The new Star Wars film,Attack of The Clones, launched recently. It's funny isn't it, how the word 'clone' seems to be associated with people doing evil things, but the reality is, without cloning none of us could exist.
In the time it takes you to read this, your body will have cloned hundreds of metres of new DNA. DNA is essentially the recipe book that tells the cells that make up all of our tissues how to produce the substances that they need to survive, and how to perform the tasks they are supposed to do in the body.
These include roles such as fighting infection, which is done by white blood cells, or removing waste from the body, which occurs in the kidneys. Cells like these are continuously being lost in the body - after a big bowl of "All Bran" for instance, millions of cells are scraped off the insides of the intestines as the fibre goes through you like a scouring pad.
The lost cells are replaced by new cells from beneath which are continuously dividing, and in so doing, constantly copying - cloning - their DNA so that they can pass a copy of the bodies' recipe book into each of their daughter cells. In much the same way we also need new cells to help us to grow from babies to adults. So, in essence, our life depends on cloning.
在微观尺度的克隆,但what about on the whole person scale ? Well, nature has been doing that too. Indeed, Humans have been harmlessly cloning themselves for generations, the commonest example being identical twins. Their DNA is identical and hence they are clones of each other.
But anyone who has met a pair of twins knows only too well that whilst they look identical (except for their fingerprints which are different !) they often have very different temperaments and preferences. This is an important point because many people assume that if they clone their dead dog or cat they will get a new pet with the same lovable personality traits as the animal they owned previously.
You wouldn't assume that a new born baby would know how to talk because its mother and father could, and similarly you wouldn't expect a newborn dog to obey commands - they both need training - so why assume that if you clone your dead dog you'll get anything other that a totally new pet that merely looks like your old one?
With that argument in mind, why bother cloning the dog at all? Why not just get a new one, it would be much cheaper! The key point is that humans' brains, and those of other animals, are shaped throughout life by experience and so if two clones have different experiences in life, they will be two totally different individuals.
So are humans alone in cloning themselves naturally ? Certainly not - as a matter of course nine-banded Armadillos produce quads, where the embryo splits four ways, forming four clones, whilst female greenfly clone themselves to quickly increase their numbers when they find a good source of food.
For them, the reason is probably safety in numbers. If there are lots of them and some get eaten by predators, the chances of an individual greenfly getting picked on are much smaller if it is one of many. At the smaller end of the spectrum, bacteria clone themselves by copying their DNA and then splitting in half, and there are many species of plants and even fungi that reproduce merely by copying themselves. So what's the fuss about cloning considering that it's been going on under our noses, and even in our noses, for donkeys years?
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