I think that using animal models is better than directly testing on humans initially. I am of the opinion that using laboratory rats and other organisms to benefit people is not morally wrong. Eventually, the new drug or therapy will progress to human trials, but putting humans at risk initially is something I wouldn't agree with. While computer simulations may increase our knowledge, they can never replace real interactions between cells, tissues and organs. Many of the test subjects come from pounds and most are euthanized after the experiment. Experiments in genetics, xenotransplantation, behavioral studies, toxicology and drug research have all used animals as their test subjects. Not only are vertebrates used, but many invertebrates are used as well. Armadillos can be used to research Hansen's disease (leprosy) because they can catch this disease, just as humans can. Using animals for testing can be traced back to Aristotle, therefore, it is a practice that has its roots in our ancient history. Until something else can be developed, this is our best way to allow the medical field to progress.