> i'm curious how human kind evolved from a non-upright species that could give birth fairly easily (due to the wide hips, etc.) into an upright walking species with closed hips that made it extremely difficult to give birth and resulted in huge amounts of death in the reproduction process.
While infant mortality may go up due to trying to shove out a large-headed baby, this is offset by the advantages that come with larger brains. This is apparent just by looking at the world around us: even before the scientific revolution, when infant mortality was overall atrocious, humans had managed to colonize the entire planet and bend it to our will.
that's the "well, we're here so it must have worked" answer. regardless, this isn't the forum to find an answer regarding seemingly unlikely survival during the transistion.