Say you’re designing a four-legged, cross-country robot for reconnaissance, like I’m sure some militaries have. One thing that comes up is that all the joints n

Say you’re designing a four-legged, cross-country robot for reconnaissance, like I’m sure some militaries have. One thing that comes up is that all the joints need to be constantly lubricated by movement or else they will stiffen and become unusable. This turns out to not be a problem because the robot will be used for continual movement while it is in use. So there is no need to worry about it: it would be wasted effort. Same with our bodies. The potential downsides of being biomechanically completely immobile for hours at a time (something like a deep squat is not completely immobile) have not been an issue for most of history. The way I (intuitively) understand it is that we’ve been selected through generations to deal with certain situations well. Like endurance running. But when we get thrown into novel in the evolutionary sense situations, all bets are off. And it turns out that things work worse. For perhaps all kinds of possible reasons: maybe the baseline metabolism that hunter-gatherers had 20,000 years just because of their exact kind of activity levels turned out to be optimal for all kinds of biological functions as a sort of side effect.[1] Another potential example is sleeping. In my experience I feel better in my muscles after sleeping on a hard surface. If you try to lay on your side on the floor you will feel like you are either stretching or massaging your muscles, or both. And maybe this low-intensity impact on the muscles throughout the night is necessary for some biological process? Contrast that with memory foam mattresses. Now if we were “designed” intentionally (tens of thousands of years ago), the designer would not have to worry about the biological implications of our bodies staying almost still on a soft surface for hours at a time. The best we would have is the ground, ranging from a soft, grassy meadow to just hard and sandy. It’s like our bodies are constantly are subjected to conditions that no process (evolution) ever had to deal with (on an evolutionary scale). [1] Now it could be that if we both undershot and overshot this baseline we could get in trouble. But it seems hard for most people to overshoot for some reason.