Despite a steady increase in the number and diversity of African Middle Pliocene hominin fossils, paleoanthropolo-gists are not now substantially closer to understanding the temporal, geographical or ecological contexts of the origin of the Homo clade than was the case in 1964, when Louis Leakey, Phillip Tobias and John Napier introduced Homo habilis as the earliest species of the human genus. The reasons for this circumstance are several. The fi rst is a still data-poor record in the relevant time periods. Although the half-million year interval between 2.5 and 3 Ma witnessed heightened morphological, taxonomic and diet-driven adaptive diversity in extinct hominins, all of the known taxa from this interval are of australopith grade (i.e., Australopithecus africanus, A. garhi, A. aethiopicus, late A. afarensis) and none shares derived morphological characteristics exclusively with geologically younger, securely attributed representatives of the Homo lineage. A few specimens that at one time or another have been attributed to Homo fall in the time period 2.5–2.0 Ma but most of these are fragmentary and/or of questionable (or at least debated) diagnostic value (see discussion below). The earliest well-sampled record of fossil hominins that bear characters found only in the genus Homo date to ca. 1.7–1.8 Ma. The fact that as many as three species with unique ties to Homo (H. habilis, H. rudolfensis, H. erectus) have their apparent FADs at about this time (Kimbel, 1991; Wood, 1991; Spoor et al., 2007) speaks to an earlier differentiation of the lineage, but other than the Hadar maxilla A.L. 666-1, with an age of ca. 2.3 Ma (Kimbel et al., 1997), the record of specimens bearing on the earliest phases of the lineage's evolution is mostly uninformative.

The second reason for our poor comprehension of Homo origins is conceptual. Historically, the search for the origins of Homo has been confl ated with defi ning the morphological and behavioral boundaries between ape and human. In 1871, Darwin postulated an evolutionary scenario linking terrestrial bipedality, canine reduction, tool manufacture, and brain enlargement at the base of the human lineage. When growing knowledge of Australopithecus (including Paranthropus) made it clear by the 1940s that bipedality and canine reduction evolved well before hominins became signifi cantly encephalized and began to leave a record of their lithic technology, large brains and stone tools were elevated to a foun-dational role in the divergence of the Homo lineage from some generalized australopith form. Thus, Oakley's (1959) “Man the Tool-maker” joined Leakey et al.'s (1964) recognition of the “handy man” Homo habilis in framing thinking about the emergence of Homo for the latter half of the twentieth century (Tattersall, 1998).


Taxonomy Homo habilis Homo rudolfensis Homo erectus 


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  1. Aiello, L.C, Wheeler, P. E., 1995. The expensive-tissue hypothesis: the brain and the digestive system in human and primate evolution. Current Anthropology 36, 199–221.CrossRefGoogle Scholar
  2. Asfaw, B., White, T., Lovejoy, C.O., Latimer, B., Simpson, S., Suwa, G., 1999. Australopithecus garhi: a new species of early hominid from Ethiopia. Science 284, 629–635.CrossRefGoogle Scholar
  3. Bramble, D.M., Lieberman, D.E., 2004. Endurance running and the evolution of Homo. Nature 432, 345–352.CrossRefGoogle Scholar
  4. Bromage, T.G., Schrenk, F., Zonnevel, F.W., 1995. Paleoanthropology of the Malawi Rift: an early hominid mandible from the Chiwondo Beds, northern Malawi. Journal of Human Evolution 28, 71–108.CrossRefGoogle Scholar
  5. Broom, R., Robinson, J.T., Schepers, G., 1950. The Sterkfontein Ape-Man Plesianthropus transvaalensis. Transvaal Museum Memoir 4, Pretoria.Google Scholar
  6. Clarke, R.J., 1977. A juvenile cranium and some adult teeth of early Homo from Swartkrans, Transvaal. South African Journal of Science 73, 46–49.Google Scholar
  7. Collard, M., Wood, B.A., 2007. Defi ning the genus Homo. In: Henke, W., Tattersall, I. (Eds), Handbook of Paleoanthropology, Volume 3: Phylogeny of Hominids. Springer, Berlin, pp. 1575–1610.CrossRefGoogle Scholar
  8. Dean, M.C., Wood, B.A., 1982. Basicranial anatomy of Plio-Pleistocene hominids from East and South Africa. American Journal of Physical Anthropology 59, 157–174.CrossRefGoogle Scholar
  9. Falk, D., 1992. Evolution of the brain and cognition in hominids. James Arthur Lectures on the Evolution of the Human Brain, Number 62. American Museum of Natural History, New York.Google Scholar
  10. Hill, A., Ward, S.C., Deino, A.L., Curtis, G.H., Drake, R.E.,1992. Earliest Homo. Nature 355, 719–722.CrossRefGoogle Scholar
  11. Holloway, R.L., Broadfi eld, D., Yuan, M., 2004. Brain Endocasts: The Paleoneurological Record. The Human Fossil Record, Volume 3. Wiley-Liss, Hoboken, NJ.CrossRefGoogle Scholar
  12. Johanson, D.C., Masao, F. T., Eck, G.G., White, T.D., Walter, R.C., Kimbel, W.H., 1987. New partial skeleton of Homo habilis from Olduvai Gorge, Tanzania. Nature 327, 205–209.CrossRefGoogle Scholar
  13. Kimbel, W.H., 1991. Species, species concepts and hominid evolution. Journal of Human Evolution 20, 355–371.CrossRefGoogle Scholar
  14. Kimbel, W.H., Rak, Y.,1993. The importance of species taxa in paleo-anthropology and an argument for the phylogenetic concept of the species category. In Kimbel, W.H., Martin, L.B. (Eds), Species, Species Concepts, and Primate Evolution. Plenum, New York, pp. 461–484.CrossRefGoogle Scholar
  15. Kimbel, W.H., Johanson, D.C., Rak, Y., 1997. Systematic assessment of a maxilla of Homo from Hadar, Ethiopia. American Journal of Physical Anthropology 103, 235–262.CrossRefGoogle Scholar
  16. Leakey, L.S.B., Tobias, P.V., Napier, J.,1964. A new species of the genus Homo from Olduvai Gorge. Nature 202, 7–9.CrossRefGoogle Scholar
  17. Leakey, M., Spoor, F., Brown, F.H., Gathogo, P.N., Kiarie, C., Leakey, L.N., MacDougall, I., 2001. New hominin genus from eastern Africa shows diverse middle Pliocene lineages. Nature 410, 433–440.CrossRefGoogle Scholar
  18. Lockwood, C.A., Kimbel, W.H., n.d. The temporal bone of early Homo. In preparation.Google Scholar
  19. Lockwood, C.A., Kimbel, W.H., Lynch, J., 2002. Temporal bone morphology and earliest Homo. American Journal of Physical Anthropology S34, 102.Google Scholar
  20. Martyn, J., Tobias, P.V., 1967. Pleistocene deposits and new fossil localities in Kenya. Nature 215, 476–480.CrossRefGoogle Scholar
  21. McHenry, H.M., Coffi ng, K., 2000. Australopithecus to Homo: transformations in body and mind. Annual Review of Anthropology 29, 125–146.CrossRefGoogle Scholar
  22. Oakley, K.P., 1959. Man the Tool-Maker. University of Chicago Press, Chicago, IL.Google Scholar
  23. Prat, S., Brugal, J-P., Tierceling, J-J., Barrat, J-A., Bohn, M., Delagnes, A., Harmand, S., Kimeu, K., Kibunjia, M., Texier, P-J., Roche, H., 2005. First occurrence of early Homo in the Nachukui Formation (West Turkana, Kenya) at 2.3–2.4 Myr. Journal of Human Evolution 49, 230–240.CrossRefGoogle Scholar
  24. Reno, P., DeGusta, D., Serrat, M., Meindl, R., White, T., Eckhardt, R., Kuperavage, A., Galik, K., Lovejoy, C.O., 2005. Plio-Pleistocene hominid limb proportions. Current Anthropology 46, 575–588.CrossRefGoogle Scholar
  25. Semaw, S., 2000. The world's oldest stone artifacts from Gona, Ethiopia: their implications for understanding stone technology and patterns of human evolution between 2.6–1.5 million Years ago. Journal of Archaeological Science 27, 1197–1214.CrossRefGoogle Scholar
  26. Sherwood, R., Ward, S.C., Hill, A., 2002. The taxonomic status of the Chemeron temporal (KNM-BC 1). Journal of Human Evolution 42, 153–184.CrossRefGoogle Scholar
  27. Spoor, F., Leakey, M.G., Gathogo, P.N., Brown, F.H., Anton, S.C., McDougall, I., Kiarie, C., Manthi, F.K., Leakey, L.N., 2007. Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya. Nature 448, 688–691.CrossRefGoogle Scholar
  28. Stanley, S.M., 1992. An ecological theory for the origin of Homo. Paleobiology 18, 237–257.Google Scholar
  29. Strait, D.S., Grine, F.E., Moniz, M.A., 1997. A reappraisal of early hominid phylogeny. Journal of Human Evolution 32, 17–82.CrossRefGoogle Scholar
  30. Strait, D.S., Grine, F.E., 1999. Cladistics and early hominid phylogeny. Science 285, 1210.CrossRefGoogle Scholar
  31. Strait, D.S., Grine, F.E., 2001. The systematics of Australopithecus garhi. Ludus Vitalis, 9, 109–135.Google Scholar
  32. Strait, D.S, Grine, F.E., 2004. Inferring hominoid and early hominid phylogeny using craniodental characters: the role of fossil taxa. Journal of Human Evolution 47, 399–452.CrossRefGoogle Scholar
  33. Strait, D.S., Grine, F.E., Fleagle, J.G., 2007. Analyzing hominid phylogeny. In: W. Henke, I. Tattersall (Eds.), Handbook of Paleoan-thropology, Volume 3: Phylogeny of Hominids. Springer, Berlin, pp. 1781–1806.CrossRefGoogle Scholar
  34. Suwa, G., 1990. A comparative analysis of hominid dental remains from the Shungura and Usno Formations, Omo Valley, Ethiopia. Ph.D. dissertation, University of California, Berkeley.Google Scholar
  35. Suwa, G., White, T.D., Howell, F.C., 1996. Mandibular postcanine dentition from the Shungura Formation, Ethiopia: crown morphology, taxonomic allocations, and Plio-Pleistocene hominid evolution. American Journal of Physical Anthropology 101, 247–282.CrossRefGoogle Scholar
  36. Tattersall, I., 1998. Becoming Human. Harcourt Brace, New York.Google Scholar
  37. Tobias, P.V., 1987. The brain of Homo habilis: a new level of organization in cerebral evolution. Journal of Human Evolution 16, 741–761.CrossRefGoogle Scholar
  38. Tobias, P.V., 1991. The Skulls, Endocasts and Teeth of Homo habilis. Olduvai Gorge, Volume 4. Cambridge University Press, Cambridge.Google Scholar
  39. Wood, B.A., 1991. Hominid Cranial Remains. Koobi Fora Research Project, Volume 4. Oxford University Press, Oxford.Google Scholar
  40. Wood, B.A., 2009. Where does the genus Homo begin, and how would we know? In: Grine, F.E., Fleagle, J.G., Leakey, R.E. (Eds), The First Humans: Origin and Early Evolution of the Genus Homo. Springer, Dordrecht, pp. 17–28.CrossRefGoogle Scholar
  41. Wood, B.A., Collard, M., 1999. The human genus. Science 284, 65–71.CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • William H. Kimbel
    • 1
  1. 1.Institute of Human Origins, School of Human Evolution and Social ChangeArizona State UniversityUSA

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