So there's probably some risk to group living.

所以群体生活可能存在一些风险。

Those are members who enjoy the benefits of group living without pitching in.

这些成员无需投入即可享受集体生活的好处。

An increase in red blood cells can help a person or group living at high elevations to move and breathe more easily because more red cells can carry more oxygen.

对于生活在海拔较高的地方的某个人或某群人，增加红细胞可以使他们活动和呼吸顺畅，因为更多的红细胞能够携带更多的氧气。