Originally, man’s position was probably not upright. Indeed, schematically, observing the medullar centres, we notice that the horizontal exit of nerves from the spinal cord towards the effectors bodies (dermatomes) are carried out without ever crossing themselves (cervical and dorsal cord). The highest medullar centre located gives the highest nervous root, which corresponds to the highest dermatome and so on: example C2-3 innerves the head and the neck (dorsal roots), C5-6 – the biceps (ventral roots), T4-5 – the nipple, etc. If we consider that the highest part of man is the head and the lowest – the feet (in upright position), then the lowest medullar centres should be those of the feet. But this is not the case. The medullar centres of thighs and feet (L1-S1) are above these of the genital organs and bladder (S2-S4). The result is that after their exit of spinal -cord their nerves cross those of the genital organs, bladder and anus to join the thighs and the feet making nature illogical! On the contrary, if we put man on four legs, the posterior and thus the lowest part of the body becomes the genital organs and the anus corresponding exactly to the lowest medullar centres in the spinal cord, i.e. S4-S5-Coccygeal 1. Then the nerves destined to the feet do not cross any more these destined to the bladder, the genital organs and the anus. Indeed, the thighs and the feet and thus their nerves find themselves in front of the anus in the four legs position.