ホモサピエンスは言語を得たことにより，膨大な量の情報を柔軟に収集し，保存し，伝達できるようになった．しかし，どのような情報を何のために言語で伝えたのだろうか．Harari によれば，これには2つの説があるという．1つは「川の近くにライオンがいる」説，もう1つは「噂話」説である．前者は人間の生命に直接関わる関心事に端を発する説であり，後者は人間の社会性に注目した説である．まず，前者の "the there-is-a-lion-near-the-river theory" について，Harari (24--25) は次のように説明する．
A green monkey can yell to its comrades, 'Careful! A lion!' But a modern human can tell her friends that this morning, near the bend in the river, she saw a lion tracking a herd of bison. She can then describe the exact location, including the different paths leading to the area. With this information, the members of her band can put their heads together and discuss whether they should approach the river, chase away the lion, and hunt the bison.
2つ目の "the gossip theory" については，次の通り (Harari 25--26) ．
A second theory agrees that our unique language evolved as a means of sharing information about the world. But the most important information that needed to be conveyed was about humans, not about lions and bison. Our language evolved as a way of gossiping. According to this theory Homo sapiens is primarily a social animal. Social cooperation is our key for survival and reproduction. It is not enough for individual men and women to know the whereabouts of lions and bison. It's much more important for them to know who in their band hates whom, who is sleeping with whom, who is honest, and who is a cheat.
The amount of information that one must obtain and store in order to track the ever-changing relationships of even a few dozen individuals is staggering. (In a band of fifty individuals, there are 1,225 one-on-one relationships, and countless more complex social combinations.) All apes show a keen interest in such social information, but they have trouble gossiping effectively. Neanderthals and archaic Homo sapiens probably also had hard time talking behind each other's backs --- a much maligned ability which is in fact essential for cooperation in large numbers. The new linguistic skills that modern Sapiens acquired about seventy millennia ago enabled them to gossip for hours on end. Reliable information about who could be trusted meant that small bands could expand into larger bands, and Sapiens could develop tighter and more sophisticated types of cooperation.
Harari (27) は，おそらく2つの説とも妥当だろうと述べている．これらは言語の起源と初期の発展を考える上で重要な説だが，それ以上に言語の役割と効能を論じる上で本質的な説となっているのではないか．
・ Harari, Yuval Noah. Sapiens: A Brief History of Humankind. 2011. London: Harvill Secker, 2014.
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