Fossil teeth suggest a long childhood is the prelude to the evolution of a large brain

Compared to the great apes, humans have an exceptionally long childhood, during which parents, grandparents and other adults contribute to their physical and cognitive development. This is a key developmental period for acquiring ...

However, the "big brain—long childhood" hypothesis may need to be revised, as shown by an international team of researchers in the journal Nature , based on an analysis of the dental growth of an exceptional fossil . Teeth are the key The research team, made up of scientists from the University of Zurich (Switzerland), the European Synchrotron Radiation Facility (ESRF, Grenoble, France), and the Georgian National Museum (Georgia), used synchrotron imaging to study the dental development of a near-adult fossil of early Homo from the Dmanisi site in Georgia, dated to around 1.77 million years ago.

"Childhood and cognition do not fossilize, so we have to rely on indirect information. Teeth are ideal because they fossilize well and produce daily rings, in the same way that trees produce annual rings, which record their development," explains Christoph Zollikofer from the University of Zurich and first author of the publication. "Dental development is strongly correlated with the development of the rest of the body, including brain development . Access to the details of a fossil hominid's dental growth therefore provides a great deal of information about its general growth," adds Paul Tafforeau, scientist at the ESRF and co-author of the study.

3D reconstruction of the fossil skull of the sub-adult early Homo from the Dmanisi site in Georgia. The green, orange and red colors represent the preserved teeth (imaged respectively with the synchrotron at 5um, with the synchrotron at 47um, and with an industrial scanner at 250um). The blue teeth are missing ones added by mirroring their symmetrical counterparts. The purple first lower incisors have not been recovered, and have been extrapolated form the second lower incisor. Credit: ESRF/Paul Tafforeau, Vincent Beyrand. Credit: ESRF/Paul Tafforeau, Vincent Beyrand Read more

Paul Tafforeau and Vincent Beyrand at the European Synchrotron (ESRF), scanning teeth. Credit: ESRF/Stef Candé. Credit: ESRF/Stef Candé Read more

Fossil of the near-adult Homo from the Dmanisi site in Georgia, dated to around 1.77 million years ago, scanned at the European synchrotron (ESRF). Credit: Georgian National Museum Read more