Why? Because they're easy to test.

为什么因为它们易于检测
People generally don't like to give bone samples so that

一般人不愿提供骨骼样本
their bones can be tested for strontium-90.

以进行锶90的检测
By the way, there's an interesting kind of way to

顺便一提有一种有趣的方式
figure out what's in your bone by testing teeth.

可通过牙齿检测确定骨骼内的物质
So by testing the deciduous teeth of young kids,

因此通过检测孩子的乳牙
the Atomic Energy Commission figured this out

原子能委员会解决了问题
and they were actually going around from dentist

他们竟然还跑去各大牙医处
to dentist collecting teeth from people, thinking,

收集人们的牙齿心想
"Why were we crazy enough to have to collect bones from dead people

"为什么我们要疯狂地从尸体上收集骨骼
when we could have just collected teeth?"

只要收集牙齿不就得了"
So you find this pattern of recognition first in wildlife,

这种探知过程首先出现在野生动物上