Scientists yesterday revealed they had cloned two monkeys, potentially paving the way to ‘copying’ humans.

Using the technique that led to Dolly the sheep, a Chinese laboratory has created a pair of identical macaques.

The researchers said they had cleared the final barrier to human cloning and offered hope of treatments for Alzheimer’s, Parkinson’s and other illnesses.

The monkeys are the most human-like animals yet to be created through ‘true cloning’ – effectively carbon-copying the DNA of a single individual.

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Two monkeys have followed in the footsteps of Dolly the Sheep by becoming the world's first primates to be cloned from transferred DNA. Identical long-tailed macaques Zhong Zhong (pictured) and Hua Hua were born eight and six weeks ago respectively at a laboratory in China

Mu-Ming Poo, of the Shanghai research team, was asked yesterday whether the same method could be used on human cells. He replied: ‘Yes. A macaque monkey is a primate species, humans are primates – the technical barrier is now broken.’

But campaigners said the development was worrying. ‘We are concerned that this is a stepping stone to the creation of human clones,’ said Dr David King of the lobby group Human Genetics Alert.

‘Although it looks like that would be technically difficult, those with enough financial resources and the ambition to be the first to create a cloned child are likely to try.’

The monkeys – Zhong Zhong and Hua Hua – are the first primates to be cloned using the somatic cell nuclear transfer technique. DNA was taken from a macaque foetus cell, put in an egg and fertilised artificially to form an embryo later born to a surrogate mother.

The same method was used more than 20 years ago in Edinburgh to create Dolly from a single adult udder cell.

Cats, dogs, rats and cows are among 23 species of mammal also to have been cloned in this way.

Zhong Zhong and Hua Hua were born eight and six weeks ago respectively at the neuroscience arm of the Chinese Academy of Sciences. It took 21 surrogate monkeys, which had only six successful pregnancies, for the two cloned monkeys to be born. Another pair created from the DNA of a live adult failed to survive.

The success is credited to reprogramming the genes of the cloned embryos to allow them to develop properly in the womb.

The scientists hope to pave the way for populations of genetically uniform monkeys that can be customised for ground-breaking research into human diseases. Pictured is Hua Hua, one of two clones produced in a groundbreaking new study

WHAT IS CLONING AND COULD WE ONE DAY CLONE HUMANS? What is cloning? Cloning describes several different processes that can be used to produce genetically identical copies of a plant or animal. In its most basic form, cloning works by taking an organism's DNA and copying it to another place. There are three different types of artificial cloning: Gene cloning, reproductive cloning and therapeutic cloning. Gene cloning creates copies of genes or parts of DNA. Reproductive cloning creates copies of whole animals. Therapeutic cloning produces embryonic stem cells for tests aimed at creating tissues to replace injured or diseased tissues. To create somatic cell nuclear transfer (SCNT) clones, scientists take DNA (red circle) from tissue and insert it into egg cells (yellow) with their DNA (green) removed. The scientists then switch on or off certain genes to help the cells replicate (right) Dolly the Sheep was cloned in 1996 using a reproductive cloning process known as somatic cell nuclear transfer (SCNT). This takes a somatic cell, such as a skin cell, and moves its DNA to an egg cell with its nucleus removed. Another more recent method of cloning uses Induced pluripotent stem cells (iPSC). iPSCs are skin or blood cells that have been reprogrammed back into an embryonic-like state. This allows scientists to design them into any type of cell needed. Could we ever clone a human? Currently there is no scientific evidence that human embryos can be cloned. In 1998, South Korean scientists claimed to have successfully cloned a human embryo, but said the experiment was interrupted when the clone was just a group of four cells. In 2002, Clonaid, part of a religious group that believes humans were created by extraterrestrials, held a news conference to announce the birth of what it claimed to be the first cloned human, a girl named Eve. This was widely dismissed as a publicity stunt. In 2004, a group led by Woo-Suk Hwang of Seoul National University in South Korea published a paper in the journal Science in which it claimed to have created a cloned human embryo in a test tube. Gene cloning creates copies of genes or parts of DNA. Reproductive cloning creates copies of whole animals (stock image) In 2006 that paper was retracted. According to the National Human Genome Research Institute, from a technical perspective cloning humans is extremley difficult. 'One reason is that two proteins essential to cell division, known as spindle proteins, are located very close to the chromosomes in primate eggs,' it writes. 'Consequently, removal of the egg's nucleus to make room for the donor nucleus also removes the spindle proteins, interfering with cell division.' The group explains that in other mammals, such as cats, rabbits and mice, the two spindle proteins are spread throughout the egg. Advertisement

DNA taken from their ears confirmed that Zhong Zhong and Hua Hua were completely identical. The two females are being bottle fed and are said to be growing normally. Dr Poo said his team had no intention of using their method to create humans.

However Darren Griffin, professor of genetics at the University of Kent, said: ‘The first report of cloning of a non-human primate will undoubtedly raise a series of ethical concerns, with critics evoking the slippery slope argument of this being one step closer to human cloning.’

Technically the first cloned primate was Tetra, a rhesus monkey born in 1999 through the much simpler method of embryo splitting. However experts say this method, which replicates the embryo splitting to form twins in the womb, is not really cloning but just ‘enforced twinning’.

The latest DNA method, described in the journal Cell, allows limitless clones instead of a maximum of four.

Until now, there has never been a single cell nuclear transfer (SCNT)-cloned primate. The cloning of monkeys will be seen by some as a step toward the creation of human clones. Pictured are the two new clones

The Chinese team made the breakthrough using DNA from foetal connective tissue cells. After the DNA was transferred to donated eggs, genetic reprogramming was used to switch on or off genes that would otherwise have suppressed embryo development

Zhong Zhong and Hua Hua were the result of 79 nuclear transfer attempts. Two other monkeys were initially cloned from a different type of adult cell, but died shortly after they were born

HOW WAS DOLLY THE SHEEP CREATED? Dolly was the only surviving lamb from 277 cloning attempts and was created from a mammary cell taken from a six-year-old Finn Dorset sheep. She was created in 1996 at a laboratory in Edinburgh using a technique called somatic cell nuclear transfer (SCNT). The pioneering technique involved transferring the nucleus of an adult cell into an unfertilised egg cell whose own nucleus had been removed. Dolly the sheep made history 20 years ago after being cloned at the Roslin Institute in Edinburgh. Pictured is Dolly in 2002 An electric shock stimulated the hybrid cell to begin dividing and generate an embryo, which was then implanted into the womb of a surrogate mother. Dolly was the first successfully produced clone from a cell taken from an adult mammal. Dolly's creation showed that genes in the nucleus of a mature cell are still able to revert back to an embryonic totipotent state - meaning the cell can divide to produce all of the difference cells in an animal. Advertisement

Cloned monkeys would allow scientists to study 'a lot of questions' about primate biology, the researchers said. The scientists insisted they followed strict international guidelines for animal research, set by the US National Institutes of Health

British cloning expert Professor Robin Lovell-Badge, from The Francis Crick Institute, London, said he did not believe successfully cloning monkeys has increased the chances of humans being cloned

WHAT ARE THE CRITICISMS OF CLONING? The vast majority of animals cloning procedures end in failure with as little as 1 per cent resulting in living, apparently healthy offspring. Dolly, who was cloned at the Roslin Institute in 1996, has developed arthritis earlier than might have been expected. Scientists believe she may have aged prematurely because she was cloned from a six-year-old adult. A study by professor Ian Wilmut, leader of the team that cloned Dolly the Sheep, highlighted unpredictable defects suffered by cloned animals. He found a calf cloned in France did well for several weeks but died suddenly at 51 days after its ability to produce white blood cells failed. Scientists at Roslin had to put down a 12- day- old cloned lamb because the muscles around its lungs had grown so thick that it had great difficulty breathing. Dr Julia Baines, Science Policy Adviser at PETA UK, said: 'Cloning is a horror show: A waste of lives, time, and money – and the suffering that such experiments cause is unimaginable. 'Because cloning has a failure rate of at least 90 per cent, these two monkeys represent misery and death on an enormous scale.' Yesterday scientists revealed they had cloned two monkeys, potentially paving the way to ‘copying’ humans. 'The work in this paper is not a stepping-stone to establishing methods for obtaining live born human clones', said Professor Robin Lovell-Badge, Group Leader of The Francis Crick Institute. 'This clearly remains a very foolish thing to attempt, it would be far too inefficient, far too unsafe, and it is also pointless. 'Clones may be genetically identical, but we are far from only being a product of our genes.' Advertisement

Professor Griffin said: ‘A primate model that can be generated with a known and uniform genetic background would undoubtedly be very useful in the study, understanding and ultimately treatment, of human diseases, especially those with a genetic element.

‘Careful consideration now needs to be given to the ethical framework under which such experiments can, and should, operate.’

Professor Robin Lovell-Badge, a cloning expert at the Francis Crick Institute in London, said he did not believe the research increased the chances of humans being cloned. ‘The work in this paper is not a stepping-stone to establishing methods for obtaining live-born human clones,’ he said. ‘This clearly remains a very foolish thing to attempt. It would be far too inefficient, far too unsafe, and it is also pointless.’

Cloning has captured the imagination of science fiction writers, with human clones created for spare organs in the film and novel Never Let Me Go.Dolly was cloned at the Roslin Institute in 1996 and named after country singer Dolly Parton.

Technically Zhong Zhong and Hua Hua (pictured) are not the first primate clones. That title goes to Tetra, a rhesus monkey born in 1999 through the much simpler method of embryo splitting that does not employ DNA transfer

On the new experiment, Dr Julia Baines, Science Policy Adviser at PETA UK, said: Experimenters constantly receive funds to perform monstrous experiments on animals, and cloning monkeys is the latest Frankenscience that PETA condemns.

'Cloning is a horror show: A waste of lives, time, and money – and the suffering that such experiments cause is unimaginable.

'Because cloning has a failure rate of at least 90 per cent, these two monkeys represent misery and death on an enormous scale.'