To end on a lighter note, the last chapter in Part VII takes us full circle by examining the current and fascinating issue of the importance of Paleolithic nutrition to humans entering the twenty-first century.

句中to humans entering the twenty-first century 做什么成分？

 entering thetwenty-first century 是做humans的后置定语，还是 分析为介词to的宾语humans的宾语补主语？该怎么分析呢？