At around 1. 65 million years ago, another early human, Homo ergaster, started to create tools in a slightly different fashion.

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问题     At around 1. 65 million years ago, another early human, Homo ergaster, started to create tools in a slightly different fashion. This so-called Acheulean tradition was the tool-making technology used for nearly the entire Stone Age, and practiced until 100,000 years ago. Acheulean tools, such as hand axes and cleavers, were larger and more sophisticated than their predecessors’. They may have been status symbols as well as tools.
    Homo ergaster first appeared in Africa around 2 million years ago, and in many ways resembled us. Though they had brow ridges, they had lost the stoop and long arms of their ancestors. They may have been even more slender than us and were probably well-adapted to running long distances. Some experts believe that they were the first to sport largely hairless bodies, and to sweat, though another theory puts our hairlessness down to an aquatic phase.
    One famous example of a more modern looking early human is the Turkana boy, a teenager when he died, 1. 6 million years ago in Kenya. The shape of this fossil showed that the human pelvis had reached today’s narrow proportions. Combined with the growing size of the human head and brain, this had far-reaching implications; human women now need help for a successful birth; and human babies are born earlier, and need a longer period of childhood care, than those of apes.
    Meat-eating, however, may have allowed us to become early weaners.
    H. ergaster may have been the first early human to leave Africa. Bones dated to around 1. 75 million years ago have been found in Dmanisi in Georgia.
    Shortly afterwards, Homo erectus appeared—the first early human whose fossils have been seen in large numbers outside of Africa. The first specimen discovered, a single cranium, was unearthed in Indonesia in 1891. H. erectus was highly successful, spreading to much of Asia between 1. 8 and 1. 5 million years ago, and surviving as recently as 27,000 years ago.
    This species, with a brain volume of around 1000 cm3 would have interacted with modern humans. They may have been the first people to take to the seas and habitually hunt prey such as mammoths and wild horses, although there is some debate about this. They may also have harnessed the use of fire and built the first shelters.
    In 2004, the remains of a tiny and mysterious human species, that may have lived as recently as 13,000 years ago, was discovered on an Indonesian island. More bones of the "hobbit", or Homo floresiensis, were uncovered in 2005. Some studies suggest it had an advanced brain and was unequivocally a separate species—but others argue that these people were modern humans suffering from a genetic disorder.
Help is needed for a woman to bear a baby mainly because______.

选项 A、human babies are larger
B、human pelvis is narrower
C、human babies are born earlier
D、childhood care is much longer

答案B

解析 根据第三段第二句“…the human pelvis had reached today’s narrow proportions”和第三句“…this had far-reaching implications:human women now need help for a successful birth…”,B应为答案。
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