Detail Making a Fist of It; The Evolution of the Hand   Oleh:  [s.n] Jenis: Article from Bulletin/Magazine Dalam koleksi: The Economist (http://search.proquest.com/) vol. 405 no. 8816 (Dec. 2012), page 115. Topik: Human Organ; Bodily Structure; Hands; Human Evolution Ketersediaan Perpustakaan Pusat (Semanggi) Nomor Panggil: EE29.75 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada     Lihat Detail Induk Isi artikel How a dual-use bodily structure came into existence. The appendage at the end of a human being's arm is a strange organ. It is the only one that has different names, depending on what it is being used for. Employ it to hold something, and it is called a hand. Employ it to hit someone, and it is called a fist. That second use, though, is almost unknown in other primates. Most primate hands are long of palm and finger, short of thumb, and suited for climbing. Human hands have short palms, short fingers and long thumbs, which are not. These proportions do, though, make it possible to grip things in two ways that other apes' hands cannot manage well. One is by using what is known as a precision grip, in which an object is held between the pads of the finger tips (especially the first and second fingers) and the pad of the thumb. The other is by means of a power grip, in which all the fingers and the thumb are wrapped around what is being grasped. These two grips are crucial to Homo sapiens's characteristic tool-crafting skills, and it has thus long been thought that the widespread use of tools by humanity's ancestors was the driving force behind the modern hand's proportions. Opini Anda Klik untuk menuliskan opini Anda tentang koleksi ini! Kembali

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