The research found that 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. This is so incisors are ready to erupt after birth, at approximately six months of age, when a baby makes the transition from breast-feeding to weaning.
Weaning in humans takes place relatively early compared to some primates, such as chimpanzees. As a result, there is less time available for human incisors to form, so the enamel grows rapidly to compensate.
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. Enamel cells deposit new tissue at different times and different rates, depending on the tooth type.
Exactly when early weaning in humans first began is a hotly debated topic amongst anthropologists. Current dental approaches rely on finding fossil skulls with teeth that are still erupting – which is an extremely rare find. 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.
The research, funded by a Royal Society equipment grant, was conducted by Dr Patrick Mahoney from the Human Osteology Research Lab in the University’s School of Anthropology and Conservation.
Dental fast track: prenatal enamel growth, incisor eruption, and weaning in human infants is published in theAmerican Journal of Physical Anthropology on 12 November 2014.