Paleobiological Implications of the Ardipithecus ramidus Dentition

Abstract

The Middle Awash Ardipithecus ramidus sample comprises over 145 teeth, including associated maxillary and mandibular sets. These help reveal the earliest stages of human evolution. Ar. ramidus lacks the postcanine megadontia of Australopithecus . Its molars have thinner enamel and are functionally less durable than those of Australopithecus but lack the derived Pan pattern of thin occlusal enamel associated with ripe-fruit frugivory. The Ar. ramidus dental morphology and wear pattern are consistent with a partially terrestrial, omnivorous/frugivorous niche. Analyses show that the ARA-VP-6/500 skeleton is female and that Ar. ramidus was nearly monomorphic in canine size and shape. The canine/lower third premolar complex indicates a reduction of canine size and honing capacity early in hominid evolution, possibly driven by selection targeted on the male upper canine.

A multidisciplinary reconstruction of Palaeolithic nutrition that holds promise for the prevention and treatment of diseases of civilisation

“…Ardipithecus ramidus's preference for an omnivorous/frugivorous diet was confirmed by microwear studies (183) , suggesting a diet of fleshy fruits and soft young leaves (150) . Conversely, microwear textures of Australopithicus afarensis and anamensis show striations rather than pits (low complexity and low anisotrophy), i.e.…”

Retrieving chronological age from dental remains of early fossil hominins to reconstruct human growth in the past

“…(c) Tooth initiation times, sequences and overlaps Swindler (1985), Anemone et al (1991), Anemone & Watts (1992), Kuykendall (1996) and Reid et al (1998) have all noted that the times for initial mineralization of the permanent incisors and canines in Pan are very similar to those described for humans (Kronfeld 1935) and that the sequence of mineralization is identical. Lower permanent incisors initiate at approximately 3 -4 m after birth and canines at 4-5 m although both earlier and later times have been recorded (Kronfeld 1935;Anemone et al 1991;Kuykendall 1996;Winkler 1996;Schwartz et al 2006).…”

“…The results are a close match with those of Zihlman et al (2004) for M1 and to some extent for M2 with simulated median age of attainment of M1 at approximately 4.0 years, M2 at approximately 7.0 years and M3 at approximately 10 years. Interestingly, they also fall close to the 32.6, 59.4 and 86 per cent of the total time to complete dental development that Swindler (1985) calculated for modern human molar eruption times, assuming that this total time is approximately 12 years in P. troglodytes. However, with the exception of M1, these simulated median ages of attainment for molar gingival emergence still fall within the ranges reported for captive chimpanzees.…”

“…Here, canine enamel formation times come closest to those known for modern humans. Suwa et al (2009a) counted 193 perikymata on the upper canine of ARA-VP-6/1 (the holotype of Ardipithecus ramidus and a probable male). This suggests that canine crown formation took between 4.3 and 4.8 years in this specimen (Suwa et al 2009a) and so was potentially within the range recorded for female Gorilla and Pongo, but below the range so far recorded for female Pan canines .…”

“…Dental development is just one measure of biological maturity, but is arguably the most stable, and it occurs over an unusually long period of time from before birth to maturity. Besides enabling us to discover things about the evolutionary history of our own growth period, studies of comparative dental development provide us with an opportunity for investigating the biological processes that govern tooth formation from the initial mineralization of teeth to the completion of their roots (Swindler 1985). Smith (1989) has shown that certain key marker events during dental development actually correlate better with important variables that describe lifehistory variation than any of these life-history variables do with each other.…”