Some people think it's wrong to use animals for food.
In 1996 three percent said they did not use animals for any purpose.
"I never thought about using live animals in my work before," he said.
They often use animals with special behaviors in their research.
For 3,000 years, they were the most popular animals used by farmers.
"Some military units have been known to use animals for target practice."
This number makes a very small fraction of all animals used in research.
"So you agree that there is a moral cost to using animals?"
"I didn't realize you were still allowed to use animals."
Using animals for work is considered by some as animal slavery.