The part that makes us sentient is 3 pounds of grey matter packed in an 8 pound cranium balanced atop a bone stalk. It takes 206 bones wrapped in about 600 muscles and 40-55 pounds of fascia to move it around. As if that weren't hard enough we also have to use this precariously balanced structure to intake and process daily life, everything from work to family to self awareness passes through the sensory organs to the brain at some point.