From Room 4:  Birds as a Means of Understanding Biology

Art Greek coins first appeared about 600 BCE and within a century had spread well beyond the mainland. Although the Greeks had no banks, from an economic standpoint the effort to standardize payments was revolutionary. From an artistic one, minting coins with images like the eagles seen here established a standard that endures to this day. The eagles conveyed a message to the citizenry, just as those on modern coins do now. Then, however, the birds were considered to be emissaries of Zeus, serving as omens and handing out punishment. Zeus had one eagle do to Prometheus more or less what an eagle appears to be doing to the hare in the coin. The circadian punishment--the eagle extracted Prometheus’s liver each day (the liver repaired itself each night)--was imposed for two acts of defiance. In the first he shorted Zeus a measure of sacrificial meat by providing a choice between two offerings: one contained ox entrails wrapped in fat, and the other contained choice bits of ox placed in its stomach. Zeus made a bad choice and in his rage took fire away from humanity. In the second act of defiance Prometheus returned fire to humanity, and in a second display of rage Zeus had Prometheus arrested and chained to a rock for the daily liver extractions.

Eagles often appear on coins from Akragas (present-day Agrigento), so perhaps the image was a coat of arms. Still extant in Agrigento are the remains of a large temple dedicated to Zeus, built during the reign of Theron (488–472 BCE), more than half a century before this coin was minted.[52]

Science n ancient Greece the eagle was a symbol of victory, freedom and Zeus. Two eagles feeding on a pregnant hare constituted a powerful metaphor about overtaking a vulnerable but rapidly growing community; the biological message is clear even though it reflects a sophisticated ecological principle. The hare is an animal associated in contemporary as well as ancient times with “irruptive” population cycles: boom years with high birthrates, are followed by low-density “bust” years as resources become sparse from overconsumption. A significant increase in the population of hares (the prey) will lead to a significant increase in the population of eagles (the predators). But the balance between predator and prey is self-regulating. If the prey population overwhelms its resources or invites disease, it will crash, to be followed by a sharp reduction in an increasingly hungry predator population.[53]

When the Greek dramatist Aeschylus used the metaphor in his play Agamemnon (458 BCE), it served as a dramatic reminder that military success always bears the hidden cost of future retribution. The play recounted the triumph of the Greek warrior princes Agamemnon and Menelaus over the Trojans. Priam, the king of Troy, reputedly sired fifty sons and fifty daughters--a crowded lineage and a threatening rate of growth.[54] The image on the coin, then, warned of the dual threats of overpopulation and reprisal. It is a curious coincidence that a grasshopper, another species whose populations periodically overwhelm its food supply, is also depicted here.

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Plate 25
Ten Drachma Silver Coin, Arkagas, Sicily,
c. 412–411 BCE, by an unknown artist
Photo credit: Max Hirmer. © Hirmer Fotoarchiv München.