Articles that tend to be difficult to obtain are available for download as PDF below. Please contact me by e-mail if you require PDFs of other publications. [full list here]
Cranio-dental evolution of African Plio-Pleistocene hominins
This research focuses on the description and comparative analysis of fossil hominin skull remains recovered by the Koobi Fora Research Project (KFRP), under the direction of Meave Leakey and Louise Leakey. Current projects concern Pliocene fossils from Lomekwi (west of Lake Turkana, Kenya), including the cranium KNM-WT40000 (holotype of Kenyanthropus platyops), and of Plio-Pleistocene fossils found during renewed fieldwork at Koobi Fora and Ileret (east of Lake Turkana, Kenya). A particular focus is on new fossil evidence documenting the radiation of early Homo, a project in collaboration with Susan Antón (New York University), and Christopher Dean (UCL). Recent Findings indicate that Homo habilis and Homo erectus did not form a single evolutionary lineage, but lived side by side in eastern Africa for nearly half a million years. Moreover, the discovery of a particularly small calvaria of H. erectus (KNM-ER 42700) indicates that this taxon overlapped in size with H. habilis, and may have shown marked sexual dimorphism. Supported by the National Geographic Society (USA).
Additional projects concern the Pliocene juvenile Australopithecus afarensis skeleton DIK-1-1 from Dikika, Ethiopia, in collaboration with Zeresenay Alemseged (California Academy of Sciences; Dikika Research Project), and the Pleistocene partial Homo cranium KNM-OG 45500 from Olorgesailie, Kenya, in collaboration with Rick Potts (Smithsonian National Museum of Natural History).
Left to right: Kenyanthropus platyops cranium KNM-WT 40000 from Lomekwi (Kenya), 3.5 Myr old;
Juvenile Australopithecus afarensis skeleton DIK-1-1 from Dikika (Ethiopia), 3.3 Myr old;
Homo erectus crania KNM-ER 42700 (small) and OH 9 (large), 1.4-1.6 Myr old.
Spoor F, Leakey MG, Antón SC & Leakey LN (2008). The taxonomic status of KNM-ER 42700; a reply to Baab. J. Hum. Evol.55, 747-750.
Spoor F, Leakey MG, Gathogo PN, Brown FH, Antón SC, McDougall I, Kiarie C, Manthi FK & Leakey LN (2007) Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya. Nature 448, 688-691.
Antón SC, Spoor F, Fellmann CD & Swisher III CC (2007) Defining Homo erectus: Size Considered. In: Handbook of Paleoanthropology Volume III (Henke, Rothe, and Tattersall, eds) Chapter 11, 1655-1693.
Alemseged Z, Spoor F, Kimbel WH, Bobe R, Geraads D, Reed D & Wynn JG. (2006). A juvenile early hominin skeleton from Dikika, Ethiopia. Nature 443, 296-301.
Spoor F, Leakey MG & Leakey LN (2005) Correlation of cranial and mandibular prognathism in extant and fossil hominids. Trans Roy Soc S. Afr. 60, 85-89. [PDF]
Leakey MG, Spoor F, Brown FH, Gathogo PN, Kiarie C, Leakey LN & McDougall I (2001) New hominin genus from eastern Africa shows diverse middle Pliocene lineages. Nature 410, 433-440.
Spoor F, O'Higgins P, Dean C & Lieberman DE (1999) Anterior sphenoid in modern humans. Nature 397, 572.
Spoor, F (1997) Basicranial architecture and relative brain size of Sts 5 (Australopithecus africanus) and other Plio-Pleistocene hominids. South Afr. J. Science 93: 182-187. [PDF]
NB: If you own, or are considering to buy a BoneClones "cast" of the Kenyanthropus cranium KNM-WT 40000, please read this: Spoor F, Leakey LN & Leakey MG (2002) Bone Clones’ "re-creation" of Kenyanthropus. Physical Anthropology 3: 2. [PDF]
Comparative and functional morphology of the bony labyrinth
The bony labyrinth inside the petrous temporal bone houses the organ of hearing in the cochlea and the organs perceiving movement and spatial orientation in the vestibule and semicircular canals (structures jointly known as the inner ear).
The semicircular canal system senses head rotations and contributes to the stabilization of gaze and control of locomotion. During human evolution there were notable changes in semicircular canal morphology. Interestingly, the most prominent of these is not found in association with the origin of bipedal posture and gait well over 4 Million years ago. Rather, the main change occurs around 2 Million years ago when our ancestors acquired a body plan and types of gait broadly similar to modern humans.
Apart from the functional link with locomotion the bony labyrinth is also affected by shape changes of the surrounding cranial base and brain. Hence, studying the bony labyrinth of fossil hominins provides information about two key processes of human evolution: the emergence of bipedal locomotion and brain expansion.
Comparisons of Neanderthals and modern humans show that the bony labyrinth can differ between hominin species, even when they are closely related. Collaborative research with Jean-Jacques Hublin (Max Planck Institute for Evolutionary Anthropology) investigates the unique nature of the Neanderthal labyrinth, and how it emerged during the middle Pleistocene.
Lateral view of the right bony labyrinths of a modern human (left) and the Neanderthal
specimen Petit Puymoyen 5 (right), reconstructed from medical CT scans. Scale bar is 5 mm.
Work on the bony labyrinth of hominin fossils was initially based on medical CT scans with limited resolution, which largely restricted the quantitative analysis of size and shape to 2D measurements. Now high resolution CT has become increasingly available and with Philipp Gunz (Max Planck Institute for Evolutionary Anthropology) a new protocol has been developed for 3D analyses using geometric morphometric approaches.
Gunz P, Spoor F, Tilgner R & Hublin JJ (2009) The Neanderthal bony labyrinth reconsidered, introducing a new geometric morphometric approach. Am. J. Phys. Anthrop. 138, S48: 142
Spoor F, Hublin JJ, Braun M & Zonneveld F (2003) The bony labyrinth of Neanderthals. J. Hum Evol. 44, 141-165.
Spoor F (2003) The semicircular canal system and locomotor behaviour, with special reference to hominin evolution. Cour. Forsch. Senckenberg. 243: 93-104 [PDF]
Spoor F & Zonneveld F (1998) Comparative review of the human bony labyrinth. Yrbk Phys. Anthrop. 41, 211-251.
Hublin J-J, Spoor F, Braun M, Zonneveld F & Condemi S. (1996) A late Neanderthal from Arcy-sur-Cure associated with Upper Palaeolithic artefacts. Nature 381, 224-226.
Spoor F, Wood B & Zonneveld F (1994) Implications of early hominid labyrinthine morphology for the evolution of human bipedal locomotion. Nature 369, 645-648.
In a wider comparative setting I study primates, as well as other groups of mammals to assess the relationship between the semicircular canal system and locomotor behaviour. Research in collaboration with Alan Walker (Penn State University) shows empirically that the arc sizes of the semicircular canals are significantly larger in mammals that are agile and acrobatic than in species that are more cautious in their locomotion. A plausible factor underpinning this relationship appears to be that arc size affects the mechanical sensitivity of the canal system. This functional relationship provides the opportunity to assess the locomotor behaviour of extinct taxa based on their semicircular canals. A wide range of fossil and subfossil primates has been investigated thus far. Supported by the National Science Foundation (USA).
Silcox MT, Bloch JI, Boyer DM, Godinot M, Ryan TM, Spoor F & Walker A (2009). The semicircular canal system in early primates. J. Hum. Evol.56, 315-327.
Walker A, Ryan TM, Silcox MT, Simons E & Spoor F (2008) The semicircular canal system and locomotion: the case of extinct lemuroids and lorisoids. Evol. Anthrop. 17, 135-145.
Spoor, F., Garland, Th., Krovitz, G., Ryan, T.M., Silcox, M.T. and Walker, A. (2007) The Primate Semicircular Canal System and Locomotion. Proc. Nat. Acad. Sci. 104, 10808-10812.
Lateral view of the left bony labyrinths of galago (left) and loris (right), reconstructed from
high-resolution CT scans. Scale bar is 1 mm. The semicircular canals of the leaping galagid
are substantially larger than those of the slow, quadrupedal climbing lorisid (both have
similar body size).
Additional work with Nathan Jeffery (University of Liverpool) explored the fetal development of the primate inner ear, as well as the structural relationship between the subarcuate fossa and the semicircular canals. The latter to assess if spatial constrains of the fossa and its brain contents (the petrosal lobule of the paraflocculus) are a factor influencing the arc size of the surrounding semicircular canals.
Jeffery N, Ryan TM & Spoor F. (2008) The primate subarcuate fossa and its relationship to the semicircular canals part II: adult interspecific variation. J. Hum. Evol. 55, 326-339.
Jeffery N, Spoor F. (2006) The primate subarcuate fossa and its relationship to the semicircular canals part I: prenatal growth. J. Hum. Evol. 51, 537-549.
Jeffery N, Spoor F. (2004) Prenatal growth and development of the modern human labyrinth. J. Anatomy. 204, 71-92.
Cetaceans (whales and dolphins) are the order showing the most derived inner ear and bony labyrinth among mammals. Most strikingly, they have remarkably small semicircular canals, a phenomenon which appears related to the transition from a terrestrial to a marine environment. In collaboration with Hans Thewissen (North Eastern Ohio College of Medicine, USA) the evolutionary history of this dramatic change is investigated by examining Eocene archaeocete fossils. Supported by the National Science Foundation (USA).
Spoor F and Thewissen JGM (2008) Balance: Comparative and functional Anatomy in Aquatic Mammals. In: Sensory Evolution on the Threshold, Adaptations in Secondarily Aquatic Vertebrates (Thewissen JGM and Nummela S, eds), Chapter 16. University of California Press, Berkeley, 257-284.
Spoor F, Bajpai S, Hussain ST, Kumar K., Thewissen JGM (2002) Vestibular evidence for the evolution of aquatic behaviour in early cetaceans. Nature 417, 163-166.
Computed tomography & palaeontology
Ever since the discovery of x-rays, palaeontology has greatly benefited from radiological techniques such as radiography and, more recently, computed tomography (CT). In the past I have done some research, and have written some reviews on the practical aspects of using CT to study fossils.
Imaging the Homo erectus cranium KNM-WT 15000: lateral radiograph (left), parasagittal CT scan at the level
of the right dental row and inner ear (middle), and 3D surface visualization extracted from a stack of CT scans
(right). Unlike radiographs, CT scans have the ability to distinguish between fossil bone and the sedimentary
matrix in the maxillary sinus (asterisk), and to resolve details such as the root canals of the molars
(arrowhead), and structures of the bony labyrinth (arrow).
Spoor F, Jeffery N & Zonneveld F. (2000a) Using diagnostic radiology in human evolutionary studies. J. Anatomy 197, 61-76.
Spoor F, Jeffery N & Zonneveld F. (2000b) Imaging skeletal growth and evolution. In: Development, Growth and Evolution: implications for the study of the hominid skeleton. (O'Higgins P and Cohn M eds.). Academic Press, London, pp.123-161. [PDF]
Spoor CF, Zonneveld FW & Macho GA (1993) Linear Measurements of Cortical Bone and Dental Enamel by Computed Tomography: Applications and Problems. Am. J. Phys. Anthrop. 91, 469-484. [PDF]
Selected blasts from the past
Hyena locomotion and morphology
For my MSc Biology in the Netherlands I did some work on hyenas: skeletal proportions, gait analysis and muscle dissection of Hyaena hyaena and Crocuta crocuta. Following occasional requests for reprints the resulting articles are listed below, with links to PDFs.
Spoor CF and Badoux DM (1989). Descriptive and functional morphology of the locomotory apparatus of the spotted hyena (Crocuta crocuta Erxleben, 1777). Anat. Anz. 168, 261-266. [PDF]
Spoor CF and Badoux DM (1988). Descriptive and functional myology of the back and hindlimb of the striped hyena (Hyaena hyaena L. 1758). Anat. Anz. 167, 313-321. [PDF]
Spoor CF and Badoux DM (1986). Descriptive and functional myology of the neck and forelimb of the striped hyena. Anat. Anz. 161: 375-387. [PDF]
Spoor CF and Belterman Th (1986). Locomotion in Hyaenidae. Contrib. to Zool. 56, 24-28. [PDF]
Spoor CF (1985): Body proportions in Hyaenidae. Anat. Anz. 160, 215-220. [PDF]
Corbeddu Cave (Sardinia)
Between 1982 and 1990 I participated in the palaeontological excavations at Corbeddu Cave, Sardinia, under the direction of the late Paul Sondaar (Institute of Earth Sciences, Utrecht University). Prior to my PhD, and as a first venture into hominin palaeontology I described the human maxilla and temporal bone we had found in pre-Neolithic layers (~9000 yBP). These specimens, and other evidence, suggest that humans co-existed for substantial time with the endemic island fauna of Pleistocene Sardinia. Such co-existence, as opposed to near-instant eradication of endemic island species, is now a phenomenon of particular interest, following the discovery of hominin (“hobbit”) remains as part of the Pleistocene fauna of the island Flores (Indonesia).
Left: the 1983 Utrecht University team at Corbeddu Cave.
Right: occlusal view of the left maxilla CB85.3013 from Corbeddu Cave, combined with a mirror-imaged cast
of the specimen and an extant human molar that fits the wide M1 alveolus.
Spoor F (1999) The human fossils from Corbeddu Cave, Sardinia: a reappraisal. Deinsea 7, 297-302. [PDF]
Spoor CF and Sondaar PY (1986). Human fossils from the endemic island fauna of Sardinia. J. Human Evol. 15, 399-408.