Two monkeys are the first ever primates to be cloned using the technique that created Dolly the sheep.
The technique brings the prospect of cloned human beings even more closer.
But scientists caution that there may be no good reason to create such clones, and that ethical and legal questions need to be answered about such research.
More immediately, the technique will allow researchers to create whole labs full of genetically identical monkeys.
That could prove tremendously useful in scientific and medical research – allowing doctors to watch how specific treatments affect the genetic makeup of animals that are otherwise exactly the same, for instance.
The two identical long-tailed macaques – named Zhong Zhong and Hua Hua – were born eight and six weeks ago at a laboratory in China. They represent the furthest reaches of cloning technology, genetically resembling each other entirely.
They aren’t, strictly, the first primates to have been cloned. But they are the first to be produced using the single cell nuclear transfer (SCNT) technique, which involves transferring cell nucleus DNA to a donated egg cell that is then prompted to develop into an embryo, and is the same process used for Dolly the sheep.
Previous work has relied on splitting embryos, which is the same phenomenon that happens when twins are born and can only produce four offspring.
The two monkeys were part of a total of 79 different transfer attempts, which used different techniques. Scientists had some luck cloning monkeys using adult cells, but those were only able to survive for a few days.
That genetic symmetry of the monkeys means that scientists could create a whole experiment’s worth of identical monkeys, save for the specific genetic changes that they want to study.
But the research has already led to fears about where it could lead.
The scientists stress they did the work under strict international codes, and co-author Muming Poo said the team was aware “that future research using non-human primates anywhere in the world depends on scientists following very strict ethical standards”.
The breakthrough means that it would theoretically be easier to clone a human, since primates share so much of their makeup with us.
But actually doing so is much less likely, given the ethical and regulatory objections there would be to any such plan.
Scientists will keep watch on Zhong Zhong and Hua Hua, who for now appear to be growing and developing like normal monkeys. They expect more clones to be born in the coming months.
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