Human impacts on the natural environment during the later part of the Holocene (beginning about 4,000 years ago) complicate investigations into environmental change during that period because the signals produced by human-and climate-induced change are sometimes difficult to separate. For example, in the later Holocene, one indicator of increased aridity due to climate change is an increase in pollen from grasses, as forest vegetation gives way to grassland. Such a change in vegetation could alternatively be attributed to human impact in the form of agricultural development. Examples of such human impact from 4,000 years ago would be small-scale, however, since the broad ecosystem changes brought about by the widespread adoption of agricultural technologies occurred later.
2. According to the passage, which of the following is true regarding environmental changes 4,000
years ago?
A. No localized increases in grass pollen were caused by agricultural development.
B. Increases in grass pollen were at least sometimes a reflection of an increase in aridity.
C. Wholesale ecosystem changes probably resulted from agricultural development.
D. Any small-scale changes occurring then would not be detectable now.
E. Environmental change helped induce the adoption of agricultural technologies.
如果是这样领结的话,那么我觉得应该选C才对。
答案是B。
B在原文里是For example, in the later Holocene, one indicator of increased aridity due to climate change is an increase in pollen from grasses
一个由气候变化引起的干旱增加的标志是pollen from grass
那么就是干旱是pollen from grass 的indicator 或者说reflection,这也能说的通。
根据文章最后一句话可知:4000年前人类的农业活动是small-scaled,因此无法带来broad ecosystem changes, 侧面的说明了4000年前的increased aridity是因为气候原因导致的increase in pollen from grass,而不是人类导致的。选B正确