A prehistoric example of polydactyly from the Iron Age site of Simbusenga, Zambia

Human burials, dated AD 1100-1500, were examined from the Iron Age site of Simbusenga, located some 35 miles northwest of Victoria Falls in Zambia. Pedal polydactyly was discovered in the fragmentary remains of a young adult of indeterminate sex aged 14-25. The preaxial form of polydactyly is indicated with bilateral involvement of the first metatarsals. There is incomplete hypoplastic duplication of both first metatarsals with broad heads for the metatarsal-phalangeal joints. No digital malformations were found in the other seven individuals with feet and/or hands from the site. Several studies point to autosomal dominance for cases of isolated polydactyly, but inheritance and patterning of preaxial polydactyly are still incompletely understood. The condition is also found in conjunction with genetic malformation syndromes such as Acrocephalypolysyndactyly, Lambotte, Oro-facio-digital, and VATER. High frequencies of polydactyly are reported for African and African-American populations, but further analysis reveals that the bulk of previously reported cases of polydactyly are representative of the postaxial form as opposed to the preaxial expression seen here.