While governments debate how to prevent human reproductive cloning, it seems that nature has put a few hurdles of its own in the way. On page 297, a team reports that in rhesus monkeys, cloning robs an embryo of key proteins that allow a cell to divvy up chromosomes and divide properly. Unpublished data from this and other groups suggest that the same problem may also thwart attempts to clone humans.

Your methods are broken. Return to the drawing board. Do not pass go. Do not collect $200.

'The Primates Will Not Be Cloned' | Science Magazine