Comment by trhway

>why handed vs ambidextrous

may be high dexterity is expensive, brain-wise, i.e. may be the choice given average brain is either 2 hands with mild dexterity or a one of high dexterity at the expense of the other. With tools, etc. the latter choice seem to be preferable and was selected for (and the lucky ones get to have 2 of high dexterity) Bipedalism and brain expansion in this situation are indirectly connected to the handedness as they are enablers and drivers of tools use.