为什么会出现“生物钟”“生物钟”是自然界中普遍存在的现象。例如:雄鸡报晓、布谷啼春、候鸟迁徒等都是其具体表现。锯断一棵大树看到一圈圈的年轮,这是树的“生物钟”;大象的象牙上有一节节的同心圆状的生长环,这是大象的“生物钟”。为什么会出现“生物钟” Why does it appear that the “biological clock” “biological clock” is a common phenomenon in nature. For example: rooster reported Xiao Chu Cloth spring, migratory birds and so on are its specific performance. Saw a tree to see a ring of rings, which is the tree’s “biological clock”; the elephant’s ivory has a concentric ring-like growth ring, which is the elephant’s “biological clock ”. Why does it appear “biological clock”