoo visitors would take a few moments to watch the dull brown animal's quiet and nervous pacing and then move on.
What visitors to Hobart's zoo had seen was the Tasmanian tiger (Thylacinus cynocephalus). A predator native to Australia, New Guinea, and Tasmania, its common name was misleading. It didn't look much like a tiger, except for the bold stripes on its back. At five feet in length, it looked more like a large dog or wolf, but it wasn't one of those either. It was a marsupial, more closely related to the koala or kangaroo than to any big cat or wolf. Shy and secretive, these "tigers" wandered the forests and grasslands, hunting and scavenging for wallabies and other animals.
Driven off Australia and New Guinea by the introduction of wild dogs thousands of years earlier, Tasmania became the shy hunter's last refuge. But after sheep farmers settled Tasmania in the 1800s, its days were numbered. Once the tiger decided sheep made a pretty good snack, farmers vilified the predator as a menace and put a bounty on its head. For 75 years, the tigers were trapped and shot in large numbers. Slow moving and unused to dealing with humans, they were easily killed or captured. Those that were brought to zoos didn't last very long, and in spite of efforts to breed them, they never reproduced in captivity.
So it was on September 9, 1936, that the last Tasmanian tiger on display at Hobart died alone in its cage. Almost before anyone realized it, the Tasmanian tiger had gone extinct. Ironically, the zoo itself closed its doors the following year, and all that remained of the strange predator were pictures, a few skeletons and pelts, and the preserved specimen of a pup floating in alcohol on a shelf at the Australian Museum.
With the successful cloning of Dolly, the directors of the Australian Museum knew they had an incredible opportunity floating in that jar. Thousands or even millions of years had passed since other extinct species walked the Earth, but the Tasmanian tiger had been gone for just a little more than six decades. The question was whether or not the DNA had remained intact enough in the alcohol to be converted into a complete, viable set.
Scientists intend to find out. To see whether they can render the tiger's complete genetic code, they are relying on a technique called polymerase chain reaction (PCR), which uses DNA's natural ability to replicate itself to make many copies. By replicating enough of the pieces of DNA they find, scientists hope to piece together the puzzle and come up with the tiger's complete genome. Early results have been positive, as scientists have successfully replicated DNA. Now the researchers believe that no technological barriers prevent them from accomplishing their goal--only countless hours of hard work.
Whether or not the scientists can successfully clone the pickled tiger they possess, it's doubtful that tigers will ever again walk the forests of Tasmania. One clone is still just one clone, and since you obviously need one of each sex to reproduce, creating a viable population remains impossible. But for many, that is not the point. Just accomplishing the difficult task would be its own reward. For others, though, the implications give pause. Whether recent or ancient, extinction is nature's way of removing that which no longer belongs. Like Frankenstein, the cloners might be focused too hard on creating life, and not enough on what happens next.
I'm presently reading "DNA" by James Watson, which discusses many of these topics including PCR DNA duplication, etc. Through the course of the book I've begun to have Jurassic Park-like thoughts of bringing back pre-historic or otherwise extinct beasts. I think it's a scientifically interesting thing to do, but probably dinosaurs are not quite the right target.
I like the idea of rejeuvenating a species that has been displaced by mankind. There are plenty of creatures that we have hunted to the brink of extinction and ultimately to complete extinction as well. Hundreds of hours of hard work though it may be, I look at it as our responsibility. Just think of how we could help in a lab endangered species by introducing new breeders into the population that could induce a booming population growth. There are all types of fowl and plenty of mammals that meet these criteria.
How neat would it be to revive the wooly mammoth?
Though it's a long shot, we even have DNA samples from 30,000 year old Homo Neanderthalus - that would be the ultimate in research value to understand the "missing link" in evolution, study real physiological and even psychological differences in the living, breathing predecessor to man-kind. To some it may make no sense to dig up the past, but I see clear understanding of the past as equating to clarevoyance into the future. A complete understanding of what has transpired and what are all the underpinnings of it all will make it increasingly possible to save our own selves when the time comes that we face another ice age, or some horrible epidemic, etc.
See, I agree with you, and IN CASES agree with it to. BUT, it could get out of hand. Imagine Galleo (sp?) or DiVinci with us again. That would be great. But it also can go wrong, bring evil back. Of course, there is a negitive to everything. :/
It would be 'neat' so to say, to get an extinct species from decades ago. But what the hell for? curiousity and greed for fame and money. mainly those three elements are in their minds. Do they hope to someday balance the circle of life? which I must say is already balanced, if not abit doubtfu at some times.... there may be CAUSE —reason— that those animals were extinct in the first place, whether spiritual, religious or simply the balance of life....
Still, I am quite curious to those 'horrible experiments'. maybe there would be a cure for aids? or somehow create a plague that would help our ever growing population.
have you ever thought, just once, that the earth needs more death? I don't mean it personally, OF COURSE NOT..... but what will happen when the world finally runs out of space....
HA... it leads to them inventing bigger machines and go off looking for a planet with oxygen! ..... or create a machine that could make oxygen atoms!....
either way, everything contridicts itself.
there's a saying I say to people anywhere everywhere, and to some, it is well known, "life contridicts itself." ever think of that?
I'm getting off topic there....
It is folly to punish your neighbor by fire when you live next door.
Publilius Syrus
Jachetta said this in post #5 : You will be long dead before the world runs out of space. So, why the hell do you even care?
This is pretty good justification for littering and defacating wherever we feel like it - in fact, straight up dumping of toxic waste in the forest should be just fine because you'll be long dead before you're ever directly affected, so what should you care, right?
oookkk.... I KNOW all that but yeah, if you don't care, you would seem like selfish brats who think nothing of civilization. Why should I care? well, that a pretty dumb and rhectoral question.
It is folly to punish your neighbor by fire when you live next door.
Publilius Syrus
That is a pretty sucky attidude :/ I hope a lot of people don't feel that way, becasue if they did, the world would be in pretty deep **** in a few years.
Let us hope that people didn't think that way too much 10 years ago. We would be in for some nasty suprises.
02-17-2004 01:02 PM
