It is quite odd how some things that should be obvious are not so purely because tradition has deadened our sensibility. For example, it has long been standard practice for medical research on animals to use only male specimens since it was argued that the presence of female hormones would add another uncontrollable variable in the testing. This seemed reasonable enough that it was uncontroversial until people started finding that when the resulting medicines were used on women, unexpected things happened. The National Institutes of Health now demands that all testing be done on both males and females, something that seems glaringly obvious now.
Stephen Colbert has more.
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