另一个指标，地球生命指数，是1 686种脊椎动物的种群数量变化的平均数。
Another indicator, the Living Planet Index, averages changes in the sizes of populations of 1, 686 vertebrate species.
如果，正像我们人类要控制自己的种群一样控制各种动物的种群数量，那么，我们既保护了它们，也可以少点儿麻烦，少点儿死亡，少点儿悲哀。
If we can control the amount of animal RACES as well as we control our population, then we both can protect animals and can be less trouble, less dead and less sad.
此外，肮脏、拥挤的住所促进疾病在许多动物种群中扩散，这实际上是昆虫对居住地方的选择。
Furthermore, the squalid, cramped quarters that encourage diseases to propagate among many animal populations are actually the residental choice for insects.
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