In the Light of Evolution Volume IV: The Human Condition (2010) / Chapter Skim
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1 Reconstructing Human Evolution: Achievements, Challenges, and Opportunities--Bernard Wood
1 Reconstructing Human Evolution: Achievements, Challenges, and Opportunities--Bernard Wood
Pages 5-26
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From page 5... ...
how can homoplasy be recognized and factored into attempts to recover phylogeny? T his contribution begins by considering two achievements relevant to reconstructing human evolution: resolving the branching struc ture of the higher primate part of the tree of life and the recovery of a substantial body of fossil evidence for human evolution (Fig.
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From page 6... ...
however, the time between the FAD and the lAD is likely to represent the minimum time span of a taxon, because it is highly unlikely that the fossil record of a taxon, and particularly the relatively sparse fossil records of early hominin taxa, include the earliest and most recent fossil evidence of a taxon. The newest archaic hominin taxon, the ca.
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From page 7... ...
The Human Fossil Record The fossil record of the human clade consists of fossil evidence for modern humans plus that of all extinct taxa that are hypothesized to be more closely related to modern humans than to any other living taxon. not so long ago nearly all researchers were comfortable with accord ing the human clade the status of a family, the hominidae, with the nonhuman extant great apes (i.e., chimpanzees, bonobos, gorillas, and orangutans)
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From page 8... ...
The grades used in this review are "Anatomically modern Homo," "Premodern Homo," "Transitional hominins," "Archaic hominins," "Megadont archaic hominins," and "Possible hominins." We use a relatively speciose taxonomic hypothesis (Table 1.1) and present the species within each grade in the historical order the taxa were recognized, not in their temporal order.
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robustusa Megadont archaic hominins P boisei P
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Anatomically Modern Homo This grade includes hominin fossil evidence that is indistinguishable from the morphology found in at least one regional population of modern humans. Modern humans belong to the species Homo sapiens linnaeus 1758, and the earliest H
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From page 11... ...
heidelbergensis, but the variation in the later Homo fossil record is too great to be accommodated in a single taxon. researchers who wish to make a distinction between fossils such as Florisbad and laetoli 18 and subrecent and living modern humans either do so taxonomically by referring the former specimens to a separate species, Homo helmei Dreyer 1935, or they distinguish them informally as "archaic Homo sapiens." Premodern Homo This grade grouping includes Pleistocene Homo taxa that lack the derived and distinctive size and shape of the modern human cranium and postcranial skeleton.
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The initial discovery and the type specimen, the Mauer 1 adult mandible, was found in 1907 in a sand quarry near heidelberg, Germany. other evidence included in the taxon comes from sites in europe (e.g., Petralona)
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From page 13... ...
74–17 ka. The initial discovery and type specimen is lB1, an associated partial adult skeleton, but a second associated skeleton and close to 100 separate fossils representing up to 10 individuals have subsequently been recovered.
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From page 14... ...
habilis with confidence are the postcranial bones associated with the type specimen, oh 7, and the associated skeleton, oh 62; isolated postcranial bones from olduvai Gorge assigned to H habilis (e.g., oh 10)
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The Au. afarensis hypodigm includes a well-preserved skull, partial and fragmented crania, many lower jaws, sufficient limb bones t o be able to estimate stature and body mass (Kimbel and Delezene, 2009)
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4.2–3.9 Ma. The fossil evidence consists of jaws, teeth, and postcranial elements from the upper and lower limbs.
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Megadont Archaic Hominins This grade includes hominin taxa conventionally included in the genus Paranthropus and one Australopithecus species, Australopithecus garhi. The genus Paranthropus, into which Zinjanthropus and Paraustralopithecus are subsumed, was reintroduced when cladistic analyses suggested that the first three species discussed in this section most likely formed a clade.
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From page 18... ...
robinson 1960. Additional fossils from olduvai Gorge have subsequently been added to the hypodigm, as well as fossil evidence from the east African sites of Peninj, omo shungura, Konso, Koobi Fora, Chesowanja, and West Turkana.
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From page 19... ...
The hypodigm is presently restricted to fossils recovered from the hata Member in the Middle Awash study area, ethiopia. The type specimen, the ca.
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The type specimen is TM266-01-060-1, a plastically deformed adult cranium, and the rest of the small hypodigm consists of mandibles and some teeth; there is no published postcranial evidence.
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. These four taxa could be primitive hominins, but they could also belong to separate clades of apes that share homoplasies with the human clade.
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so why do competent researchers disagree about how many species should be recognized within the hominin fossil record? researchers who favor a more anagenetic (or gradualistic)
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From page 23... ...
if these adaptations of the megadont archaic hominins were inherited from a recent common ancestor, then a separate Paranthropus genus is justified; however, if they occurred independently in the P aethiopicus and P
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From page 24... ...
First, it provides morphological information in 3D about the eDJ, a structure that was hitherto inaccessible without destructively sectioning a tooth crown, and second, by focusing on the morphology of eDJ it means that worn teeth, which may preserve very little in the way of detailed outer enamel surface morphology, can be used to generate information about the range of intraspecific variation in hominin fossil taxa (skinner et al., 2008b)
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From page 25... ...
. since 1863 much progress has been made in both the accumulation of fossil evidence germane to human evolution, in the techniques used to capture morphologic information from that fossil evidence, and in the methods used to analyze those data.
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