66. Ethics, Experiments, and Observational Studies. According to the British medical journal The Lancet, experimental studies performed on animals (nonhuman primates, squirrel monkeys, and rodents) have revealed that large doses of the drug Ecstasy (methylene-dioxymethamphetamine, or MDMA) produce “large and possibly permanent damage” to neural axons in the brain.9 Explain why the researchers did not perform their experiment on humans.