That applies to humans as well 'with a vengeance, ' says Stanford biologist Robert Sapolsky, author of 'Why Zebras Don't Get Ulcers.

For instance, says Sapolsky, let's say an individual goes to a therapist to work out some long-standing issues such as trauma or abuse.

Professor Sapolsky claims he is on the path to a genetically engineered formula that would remove the need for human beings to feel threatened.