Where are all the baby remains?
As Bone Don't Lie explains:
When excavating primary cemeteries in some regional eras, such as Ancient Rome or Greece, we rarely find the remains of infants. Given that infant mortality was high in the past, the lack of remains is odd. There are a number of potential hypotheses regarding this contradiction between the archaeological record and historic texts reporting high infant mortality: 1) Infants are buried in separate cemeteries, 2) due to their fragility, infant remains degrade quickly in soil and rarely preserve, or 3) infant remains when properly cremated are completely destroyed in the process and cannot be identified. It is this final possibility that we are interested in today.
To answer this question, some researchers conducted an experiment to test whether baby remains would survive the process. The used the remains of piglets weighing 2000-6000 grams to create a small funeral pyre to see if their bones would survive.
Bones Don't Lie:
The results of the study showed that the skeletal remains of the piglet made up between 2.18 and 3.28 % of the original weight prior to burning. This fits with similar findings for infant human remains when done at modern crematoria- though the remains of the piglet were slightly more intact than modern infant cremation due to the conditions of a pyre versus professional crematoria. Jæger and Johanson (2013) argue that based on this experiment, infant remains would be able to withstand the thermic stress of a cremation. They conclude that we should look to socio-anthropological sources of difference in burial- not preservation as the reason for low infant remains in the past. They propose that it is likely that cultural conditioning caused treatment and burial of deceased infants to be done differently from adults, and it is likely that we’re just not looking in the right places for them. They end with the hope to continue these experiments under different condition such as wrapping the body in linens or burning the piglet directly on the ground instead of raised on a pyre.