Baka pygmies have larger teeth than neighbouring taller tribes
For the first time, scientists obtain dental in vivo impressions of juvenile and adult individuals in this population characterised by their short height, not taller than 1.55 metres
The study arouses great interest for evolutionary biology given the genetic similarity with our ancestors
Alicante. Monday, 23 July 2018
In the tropical forest of Central Africa, hunter-gatherer groups known collectively as "Pygmies” - a term used by Homer to designate mythical populations of short stature - are characterised by an adult height of no more than five feet. The study arouses great interest for evolutionary biology given the genetic similarity with our ancestors. Moreover, these populations continue to live as they did 200,000 years ago, regardless of industrialisation.
UA work led by researcher Alejandro Romero, from the University of Alicante Department of Biotechnology has just solved a paradigm on this unique population in the world: the negative allometry in pygmies in relation to their height and the dental size, that is to say, that the short stature of these populations is associated with large teeth. According to the researcher, "the morphogenetic factors that control tooth size must be independent of those that determine postnatal growth."
The research has been carried out with in vivo dental impressions of 120 juvenile individuals (15/16 years) and adults (maximum of 35 years of age) of both sexes in Baka Pygmies from Le Bosquet (Cameroon), in the middle of the tropical forest of Central Africa, compared to neighbouring tribes of non-pygmy Bantu of greater stature, the Mvae and Yassa (between 5.4 and 5.6 feet tall).
These dental impressions have served to design high-resolution copies in the laboratory of the UA Department of Biotechnology. Morphological measurements relative to the size of the anterior and postcanine teeth have registered from digital images.
The analysis of these impressions has surprisingly revealed a significantly larger size of the teeth in Baka pygmies with respect to Bantu populations, who also showed an almost absent sexual dimorphism. "The available genomic data also identify signals of differential polygenic adaptation involved in growth and height between pygmies and Bantus. The tooth model in pygmies has not evolved and is more similar to the hominid species from a million years ago”, Romero explained.
Unlike other previous scientific studies, this is the first one that has been done with samples of living individuals after more than ten years of fieldwork and thanks to a mission of French nuns that, since the 80s, have been making notes of birth dates of Baka children in Le Bosquet. "It is a unique age census in the world corresponding to a tribe of hunter-gatherers that allows to rigorously analyse the changes in the development of individuals," the UA researcher pointed out.
This means that for the first time in history you can know the exact age of a Baka child or adolescent. "Hence, this work is unique because it opens new lines of research about a society that has a particular phenotype due to their isolation in a tropical closed forest, which maintains an ancestral way of life”, Alejandro Romero said.
This researcher’s work has been published in the American Journal of Physical Anthropology, with the collaboration of internationally renown authority in the study of Fernando Ramírez-Rozzi, from UPR 2147 CNRS Université Paris V, and Alejandro Pérez-Pérez, from the University of Barcelona.