Estimating sexual dimorphism by method‐of‐moments

Josephson, Steven C.; Juell, Kenneth E.; Rogers, Alan R.

doi:10.1002/(sici)1096-8644(199606)100:2<191::aid-ajpa3>3.3.co;2-0

Cited by 11 publications

(17 citation statements)

References 27 publications

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“…SD has been measured in many ways, but typically when the sex of each specimen is known it is measured as the ratio of mean male size to mean female size, or as the logarithm of that ratio if it is to be used in statistical analyses (Smith, 1999). When sexes are unknown, a variety of methods have been used to estimate SD, including max/min ratio (e.g., Richmond and Jungers, 1995), mean method ratio (e.g., Simons et al, 1999), method of moments (e.g., Josephson et al, 1996), coefficient of variation (e.g., Leutenegger and Shell, 1987;Lockwood et al, 1996), and the binomial dimorphism index (e.g., Reno et al, 2003). Each of these techniques is susceptible to error under various conditions, although simulation studies and studies of actual primate data have shown max/min ratios to be particularly poor estimators while mean method ratios are relatively good estimators (Plavcan, 1994;Rehg and Leigh, 1999).…”

Section: Measuring Dimorphismmentioning

confidence: 99%

Strong postcranial size dimorphism in Australopithecus afarensis: Results from two new resampling methods for multivariate data sets with missing data

Gordon

Green

Richmond

2007

American J Phys Anthropol

106

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There is considerable debate over the level of size dimorphism and inferred social behavior of Australopithecus afarensis. Most previous studies have analyzed size variation in single variables or multiple variables drawn from single elements. These approaches suffer from small sample sizes, underscoring the need for new techniques that incorporate measurements from multiple unassociated elements, reducing the influence of random sampling on size variation in fossil samples. One such technique, the template method, has recently been proposed but is limited to samples with a template specimen and is sensitive to a number of assumptions. Here we present two new resampling methods that do not require a template specimen, allow measurements from multiple unassociated elements to be included in a single analysis, and allow for significance tests between comparative and fossil multivariate data sets with missing data. Using these new methods, multivariate postcranial size dimorphism is measured using eight measurements of the femur, tibia, humerus, and radius in samples of A. afarensis, modern humans, chimpanzees, gorillas, and orangutans. Postcranial dimorphism in A. afarensis is similar to that of gorillas and orangutans, and significantly greater than in modern humans and chimpanzees. Because studies in living primates have examined the association of behavior with dimorphism in body mass and craniodental measurements, not postcrania, relationships between postcranial dimorphism and social behavior must be established to make robust behavioral inferences for A. afarensis. However, the results of this and past studies strongly suggest behavioral and mating strategies differed between A. afarensis and modern humans.

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Section: Measuring Dimorphismmentioning

confidence: 99%

Strong postcranial size dimorphism in Australopithecus afarensis: Results from two new resampling methods for multivariate data sets with missing data

Gordon

Green

Richmond

2007

American J Phys Anthropol

106

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“…We would add that in fossil samples covering large geographic and chronologic ranges, interpopulational variation, directional trends or diachronic fluctuations can contribute more to the sample variation (even if the sample is large) than sexual dimorphism (this would not be the case of the Sima de los Huesos sample if, as we believe, it comes from one single population). Josephson et al (1996) used the method-of-moments to estimate the degree of sexual dimorphism in samples of unknown sex. It has the advantage over other methods of allowing estimation of confidence intervals.…”

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confidence: 99%

Intrapopulational body size variation and cranial capacity variation in middle pleistocene humans: The Sima de los Huesos sample (Sierra de Atapuerca, Spain)

Lorenzo

Carretero

Arsuaga

et al. 1998

Am. J. Phys. Anthropol.

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A sexual dimorphism more marked than in living humans has been claimed for European Middle Pleistocene humans, Neandertals and prehistoric modern humans. In this paper, body size and cranial capacity variation are studied in the Sima de los Huesos Middle Pleistocene sample. This is the largest sample of non-modern humans found to date from one single site, and with all skeletal elements represented. Since the techniques available to estimate the degree of sexual dimorphism in small palaeontological samples are all unsatisfactory, we have used the bootstraping method to asses the magnitude of the variation in the Sima de los Huesos sample compared to modern human intrapopulational variation. We analyze size variation without attempting to sex the specimens a priori. Anatomical regions investigated are scapular glenoid fossa; acetabulum; humeral proximal and distal epiphyses; ulnar proximal epiphysis; radial neck; proximal femur; humeral, femoral, ulnar and tibial shaft; lumbosacral joint; patella; calcaneum; and talar trochlea. In the Sima de los Huesos sample only the humeral midshaft perimeter shows an unusual high variation (only when it is expressed by the maximum ratio, not by the coefficient of variation). In spite of that the cranial capacity range at Sima de los Huesos almost spans the rest of the European and African Middle Pleistocene range. The maximum ratio is in the central part of the distribution of modern human samples. Thus, the hypothesis of a greater sexual dimorphism in Middle Pleistocene populations than in modern populations is not supported by either cranial or postcranial evidence from Sima de los Huesos.

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“…While previous studies of pattern have focused on sexual dimorphism, this study examines intraspecific variation as a whole. This difference in focus is important because, although there is a relationship between sexual dimorphism and intraspecific variation, particularly when levels of dimorphism are high and intrasexual variation is low (Fleagle et al, 1980; Plavcan, 1994), a measure of sexual dimorphism is not an exact proxy for a measure of variation, particularly when levels of dimorphism are low (Plavcan, 1994; Josephson et al, 1996; Rehg and Leigh, 1999), as they are in the dentition.…”

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confidence: 99%

Patterns of tooth crown size and shape variation in great apes and humans and species recognition in the hominid fossil record

Scott

Lockwood

2004

American J Phys Anthropol

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It has been suggested that patterns of craniodental variation in living hominids (Gorilla, Homo, Pan, and Pongo) may be useful for evaluating variation in fossil hominid assemblages. Using this approach, a fossil sample exhibiting a pattern of variation that deviates from one shared among living taxa would be regarded as taxonomically heterogeneous. Here we examine patterns of tooth crown size and shape variation in great apes and humans to determine 1) if these taxa share a pattern of dental variation, and 2) if such a pattern can reliably discriminate between samples that contain single species and those that contain multiple species. We use parametric and nonparametric correlation methods to establish the degree of pattern similarity among taxa, and randomization tests to assess their statistical significance. The results of this study show that extant hominids do not share a pattern of dental size variation, and thus these taxa cannot be used to generate expectations for patterns of size variation in fossil hominid species. The hominines (Gorilla, Homo, and Pan) do share a pattern of shape variation in the mandibular dentition; however, Pongo is distinct, and thus it is unclear which, if either, pattern should be expected in fossil hominids. Moreover, in this case, most combined-species samples exhibit patterns of shape variation that are similar to those for single hominine species samples. Thus, although a common pattern of shape variation is present in the mandibular dentition, it is not useful for recognizing taxonomically mixed paleontological samples.

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Estimating sexual dimorphism by method‐of‐moments

Cited by 11 publications

References 27 publications

Strong postcranial size dimorphism in Australopithecus afarensis: Results from two new resampling methods for multivariate data sets with missing data

Strong postcranial size dimorphism in Australopithecus afarensis: Results from two new resampling methods for multivariate data sets with missing data

Intrapopulational body size variation and cranial capacity variation in middle pleistocene humans: The Sima de los Huesos sample (Sierra de Atapuerca, Spain)

Patterns of tooth crown size and shape variation in great apes and humans and species recognition in the hominid fossil record

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