>>509896554>>509896622Sorry fren your question is a little lost on me, but I think what you're asking is what were the actual selective pressures that reduced facial robusticity? Evolutionarily speaking, once a species doesn't make significant use of a trait, or the trait is no longer adaptive for their fitness, over generations they will lose that trait. The powerful chewing muscles, the building of larger teeth with dense enamel (in the case of Australopithecus and other earlier hominins) the growth of large facial bones, these are all energetically costly. If the trait isn't being used, it's not adaptive to waste energy maintaining it and as a result it begins to disappear. Large mastication prowess was no longer contributing to species fitness post tools and fire, thus over time it became reduced and that caloric expenditure was used elsewhere. This is then compounded by the fact that as food processing (especially the use of fire 1mya) allowed for a greater surplus of energy, suddenly the genus homo could begin selecting for the extremely energetically costly neurological adaptations (the expansion of the brain) so as the frontal bone expanded outwards, the face was also being reduced inwards to the point where our faces are now positioned underneath our cranium.