Should animal testing be illegal or legal?

Have you ever heard about animal testing? It\'s an experiment conducted on laboratory animals for scientific purposes. Some people say animal testing should be illegal because it is unethical, but I think animal testing should be legal. We don\'t have alternatives to replace animal testing. There are only animals that have similar cell characteristics. If animal testing is illegal, do you think scientists will do human experiments? I\'m not sure they will do. It\'s true that animal testing use animal\'s life, but I think animal\'s sacrifice are essential for survival of humanity.