The image of an infant wailing alone in the dark is largely a byproduct of modern parenting. In modern Western societies, it is normal to put a baby down in a crib, bassinet, or separate room. Modern baby gear — from warm clothes to diapers— is designed to let parents put their babies down. As a result, to get a caregiver's attention, the baby has to escalate its signaling from mild squirming to full-blown crying.

Babies cry when they are uncomfortable, hungry, lonely or bored. Having babies in diapers and sleeping in separate beds etc. is a relatively new phenomenon and the new levels of crying are testimony to the distress it causes.

However, for the vast majority of human history, that separation between parent and infant never happened. Anthropologists studying modern hunter-gatherer societies — such as the !Kung San of southern Africa or the Efe of Central Africa — note that infants are in physical contact with a caregiver virtually 100 percent of the time. They are carried in slings against the body during the day and sleep right next to their mothers at night. In hunter-gatherer societies, babies were kept in near-constant physical contact with a caregiver, allowing their needs to be met before they begin to cry.

Because the mother is in constant contact with the infant, she can sense the earliest physical signs of hunger or discomfort—a twitch, a rooting motion, or a change in breathing. The baby is immediately offered the breast or adjusted before it ever needs to escalate to a vocal cry. When anthropologists timed infant vocalizations in these tribes, they found that babies fussed for only seconds at a time before being attended to, compared to modern babies who might cry for minutes on end.

The lack of diapers was solved through a practice modern anthropologists call "elimination communication," which is still used by contemporary hunter-gatherer societies like the San of southern Africa and the Pirahã of the Amazon. Because caregivers carried their infants constantly, they became highly attuned to the subtle physical cues that preceded elimination—a specific squirm, a change in breathing, or a vocalization. When the baby signaled the need to go, the mother simply held them away from her body and the sleeping area. This constant monitoring meant babies rarely sat in their own waste, preventing severe diaper rash and dangerous skin infections.

Nutrition and hydration were handled entirely by extended, on-demand breastfeeding. Because the baby was always held, they nursed frequently throughout the day and night. This provided dense calories, continuous hydration, and a constant transfer of maternal antibodies to fight off pathogens. The frequent nursing also naturally spaced out births by delaying the return of ovulation, ensuring the mother could dedicate her energy to one highly dependent infant at a time.

This intensive care was rarely managed by the mother alone. Prehistoric childcare relied heavily on "alloparenting" — shared caregiving by grandmothers, aunts, and older siblings. If the mother needed her hands free to forage or process food, another family member immediately took the baby, ensuring the infant was always held, warm, and off the ground. A restless baby was immediately passed to an aunt, a grandmother, an older sibling, or even another nursing mother in the tribe. There was always a set of arms ready to soothe a restless child.


Sources

https://www.quora.com/What-do-we-know-about-how-pre-historic-mothers-kept-their-babies-mostly-alive-without-diapers-and-clothing-in-their-caves-and-other-habitats/answer/MosaicPalate

https://www.quora.com/Babies-cry-a-lot-how-did-ancient-humans-keep-their-babies-quiet-so-predators-didn-t-find-them-at-night/answer/NovaPrism-1

https://www.quora.com/How-did-tribal-humans-survive-when-crying-babies-wouldve-called-to-predators/answer/Ricky-Hall-17