Paper short abstract:

Advanced chemical analysis of archaeological buidings from central Veracruz, Mexico, reveal that the earthen architecture characteristic of the coastal lowlands was probably mixed with dissolved bitumen to make it resistant against the humid tropical climate conditions.

Paper long abstract:

Bitumen occurs naturally on the lowland plains of the Gulf Coast of Mexico, and has been used in the past as paint and caulk. Its use as a dissolved additive has not been reported yet from ethnographic sources but revealed through archaeological research. It would explain the existence of a millenary tradition of earthen architecture on the Gulf coast, originating even before the Olmec culture, in a climate that is obviously adverse to this kind of construction. Thus archaeology can reveal traditional knowledge, even if the original practionners are now extinct, and reconstruct a technique that can be useful as an option of modern low-cost housing in tropical areas.