Form, function and evolution of the human hand

Abstract

The modern human hand is an intriguing mix of primitive morphology and derived function. Traditionally, its form and function are explained as a functional “trade‐off” between the requirements of locomotion and manipulation, but recently acquired comparative, experimental and fossil evidence suggests that this functional trade‐off is more complex than conventional wisdom suggests. Moreover, when studying hand evolution within the hominin clade, the only morphological evidence comes from the hard‐tissues, and evidence about hand function must be inferred indirectly from the archaeological record. We lack information about critical aspects of hand form (e.g., soft tissues) and function (e.g., neurology) as well as non‐lithic evidence about behavior. Thus, comparative anatomical, experimental and ethological studies of modern humans and other primates are critical to making more informed inferences about hand use in the past. We review the relevant fossil and archaeological evidence within the relevant comparative context (e.g., other extant apes and dexterous monkeys) in an attempt to reconstruct hand evolution within the hominin clade. We conclude by summarizing our current understanding—or lack thereof—of the evolutionary history of the modern human hand.

Lower Paleolithic Shaped Stone Balls—What Is Next? Some Cultural–Cognitive Questions

“…Nonetheless, there are limitations in these approaches, and there are still many disagreements on the evolutionary changes associated with the evolution of the manipulative abilities in the human lineage [46][47][48]. In fact, the gross hand anatomy can supply poor and incomplete information on hand functions, the fossil record is largely fragmented, and the evolution of the hand has probably experienced mosaic, parallel and independent phylogenetic diversification [49]. Indeed, because of these limitations, the most we can do is integrate anatomical and behavioural differences in order to provide speculative but reasonable hypotheses on the evolution of the body-tool perceptual and cognitive system [50,51].…”

Cortical bone architecture of hominid intermediate phalanges reveals functional signals of locomotion and manipulation

“…Notably, the manual intermediate phalanges within the hominin fossil record show a mix of primitive and derived morphologies that suggest a diverse range of manual behaviors during the evolution of the hominin hand (Alba et al, 2003;Haile-Selassie & WoldeGabriel, 2009;Kivell et al, 2015Kivell et al, , 2018Kivell et al, , 2020Larson et al, 2009;Napier, 1962;Susman & Creel, 1979). Functional inferences regarding manual behaviors of these fossil specimens have been made using elements of the carpus (Kivell et al, 2013;Marzke et al, 2010;Tocheri et al, 2007), the metacarpus Galletta et al, 2019;Skinner et al, 2015) and the phalanges (Almécija et al, 2010;Kivell et al, 2015Kivell et al, , 2018Kivell et al, , 2022Syeda et al, 2022), but the intermediate phalanges are relatively understudied. Here we build on our previous work (Syeda et al, 2023) and investigate variation in cortical bone structure of the intermediate phalanges of digits 2-5 (IP2-IP5) within the context of inferred hand use in humans and other extant hominids (Pongo, Gorilla, and Pan).…”

“…Extant great apes and modern humans use a range of hand postures during positional (locomotor and postural) and manipulative behaviors (e.g., Kivell et al, 2020; Schmitt et al, 2016), which have been successfully linked to the morphological variation within great ape hands (Bird et al, 2021, 2022; Dunmore et al, 2019; Dunmore, Bardo, et al, 2020; Dunmore, Skinner, et al, 2020; Marchi, 2005; Matarazzo, 2008, 2015; Tsegai et al, 2013). This form‐function link among extant taxa has been used to infer habitual manual activities of fossil taxa, ranging from Miocene apes (Almecija et al, 2009; Almécija et al, 2012; Susman, 2004) to fossil Homo sapiens (Bardo et al, 2020; Kivell et al, 2022; Stephens et al, 2018). Recent discoveries of hominin hand fossils have revealed mosaic morphologies suggesting hand use during both arboreal locomotion and dextrous manipulation (Dunmore, Skinner, et al, 2020; Kivell et al, 2015, 2018).…”

Influence of food physical properties and environmental context on manipulative behaviors highlighted by new methodological approaches in zoo‐housed bonobos (Pan paniscus)

“…If human hand presents the highest level of dexterity compared with other primates (Key et al, 2018;Marzke et al, 1992;Marzke, 2013), with forceful precision grips between the pad of the thumb and the pads of the fingers and complex intra-manual precision manipulative movements (Kivell, 2015;Marzke et al, 2015;Marzke, 1997Marzke, , 2013Napier, 1960;Pouydebat et al, 2011), other species have shown their ability to process food in complex ways, using tools or not (e.g., Byrne et al, 2001). Comparative behavioral studies of hand use in our closest living relatives, in zoo and free-ranging conditions, can improve our understanding of the functional morphology in early hominins (i.e., Homo sapiens and their extinct relatives) as well as fossil apes (Bardo et al, 2017;Feix et al, 2015;Kivell et al, 2022;Pouydebat et al, 2008Pouydebat et al, , 2011Susman, 1998;Tbnooka & Matsuzawa, 1995). These studies continuously contribute to a better understanding of the evolution of manipulative behaviors that led to this extremely large manipulative flexibility in humans.…”