Researchers in Britain have found a link between prenatal enamel growth rates in teeth and weaning in human babies.
The incisor teeth grow quickly in the early stages of the second trimester of a baby's development, while molars grow at a slower rate in the third trimester.
Incisors are ready to erupt after birth, at approximately six months of age, when a baby makes the transition from breast-feeding to weaning, showed the study.
Weaning in humans takes place relatively early compared to some primates, such as chimpanzees.
So, there is less time available for human incisors to form, so the enamel grows rapidly to compensate.
Exactly when the early weaning in humans first began is a debatable issue among anthropologists.
"Anthropologists will now be able to explore the start of weaning in an entirely new way because 'milk teeth' preserve a record of prenatal enamel growth after they have erupted and for millennia after death," said Patrick Mahoney from Human Osteology Research Lab in University of Kent, in Britain.
Enamel cells deposit new tissue at different times and rates, depending on the tooth type.
The present dental approaches depend on finding fossil skulls with teeth that are still erupting - which is an extremely rare find.
"This research can increase our understanding of weaning in our fossil ancestors and could also help dentists as dental problems do not register in all teeth in the same way," said Mahoney.
The study appeared in the American Journal of Physical Anthropology.
