Complex Tasks Force Hand Laterality and Technological Behaviour in Naturalistically Housed Chimpanzees: Inferences in Hominin Evolution

Clear hand laterality patterns in humans are widely accepted. However, humans only elicit a significant hand laterality pattern when performing complementary role differentiation (CRD) tasks. Meanwhile, hand laterality in chimpanzees is weaker and controversial. Here we have reevaluated our results on hand laterality in chimpanzees housed in naturalistic environments at Fundació Mona (Spain) and Chimfunshi Wild Orphanage (Zambia). Our results show that the difference between hand laterality in humans and chimpanzees is not as great as once thought. Furthermore, we found a link between hand laterality and task complexity and also an even more interesting connection: CRD tasks elicited not only the hand laterality but also the use of tools. This paper aims to turn attention to the importance of this threefold connection in human evolution: the link between CRD tasks, hand laterality, and tool use, which has important evolutionary implications that may explain the development of complex behaviour in early hominins

The cientificWorldJOURNAL Review Article Complex Tasks Force Hand Laterality and Technological Behaviour in Naturalistically Housed Chimpanzees: Inferences in Hominin Evolution

Clear hand laterality patterns in humans are widely accepted. However, humans only elicit a significant hand laterality pattern when performing complementary role differentiation (CRD) tasks. Meanwhile, hand laterality in chimpanzees is weaker and controversial. Here we have reevaluated our results on hand laterality in chimpanzees housed in naturalistic environments at Fundació Mona (Spain) and Chimfunshi Wild Orphanage (Zambia). Our results show that the difference between hand laterality in humans and chimpanzees is not as great as once thought. Furthermore, we found a link between hand laterality and task complexity and also an even more interesting connection: CRD tasks elicited not only the hand laterality but also the use of tools. This paper aims to turn attention to the importance of this threefold connection in human evolution: the link between CRD tasks, hand laterality, and tool use, which has important evolutionary implications that may explain the development of complex behaviour in early hominins

Complex Tasks Force Hand Laterality and Technological Behaviour in Naturalistically Housed Chimpanzees: Inferences in Hominin Evolution

Clear hand laterality patterns in humans are widely accepted. However, humans only elicit a significant hand laterality pattern when performing complementary role differentiation (CRD) tasks. Meanwhile, hand laterality in chimpanzees is weaker and controversial. Here we have reevaluated our results on hand laterality in chimpanzees housed in naturalistic environments at Fundació Mona (Spain) and Chimfunshi Wild Orphanage (Zambia). Our results show that the difference between hand laterality in humans and chimpanzees is not as great as once thought. Furthermore, we found a link between hand laterality and task complexity and also an even more interesting connection: CRD tasks elicited not only the hand laterality but also the use of tools. This paper aims to turn attention to the importance of this threefold connection in human evolution: the link between CRD tasks, hand laterality, and tool use, which has important evolutionary implications that may explain the development of complex behaviour in early hominins

DETERMINING HOMINID HANDEDNESS IN LITHIC DEBITAGE: A REVIEW OF CURRENT METHODOLOGIES

Handedness is inextricably linked to brain lateralization and language in humans, and identifying handedness in the paleo-archaeological record is important for understanding hominid cognitive evolution. This study reports on experiments for identifying knapper handedness in lithic debitage using three previously established methods: , and . A blind study was conducted on lithic debitage (n = 631) from Acheulean handaxes (n = 10) created by right- and left-handed subjects. Blinded handedness predictions for flakes were compared to their true handedness in order to assess each method's reliability. In order to test replicability, multiple observers classified a sample of flakes and inter-observer agreement was assessed. None of the methods were better than chance in predictive accuracy, and there were significant issues with inter-observer agreement. This study suggests that identifying knapper handedness in lithic debitage is extremely difficult, but also that some existing methodological issues may have simple solutions; suggestions for future research on this topic are provided

Two million years of flaking stone and the evolutionary efficiency of stone tool technology

Temporal variability in flaking stone has been used as one of the currencies for hominin behavioural and biological evolution. This variability is usually traced through changes in artefact forms and techniques of production, resulting overall in unilineal and normative models of hominin adaptation. Here, we focus on the fundamental purpose of flaking stone—the production of a sharp working edge—and model this behaviour over evolutionary time to reassess the evolutionary efficiency of stone tool technology. Using more than 19,000 flakes from 81 assemblages spanning two million years, we show that greater production of sharp edges was followed by increased variability in this behaviour. We propose that a diachronic increase in this variability was related to a higher intensity of interrelations between different behaviours involving the use and management of stone resources that gave fitness advantages in particular environmental contexts. The long-term trends identified in this study inform us that the evolutionary efficiency of stone tool technology was not inherently in advanced tool forms and production techniques, but emerged within the contingencies of hominin interaction with local environments