Duplicating my comment below for the the sake of visibility, the OED defines "animal" as: a. A living organism which feeds on organic matter, typically having

Duplicating my comment below for the the sake of visibility, the OED defines "animal" as: a. A living organism which feeds on organic matter, typically having specialized sense organs and a nervous system and able to respond rapidly to stimuli; any living creature, including man. b. In ordinary or non-technical use: any such living organism other than a human being. In a technical context, such as a scientific journal, I expect that "animal" would include humans. In the headline of a science-focused mainstream media article, I think it's ambiguous. Given that the context, I think it's clear they're using the non-technical definition of the word.