Further evidence on relative dental maturation and somatic developmental rate in hominoids

Abstract

New data on hominoid dental development are presented. Individual bivariate pairings of all mandibular teeth were made for African apes and humans. Data were analyzed with a full linear regression model. No statistically significant differences were found among apes, although a consistent pattern of earlier incisal development was observed in Pan relative to Gorilla. This is concordant with an earlier fusion of the premaxillary:maxillary suture in Pan. Only one tooth pair differed significantly by sex among apes. Two biologically distinct human samples (Libben and Hamann-Todd), although assessed differently (extraction and radiography) yielded virtually identical results. Humans differ from apes only by earlier relative calcification of their anterior teeth. This can be viewed as a consequence of reduced facial prognathism and a shift in hominid canine function.

Permanent tooth calcification in chimpanzees (Pan troglodytes): Patterns and polymorphisms

“…Although these stages do not represent developmentally equivalent periods or amounts of calcification, this system is preferable to those using criteria such as fractional estimates of crown and root development (Fanning, 1961;Fanning and Brown, 1971;Moorrees et al, 1963;Nolla, 1960), which are accurate only with longitudinal data (i.e., sequential xrays) (Demirjian, 1986;Moorrees et al, 1963). Additionally, continuous scales such as those used by Simpson et al (1990Simpson et al ( , 1991Simpson et al ( , 1992 are problematic since tooth calcification does not follow a linear trajectory, but rather its rate varies throughout the developmental period (Anemone and Watts, 1992).…”

“…As a result, patterns of dental development in both "gracile" and "robust" australopithecines have been characterized in several ways, notably a ) human like (Dart, 1925;Mann, 1975Mann, ,1988Mann et al, 1987;Wolpoff et al, 1988); b) pongid like (Bromage and Dean, 1985;Conroy, 1988;Conroy andVannier, 1987, 1988;Smith, 1986Smith, , 1987aSmith, ,b, 1991; and c) demonstrating different patterns from each other, and also from modern humans or apes (Broom andRobinson, 1951, 1952;Bromage, 1987;Beynon andDean, 1988, 1990;Conroy and Vannier, 1991a,b;Dean, 1985Dean, ,1986Dean, ,1989Simpson et al, 1990Simpson et al, , 1991Simpson et al, ,1992Smith, 1986,198913). A final possibility implied by some researchers is that modern human and ape patterns of dental development are so variable that australopithecine patterns cannot be associated with either (Mann et al, 1987(Mann et al, ,1990Mann, 1988;Wolpoff et al, 1988).…”

“…A review of the literature reveals a t least three usages of the term "patterns" in tooth calcification: a) a "pattern" involving groups of teeth which are functionally or developmentally similar in comparison to other such groups, such as anteriors vs. postcanines (Anemone et al, 1991;Anemone and Watts, 1992;Simpson et al, 1990Simpson et al, ,1991Simpson et al, ,1992; b) a n overall "pattern" or sequence among all teeth which relates the typical order for achievement of developmental events, as used commonly to report sequences of tooth emergence (Conroy and Mahoney, 1991;Kuykendall et al, 1992;Nissen and Riesen, 1964;Schultz, 1935;Smith and Garn, 1987); and c) "patterns" of relative development between particular tooth pairs, which are sometimes referred to as "pairwise seq u e n c e~'~ (Smith, 1994;Smith and Garn, 1987).…”

“…Research comparing dental development patterns among fossil and modern taxa has a long history in paleoanthropology, and has been conducted using a variety of approaches, including tooth emergence (e.g., Broom andRobinson, 1951, 1952;Clark, 1967;Dart, 1925Dart, ,1948Wallace, 19771, tooth crown and root calcification (Bromage and Dean, 1985;Conroy, 1988;Conroy and Vannier, 1987;Mann, 1975;Simpson et al, 1990Simpson et al, , 1991Simpson et al, , 1992Smith 1986), and incremental growth markings in tooth enamel and dentin (e.g., Aiello and Dean, 1990;Beynon and Dean, 1988;Beynon and Wood, 1987;Bromage and Dean, 1985;Dean, 1987a7b, 1989Dean and Wood, 1981;Mann et al, 1990). As a result, patterns of dental development in both "gracile" and "robust" australopithecines have been characterized in several ways, notably a ) human like (Dart, 1925;Mann, 1975Mann, ,1988Mann et al, 1987;Wolpoff et al, 1988); b) pongid like (Bromage and Dean, 1985;Conroy, 1988;Conroy andVannier, 1987, 1988;Smith, 1986Smith, , 1987aSmith, ,b, 1991; and c) demonstrating different patterns from each other, and also from modern humans or apes (Broom andRobinson, 1951, 1952;Bromage, 1987;Beynon andDean, 1988, 1990;Conroy and Vannier, 1991a,b;…”

Paleobiological Implications of the Ardipithecus ramidus Dentition

“…Compared with extant apes, both its UC and LC development are advanced relative to M2 and M3 ( fig. S28) (39).…”