According to a theory advanced
by researcher Paul Martin, the wave
of species extinctions that occurred
Line in LACE>North AmericaLACE> about 11,000 years
(5) ago, at the end of the Pleistocene era,
can be directly attributed to the arrival
of humans, i.e., the Paleoindians, who
were ancestors of modern Native
Americans. However, anthropologist
(10) Shepard Krech points out that large
animal species vanished even in areas
where there is no evidence to demon-
strate that Paleoindians hunted them.
Nor were extinctions confined to large
(15) animals: small animals, plants, and
insects disappeared, presumably not
all through human consumption. Krech
also contradicts Martin’s exclusion of
climatic change as an explanation by
(20) asserting that widespread climatic
change did indeed occur at the end of
the Pleistocene. Still, Krech attributes
secondary if not primary responsibility
for the extinctions to the Paleoindians,
(25) arguing that humans have produced
local extinctions elsewhere. But,
according to historian Richard White,
even the attribution of secondary
responsibility may not be supported
(30) by the evidence. White observes that
Martin’s thesis depends on coinciding
dates for the arrival of humans and the
decline of large animal species, and
Krech, though aware that the dates
(35) are controversial, does not challenge
them; yet recent archaeological
discoveries are providing evidence
that the date of human arrival was
much earlier than 11,000 years ago.
Q7:
Which of the following, if true, would most weaken Krech’s objections to Martin’s theory?
- Further studies showing that the climatic change that occurred at the end of the Pleistocene era was even more severe and widespread than was previously believed
- New discoveries indicating that Paleoindians made use of the small animals, plants, and insects that became extinct
- Additional evidence indicating that widespread climatic change occurred not only at the end of the Pleistocene era but also in previous and subsequent eras
- Researchers’ discoveries that many more species became extinct in LACE>North AmericaLACE> at the end of the Pleistocene era than was previously believed
- New discoveries establishing that both the arrival of humans in LACE>North AmericaLACE> and the wave of Pleistocene extinctions took place much earlier than 11,000 years ago
答案B
请问，这题中的C选项是否也有削弱的作用呢？如果在物种消失以前就有这种天气的变更，那“由天气变更引起物种灭绝”的假设就有问题了啊。我的想法有问题吗？ | 
