Aristotle

==== Empirical research ====
Aristotle was the first person to study biology systematically,{{sfn| Leroi | 2015 | page=7}} and biology forms a large part of his writings. He spent two years observing and describing the zoology of [[Lesbos]] and the surrounding seas, including in particular the Pyrrha lagoon in the centre of Lesbos.{{sfn| Leroi | 2015 | page=14}}{{sfn| Thompson | 1910 | page=Prefatory Note}} His data in ''[[History of Animals]]'', ''[[Generation of Animals]]'', ''[[Movement of Animals]]'', and ''[[Parts of Animals]]'' are assembled from his own observations,<ref>{{Cite web|url=https://www.independent.co.uk/arts-entertainment/books/reviews/darwins-ghosts-by-rebecca-stott-7808310.html|title=Darwin's Ghosts, By Rebecca Stott
|website=independent.co.uk|date=2 June 2012
|access-date=19 June 2012}}</ref> statements given by people with specialized knowledge, such as beekeepers and fishermen, and less accurate accounts provided by travellers from overseas.{{sfn| Leroi | 2015 | pages=196, 248}} His apparent emphasis on animals rather than plants is a historical accident: his works on [[botany]] have been lost, but two books on plants by his pupil Theophrastus have survived.{{sfn| Day | 2013 | pp=5805–5816}}

Aristotle reports on the sea-life visible from observation on Lesbos and the catches of fishermen. He describes the [[catfish]], [[electric ray]], and [[frogfish]] in detail, as well as [[cephalopod]]s such as the [[octopus]] and [[paper nautilus]]. His description of the [[hectocotylus|hectocotyl arm]] of cephalopods, used in sexual reproduction, was widely disbelieved until the 19th century.{{sfn| Leroi | 2015 | pages=66–74, 137}} He gives accurate descriptions of the four-chambered fore-stomachs of [[ruminant]]s,{{sfn| Leroi | 2015 | pages=118–119}} and of the [[Ovoviviparity|ovoviviparous]] embryological development of the [[hound shark]].{{sfn| Leroi | 2015 | page=73}}

He notes that an animal's structure is well matched to function so birds like the [[heron]] (which live in marshes with soft mud and live by catching fish) have a long neck, long legs, and a sharp spear-like beak, whereas [[duck]]s that swim have short legs and webbed feet.{{sfn| Leroi | 2015 | pages=135–136}} [[Charles Darwin|Darwin]], too, noted these sorts of differences between similar kinds of animal, but unlike Aristotle used the data to come to the theory of [[evolution]].{{sfn| Leroi | 2015 | page=206}} Aristotle's writings can seem to modern readers close to implying evolution, but while Aristotle was aware that new mutations or [[Hybridisation (biology)|hybridizations]] could occur, he saw these as rare accidents. For Aristotle, accidents, like heat waves in winter, must be considered distinct from natural causes. He was thus critical of Empedocles's materialist theory of a "survival of the fittest" origin of living things and their organs, and ridiculed the idea that accidents could lead to orderly results.{{sfn| Sedley | 2007 | page=189}} To put his views into modern terms, he nowhere says that different species can have a [[common descent|common ancestor]], or that one kind can [[speciation|change into another]], or that kinds can become [[extinction|extinct]].{{sfn| Leroi | 2015 | page=273}}