Why should robots look like us and, more to the point, why should we look like us?

 We need a thread on robots, and within that thread, we need a thread on robots that look like people.

I apologize for continuing to hammer this point, but the voices that dominate our discussion of the future—the tech messiahs, the Silicon Valley visionaries, the techno-optimists—are all working from a worldview that comes from and in most cases is largely limited to that of post-war popular science fiction, particularly the stories that made their way into comic books, pulp magazines, movies, and TV shows. One of the most striking examples of this is the continued allure of the bipedal humanoid robot, a template these retro-futurists keep coming back to despite it violating pretty much every principle of engineering and design.

One of the great ironies of this is that, though in classic science fiction pretty much any species will evolve along these lines given enough time, the reality of how we got this way appears to be more Rube Goldberg than inevitable destiny. It's possible we only look the way we do because the savannas had hot sun and tall grass.

A humanoid form is unquestionably a poor design for a robot. There is, however, some question as to whether it's a good design for a human.

From Bipedalism and Other Tales of Evolutionary Oddities by Telmo Pievani

 One such example is Ardipithecus, which was a forest biped that walked along branches. For two-thirds of the natural history of hominins (six to two million years ago), our ancestors, cousins, and relatives rightly preferred a hybrid solution: an arboreal life so they could protect themselves from predators (with persistent ancient traits such as curved fingers and long arms) and the prudent bipedal exploration of open glades in search of food. Lucy lived in this way, and died when she fell out of a tree. This was by far the most intelligent strategy at the time for those that were yet to become brave hunters, but were delicious prey for felines and giant eagles. Today, baboons and many other primates do the same. So let us forget the story of human evolution that begins with the heroic “descent from the trees” to conquer the savanna on foot. Only in the early days of the genus Homo did we become complete bipeds.

And many of our companions still curse that day. Walking upright on your legs becomes a big risk if your diet changes in the meantime, your brain starts to grow, and you have to give birth. The pelvis cannot expand much because if it did, you would not be able to stand upright. Consequently, the baby’s head passes with considerable difficulty. If you could reset and go back, the ideal engineering solution would be to give birth directly from the abdomen, but this is not possible because our birth canal is a modified version of that of reptiles, which lay eggs, and of early mammals, which give birth to tiny offspring via the pelvis. So compromises are improvised, fixing pregnancy at nine months and giving birth to helpless babies whose brains are only one-third developed, with the remaining two-thirds being completed later. It remains a truly imperfect solution, however, if we think not only of how many mothers and babies have died during childbirth, but of how painful it is for women at the best of times.

The transition to bipedalism generated negative consequences in almost every part of the body. Human feet, with their plantigrade locomotion, have to tolerate high stress levels. Our neck, with that heavy, swinging bowling ball balanced on top, becomes a weak point. The abdomen, with all of its internal organs, is exposed to all sorts of trauma. The peritoneum is being pushed down by the force of gravity, provoking a predisposition to hernias and prolapses. You might even feel the consequences on your face. The next time you have a cold and feel the mucus pressing into every orifice of your face, think about the fact that your constipated maxillary sinuses have their drainage channels pointing upward toward the nasal cavities — against gravity! This makes them completely inefficient and easily clogged up with mucus as well as with other slimy substances. This seems like a bad design, but the fact is that in a quadruped, the opening of the maxillary sinuses faces forward, which works well. Yet for former quadrupeds like us, our faces have only recently adopted a vertical position, and this is the result.

Archaeologist André Leroi-Gourhan was right in saying that the history of humanity began with good feet, before great brains. But it was an ordeal, particularly in the beginning. Then we grew to like it, and with those legs we became migrant primates, with a strong sense of curiosity and no more boundaries to hold us back.