In this thread, several examples refer to the common trope about human body features being better suited for four-legged creatures, but are drawbacks for bipeds. Everything from our skeleton to our sinuses to our uterus (well, for half of us) worked more efficiently for our evolutionary quadruped ancestors, but became liabilities once our species decided to walk upright.
So…have any experts seriously speculated about what a more efficient body design would look like, had our ancestors evolved as bipeds for millions of years, or (if you so choose to believe) our Grand Creator merely chose to make it so?
I’m not an expert in anatomy or physiology or engineering, but it would seem to me that simply placing the sinus drainholes at the lowest point would be easy enough. I’ve often wondered what the purpose of the sinus cavities is, anyway.
One thing I’ve seen pointed out when this subject comes up is the lack of sufficient internal vertical structural support in our bodies. Things tend to sag or worse.
Drainage valves at the bottom of our lungs are something else we lack; quadrupeds don’t really need anything like that since their lungs are horizontal.
A centralized placement of the spinal column and central nervous system would probably be better. Have it run through the center of the torso and neck rather than pressed up against the surface. That way, it would provide better support to the body, closer connection to other nerves, and would be better protected from injury.
One thing would be to have the birth canal not go through the most important support bone in the body. I still recall that as a young kid, I thought that birth took place through the navel. That still seems to me to be a better solution. But it could never evolve; evolution requires successful intermediate steps and I don’t see any possibilities.
It could evolve … by a slow modification of the pelvis itself. A new arch might evolve, between the anal and vaginal openings – it would add strength to the overall structure, and thus be advantageous – and then the current arch, forward and above the vaginal opening, could fade away.
Weirder things have happened (jaw bones becoming inner ear bones…)
Obviously, it isn’t in the least likely, but it isn’t completely outside the realm of possibility. If enough women die in childbirth, some solution will be evolved (or else we’ll just go extinct!)
Another design flaw; as opposed to a quadruped, whose belly faces the ground our “soft underbelly” is in front, the direction we are most likely to be facing danger with. Thanks to our bipedal natural we habitually take up a position of vulnerability that most animals take to show submission.
Birds evolved from theropods, are they optimally designed bipeds yet? That lineage has been consistently bipedal for at least ~230 million years, opposed to our ~6 million years.
Not really. In any kind of comabt situation, the human crouches down low and the belly actually becomes much less exposed. Aside from which, humans ghave their much more vulnerable throat kept farther away from danger.
I would say that most birds do not have an optimal bipedal design, because they have many adaptations to allow flight, even among birds that cannot fly.