How Humans Differ from Other Animals in Their Levels of Morphological Variation

McKellar, Ann E.; Hendry, Andrew P.

doi:10.1371/journal.pone.0006876

Cited by 34 publications

(12 citation statements)

References 41 publications

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“…Eight body mass estimates from the femur ( Table 2 ) have a standard deviation of only 4.3 kilograms, for a body mass coefficient of variation (CV) of only 9%. The CV of body mass within most human populations is substantially higher than this, with an average near 15% ( McKellar and Hendry, 2009 ). Likewise, the size variation of cranial and dental elements is minimal.…”

Section: Discussionmentioning

confidence: 99%

Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa

Berger

Hawks

Ruiter

et al. 2015

eLife

386

325

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Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Cradle of Humankind, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations but a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including Homo erectus, Homo habilis or Homo rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike foot and lower limb. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur. Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa.

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Section: Discussionmentioning

confidence: 99%

Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa

Berger

Hawks

Ruiter

et al. 2015

eLife

386

325

View full text Add to dashboard Cite

show abstract

“…We did not have enough samples within species to estimate this standard deviation from our data. Instead, we use an average value calculated across 210 taxonomically varied animal species (0.0772, McKellar and Hendry 2009).…”

Section: Methodsmentioning

confidence: 99%

Early Bursts of Body Size and Shape Evolution Are Rare in Comparative Data

et al. 2010

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George Gaylord Simpson famously postulated that much of life's diversity originated as adaptive radiations—more or less simultaneous divergences of numerous lines from a single ancestral adaptive type. However, identifying adaptive radiations has proven difficult due to a lack of broad‐scale comparative datasets. Here, we use phylogenetic comparative data on body size and shape in a diversity of animal clades to test a key model of adaptive radiation, in which initially rapid morphological evolution is followed by relative stasis. We compared the fit of this model to both single selective peak and random walk models. We found little support for the early‐burst model of adaptive radiation, whereas both other models, particularly that of selective peaks, were commonly supported. In addition, we found that the net rate of morphological evolution varied inversely with clade age. The youngest clades appear to evolve most rapidly because long‐term change typically does not attain the amount of divergence predicted from rates measured over short time scales. Across our entire analysis, the dominant pattern was one of constraints shaping evolution continually through time rather than rapid evolution followed by stasis. We suggest that the classical model of adaptive radiation, where morphological evolution is initially rapid and slows through time, may be rare in comparative data.

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“…We assumed a mean initial body size value of 27 kg for H. floresiensis and about 50 kg for H. erectus [28,29]. These values (as well as brain size; see below) were transformed to natural logarithms to stabilize variance and normalize the statistical distribution of the traits for allometric analyses of brain-body size relationships [30][31][32]. Of course, there is uncertainty in these values for the ancestor and descendent populations, especially in the sense of assuming the skull of H. floresiensis (LB1) to be a somewhat 'typical' specimen [28].…”

Section: Materials and Methods (A) Species Datamentioning

confidence: 99%

Island Rule, quantitative genetics and brain–body size evolution inHomo floresiensis

Diniz‐Filho

Raia

2017

Proc. R. Soc. B.

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Colonization of islands often activate a complex chain of adaptive events that, over a relatively short evolutionary time, may drive strong shifts in body size, a pattern known as the Island Rule. It is arguably difficult to perform a direct analysis of the natural selection forces behind such a change in body size. Here, we used quantitative evolutionary genetic models, coupled with simulations and pattern-oriented modelling, to analyse the evolution of brain and body size in , a diminutive hominin species that appeared around 700 kya and survived up to relatively recent times (60-90 kya) on Flores Island, Indonesia. The hypothesis of neutral evolution was rejected in 97% of the simulations, and estimated selection gradients are within the range found in living natural populations. We showed that insularity may have triggered slightly different evolutionary trajectories for body and brain size, which means explaining the exceedingly small cranial volume of requires additional selective forces acting on brain size alone. Our analyses also support previous conclusions that may be most likely derived from an early Indonesian, which is coherent with currently accepted biogeographical scenario for expansion out of Africa.

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How Humans Differ from Other Animals in Their Levels of Morphological Variation

Cited by 34 publications

References 41 publications

Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa

Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa

Early Bursts of Body Size and Shape Evolution Are Rare in Comparative Data

Island Rule, quantitative genetics and brain–body size evolution inHomo floresiensis

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