61.The argument that humans，even in prehistoric times，had some number sense，at least to the extent ofrecognizing the concepts of more and less when some objects were added to ortaken away from a small group，seems fair．for studies have shown that some animals possess such a sense．

(复合句，主句的主干是the argument…seems fair，其中从句that humans…had some number sense做argument的同位语)

人类甚至在史前已经有数字感，至少到有些物体被加到一小组里或者被拿走时能够辨别出“多了”还是“少了”的程度，这一观点似乎很合理，因为研究已经表明有些动物就有这样的意识。

分句1. Theargument seems fair

分句2. humans，even in prehistoric times，had some number sense，

分句3. at leastto the extent of recognizing the concepts of more and less

分句4. when someobjects were added to or taken away from a small group

分句5. forstudies have shown that some animals possess such a sense．

1和5并列

2和3嵌套

3和4嵌套

1和2嵌套

分句1是前半句的主干，和分句5并列。分句2中包含一个插入结构：even in prehistoric times，分句3是分句2的状语；分句4是分句3的定语从句；分句2是分句1的同位语从句。