In his life's work Lun Heng (Critical Essays), Wang proposes many concepts to do with species, and identifies different species 'inability to interbreed as one of their defining characteristics. His ideas are very "modern."
王充在花畢生心力所寫的《論衡》中，提到許多與種有關的概念，並且把種與種不能相交列為種的特性之一，對生物「種」的認識已非常「現代」，與十八世紀西方分類學家林奈的物種概念相似。