Many assume male fertility is limitless with some famous examples like Charlie Chaplin having kids up until his seventies.

大多数人都认为男性的生育能力不受年龄的限制，众所周知的就是卓别林一直到七十多岁还有在生育。

Research into male fertility really only began to make waves in the 1990s.

对男性生育能力的研究真正在 1990 年代才开始掀起波澜。

A study from 2013 found that there is a big change that happens in male fertility after the age of 34.

2013 年的一项研究发现，男性在 34 岁之后的生育能力发生了巨大变化。

They found that a mutation in one of the mammoths' genes could have caused reduced male fertility, and a mutation in another gene may have led to developmental defects.

他们发现，猛犸象其中一个基因的突变可能导致雄性生育能力下降，而另一个基因的突变可能导致发育缺陷。