There was some website where this woman was talking about some primitive type Indian clan who lives in the Amazon rain forest, where the babies rarely cry. There, until the baby is ready to crawl, it's always carried close to the body of the mother, or someone else.
This is actually common across many cultures from primitive to modern. The religious or spiritual aspect especially among literate cultures is usually concerning the “purity” of the infant. It is seen in Hinduism today, for instance, on the island of Bali when the infant is first “planted” on the ground on the 105 th day after birth. Until then the infant remained to close to God.
If you think about it this is a very reasonable behavior. Only considering the aspect of safety you can consider that: many pathogens are found naturally in the soil, many dangerous insects and plants can be encountered, actual predators could more easily take a child opportunistically as they crawl then in their mothers arms. As infants particularly are most susceptible to pathogens and venom the threat of catastrophe is high. I am sure everyone can think of others.
As stated, held infants don’t cry as much. What is the first thing you do to stop a crying baby? They are also probably less easily startled when held.
Going back to the premise that these where pre-human (when they would have been scavengers) there could have been considerable travel in their lives. Even if hunter-gatherers (which probably came later) this is true and so the points above would be even more relevant. For example: often going into new areas means that personal knowledge of the area and its specific threats would be minimal.
ROS: Too bad RL isn’t here to straighten you out anymore -- just like any big texN could!