OCD is not an easy disorder to treat. In fact, some people become so desperate to rid themselves of OCD symptoms that they undergo a special form of psychosurgery known as , in which a small amount of brain tissue is destroyed.

amber has allowed scientists to study dna that has been preserved over millions of years.

most community's take hundreds of years to become stable

stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms