We’re cloning everything else. Is it still that we still *can’t *(technically) do it currently or simply that we *won’t *do it for ethical & legal reasons?
A lot of both. Obviously, legal and ethical considerations are a big issue, but the technical side has a lot to be worked out too. I mean, it can be done right now if you’re willing to live with a high risk of embryonic death, birth defects, and other genetic abnormalities. Right now, humans can’t be cloned without a much higher risk of all three.
My old bio instructor pointed out that cloning involves a lot of mistakes. No one gets too upset when it’s cattle, but I can’t support just experimenting with making new people when assuredly there will be a raft of mistakes made on the way to getting the process down. I also don’t understand what the advantage is. We already know how to make new people, and there are even ways to make babies for those with normal-conception problems.
During a seminar with a cell biologist working on human stem cells last week this question came up - his response was that the success rate for cloning in mammals was something like one out of 200-300 implanted embryos. Each species is a little different, so the lessons that make rates of successful clones higher in sheep, cattle, and dogs are unlikely to be useful in humans.
It seems like if we were willing to find several hundred women willing to be implanted with embryos that have a very low chance of being carried to term, we could probably clone a human.
Sorry, no cite available, and hopefully if my source is incorrect someone will come along to correct me.
Both ethical and logistical barriers seem to exist right now, and I don’t see that changing anytime soon (nor would I want it to.)
Yes, it’s currently 1 healthy birth out of roughly 200-300 implanted embryos. With another 15-20 badly defective live births. Is that really something you’d want to do in humans?
And on the ethical side, if you clone a human you’d be responsible for it, just like if you had baby the regular way. I’m not sure many scientists would be willing to care for a child for 18 years (rather, one healthy child and 20 severely handicapped children) just because. And as noted above, you need women willing to carry all of these cloned embryos and risk their lives for this process as well.
There doesn’t seem to be a pressing need to clone humans anyways. I don’t think using them as organ farms will go over very well with the rest of humanity and making a baby is normally a fairly straightforward (and fun!) process.
Stem cell research seems much more important right now and scientists are having enough trouble as it is doing that.
I’m assuming that’s rhetorical rather than directed at me, but just in case, no - I don’t want to clone any person. 
Yeah, sorry, I didn’t mean to imply that you personally were hoping for the birth of a bunch of defective children.
Have they solved the telomere problem yet? Telomeres are non-coding repeat sections at the ends of DNA strands which have among their purposes preventing the ends of strands from sticking to other ends when they are not supposed to, and for creating a buffer for when DNA replication is imperfect. If there is some slippage in the process, there is not a lop-sided overrun at the end of the DNA molecule in a coding part of the molecule which might be important, there is merely a loss of little bit of the telomere.
But that means that over time, the telomere is slowly eroded as replications take place. Telomeres are thus important in the aging of cells and of the individual that owns them because there is a finite limit to how long the telomere can continue to be eroded like this.
Thus, cloning an adult means potentially cloning an individual who is apparently healthy, but whose telomeres are reduced in length, meaning that the individual so cloned, although a baby, and even if otherwise apparently healthy, has a reduced extra capacity to absorb transcription errors, which is related to longevity. As I understand it.
If they have fixed that for the purposes of cloning, whacko. But I don’t think they have.
Actually, despite the hype, that is sort of a non-issue for two reasons.
First: In the normal process of baby-making, a woman’s ova and man’s sperm have obviously gone through a large number of divisions since they were ova, so they also have shortened telomeres. This has to be corrected at some point. So, there is an enzyme called telomerase which adds more telomere on to the ends of the chromosomes. This enzyme naturally becomes active during the very early stages of embryonic development (from the 4-cell to the blastocyst stage, IIRC). A cloned embryo will obviously pass through the same stages of development, and so its telomeres will be lengthened in the exact same way that normal embryos’ are.
Second: There seems to be a rather large fudge-factor in the system. A strain of mice was made where the telomerase gene had been deleted. Since their embryos could not re-length their telomeres, telomeres got shorter in each generation. They made it a full six generations before having problems. Therefore, even if a cloned embryo somehow had a problem with turning on telomerase, it would probably be fine.
[Side note]Telomerase is normally ONLY active in the early embryo, but many cancer cells turn it back on so that they can divide indefinitely. How they manage this trick, and whether it matters, is actively being studied by cancer biologists.[/Side note]