Patterns and rates of enamel growth in the molar teeth of early hominids

Beynon, A.D.; Wood, B. A.

doi:10.1038/326493a0

Cited by 126 publications

(100 citation statements)

References 12 publications

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“…Extant great ape cuspal enamel formation represents only approximately 15-20% of total crown formation time, compared to approximately 40% in A. turkanensis. The A. turkanensis ratio is similar to the pattern seen in Paranthropus robustus and P. nyanzae, while an even higher ratio is seen in G. freybergi and Paranthropus boisei, which have extremely thick enamel (Beynon and Wood, 1987;Grine and Martin, 1988;Beynon et al, 1998;Smith et al, 2001). Grine and Martin (1988) considered three variables that relate to enamel thickness: ameloblast secretion rate, the total period of secretion, and the number of cells that are active at any given time.…”

Section: Crown Formation Time and Patterns Of Developmentmentioning

confidence: 99%

“…5 Dean et al (1993a). 6 Beynon and Wood (1987). These authors did not specify the tooth from which specific values were measured.…”

Section: Crown Formation Time and Patterns Of Developmentmentioning

confidence: 99%

“…Bromage and Dean (1985) reassessed the age at death of fossil hominids using incremental features, and concluded that early humans were characterized by ape-like dental development, in contrast to the previously assumed modern human pattern. These were followed by many more studies of fossil hominids that examined the nature of enamel development and enamel thickness as revealed by microstructure (Beynon and Wood, 1986;Dean et al, 1986;Beynon and Dean, 1987;Beynon and Wood, 1987;Dean, 1987a,b;Beynon and Dean, 1988;Grine and Martin, 1988;Mann et al, 1991;Beynon, 1992;Dean et al, 1993a;Ramirez Rozzi, 1993a,b;Mann et al, 1994;Ramirez Rozzi, 1994;Dean, 1995;Ramirez Rozzi, 1997;Ramirez Rozzi et al, 1997;Ramirez Rozzi, 1998;). These investigations have provided information on age at death in individuals with developing dentitions, the absolute and relative timing of dental development, differences in the developmental pathways of enamel formation, and life history characteristics.…”

Section: Introductionmentioning

confidence: 99%

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Enamel thickness, microstructure and development in Afropithecus turkanensis

Smith

Martin

Leakey

2003

Journal of Human Evolution

119

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Afropithecus turkanensis, a 17-17.5 million year old large-bodied hominoid from Kenya, has previously been reported to be the oldest known thick-enamelled Miocene ape. Most investigations of enamel thickness in Miocene apes have been limited to opportunistic or destructive studies of small samples. Recently, more comprehensive studies of enamel thickness and microstructure in Proconsul, Lufengpithecus, and Dryopithecus, as well as extant apes and fossil humans, have provided information on rates and patterns of dental development, including crown formation time, and have begun to provide a comparative context for interpretation of the evolution of these characters throughout the past 20 million years of hominoid evolution. In this study, enamel thickness and aspects of the enamel microstructure in two A. turkanensis second molars were quantified and provide insight into rates of enamel apposition, numbers of cells actively secreting enamel, and the time required to form regions of the crown. The average value for relative enamel thickness in the two molars is 21.4, which is a lower value than a previous analysis of this species, but which is still relatively thick compared to extant apes. This value is similar to those of several Miocene hominoids, a fossil hominid, and modern humans. Certain aspects of the enamel microstructure are similar to Proconsul nyanzae, Dryopithecus laietanus, Lufengpithecus lufengensis, Graecopithecus freybergi and Pongo pygmaeus, while other features differ from extant and fossil hominoids. Crown formation times for the two teeth are 2.4-2.6 years and 2.9-3.1 years respectively. These times are similar to a number of extant and fossil hominoids, some of which appear to show additional developmental similarities, including thick enamel. Although thick enamel may be formed through several developmental pathways, most Miocene hominoids and fossil hominids with relatively thick enamel are characterized by a relatively long period of cuspal enamel formation and a rapid rate of enamel secretion throughout the whole cusp, but a shorter total crown formation time than thinner-enamelled extant apes.

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Section: Crown Formation Time and Patterns Of Developmentmentioning

confidence: 99%

“…5 Dean et al (1993a). 6 Beynon and Wood (1987). These authors did not specify the tooth from which specific values were measured.…”

Section: Crown Formation Time and Patterns Of Developmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enamel thickness, microstructure and development in Afropithecus turkanensis

Smith

Martin

Leakey

2003

Journal of Human Evolution

119

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“…This is due to a combination of more enamel secretion per day by ameloblasts and a faster rate of ameloblast activation. 96 We need more information before we can determine whether these differences are due to selection operating on life history, on diet, or on a combination of the two.…”

Section: Dental Ontogenymentioning

confidence: 99%

The Evolution of Zinjanthropus boisei

Constantino

Wood

2007

Evolutionary Anthropology

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Many people assume that OH 5, the type specimen of Paranthropus boisei, collected in 1959, was the first evidence of that taxon to be found, but OH 3, recovered in 1955, predated the discovery of OH 5 by four years. Thus, Paranthropus boisei recently celebrated the equivalent of its fiftieth birthday. This review marks that milestone by examining the way our understanding of this taxon has changed during its fifty, or so, year history.

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“…afarensis molar fragments (AL 333-52 and AL 336-1) at between 2.2 and 2.4 years. Beynon & Wood (1987) calculated a range of molar crown formation times of 2.12 -2.59 years in P. boisei, while Ramirez Rozzi (1993,1995) found ranges of 1.93-2.49 years for P. aethiopicus but a greater range for enamel formation times of P. boisei molars of all types (2.67 -3.43 years). In P. robustus from Kromdraai, Lacruz (2006) calculated protoconid formation times at between 1.98 and 2.38 years and metaconid time to be near identical (1.92 -2.37 years) but Lacruz et al (2006) reported protocone formation times in two Au.…”

Section: (B) Molar Initiation Timesmentioning

confidence: 99%

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

Dean

2010

Phil. Trans. R. Soc. B

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A chronology of dental development in Pan troglodytes is arguably the best available model with which to compare and contrast reconstructed dental chronologies of the earliest fossil hominins. Establishing a time scale for growth is a requirement for being able to make further comparative observations about timing and rate during both dento-skeletal growth and brain growth. The absolute timing of anterior tooth crown and root formation appears not to reflect the period of somatic growth. In contrast, the molar dentition best reflects changes to the total growth period. Earlier initiation of molar mineralization, shorter crown formation times, less root length formed at gingival emergence into functional occlusion are cumulatively expressed as earlier ages at molar eruption. Things that are similar in modern humans and Pan, such as the total length of time taken to form individual teeth, raise expectations that these would also have been the same in fossil hominins. The best evidence there is from the youngest fossil hominin specimens suggests a close resemblance to the model for Pan but also hints that Gorilla may be a better developmental model for some. A mosaic of great ape-like features currently best describes the timing of early hominin dental development.

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Patterns and rates of enamel growth in the molar teeth of early hominids

Cited by 126 publications

References 12 publications

Enamel thickness, microstructure and development in Afropithecus turkanensis

Enamel thickness, microstructure and development in Afropithecus turkanensis

The Evolution of Zinjanthropus boisei

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

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