The entire tribe slept around a fire. In order to have the strength to survive the hardships of tomorrow, you had to sleep well tonight. Now imagine a new born lay screaming among the tribe.
Nothing soothes the cries.
Either the baby goes or the whole tribe could come to peril the next day due to a lack of sleep. Babies that survived to older childhood could be cherished. Swaddling is wrapping cloths around a child so tightly it cannot move and may have difficulty breathing. These were superstitious times. People believed babies, if their hands were left free, might accidently pull off their nose.