Frogs legs are perhaps most associated these days with France, however a recent paper by Kysely (2008) investigates the evidence for frogs legs in the diet of the Eneolithic people of the Czech Republic.
The bones in question belong to the Common Frog (Rana temporaria), a member of the ‘Brown Frogs’ group, which are not strictly dependent on an aquatic environment during the whole year. It is, however, required for reproduction, and during this period frogs migrate to pools, puddles, ponds and other water sources. These reservoirs are used as a dwelling by adult males, who call and allure the females. During this short reproductive period, males are easily caught, since they accumulate in one place and call out with strong voices.
The primary reason for the popularity of Common Frogs as a food item is their ability to leap as a way of locomotion, which results in the development of powerful muscles in their hind legs. The frogs’ legs that are served in modern restaurants typically include the ilium and tarsalia, and occasionally even the urostyl. In Europe, they are commonly consumed as a delicacy mainly, but not only, in France. They have also been part of the Central European diet.
Approximately 15,000 fragments were analysed from the site at Kutna Hora-Denemark in central Bohemia. Only 23% were identified to species due to a high degree of fragmentation and taphonomic change. All of the frog bones (NISP=865) come from anthropogenic fills in specific features where preservation was particularly good. In general, frog bones dominate the number of identified bones from the site.
Frog bones in archaeological assemblages may be explained by five possible hypotheses:
- Predator kills
- Natural trap
- Human consumption
- Human association with frogs other than for food
When the skeletal elements present were examined, it was apparent that hind limb bones predominated. Gender was distinguished according to the presence, shape and relative size of crests on humerus bones and according to the presence of the sulcus which appears on those crests. This showed that males were much more common than females. Part of the assemblage was undoubtedly charred or burned.
These facts, along with the uniformity and singularity of the species present, allowed the first three hypotheses to be excluded. The hilly nature of the site (with ramparts) would have made natural access by the frogs difficult, and a natural trap would be expected to contain more than one species. Other microvertebrate species would also be expected if the assemblage were due to predator kills.
Hypothesis five was considered to be improbable because the selection of elements argues against accidental frog-human contact, as does the charring. The almost exclusive representation of meaty, hind limb elements, suggests their use as a food source (hypothesis four). Other body parts could be absent because the primary waste after preparation was thrown out to a different place.
An alternative, less probable, explanation is that the revealed anatomical parts were the unused waste and the usable body parts were those not found. Gaining poison could not be a potential use since the Common Frog does not have any poison potential. However, the use of frogs in ritual, magic, supernatural and religious practices is attested to by ethnographic observations.
Reference: Kysely, R. 2008. Frogs as part of the Eneolithic diet: archaeological records from the Czech Republic (Kutna Hora-Denemark site, Rivnac Culture). Journal of Archaeological Science 35: 143-157