However, others have argued that this species has been prematurely identified and that more evidence is needed before splitting the taxa, since the variation appears subtle and may be due to slightly different niche occupations between populations over time. Figure 9.3 CO₂ increase since the Industrial Revolution by NASA, original from Luthi, D., et al.. 2008; Etheridge, D.M., et al. Originally these specimens were referred to as a subspecies of Ar. The fact that it was discovered in Africa simply served to strengthen this bias. The people who fractured rocks in order to manufacture of tools. A descriptor for an organism that spends most of its time in trees. This also allows for a more fluid interpretation of the Turnover Pulse Hypothesis, where species turnover is meant to be more rapid. “‘Mrs. However, our closest relatives all have very long, pointy canines, particularly on their upper dentition. When the teeth from the maxilla come into contact with the teeth in the mandible. It was first discovered through a clavicle bone in 2008 by nine-year-old Matthew Berger, son of paleoanthropologist Lee Berger. It has thus been placed in the species Australopithecus prometheus. We refer to these as chronospecies. All early hominins have the primitive condition shared with other great apes. 2002. garhi, indicates this species may be longer-limbed than Au. It suggests that the expansion of the savannah (or less densely forested, drier environments) forced early hominins from an arboreal lifestyle (one living in trees) to a terrestrial one where bipedalism was a more efficient form of locomotion (Figure 9.4). These specimens are currently dated to 1.97 mya (Dirks et al. This techno-complex is the most recently defined and pushed back the oldest known date for lithic technology. It is possible that the majority of early hominin tool use and manufacture may be invisible to us because of this preservation bias. The vast majority of our understanding of these early hominins comes from fossils and reconstructed paleoenvironments. Prognathic: In reference to the face, the area below the eyes juts anteriorly. Obligate bipedalism: Where the primary form of locomotion for an organism is bipedal. Her current research focuses on the evolution and biomechanical implications of bipedal walking through analyses of trabecular bone structure in the joints of the lower limb. In Ardipithecus ramidus, there is no obvious difference between male and female canine size, yet they are still slightly larger and pointier than in humans. “2.5-my Australopithecus boisei from West of Lake Turkana, Kenya.” Nature 322 (6079): 517–522. Postcranium: The skeleton below the cranium (head). Lower limb bones (tibia and femur) indicate bipedality; arboreal features in upper limb bones (humerus) found. This allows for gripping onto curved surfaces during locomotion. She has excavated at Stone Age sites across South Africa and East Africa. New Haven: Yale University Press. afarensis (which means “from the Afar region”) is dated to between 2.9 mya and 3.9 mya and is found in sites all along the EARS system, in Tanzania, Kenya, and Ethiopia (Figure 9.12). The name was shortened by contemporary journalists to “Ples” (Figure 9.17). 1995; Patterson and Howells 1967) is currently found from sites in the Turkana region (Kenya) and Middle Awash (Ethiopia; Figure 9.11). DeHeinzelin, J., J. D. Clark, T. White, W. Hart, P. Renne, G. WoldeGabriel, Y. Beyene, and E. Vrba. A large hallux (big toe) bone indicates a bipedal “push off.”. afarensis, the geographic range of the species would be extended even further. Aridity Hypothesis: The hypothesis that long-term aridification and expansion of savannah biomes were drivers in diversification in early hominin evolution. Every site discovery in the patchy hominin fossil record tells us more about our evolution. For instance, while there are definitely high levels of sexual dimorphism in Au. Maintaining body temperature through physiologically cooling or warming the body. 2006. “Human Evolution.” In Evolution: The First Four Billion Years, edited by M. Ruse and J. Travis, 256–280. Hay, R. L. 1990. 1938b. By Ann Gibbons Jun. Petit et al. A phrase typically referring to a woodland, or tree-filled, environment. Cut marks on fossilized animal bones may illuminate the functionality of stone tools. Females were much smaller and less muscular. This femur indicates that Ororrin was bipedal, and recent studies suggest that it walked in a similar way to later Pliocene hominins. Though the fossil was found early on during the excavation, it was not dated until 2014/2015. Faunal assemblages: Collections of fossils of other animals found at a site. Early on in human evolution, we see a reduction in canine size. Figure 9.13 Lucy blackbg (AL 288-1, Australopithecus afarensis, cast from Museum national d’histoire naturelle, Paris) by 120 is used under a CC BY-SA 3.0 License. 7, 2017 , 1:00 PM. is copyrighted and used for educational and noncommercial purposes as outlined by the Smithsonian. The first factor is the diversification of taxa, where high morphological variation between specimens has led to the naming of multiple hominin genera and species. In animals with large canines (such as baboons), there is also often a honing P3, where the first premolar (also known as P3 for evolutionary reasons) is triangular in shape, “sharpened” by the extended canine from the upper dentition. Because Oldowan knapping requires skill, earlier researchers have attributed these tools to members of our genus, Homo. Researchers often need to make several important claims when announcing or publishing a find: a secure date (if possible), clear association with other finds, and an adequate comparison among multiple species (both extant and fossil). Have any problems using the site? Figure 9.7b Sahelanthropus tchadensis: TM 266-01-060-1 posterior view by eFossils is copyrighted and used for noncommercial purposes as outlined by eFossils. Both local and global climatic/environmental changes have been used to understand parameters affecting our evolution (DeHeinzelin et al. “Australopithecus africanus, the Man-Ape of South Africa.” Nature 115: 195–199. Historic interpretations of our evolution, prior to our finding of early hominin fossils, varied. Julio Mercader, Pam Akuku, Nicole Boivin, Revocatus Bugumba, Pastory Bushozi, Alfredo Camacho, Tristan Carter, Siobhán Clarke, Arturo Cueva-Temprana, Paul Durkin, Julien Favreau, Kelvin Fella, Simon Haberle, Stephen Hubbard, Jamie Inwood, Makarius Itambu, Samson Koromo, Patrick Lee, Abdallah Mohammed, Aloyce Mwambwiga, Lucas Olesilau, Robert Patalano, Patrick Roberts, Susan Rule, Palmira Saladie, Gunnar Siljedal, María Soto, Jonathan Umbsaar, Michael Petraglia. Burckle, 262–288. The incisors themselves were vertical and close together, and not at an angle to the mouth (procumbent), as seen in other apes. Paranthropus is usually referred to by scholars as the “robust” australopithecine, because of its defining distinct morphological features. The face below the eyes is relatively flat and does not jut out anteriorly. Figure 9.6 Skeletal comparisons between modern humans and non-obligate bipeds original to Explorations: An Open Invitation to Biological Anthropology is under a CC BY-NC 4.0 License. Projecting cheekbones and primitive earholes. Another famous Au. Clear evidence for bipedalism from lower limb postcranial bones. Kerryn Warren is a postdoctoral researcher at the University of Cape Town. This would mean that both humans and chimpanzees can be considered “derived” in terms of locomotion since chimpanzees would have independently evolved knuckle-walking. 1995. Relatively larger brain size, robust zygomatic arch, and a flatter midface. 2019. Crude/primitive stone tools resembling Oldowan (described later) have been found in association with Au. Gracile: Slender, less rugged, or pronounced features. As pertaining to palaeoanthropology, this term refers to the place where an artifact or fossil is found. Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Science 269 (5223): 521–524. However, the link between climate and speciation is only vaguely understood (Faith and Behrensmeyer 2013). However, the sloping face and curved phalanges (indicative of retained arboreal locomotor abilities) show some primitive features. Figure 9.16b Australopithecus africanus Sts 5 posterior view by eFossils is copyrighted and used for noncommercial purposes as outlined by eFossils. Similarly, the “Laetoli Footprints” (discussed in Chapter 7; Hay and Leakey 1982; Leakey and Hay 1979) have drawn much attention. Human Variation: An Adaptive Significance Approach, 15. Skeletal evidence indicates that this species was bipedal, primarily through examining the pelvis and lower limb, which demonstrate a humanlike femoral neck, a valgus knee, and bowl-shaped hip. Hyper-robust: Even more robust than considered normal in the Paranthropus genus. 2015. “The Evolution of Zinjanthropus boisei.” Evolutionary Anthropology: Issues, News, and Reviews 16 (2): 49–62. The study of the evolutionary relationships between groups of organisms. Solar precessional cycles: cyclical changes in earth’s axis rotation that have global climatic effects. 2001. 2015; Toth 1985). Smaller teeth with thicker enamel than seen in Au. afarensis, which we will discuss in the next section, the canine teeth are reduced in size, implying that while canines may be useful indicators for sexual dimorphism, it is also worth noting other lines of evidence. “New Species from Ethiopia Further Expands Middle Pliocene Hominin Diversity.” Nature 521 (7553): 432–433. Isotopes: Two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons, giving them the same chemical properties but different atomic masses. Figure 9.17 The “Mrs. Smaller cheek teeth (molars and premolars) than those in even more recent hominins (i.e., derived), thick enamel, and reduced, but apelike, canines characterize this species. Others, known as “splitters,” argue that species variability can be measured and that even subtle differences can imply differences in niche occupation that are extreme enough to mirror modern species differences. These techniques allow us to use chemistry (such as nitrogen and oxygen isotopes in shells and sediments) or pollen grains (which show directly the kinds of flora surviving in an environment at a specific time period). The well-known fossil of a juvenile Australopithecine, the “Taung Child,” was the first early hominin evidence ever discovered and was the first to demonstrate our common human heritage in Africa (Figure 9.15; Dart 1925). It is one of the most complete cranial finds of this species (Ward et al. The largest teeth at the back of the mouth; used for chewing; in primates, these teeth usually have between three and five cusps. We identified 40 tracks, estimated to be around 90,000 years old and indicating a party of humans traveling fast down a … He asked Stephen Motsumi and Nkwane Molefe to identify the known records of the fossils, which allowed them to find the rest of the specimen within just days of searching the Sterkfontein Caves’ Silberberg Grotto. Figure 9.19 The “Black Skull” (Paranthropus aethiopicus) had a large sagittal crest and large, flared zygomatic arches that indicate it had large chewing muscles and a powerful biting force. Environmental change acts as an important keystone in hypotheses regarding the onset of several important hominin traits that are seen in early hominins and which are discussed in this chapter. Evidence for knuckle-walking in our more distant ancestors is also highly contested. The study of the form or size and shape of things; in this case, skeletal parts. Unlike previous notions, this hypothesis states that hominin evolution does not respond to habitat-specific changes or to specific aridity or moisture trends. Large-scale changes in global and regional climate, as well as alterations to the environment, are all linked to hominin diversification, dispersal, and extinction (Maslin et al. Canines worn at the tips. New York: Simon & Schuster. “‘Mrs. Tools dated to 2.5 mya in Ethiopia have been argued to possibly belong to this species. This species was discovered in 1997 by paleoanthropologist Dr. Yohannes Haile-Selassie. Evolving from a non-obligate bipedal ancestor means that the adaptations we have are evolutionary compromises. Earliest stone-tool industry consisting of simple flakes and choppers. “The Makapansgat Australopithecine Environments.” Journal of Human Evolution 24(3): 219–231. As with all robust Australopithecines, P. aethiopicus has the shared derived traits of large, flat premolars and molars; large, flaring zygomatic arches for accommodating large chewing muscles (the temporalis muscle); a sagittal crest for increased muscle attachment of the chewing muscles to the skull; and a robust mandible and supraorbital torus (brow ridge). Figure 9.19b Paranthropus aethiopicus: KNM-WT 17000 lateral right view by eFossils is copyrighted and used for noncommercial purposes as outlined by eFossils. Australopithecus anamensis (after “Anam,” meaning “lake” from the Turkana region in Kenya; Leakey et al. In general, these adaptations allow for greater stability and strength in the lower limb, by allowing for more shock absorption, for a larger surface area for muscle attachment, and for the “stacking” of the skeleton directly over the center of gravity to reduce energy needed to be kept upright. Dates of these early relatives range from around 7 million years ago (mya) to around 1 mya, overlapping temporally with members of our genus, Homo (Figure 9.1). First attributed as Zinjanthropus boisei (with the first discovery going by the nickname “Zinj” or sometimes “Nutcracker Man”), Paranthropus boisei was discovered in 1959 by Mary Leakey (see Figure 9.20 and 9.21; Hay 1990; Leakey 1959). Researchers who prefer to split a highly variable taxon into multiple groups or species. We identified 40 tracks, estimated to be around 90,000 years old and indicating a party of humans travelling fast down a dune slope. A species that can thrive in a wide variety of habitats and can have a varied diet. Leakey, M. 1971. Potential toolmaking capability based on hand morphology, but nothing found directly. 1999), and the femur of a fragmentary partial skeleton (argued to belong to Au. Figure 9.9 Adult human teeth by Genusfotografen (Tomas Gunnarsson) through Wikimedia Sverige Wikimedia Sverige is used under a CC BY-SA 4.0 License. The most divergent group, however, is humans. Or hind dentition (molars and premolars). In recent years, researchers have discovered and assigned a proximal tibia and juvenile cranium (L.338y-6) to the species (Wood and Boyle 2016). Bioarchaeology and Forensic Anthropology, 16. Figure 9.19d Paranthropus aethiopicus: KNM-WT 17000 posterior view by eFossils is copyrighted and used for noncommercial purposes as outlined by eFossils. More evidence of bipedalism is found not in the skeleton but in the footprints of this species. ———. Polytypic: In reference to taxonomy, having two or more group variants. In total that is eight teeth a quadrant, for a total of 32 teeth. The fracturing of rocks for the manufacture of tools. As a collective, this genus spans 2.7 mya to 1.0 mya, although the dates of the individual species differ. Reconstruction based on AL-288-1 by artist John Gurche, front view close-up. garhi. In this chapter, this term refers to a tooth gap occurring between the incisors and canines. Interpretation(s): This hypothesis can be considered in contrast to the Savannah Hypothesis, and it does appear to be evidence based. The bumps on the chewing surface of the premolars and molars, which can be quite sharp in some species. If the environment for some reason becomes drier, it is expected that hippopotamus populations will reduce. In some ways, this hypothesis accommodates both environmental data and our interpretations of an evolution toward greater variability among species and the survivability of generalists. afarensis. She now works as the Community Relations and Development Director for the Center for Academic Research and Training in Anthropogeny (CARTA) at UCSD. However, some retained primitive traits, such as an opposable hallux in Ardipithecus, indicate some retention in climbing ability. africanus and is now argued to be a young male rather than an adult female cranium (Thackeray 2000, Thackeray et al. The femur is the thigh bone, and the proximal part is that which articulates with the pelvis—it is very important when studying posture and locomotion. Richard Leakey and Bernard Wood have both suggested that P. boisei could have made and used stone tools. Adult male australopithecines were usually only about 4.3-4.9 feet tall and weighed around 88-108 pounds. Oxford: Oxford University Press. “The Expansion of Grassland Ecosystems in Africa in Relation to Mammalian Evolution and the Origin of the Genus Homo.” Palaeogeography, Palaeoclimatology, Palaeoecology 207 (3–4): 399–420. These advances in technology go together with the developments in human evolution and cognition, dispersal of populations across the African continent and the world, and climatic changes. Discovery of New Praying Mantis Species from the Time of the Dinosaurs, 50 Million-Year-Old Fossil Assassin Bug Has Unusually Well-Preserved Genitalia, Dinosaur-Era Sea Lizard Had Teeth Like a Shark. Past animals navigating the landscape and falling into cave openings, or caves used as dens by carnivores, led to the accumulation of deposits over millions of years. This would allow certain groups to develop genetic combinations that would increase their ability to survive in shifting environments. Interpretation(s): Despite a relatively scarce early hominin record, it is clear that two important factors occur around the time period in which we see increasing aridity. Figure 9.16c Australopithecus africanus Sts 5 superior view by eFossils is copyrighted and used for noncommercial purposes as outlined by eFossils. Assemblage: A collection demonstrating a pattern. Ples’ from Sterkfontein: Small Male or Large Female?” The South African Archaeological Bulletin, 55: 155–158. The Peninj mandible from Tanzania, found in 1964 by Kimoya Kimeu. Understand changing paleoclimates and paleoenvironments during early human evolution, and contextualize them as potential factors influencing adaptations during this time. These species have coined the term “gracile australopithecines” because of the less exaggerated, smaller, and less robust features seen in the divergent “robust” group. Leakey, L. S. B. These mixed morphologies may indicate that earlier hominins were not fully obligate bipeds and thus thrived in mosaic environments. Selected Answer: e. lamprey Correct Answer: e. “Hominin Evolution in Settings of Strong Environmental Variability.” Quaternary Science Reviews 73: 1–13. Small dentition with Australopithecine cusp-spacing. afarensis indicate some derived traits. ; NOAA Mauna Loa CO₂ record is in the public domain and used within NASA guidelines on re-use. “Australopithecus garhi: A New Species of Early Hominid from Ethiopia.” Science 284 (5414): 629–635. 1986; Constantino and Wood 2007; Hlazo 2015; Kimbel 2015; White 1988). Describe the anatomical changes associated with bipedalism in early hominins and the implications for changes in locomotion. This is documented by the increase of diatomaceous lake sediments during these times. Paranthropus Paleobiology. “Reconstructing Human Evolution: Achievements, Challenges, and Opportunities.” Proceedings of the National Academy of Sciences 10(2): 8902–8909. These are traits (in the case of early hominins, morphological) that are evolved, differing from those seen in earlier populations or forms. afarensis. Partridge, and L.H. This active geological structure is responsible for much of the visibility of the paleoanthropological record in East Africa. The large hole (foramen) at the base of the cranium, through which the spinal cord enters the skull. 1988. Smaller than in extant great apes, larger and pointier than in humans. University of Cape Town, firstname.lastname@example.org. We smash and grind up hard seeds, instead of crushing them with our hind teeth (molars). Enamel hypoplasia is also common in this species, possibly because of instability in the development of large, thick-enameled dentition. Even more robust than considered normal in the Paranthropus genus. Afar Region, Omo, Maka, Fejej, and Belohdelie (Ethiopia); Laetoli (Tanzania); Koobi Fora (Kenya). It possessed the musculature required for tree climbing, and while moving quadrupedally, it likely placed weight on the palms of the hands rather than on the knuckles. afarensis or Au. Figure 9.6 Skeletal comparisons between modern humans (obligate bipeds) and non-obligate bipeds (e.g., chimpanzees). While the level of bipedality in Salehanthropus tchadenisis is debated since there are few fossils and no postcranial evidence, Orrorin tugenensis and Ardipithecus show clear indications of some of these bipedal trends. In general, the robust australopithecines have large temporalis (chewing) muscles, as indicated by flaring zygomatic arches, sagittal crests, and robust mandibles (jawbones). Ardi demonstrates a mosaic of ancestral and derived characteristics in the postcrania. New York: Aldine de Gruyter. In the past, taxonomy was primarily based on morphology (i.e., the physical features of organisms). This term is often used to refer to the Rift Valley, expanding from Malawi to Ethiopia. The generalist nature of the teeth of the gracile australopithecines, and certainly early Homo, would have made these hominins more capable of surviving through and adapting to to environmental change.
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