Jacobs said the world may need several vaccines to protect different groups within a population.

贾各布说全球可能需要多种疫苗来保护不同种族的人群。

As Dr Bowles himself says, one cannot always distinguish between deaths due to intergroup violence and that occurring within groups.

正如鲍尔斯本人所说，总是分不清哪些死亡是族群间暴力所致，哪些是同族群暴力所致。

But they do use within group and between group communication.

但他们确实使用组内和组间交流。

It's truly not surprising that tempers might be running wild, and that conflict within groups who needed to stay together for safety might be commonplace.

脾气失控并不奇怪，为了安全需要团结在一起的群体内部的冲突可能是司空见惯的。