 Alcmaeon, son of Peirithous (otherwise unknown), lived in the Greek city of Croton on the instep of the boot of Italy. Diogenes Laertius, in his brief life of Alcmaeon (VIII. 83), asserts that he wrote mostly on medical matters. There is, however, little direct evidence for his work as a practicing physician. Later writers in the medical tradition, such as Galen (DK A2), treat him as a philosopher-scientist rather than as a physician, so that some scholars (Mansfeld 1975; cf. Perilli 2001 for a critique) have concluded that he was not a doctor at all but rather a typical Presocratic physiologos (writer on nature). The majority of scholars, however, because of Diogenes’ remark and because of the focus on the functioning of the human body in the testimonia and fragments, refer to Alcmaeon as a physician-philosopher. The historian Herodotus tells us that, in the second half of the sixth century, the physicians of Croton were the best in the Greek world (III. 131) and recounts in some detail the activities of the most prominent Crotoniate physician of the time, Democedes (III. 125–138). Thus, whether a practicing physician or not, Alcmaeon undoubtedly owes some of his interest in human physiology and psychology to the medical tradition in Croton. In the fifth century, it is difficult to draw clear lines between the work of a medical writer/physician and a philosopher/scientist. Presocratic cosmologies of this period devoted some attention to questions of human physiology and medicine, and conversely the early treatises in the Hippocratic corpus often paid some attention to cosmology (see Aristotle, Resp. 480b23 ff.). The earliest Presocratic cosmologies in Ionia (e.g., those of Anaximander and Anaximenes) did not deal with physiology, and it is possible that the new interest in physiology in cosmologies of the fifth century (e.g., those of Empedocles and Anaxagoras) was due to the influence of Alcmaeon (Zhmud 2012a, 366; 2014, 100).