' … a truly monumental compendium of everything you might have wanted to know about same-sex biology, its proximate as well as ultimate causation … a goldmine … with a treasure-trove of many hundreds of references … Aldo Poiani, in this admirable volume, has drawn together the best, most coherent summary to date of the currently available evidence.' Evolutionary Psychology … [a] remarkable new book … a well-presented and easily navigated text. … it precisely reflects the strongest conclusion that the current literature can make: animal homosexuality can only be understood as a diverse collection of multicausal phenomena. Importantly, it is this firm commitment to an integrative and pluralistic perspective that marks out Poiani's contribution to the literature.' Animal Behaviour