A tough nut to crack

Jennings, Justin; Macmillan, Neil A.

doi:10.1007/bf01114704

Cited by 75 publications

(86 citation statements)

References 1 publication

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“…Consequently, their strength is largely independent of the point on the external surface receiving the percussive strike, which must therefore simply apply enough force to induce fracturing. Nut shells can be very hard indeedmacadamia nuts, for example, have an elastic modulus (a measure of the material's stiffness, or resistance to permanent deformation under compressive loading) of the order of 2 -6 kN mm -2 [31], and require a force of the order of 2 kN to fracture them [32 -34], while typical orally processed primate foodstuffs given in captivity have an elastic modulus in the range 0.1 -350 N mm -2 [35]. The force required to fracture nuts of the species used by wild chimpanzees varies with the nut species and condition: typical forces required to fracture such nuts range from 2.8 kN for Coula edulis to 8.1 kN for Parinari excelsa, and between 9.7 and 12.5 kN for Panda oleosa ( [36]; cf.…”

Section: Functional Parameters Of Percussive Technologiesmentioning

confidence: 99%

Functional mastery of percussive technology in nut-cracking and stone-flaking actions: experimental comparison and implications for the evolution of the human brain

Bril¹,

Smaers

Steele

et al. 2012

Phil. Trans. R. Soc. B

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Various authors have suggested behavioural similarities between tool use in early hominins and chimpanzee nut cracking, where nut cracking might be interpreted as a precursor of more complex stone flaking. In this paper, we bring together and review two separate strands of research on chimpanzee and human tool use and cognitive abilities. Firstly, and in the greatest detail, we review our recent experimental work on behavioural organization and skill acquisition in nut-cracking and stoneknapping tasks, highlighting similarities and differences between the two tasks that may be informative for the interpretation of stone tools in the early archaeological record. Secondly, and more briefly, we outline a model of the comparative neuropsychology of primate tool use and discuss recent descriptive anatomical and statistical analyses of anthropoid primate brain evolution, focusing on corticocerebellar systems. By juxtaposing these two strands of research, we are able to identify unsolved problems that can usefully be addressed by future research in each of these two research areas.

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Section: Functional Parameters Of Percussive Technologiesmentioning

confidence: 99%

Functional mastery of percussive technology in nut-cracking and stone-flaking actions: experimental comparison and implications for the evolution of the human brain

Bril¹,

Smaers

Steele

et al. 2012

Phil. Trans. R. Soc. B

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“…It is made up of two distinct layers where the outer, thicker portion is a very hard sclerenchymatous tissue consisting of fibres and stone cells [1]. Jennings and MacMillan [2] and Wang and Mai [3,4] analysed the biomechanical properties of Macadamia nuts (Macadamia sp.) and came to the conclusion that the structure of the testa ought to be highly optimised for toughness.…”

Section: Introductionmentioning

confidence: 99%

Fruit walls and nut shells as an inspiration for the design of bio-inspired impact resistant hierarchically structured materials

Seidel

Thielen

Schmitt

et al. 2010

WIT Transactions on Ecology and the Environment

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Until today the structuring of different types of fruit walls has only been used as an inspiration for packaging when seen from a biomimetic perspective. However, by detailed investigation of the Macadamia nut with its tough testa, Citrus maxima, which possesses a large spongy mesocarp and Cocos nucifera, which has a combination of a fibrous mesocarp and a tough endocarp, it becomes evident that those structures also provide excellent biological role models for impact and puncture resistant materials. Both Citrus maxima and Cocos nucifera are relatively heavy, lack any aerodynamic adaptation and share the same challenge of having to withstand impact from heights of more than 10 metres. By conducting high speed camera controlled free fall experiments of Citrus maxima from six metres high we could demonstrate a deceleration of the fruits of 3100m/s², which corresponds to 316g, without any visible damage to the fruit. An analysis using cyclic quasi static compression tests of the pericarp of Citrus maxima revealed that the material behaves constantly in good approximation after the first loading cycle. During the first cycle almost 75% of the energy is dissipated. The pericarp of Citrus maxima is highly visco-elastic, which causes the samples within one minute to recover 30% of their initial deformation caused by loading to 40% strain. The mesocarp of Citrus maxima is best described as an open pore foam with gradual increase in pore size. Understanding the principles of how combining structure and material in biological constructions yields a fully functional protection layer will allow us to construct new lightweight bio-inspired materials of high impact and puncture resistance with a combination of high energy dissipation, benign failure and almost complete recovery from large deformations.

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“…Some of these champion protectors, such as the abalone shell, have inspired material science advances such as new forms of bullet-proof armor [Jackson et al 1988;Menig et al 2000]. Others, such as the Macadamia nut shell, still require ingenious methods (for example, lasers [Jennings and Macmillan 1986]) to fracture without crushing their fragile contents. One significant obstacle in predicting the strength of natural shells is understanding their complex material properties [Currey 2002].…”

Section: Introductionmentioning

confidence: 99%

Turtle shell and mammal skull resistance to fracture due to predator bites and ground impact

Hu¹,

Sielert²,

Gordon³

2011

J. Mech. Mater. Struct.

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We investigate the relation between the thickness and diameter of naturally occurring shells, such as the carapaces of turtles and the skulls of mammals. We hypothesize that shells used for different protective functions (for example, protection against headbutting or falling on the ground) will exhibit different power-law trends for shell thickness and diameter. To test this hypothesis, we examine over 600 shells from museum collections with diameters between 1 and 100 cm. Our measurements indicate that eggs, turtle shells, and mammalian skulls exhibit clear and distinct allometric trends. We use a theoretical scaling analysis based on elastic thin shell theory to show that the trends observed are consistent with the corresponding protective functions hypothesized. We thus provide theoretical evidence that shells can be classified by their protective function.

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A tough nut to crack

Cited by 75 publications

References 1 publication

Functional mastery of percussive technology in nut-cracking and stone-flaking actions: experimental comparison and implications for the evolution of the human brain

Functional mastery of percussive technology in nut-cracking and stone-flaking actions: experimental comparison and implications for the evolution of the human brain

Fruit walls and nut shells as an inspiration for the design of bio-inspired impact resistant hierarchically structured materials

Turtle shell and mammal skull resistance to fracture due to predator bites and ground impact

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