题目解析:
本题问的是与古老简单的杂食性人相比,现在的杂食者有哪些变化。选项A说他们更早地断掉了母乳喂养,我们可以在Since women are less fertile when they are breast-feeding, substituting cereals for mother s milk would have resulted in closer spacing of births and the potential for a greater number of live births for each woman发现谷类可以代替母乳,正确;选项B说他们体内脂肪含量更低,是错的,其实更高了;选项C说他们吃的谷类种类更少了,应该是更多了更丰富了;选项D说他们更难得到容易消化的食物,应该是更容易得到。选A。