translation.en: But even though we know that these differences occur, 66 percent of the brain research that begins in animals is done in either male animals or animals in whom the sex is not identified.
translation.zh: 但即使我们知道 这类差异的存在， 66% 的 动物大脑研究 是在雄性动物中完成的 或是在未鉴定性别的动物中完成的。