Première publication : janvier 2003, mise en ligne : lundi 7 juillet 2003

 I greet participants in the discussion of Initial Bipedalism ( Bipedia n°20 ) and inform the reader that after my piece "Could Bipedalism Be Initial ?" was published in Bipedia n°19, I received from friends abroad a number of books some passages of which touch on the subject of bipedalism. As, for example, the following :
 "It is apparent that human beings learn to walk. (...) In contrast to colts, whose innate quadrupedal motor-control programs enable them to run shortly after birth, humans go through a long process learning to locomote bipedally. ... Human infants (...) have to override this archaic quadrupedal motor program for walking. The process is protracted, and we crawl and toddle before we are able to walk or run without lurching and falling. Heel strike, which marks efficient bipedal locomotion, takes years to develop"( Lieberman 2000, p. 143 ).
 The change-over from quadrupedalism to bipedalism was a key factor of hominization. But every advance in evolution has to be paid for, and an example of human payment for bipedalism is given in another book, as follows :
 "In a general sense, our past is, of course, always with us, as the sufferings of those with slipped disks -- the inevitable result of adapting a quadrupedal spine to upright posture -- attest" ( Tattersall 1998, p. 203).
 The French edition of the book renders the above sentence in translation, as follows : "Un certain nombre de contraintes, provenant de notre passé évolutif, present sur nous, comme l’attestent les pathologies affectant les disques vertebraux chez un certain nombre d’entre nous ( c’est la conséquence inévitable de l’adaptation à la station debout d’une colonne vertébrale qui était jusque-la vouée à la demarche quadrupède )" ( Tattersall 1999, p. 229 ).
 Professor Tattersall mentioned only a small part of the price people pay for bipedalism. The full sum is much higher. Bipedalism is charged with the great difficulty of childbirth, in contrast to easy delivery by quadrupedal animals. The rigidity of human pelvis is a necessary condition of bipedal walking, and simultaneously a constraint of childbirth. In quadrupeds internal organs are alined horizontally, without pressing each other ; in humans, due to upright posture, they are piled up vertically, one atop the other, which contributes to cases of appendicitis and hernia.
 Other consequences of bipedalism are varicose veins and thousands, nay, millions of broken arms and legs in elderly people every winter due to falls on slippery ground.
 Heavy price indeed. The only way for humans to stop paying for upright walking, besides dropping on all fours, is ... LEVITATION ! A dream ?
 Yes, it is. But what a DREAM ! I don’t know any better night dream than levitation. It’s absolute bliss. And it’s a dream which has no scientific explanation. If our past is "always with us", what past of ours do night dreams of levitation hark back to ?
 The answer again is in the writings of Plato. According to him, every time we enjoy beauty or bliss, our soul is recalling her past condition, when she was flying free, before being imprisoned by the body. ( In Russian and in French the soul is a she ). You can object : this is no science.
 Right. But Initial Bipedalism is no science either. We owe both ideas to Plato. Still, according to him, bipedalism is a transient mode of locomotion, while levitation is both initial and final. Thus Initial Bipedalism is fine, but Initial Levitation is a lot better.
 I regret to be in disagreement with my good friend Francois de Sarre, but, as the saying goes, "Plato is dear to me, but dearer still is truth."

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Dear Dmitri :

 Thanks for your text continuing the discussion on Initial Bipedalism [ Bipedia n°19 and 20 ].
 Regarding human infants’ walking, as you did mean "( They )...have to override this archaic quadrupedal motor program...", I can only tell you from my own experience [ I am the father of 3 children ]... The one, indeed, run on all 4 ( very quickly ! ) during several weeks : he really went through a transitional quadrupedal stage ! The second went on 3 limbs, i.e. helping with arms and with a bent leg, so she ( a girl ) was transitional a "triped"... And my third child suddenly stood erect on his 2 legs without any crawling, from a sitting position, as he was only 10 months old !

Best Regards : Francois de SARRE