Patterns of size sexual dimorphism in Australopithecus afarensis: Another look

Lee, S.-H.

doi:10.1016/j.jchb.2005.07.001

Cited by 27 publications

(17 citation statements)

References 61 publications

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“…The fossil evidence provides some indication that humans have changed their mating systems through time. The robust and gracile australopithecines, as well as H. erectus, all seemingly displayed much larger sexual dimorphism in body size than modern humans (see above), but clear inferences of their sexual behavior are limited by conflicting evidence from their canines, questions of taxonomic assignment, and methodology [Gordon et al, 2008;Lee, 2005;Plavcan, 2000;Reno et al, 2003]. Our data certainly do not resolve this longstanding paleoanthropological debate, nor can they definitively conclude how important, if at all, sperm competition was in hominin evolution, but we believe that they may add some useful information.…”

Section: Patterns Within Hominoid Taxamentioning

confidence: 99%

Hominoid seminal protein evolution and ancestral mating behavior

Carnahan

Jensen‐Seaman

2008

American J Primatol

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Hominoid mating systems show extensive variation among species. The degree of sexual dimorphism in body size and canine size varies among primates in accordance with their mating system, as does the testes size and the consistency of ejaculated semen, in response to differing levels of sperm competition. To investigate patterns of evolution at hominoid seminal proteins and to make inferences regarding the mating systems of extinct taxa, we sequenced the entire coding region of the prostate-specific transglutaminase (TGM4) gene in human, chimpanzee, bonobo, western lowland gorilla, eastern lowland gorilla, orangutan, and siamang, including multiple humans, chimps, and gorillas. Partial DNA sequence of the coding regions was also obtained for one eastern lowland gorilla at the semenogelin genes (SEMG1 and SEMG2), which code for the predominant proteins in semen. Patterns of nucleotide variation and inferred protein sequence change were evaluated within and between species. Combining the present data with previous studies demonstrates a high rate of amino acid substitutions, and low intraspecific variation, at seminal proteins in Pan, presumably driven by strong sperm competition. Both gorilla species apparently possess nonfunctional TGM4, SEMG1, and SEMG2 genes, suggesting that gorillas have had low sperm competition, and therefore their current polygynous mating system, for a long time before their divergence. Similarly, orangutans show longstanding stasis at TGM4, which may be interpreted as evidence for an unchanging mating system for most of their evolution after their divergence from African apes. In contrast to the great apes, the data from humans could be interpreted as evidence of fluctuations between different mating systems or alternatively as a relaxed functional constraint in these proteins. It is our hope that this study is a first step toward developing a model to predict ancestral mating systems from extant molecular data to complement interpretations from the fossil record.

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Section: Patterns Within Hominoid Taxamentioning

confidence: 99%

Hominoid seminal protein evolution and ancestral mating behavior

Carnahan

Jensen‐Seaman

2008

American J Primatol

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“…Cephalometric studies have revealed craniofacial differences between different populations, ages, and sexes. [12] In various populations it is possible to observe many variations of cephalometric patterns within homogeneous groups. [3–5] Hanihara applied distance analysis and factor analysis to 23 craniofacial measurements in 1802.…”

Section: Introductionmentioning

confidence: 99%

A cephalometric study of skulls from the Bahriyah oasis

Zaki

Al-Tohamy

El-Bassyouni

2012

J Forensic Dent Sci

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Objectives:To determine the craniofacial characteristics of crania from the Bahariyah oasis dating from the Greco-Roman period and to compare their cephalometric traits with other ancient Egyptian samples from various time periods and to evaluate sexual dimorphism.Materials and Methods:The sample comprised 149 skulls (90 males and 59 females), belonging to the Greco-Roman (332 B.C. – 395 A.D.). Lateral and postero-anterior cephalograms were taken. Sixteen linear measurements were analyzed and six indices were calculated.Results:Significant differences were found between males and females almost in all measurements. All male measurements were greater than those of the females. The study shows notable differences in the craniofacial parameters of the present sample as compared to other ancient Egyptians from various periods and from various geographical areas.Conclusion:The present study suggests that the studied crania from Bahriyah oasis had a specific craniometric phenotype, which is distinguished from other Egyptian samples from different periods, suggesting some migration could have occurred along the Egyptian Nile Valley over various times.

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“…Such a conclusion, however, does not allow us to know enough about sexual dimorphism in extinct hominids so that it is possible to infer without a doubt whether the first Homo fossils are more or less sexually dimorphic than modern Homo sapiens. Nowadays, Australopithecus is more accepted as less dimorphic than thought before, which indicates that conclusions about sexual dimorphism in extinct hominids are still open for discussion (Lee, 2005;Reno, et al, 2003Reno, et al, , 2010.…”

Section: Discussionmentioning

confidence: 99%