Interesting question... I didn't really give this enough thought before, so I'll relate it to martial arts by way of kobujutsu taisabaki to keep it on topic.
Standing, and thus stance (kamae) in kobujutsu, is a vital aspect of proper positioning relative to the opponent. Asayama Ichiden-ryu, Masaki-ryu, Kukishin-ryu, Yagyu Shingan-ryu all stress the importance of the alignment of the spine, maintenance of the position of the shoulders over the hips, and proper stability of the legs and positioning of the feet. In other words, all stress the importance of natural body posture.
The human body when standing is in a state of constant dynamic movement; essentially, every muscle of the body is activated to one degree or another at different points. There is a constant and near imperceptible swaying along the saggital (forward/backward in relation to vision) plane, causing an action in the toes, the knees tensing and relaxing, the hips maintaining relative alignment with the shoulders, the core muscles activated. To show a diagram of this would require a video of the various muscles of the body being lit up at different times as impulses are sent at impossibly high rates of speed to maintain relative balance.
Posture, however, is a different thing. Good posture (also called "neutral spine") is the maintenance of the three natural curves (cervical, thoracic, and lumbar, in order from top to bottom) of the spine along the saggital plane without significant deviation along the coronal (left/right in relation to vision) plane. Here you're activating, again while standing, the gluteus, lumbar, thoracic, and cervical muscle groups to maintain the proper alignment, aided by the rest of the body to protect balance.
Movement (walking) among Oriental (differentiating from Occidental) cultures in the past differed significantly more from their Occidental counterparts than they do today. Take, for example, the Japanese. The Japanese had a unique method of walking influenced by their clothing, environmental habits, and body development; today this method is referred to as Nanba (ナンバ). The wearing of kimono necessitated, and the act of kneeling assisted, a form of movement in which the shoulders remained in constant alignment with the hips (Westerners walking for extended periods in kimono may find a rather annoying habit of constantly retying the obi as the whole ensemble comes open). This form of walking, which happens to be natural, less tiring, and capable of allowing one to travel further with less energy, also happens to keep the spine properly aligned and the balance properly situated in a direct line from crown through the abdomen and down to the ground. It was no surprise that the Japanese yoroi (armor) was so easily maneuvered by a people who naturally moved in a method that facilitated the wearing of that armor.
Technically speaking, every culture has different nuances to its movements. Asian cultures, specifically, tend to move with more hips; Russians lead with their abdomens; Americans slouch; Brits move upright and with a purpose; and Germans move with a rather stomping swagger. The ways people stand and move are directly related to the society in which they grew up. You can't necessarily generalize across the board.