Placebo is an inactive substance that may be given instead of a drug by a doctors to compare it's effect with the drug that should be given for the same problem. The effect of placebo is called placebo effect. This effect can be positive and negative.
A placebo looks like medicine in shape and taste and a person having it can feel better because of the perception that he has taken the correct medicine. This perception can bring changes in body chemistry like the original drug and makes the patient feel good.
Studies shows that placebo effect is seen in many individuals having pain and depression.
Vestigial structures do not have a function, yet they are homologous to functional structures in related species. They are important because they provide clues to the ancestry of the organism. Many species look similar as embryos.
