Ongoing Evolution in Humans

Madrigal, Lorena; Willoughby, Jessica Fitts

doi:10.1002/9781444320039.ch12

Cited by 3 publications

(3 citation statements)

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“…A recent study by Savell et al () provides an explicit analysis of these relationships by examining the effect of constraints imposed by trait covariance on trait evolution using a global sample of humans. This work contributes to a growing body of process‐based research confirming that human postcranial variation is shaped both by selective pressures that differ across ecogeographic regions (Betti, von Cramon‐Taubadel, Manica, & Lycett, ; Madrigal & Willoughby, ; Roseman & Auerbach, ), as well as by patterns of co‐evolution between traits. Using a quantitative genetic approach, Savell et al () estimated the force of directional selection on the six traits most commonly used in the assessment of ecogeographic variation and thermoregulatory adaptation.…”

Section: Introductionmentioning

confidence: 84%

“…Traditionally, such studies relied on identifying correlations of human morphological variation with geography—namely latitude—and ascribed evolutionary causes (i.e., adaptation) to explain this eco‐morphological relationship. More recently, research using quantitative genetic analytical methods has demonstrated that observed trait variation evolved in response to a combination of gene flow, genetic drift, and natural selection (Betti, Lycett, von Cramon‐Taubadel, & Pearson, ; Betti, von Cramon‐Taubadel, & Lycett, ; Madrigal & Willoughby, ; Roseman & Auerbach, ; Savell, Auerbach, & Roseman, ). The current study builds on this literature by examining whether humans living across a global range of ecogeographic regions exhibit differences in the ability of body size and shape to respond to natural selection.…”

Section: Introductionmentioning

confidence: 99%

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Evolvability in human postcranial traits across ecogeographic regions

Savell

2020

American J Phys Anthropol

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Objectives: Though recent quantitative genetic analyses have indicated that directional selection appears to be acting on limb lengths and measures of body size in modern humans, these studies assume equal evolvability across modern human groups. However, differences in trait covariance structure due to ancient migration patterns and/or selection may limit the evolvability of populations further from Africa. This study therefore explores patterns of human evolvability across ecogeographic regions. Materials and Methods: Mean evolvability, respondability, conditional evolvability, and autonomy were calculated from variance-covariance matrices of limb length and body size measures representing 14 human groups spanning four ecogeographic regions. Measures of evolvability were compared across groups and regions, and the minimum sample size, inaccuracy, and bias were calculated for each. Results: When compared between regions, humans demonstrate significant differences between indices of evolvability across regions. Despite the relatively recent evolution of modern humans, several measures of evolvability show a strong negative correlation with latitude across regions, demonstrating a reduction in genetic variance that is potentially reflective of human migration and/or response to selection.Conclusions: These results demonstrate the importance of establishing patterns of evolvability prior to additional quantitative genetic analyses, and emphasize the influence of sample size on the accuracy of estimated evolvability measures. These findings also suggest that while modern human groups share similar covariance structures, there is evidence for emergent differentiation in evolvability and respondability between human groups across ecogeographic regions, further complicating our ability to apply results derived from modern human groups to ancient hominin lineages.

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Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Evolvability in human postcranial traits across ecogeographic regions

Savell

2020

American J Phys Anthropol

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“…One such distinction from historical precedent in biological anthropology is that researchers over the last 15 years have begun to apply quantitative genetic methods to disentangle the evolutionary processes responsible for shaping morphological variation (e.g., Agosto & Auerbach, 2021, 2022; Baab, 2018; Betti et al, 2013; Katz et al, 2016; Lewton, 2012; Madrigal & Willoughby, 2010; Rolian, 2009; Rolian et al, 2010; Roseman, 2016; Roseman & Auerbach, 2015; Savell, 2020; Savell et al, 2016, 2022; Schroeder & von Cramon‐Taubadel, 2017; Villamil, 2018; von Cramon‐Taubadel, 2019). Methods based on quantitative genetic evolutionary models (especially following Cheverud, 1984; Lande, 1979; Lande & Arnold, 1983) provide the only avenue for distinguishing trait responses to natural selection from the effects of stochastic and/or neutral evolutionary processes while also examining how those traits interact (covary) with each other, and how that covariance affects evolutionary outcomes.…”

Section: Introductionmentioning

confidence: 99%

Morphology, evolution, and the whole organism imperative: Why evolutionary questions need multi‐trait evolutionary quantitative genetics

Auerbach

Savell

Agosto

2023

American Journal of Biological Anthropology

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Since Washburn's New Physical Anthropology, researchers have sought to understand the complexities of morphological evolution among anatomical regions in human and non‐human primates. Researchers continue, however, to preferentially use comparative and functional approaches to examine complex traits, but these methods cannot address questions about evolutionary process and often conflate function with fitness. Moreover, researchers also tend to examine anatomical elements in isolation, which implicitly assumes independent evolution among different body regions. In this paper, we argue that questions asked in primate evolution are best examined using multiple anatomical regions subjected to model‐bound methods built from an understanding of evolutionary quantitative genetics. A nascent but expanding number of studies over the last two decades use this approach, examining morphological integration, evolvability, and selection modeling. To help readers learn how to use these methods, we review fundamentals of evolutionary processes within a quantitative genetic framework, explore the importance of neutral evolutionary theory, and explain the basics of evolutionary quantitative genetics, namely the calculation of evolutionary potential for multiple traits in response to selection. Leveraging these methods, we demonstrate their use to understand non‐independence in possible evolutionary responses across the limbs, limb girdles, and basicranium of humans. Our results show that model‐bound quantitative genetic methods can reveal unexpected genetic covariances among traits that create a novel but measurable understanding of evolutionary complexity among multiple traits. We advocate for evolutionary quantitative genetic methods to be a standard whenever appropriate to keep studies of primate morphological evolution relevant for the next seventy years and beyond.

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