Đinh Văn Khương
Senior Member
Các nhà khoa học Mỹ mới công bố một giả thuyết về nguyên nhân dẫn đến hình dạng bàn tay người như hiện nay. Thật ngạc nhiên, hình dạng bàn tay của chúng ta hiện nay có được là ( một phần) kết quả của quá trình chọn lọc giới tính để người tiền sử oánh nhau một cách hiệu quả nhất.
"The derived proportions of the human hand may provide supportive buttressing that protects the hand from injury when striking with a fist. Flexion of digits 2–5 results in buttressing of the pads of the distal phalanges against the central palm and the palmar pads of the proximal phalanges. Additionally, adduction of the thenar eminence to abut the dorsal surface of the distal phalanges of digits 2 and 3 locks these digits into a solid configuration that may allow a transfer of energy through the thenar eminence to the wrist. To test the hypothesis of a performance advantage, we measured: (1) the forces and rate of change of acceleration (jerk) from maximum effort strikes of subjects striking with a fist and an open hand; (2) the static stiffness of the second metacarpo-phalangeal (MCP) joint in buttressed and unbuttressed fist postures; and (3) static force transfer from digits 2 and 3 to digit 1 also in buttressed and unbuttressed fist postures. We found that peak forces, force impulses and peak jerk did not differ between the closed fist and open palm strikes. However, the structure of the human fist provides buttressing that increases the stiffness of the second MCP joint by fourfold and, as a result of force transfer through the thenar eminence, more than doubles the ability of the proximal phalanges to transmit ‘punching’ force. Thus, the proportions of the human hand provide a performance advantage when striking with a fist. We propose that the derived proportions of hominin hands reflect, in part, sexual selection to improve fighting performance."
và đây là nguồn cơn của cái tiểu thuyết (novel) trên:
"ACKNOWLEDGEMENTS
We thank Professor Frank Fish for suggesting the null hypothesis with a wave of his fist and the exclamation ‘I can hit you in the face with this, but it did not evolve for that!’ Nadja Schilling, Frank Fish, Denise Morgan and Emma Schachner read and provided helpful feedback on early versions of the manuscript. Denise Morgan provided the drawings for figures. "
???
nguồn: http://jeb.biologists.org/content/216/2/236.full
"The derived proportions of the human hand may provide supportive buttressing that protects the hand from injury when striking with a fist. Flexion of digits 2–5 results in buttressing of the pads of the distal phalanges against the central palm and the palmar pads of the proximal phalanges. Additionally, adduction of the thenar eminence to abut the dorsal surface of the distal phalanges of digits 2 and 3 locks these digits into a solid configuration that may allow a transfer of energy through the thenar eminence to the wrist. To test the hypothesis of a performance advantage, we measured: (1) the forces and rate of change of acceleration (jerk) from maximum effort strikes of subjects striking with a fist and an open hand; (2) the static stiffness of the second metacarpo-phalangeal (MCP) joint in buttressed and unbuttressed fist postures; and (3) static force transfer from digits 2 and 3 to digit 1 also in buttressed and unbuttressed fist postures. We found that peak forces, force impulses and peak jerk did not differ between the closed fist and open palm strikes. However, the structure of the human fist provides buttressing that increases the stiffness of the second MCP joint by fourfold and, as a result of force transfer through the thenar eminence, more than doubles the ability of the proximal phalanges to transmit ‘punching’ force. Thus, the proportions of the human hand provide a performance advantage when striking with a fist. We propose that the derived proportions of hominin hands reflect, in part, sexual selection to improve fighting performance."
và đây là nguồn cơn của cái tiểu thuyết (novel) trên:
"ACKNOWLEDGEMENTS
We thank Professor Frank Fish for suggesting the null hypothesis with a wave of his fist and the exclamation ‘I can hit you in the face with this, but it did not evolve for that!’ Nadja Schilling, Frank Fish, Denise Morgan and Emma Schachner read and provided helpful feedback on early versions of the manuscript. Denise Morgan provided the drawings for figures. "
???
nguồn: http://jeb.biologists.org/content/216/2/236.full
