>And even then, you'd have to wait for evolution to take its course and produce (well, perpetuate) whatever DNA is required to produce a bigger brain over a millennium or even longer...
the previous 2M were spent on this extensive option - increasing the size (that was enabled by meat eating), and i think we pretty much exhausted that venue. The next step
is increasing the intensity of using that big brain. We use only small portion of it, and prolonged sustained thinking activities are very exhausting to our bodies in particular because it consumes a lot of energy. Evolutionary biological changes increasing brain efficiency would take long time (btw, it is very educational to read about specifics of Enstein's brain). This is why in historical short term only increasing of energy intake seems to be a viable option.
the previous 2M were spent on this extensive option - increasing the size (that was enabled by meat eating), and i think we pretty much exhausted that venue. The next step is increasing the intensity of using that big brain. We use only small portion of it, and prolonged sustained thinking activities are very exhausting to our bodies in particular because it consumes a lot of energy. Evolutionary biological changes increasing brain efficiency would take long time (btw, it is very educational to read about specifics of Enstein's brain). This is why in historical short term only increasing of energy intake seems to be a viable option.