Abstract
Aristotle is routinely blamed for several errors that, it is supposed, held 'science' back for centuries - among others, a belief in distinct, homogenous and unchanging species of living creatures, an essentialist account of human nature, and a suggestion that 'slavery' was a natural institution. This paper briefly examines Aristotle's own arguments and opinions, and the perils posed by a contrary belief in changeable species. Contrary to received opinion even amongst some of his followers, Aristotle was not a species essentialist and his ethical theory, properly expanded, provides arguments against bioengineering human and other species without a clear view of what should count as beauty