The thing about your hunting theory is that lots of other animals use coordinated social attack on prey. They have to do risk/benefit based on how many other of their kind are there and how many other of the other kind. I also don't think charging an animal has a small amount of optionality - they have to decide how
That being said I believe the freeing of the hands was probably crucial to brain development. The trade-off of sending so much energy to the brain became worth it once you had the physical means to build tools and such.
That being said I believe the freeing of the hands was probably crucial to brain development. The trade-off of sending so much energy to the brain became worth it once you had the physical means to build tools and such.