Scientists in the United Kingdom are warning future researchers that the lack of ethical rules could lead to the humanizing of animals and a possible scenario much like the movie "Rise of the Planet of the Apes," in which scientists inadvertently create a new breed of ape with human-like intelligence.

The report calls for more stringent rules to supervise sensitive research involving animals and giving them human-like characteristics. One area of concern is the "Category Three" experiments which because of very strong ethical concerns should be banned outright. One example is giving apes the power of speech.

Professor Thomas Baldwin, member of the Academy of Medical Sciences working group that produced the report, said that the possibility of humanoid apes should be taken seriously even if it is still largely fictional at the moment.

"The fear is that if you start putting very large numbers of human brain cells into the brains of primates suddenly you might transform the primate into something that has some of the capacities that we regard as distinctively human ... speech, or other ways of being able to manipulate or relate to us," he said in a news briefing in London.

Research involving great apes is illegal in the UK but allowed in other countries including the U.S. Scientists working in the United States have already implanted human embryonic stem cells into mouse embryos. The mouse cells eventually outgrew the human stem cells but a portion of the embryos still had the human stem cells.

Professor Baldwin said that researchers should apply the "Great Ape Test" on future research. If modified monkeys began to acquire abilities similar to those of chimpanzees, it was time to "hold off."