Reference Work Entry

Encyclopedia of Neuroscience

pp 1212-1215

Evolution and the Scala Naturae

  • William HodosAffiliated withDepartment of Psychology, University of Maryland


Scale of nature; Phylogenetic scale; Evolutionary scale


A hierarchical ranking of animals based on Aristotelian notions of perfection, with humans at the top. It has often been used incorrectly as a model for vertebrate evolution.


In seeking to find order and relationship in the biological world, the Greek scientist and philosopher, Aristotle (384–322 B.C.) devised a classification scheme for animals that came to be known as the scala naturae in its Latin translation from Greek. In Latin, scala means “ladder” or “flight of steps” and naturae means “of nature” or “of the universe”. Aristotle’s idea was that living things could be assigned a hierarchical position on this metaphorical ladder that would represent their degree of perfection [1,2,3]. He placed humans on the top rung and other creatures of the known world on progressively lower rungs. He based his classification system on various biological characteristics that h ...

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