"one theory has to do with our diets.Scientists say the diet of prehistoric humans probably required more chewing teeth.Life was probably a little rougher on the teeth back then,too.So it was good to have extras.”的翻译。
还有就是此句中"do with"和"rougher"是什么意思？
这段文字包含了那些句式？尽可能解析说一下？
各位可以翻译一下这段英文吗？尤其是“Life was probably a little rougher on the teeth back then,too.So it was good to have extras.”这句~我实在看不懂这是什么意思？
