I don’t think so. We see in a lot of fossils and a lot of existing hunting-gathering-gardening peoples (assuming that they are more or less living as humans have for millenia, which is supported with some exceptions) that basically everyone had/has good posture, without the damages to the knees, hips, and vertebrae that many agricultural and industrial humans have. Good posture just seems like a constant for a lot of them. What we see in terms of etiquette, and what I think is one of the central survival features of the human brain, is the universal custom of gift-giving, which facilitates both relational ties and resource distribution, forming gift economies.