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There are also indicators that altruism has biological roots .

可是也有关于利他主义具有生物学根源的证据。

Some even act out of sheer altruism .

有些行为甚至完全是利他的。

Schadenfreude is unbecoming and not just because of altruism .

幸灾乐祸并不足取，这不仅仅因为我们要无私地帮助别人。

And it 's not just about self-confidence or altruism .

而且，这不仅仅关系到自信或利他主义。

As group size increases , both forms of altruism break down .

群体规模扩大，这两种利他主义情形便消解。