In second-century Rome, the legendary Greek medical specialist Galen was about to conduct a public demonstration of one of his extraordinary findings. In a hall rented for the purpose, a squealing pig was strapped down as Galen explained to the assembled intelligentsia how he was going to show them that animals had something called nerves that controlled everything, right down to the voice. With a small nick of the appropriate nerves, he claimed, he could silence the pig without otherwise harming it.
But before he could begin the procedure, a noted philosopher named Alexander Damascenus objected that, even if the pig stopped squealing, it wouldn't prove that humans had a comparable nervous system. And in any case, said Damascenus, demonstrations were pointless. Galen's claim couldn't be true.
This was what Galen and anybody else who practiced the scientific method were up against. Ancient Greek and Roman philosophy held that seeing was not necessarily believing. Empirical evidence did not trump logic or established opinion. Aristotle held that the heart, not the brain, controlled all thinking and speaking, and for many philosophers of the time, Aristotle's word was law. Nicking a pig wasn't going to change Damascenus's mind about that.
Galen stormed out, declaring he wasn't about to waste his time with know-nothing boneheads (or words to that effect). His audience quickly condemned Damascenus and begged Galen to follow through with the experiment, and Galen obliged. The squealing pig demonstration astounded its witnesses and is one of the first recorded instances of animal experimentation conducted in the interests of science [source: Gross].
Actually, long before Galen, in the fourth century B.C.E., Aristotle had performed some live-animal testing as well, with imperfect results. And not long after, another early Greek physician by the name of Erasistratus tried his hand at animal experimentation.
In Moorish Spain in the 12th century, the Arab physician Ibn Zuhr, also known as Avenzoar, tried out some of his innovative surgical techniques on animals before applying them to humans [source: Hajar]. Of course, this was long before the benefits of anesthesia, so both the animals and the humans had a rough time of it.
In the 19th century, the French physiologist Claude Bernard (considered by many to be the father of physiology) was so effective a promoter of animal testing that he made it integral to the modern scientific method. While many people felt, like Damascenus, that the physiology of pigs and other animals had nothing to do with humans, Bernard was able to show that vertebrate mammals were actually very similar to people. Similar enough, he said, to make animal testing highly valuable in the ongoing effort to improve human health [source: Hajar]. And human health needed a lot of improving.
A harrowing chapter in the "Little House on the Prairie" book series describes the near annihilation of the Ingalls family by malaria after a plague of mosquitoes besieged them. In the 1870s, when people like the Ingallses were settling the Midwestern U.S., common opinion blamed everything from "damp air" to watermelons for the disease. Nobody had any idea that tiny blood-borne bacteria carried by mosquitoes were the killers.
Then, in the late 19th century, German microbiologist Robert Koch got some blood samples from cows killed by anthrax. Under the microscope he noted some unusual looking bacteria that he theorized might be the disease itself. The only way to know for sure was to take some of that cow blood and inject it into mice. Sure enough, the mice soon had anthrax, too. This was revolutionary, and it paved the way for Louis Pasteur's formulation of the theory that germs could cause disease [source: NAP].
Animal testing had proven its value in the area of research. A few decades later, the Elixir Sulfanilamide disaster would make it a mandatory element of all drug development.