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R B Eckhardt

Publications and source records attributed to R B Eckhardt.

12 recordsLinked to original sources
PubMed1992

Apes and apomorphies: the anterior nasal spine as a projection of cladistic conceptions.

Projections, tubercles, or spines of bone at the anterior margin of the piriform aperture occur in widely varying forms among catarrhine primates. This paper describes, illustrates, and tabulates the frequencies of such structures by age and sex in a large collection of Pan troglodytes verus skulls. In the overall sample of 263 skulls where the region could be observed, these protuberances of bone occur bilaterally in 10.7% of specimens and unilaterally in an additional 3.4%. They increase in frequency with age to a high of 16.9% in adult and older animals. Among adult specimens, these projections of bone in the anterior nasal region are present more commonly in females than in males. In a comparative context, variants on this structure in nonhuman primates, some of them documented previously, should help to counter the cladistic conception that the anterior nasal spine is an apomorphic or evolutionary novel morphological structure in hominids.

Age Factors↗
PubMed1991

Hominid brain evolution: two conceptions of science.

This paper re-examines the repeatedly-offered hypothesis (Fialkowski 1978, 1986, 1987, 1988) that hominid brain expansion was largely a side effect of evolutionary response to increased heat stress under conditions of primitive hunting, and resulted in a preadaptation to enhanced cognitive abilities. Fialkowski's hypothesis, previously shown to be based on data that are seriously inaccurate, continues to be presented in a manner that precludes testing. Consequently, however interesting these ideas may be, they are beyond the conventional domain of anthropology as a legitimate subdiscipline of modern science.

Adaptation, Biological↗
PubMed1990

Morphological variation in the nasal region of extant and fossil hominids.

We describe here the mid-facial region of a skull of anatomically modern Homo sapiens (FAI 3/2/1) that exhibits upwardly divergent nasal bones. In previous literature, that pattern has been described as a diagnostic character state for the robust early hominid taxon Paranthropus. This specimen supports our viewpoint that nasal region morphology varies extensively within and between living hominoid primate taxa, in patterns that provide a basis for understanding how microevolutionary variation serves as the basis for macroevolutionary transformations.

Animals↗
PubMed1989

Evolutionary morphology of human skeletal characteristics.

Human skeletal morphology has been a central focus of physical anthropology since the origin of the discipline about a century ago. Over that period skeletally-related characteristics, continuous and discontinuous, have been studied extensively in present and past populations. Through time our awareness of the interactions between the genetic and environmental influences reflected in skeletally-related phenotypes has become increasingly detailed and sophisticated. This paper reviews our growing knowledge of the genetic basis of human skeletal morphology, with particular emphasis on the significance of this information for the reconstruction of relationships among populations distributed broadly in space and time.

Anthropology, Physical↗
PubMed1987

Was plio-pleistocene hominid brain expansion a pleiotropic effect of adaptation to heat stress?

This paper examines the hypothesis (Fiałkowski 1978, 1986) that hominid brain expansion was largely a side effect of an evolutionary response to increased heat stress under conditions of primitive hunting, with reduction in reliability of brain components due to a rise in temperature having been offset by increases in the number of cerebral sub-units and interconnections among them. Fiałkowski's hypothesis is shown here to be based on measurements that are seriously inaccurate, and the explanatory mechanism to be contradicted by existing data on response to heat stress by smaller-brained nonhuman primates.

Animals↗
PubMed1975

The relative body weights of Bornean and Sumatran orangutans.

Although original field data suggested that the average Bornean orangutan weighed twice as much as the Sumatran ones, this is shown to be an error. The only statistically significant difference in weight is between males and females, regardless of geographical area or data source.

Analysis of Variance↗
PubMedDate not supplied

Hominoid nasal region polymorphism and its phylogenetic significance.

The morphology of the nasal bones and their articulations with the adjoining frontal and maxillary bones have recently been reported in Nature and elsewhere to be diagnostic of hominoid taxa, and cladistic analysis based on these features has been used to assign two immature Plio-Pleistocene hominoids (AL 333-105 and Taung) to different lineages (Paranthropus and Homo, respectively). Because earlier studies had established that hominoid crania are highly variable intraspecifically, it seemed desirable to try to replicate the study reporting a consistently different pattern for each hominoid taxon. My results show extensive polymorphism in the nasal region within every taxon of extant pongids, including several rather clear examples, in extant Pan troglodytes, of that recently hypothesized to be a 'paranthropine' pattern. These findings underscore the substantial risks inherent in cladistic analyses using very restricted character sets to assign individual specimens to particular taxa.

Animals↗