Research Articles

New hominin fossils from Kanapoi, Kenya, and the mosaic evolution of canine teeth in early hominins

Fredrick K. Manthi, J. Michael Plavcan, Carol V. Ward
South African Journal of Science | Vol 108, No 3/4 | a724 | DOI: https://doi.org/10.4102/sajs.v108i3/4.724 | © 2012 Fredrick K. Manthi, J. Michael Plavcan, Carol V. Ward | This work is licensed under CC Attribution 4.0
Submitted: 25 April 2011 | Published: 01 March 2012

About the author(s)

Fredrick K. Manthi, National Museums of Kenya, Kenya
J. Michael Plavcan, University of Arkansas, United States
Carol V. Ward, University of Missouri, United States


Share this article

Bookmark and Share

Abstract

Whilst reduced size, altered shape and diminished sexual dimorphism of the canine–premolar complex are diagnostic features of the hominin clade, little is known about the rate and timing of changes in canine size and shape in early hominins. The earliest Australopithecus, Australopithecus anamensis, had canine crowns similar in size to those of its descendant Australopithecus afarensis, but a single large root alveolus has suggested that this species may have had larger and more dimorphic canines than previously recognised. Here we present three new associated dentitions attributed to A. anamensis, recently recovered from the type site of Kanapoi, Kenya, that provide evidence of canine evolution in early Australopithecus. These fossils include the largest mandibular canine root in the hominin fossil record. We demonstrate that, although canine crown height did not differ between these species, A. anamensis had larger and more dimorphic roots, more like those of extant great apes and Ardipithecus ramidus, than those of A. afarensis. The canine and premolar occlusal shapes of A. anamensis also resemble those of Ar. ramidus, and are intermediary between extant great apes and A. afarensis. A. afarensis achieved Homo-like maxillary crown basal proportions without a reduction in crown height. Thus, canine crown size and dimorphism remained stable during the early evolution of Australopithecus, but mandibular root dimensions changed only later within the A. anamensis–afarensis lineage, coincident with morphological changes in the canine–premolar complex. These observations suggest that selection on canine tooth crown height, shape and root dimensions was not coupled in early hominin evolution, and was not part of an integrated adaptive package.

Keywords

Australopithecus anamensis; canine tooth roots; canine tooth evolution; hominin evolution; Kanapoi

Metrics

Total abstract views: 1080
Total article views: 1655

References


Dart RA. Australopithecus africanus: The man-ape of South Africa. Nature. 1925;115:195. http://dx.doi.org/10.1038/115195a0

Brunet M, Guy F, Pilbeam D, et al. A new hominid from the Upper Miocene of Chad, Central Africa. Nature. 2002;418:145–151. http://dx.doi.org/10.1038/nature00879, PMid:12110880

Senut B, Pickford M, Gommery D, Mein P, Cheboi K, Coppens Y. First hominid from the Miocene (Lukeino Formation, Kenya). C R Acad Sc Paris. 2001;332:137–144.

Haile-Selassie Y. Late Miocene hominids from the Middle Awash, Ethiopia. Nature. 2001;412:187–191.

Haile-Selassie Y, Suwa G, White TD. Late Miocene teeth from middle Awash, Ethiopia, and early hominid dental evolution. Science. 2004;303:1503–1505. http://dx.doi.org/10.1126/science.1092978, PMid:15001775

Haile-Selassie Y, WoldeGabriel G, editors. Ardipithecus kedabba: Late Miocene evidence from the Middle Awash, Ethiopia. Berkeley: University of California Press; 2009.

Suwa G, Kono R, Simpson S, Asfaw B, Lovejoy C, White T. Paleobiological implications of the Ardipithecus ramidus dentition. Science. 2009;236:94–99.

White T, Asfaw B, Beyene Y, et al. Ardipithecus ramidus and the paleobiology of early hominids. Science. 2009;326:64–86. http://dx.doi.org/10.1126/science.1175802

White T, WoldeGabriel G, Asfaw B, et al. Assa Issie, Aramis and the origin of Australopithecus. Nature. 2006;440:883–889. http://dx.doi.org/10.1038/nature04629, PMid:16612373

White TD, Suwa G, Asfaw B. Australopithecus ramidis, a new species of early hominid from Aramis, Ethiopia. Nature. 1994;371:306–312. http://dx.doi.org/10.1038/371306a0, PMid:8090200

Kimbel W, Lockwood C, Ward CV, Leakey M, Rak Y, Johanson D. Was Australopithecus anamensis ancestral to A. afarensis? A case of anagenesis in the hominin fossil record. J Hum Evol. 2006;51:134–152. http://dx.doi.org/10.1016/j.jhevol.2006.02.003, PMid:16630646

White TD. Earliest hominids. In: Hartwig WC, editor. The primate fossil record. Cambridge: Cambridge University Press, 2002; p. 407–417.

Greenfield L. Origins of the human canine; a new solution to an old enigma. Yearb Phys Anthropol. 1992;35:153–185. http://dx.doi.org/10.1002/ajpa.1330350607

Plavcan JM. Inferring social behavior from sexual dimorphism in the fossil record. J Hum Evol. 2000;39:327–344. http://dx.doi.org/10.1006/jhev.2000.0423, PMid:10964532

Leakey MG, Feibel CS, MacDougall I, Ward CV, Walker A. New specimens and confirmation of an early age for Australopithecus anamensis. Nature. 1998;363:62–66. http://dx.doi.org/10.1038/29972, PMid:9590689

Leakey MG, Feibel CS, McDougall I, Walker A. New four-million-year-old hominid species from Kanapoi and Alia Bay, Kenya. Nature. 1995;376:565–571. http://dx.doi.org/10.1038/376565a0, PMid:7637803

Ward CV, Leakey MG, Walker A. Morphology of Australopithecus anamensis from Kanapoi and Allia Bay, Kenya. J Hum Evol. 2001;41:255–368. http://dx.doi.org/10.1006/jhev.2001.050, PMid:11599925

Ward CV, Walker A, Leakey MG. The new hominid species Australopithecus anamensis. Evol Anthropol. 1999;7:197–205. http://dx.doi.org/10.1002/(SICI)1520-6505(1999)7:6<197::AID-EVAN4>3.0.CO;2-T

Haile-Selassie Y, Saylor B, Deino A, Alene M, Latimer B. New hominid fossils from Woranso-Mille (Central Afar, Ethiopia) and taxonomy of early Australopithecus. Am J Phys Anthropol. 2010;141:406–417. PMid:19918995

Fleagle JG, Rasmussen DT, Yirga S, Bown TM, Grine FE. New hominid fossils from Fejej, southern Ethiopia. J Hum Evol. 1991;21:145–152. http://dx.doi.org/10.1016/0047-2484(91)90005-G

McDougall I, Brown F. Geochronology of the pre-KBS Tuff sequence, Omo Group, Turkana Basin. J Geol Soc. 2008;165:549–562. http://dx.doi.org/10.1144/0016-76492006-170

Wolpoff M. Paleoanthropology. New York: Knopf; 1980.

Plavcan J. Sexual dimorphism in the dentition of extant anthropoid primates. Durham: Duke University; 1990.

Plavcan J, Ward CV, Paulus F. Estimating tooth crown height in early Australopithecus. J Hum Evol. 2009;57:2–10. http://dx.doi.org/10.1016/j.jhevol.2009.04.005, PMid:19482334

Matlab. Version 7. Natick, MA: Mathworks; 2010.

SMATR (Standardized Major Axis Tests and Routines). Version 2. Sydney: Falster D, Wharton D, Wright I; 2006.

Wharton D, Wright I, Falster D, Westoby M. Bivariate line-fitting methods for allometry. Biol Rev. 2006;81:259–291. http://dx.doi.org/10.1017/S1464793106007007, PMid:16573844

Bailit H, Friedlaender J. Tooth size reduction: A hominid trend. Am Anthropol. 1966;68:665–72. http://dx.doi.org/10.1525/aa.1966.68.3.02a00030

Brace C. Structural reduction in evolution. Am Nat. 1963;97:39–49.

Calcagno J, Gibson K. Human dental reduction: Natural selection or probable mutation effect? Am J Phys Anthropol. 1988;77:505–517. http://dx.doi.org/10.1002/ajpa.1330770411, PMid:3223518

Wolpoff M. The effect of mutations under conditions of reduced selection. Soc Biol. 1969;16:11–23. PMid:5803566

Jungers W. On canine reduction in early hominids. Curr Anthropol. 1978(19):155–156. http://dx.doi.org/10.1086/202027

Szalay FS. Hunting-scavenging protohominds: A model for hominid origins. Man. 1975;10:420–429. http://dx.doi.org/10.2307/2799811

Ungar P, Scott R, Grine F, Teaford M. Molar microwear textures and the diets of Australopithecus anamensis and Australopithecus afarensis. Philos Trans R Soc London. 2010;365:3345–3354. http://dx.doi.org/10.1098/rstb.2010.0033, PMid:20855308



Reader Comments

Before posting a comment, read our privacy policy.

Post a comment (login required)

Crossref Citations

No related citations found.