Teeth, brains, and primate life histories

Abstract

This paper explores the correlates of variation in dental development across the order Primates. We are particularly interested in how 1) dental precocity (percentage of total postcanine primary and secondary teeth that have erupted at selected absolute ages and life cycle stages) and 2) dental endowment at weaning (percentage of adult postcanine occlusal area that is present at weaning) are related to variation in body or brain size and diet in primates. We ask whether folivores have more accelerated dental schedules than do like-sized frugivores, and if so, to what extent this is part and parcel of a general pattern of acceleration of life histories in more folivorous taxa. What is the adaptive significance of variation in dental eruption schedules across the order Primates? We show that folivorous primate species tend to exhibit more rapid dental development (on an absolute scale) than comparably sized frugivores, and their dental development tends to be more advanced at weaning. Our data affirm an important role for brain (rather than body) size as a predictor of both absolute and relative dental development. Tests of alternative dietary hypotheses offer the strongest support for the foraging independence and food processing hypotheses.

Dental evidence for ontogenetic differences between modern humans and Neanderthals

“…These findings provide important insight into developmental processes that are relevant to energy allocation and survival (4). Some have argued that harsh conditions created high young adult mortality rates in Neanderthals, which may have acted as a selective pressure to maintain a rapid maturation pattern (40,41).…”

“…Moreover, when considered across the Primate order, dental eruption ages are broadly correlated with several life history events (e.g., ages at weaning and first reproduction) and physical attributes (e.g., body and brain mass) (2, 3; but see refs. [4][5][6][7]. Variation among primate life histories has primarily been ascribed to differential mortality rates, as well as ecological niches, lifestyles, social complexity, cognitive development, or a combination of these factors (4,5,8).…”

“…[4][5][6][7]. Variation among primate life histories has primarily been ascribed to differential mortality rates, as well as ecological niches, lifestyles, social complexity, cognitive development, or a combination of these factors (4,5,8). Although is it well established that humans are developmentally unique among living primates (9), weaning earlier and reproducing later than expected, the adaptive significance and evolutionary origins of our prolonged childhood are unresolved (1,(9)(10)(11).…”

The evolutionary roles of nutrition selection and dietary quality in the human brain size and encephalization

“…Recent evidence from dental microwear and stable isotope analyses have confirmed the relatively lower-quality diet for the Australopithecines, particularly for the east African robust Australopithecines, who appear to have consumed large amounts of grasses and sedges [21,22]. Moreover, fruits are more ephemeral and patchy in their distribution and often contained in a protective casing, which may make the foraging niche of frugivores relatively complex [20,[23][24][25]. Therefore, as folivores have a relatively easy foraging strategy that requires little in the way of learning, primates eating leaves could potentially start foraging fairly early on in life.…”

Endocranial volumes of primate species: scaling analyses using a comprehensive and reliable data set

“…In addition, it may sometimes be preferable to include only female data in comparative analyses, particularly in the context of maternal investment when reproductive parameters are analyzed (e.g. as in Godfrey et al, 2001). …”