Scientists have now accurately carbon-dated the sharp tip that itself carved from mastodon bone.
如今，利用放射性碳素测定年代法，科学家已确定这一用乳齿象牙雕刻而成的长矛尖端的精确年代。
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And because those artifacts closely resemble others from nearby sites previously carbon-dated to about 9000 B.C., Schmidt and co-workers estimate that Gobekli Tepe's stone structures are the same age.
Food grains, scraps of cloth, bits of wood and so on can thus be dated by finding out how much radioactive carbon is left in them: the less there is, the older they are.