In the new movie Rise of the Planet of the Apes, scientists working on a cure for Alzheimer's disease fiddle with the brains of chimpanzees, inadvertently creating a new breed of ape with human-like intelligence — and very aggressive tendencies. Now, a real-life group of British scientists is warning that unregulated experimentation on animals could someday create just that kind of scenario, with equally disastrous consequences. Here's what you need to know:

What kind of research is being conducted now?
It's at a much simpler level than what's usually shown in sci-fi movies. For example, U.S. scientists have implanted human embryonic stem cells — which can develop into any part of the human body — into mouse embryos. Though the embryos' mouse cells quickly outgrew the human stem cells, a tiny portion of the embryos retained their human cells. Last year, millions of experiments were performed using genetically modified animals like fish and mice who carried some human DNA.

Is that kind of research ethical?
Not according to some critics. Among the millions of experiments in this field, it was recently revealed that more than 150 hybrid human-animal embryos have been created in British laboratories. Some used animal eggs that were fertilized by human sperm, while others were so-called "chimeras," in which human cells are mixed with animal embryos. "Ethically, it can never be justifiable — it is dabbling in the grotesque," says U.K. parliamentarian Lord Alton, as quoted by Britain's Daily Mail. "At every stage the justification from scientists has been: 'If only you allow us to do this, we will find cures for every illness known to mankind.' This is emotional blackmail."

What are scientists worried about?
They're concerned about unregulated experiments on animal intelligence, which is largely theoretical at this point. If scientists start putting human brain cells into ape brains, "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," says Thomas Baldwin, a member of the U.K. Academy of Medical Science, as quoted by Britain's Telegraph. "You really do not want to go down that road."

Aren't there rules limiting experiments on animals?
Yes, but the rules aren't consistent from country to country. For example, British researchers are banned from experimentation on great apes like chimpanzees and gorillas, but such research is allowed and has been conducted in other countries, including the United States. Many experts are concerned that some countries have few limits on animal experiments, and enforcement of rules can be lax. 

Sources: Daily Mail (2), International Business Times, Telegraph