that many Amerindian tribes induced skull deformities by applying compression devices to head of infants.
In medical parlance, altered morphology (dysmorphology) can result in deformities that often are called "birth defects". Malformations can result from "intrinsic" factors such as genetic alterations but also from disruptions by "extrinsic" factors such as in this instance of an infant subjected to pressure from a mechanical device (in fact this is not the usual way it was done). The aim is to deform or plagiarize a sound genetic plan for a normal morphogenesis (shaping) to achieve a "plagiocephaly" (deformed skull - plagio in Spanish implies "falsehood"). Compressions before birth can cause a variety of "deformations" to be distinguished from "birth defects" due to genetic or teratogenic (malformation inducing drugs etc.) factors.
Medical Humanism owes much to John Reed (1873-1958), the first to earn a PhD in Anthropology from Harvard University. He became a premier ethnologist and his studies of Choctaws (he wrote a classic book on "Indian Tribes of the Lower Mississippi" ... fascinating passages about how after birth, the "caput" or cephalon (skull) of infant boys was subjected to compressions to flatten (achatar in Spanish) the head ... a way to become a proper mameber of a Chactaw tribe).