Abstract. Animalism is the theory that we are animals: in other words, that each of us is numerically identical to an animal. An alternative theory maintains that we are not animals but that each of us is constituted by an animal. Call this alternative theory Lockeanism.Stephan Blatti (2012) offers to advance the debate between animalism and Lockeanism by providing a new argument for animalism. In this note, we present our own objection to Blatti's argument, and argue that Carl Gillett's earlier reply misses the fundamental problem.We also use Blatti's argument to illustrate a common methodological error, namely, uncritical deference to best theories from other disciplines.Animalism is the theory that we are animals: in other words, that each of us is numerically identical to an animal. An alternative theory maintains that we are not animals but that each of us is constituted by an animal. Call this alternative theory Lockeanism. Stephan Blatti (2012) offers to advance the debate between animalism and Lockeanism by providing a new argument for animalism.Carl Gillett (2013) replies to Blatti. In this note, we present our own objection to Blatti's argument, and argue that Gillett's reply misses the fundamental problem. We also use Blatti's argument to illustrate a common methodological error.Blatti's argument appeals to standard evolutionary theory. If animalism is false, then we are not animals, and none of our ancestors were animals either; but standard evolutionary theory says that our distant ancestors were animals; since 'the rejection of evolutionary theory is too high a price to pay' (Blatti 2012: 686), animalism is not false. To put the argument another way: standard evolutionary theory is true only if animalism is true; since we should not reject standard evolutionary theory, we should endorse animalism. Blatti calls this the Animal Ancestors Argument (AAA).According to Gillett (2013: 272), AAA relies on the following premise (which he labels '(2)'):(2) If you are not identical to an organism, then you are not evolved or a product of evolution. Gillett (2013: 273, 275-6) points out that many products of evolution are not animals: DNA and RNA molecules, cellular constituents, and superorganisms (such as the Portugese Man-of-War), which are made up of organisms. He concludes that premise (2) is false, and rejects AAA on this basis.