Our ape-men forefathers had no obvious natural weapons in
the struggle for survival in the strong claws of the big cats. They had
neither the powerful teeth nor the strong claws, and could not rival with the
bear, whose strength and speed provided an impressively "small-fire"
weaponry. 67.
______. They could not even defend themselves by running swiftly like horses.
If the ape-men attempted to compete on those terms in the open, they would
have 68. ______. been
doomed to failure and extinction. But they were born with enormous concealing
69. ______. advantages of a kind not possessed by any of
its competitors.
70. ______. In the search for
the pickings of the forest, the ape-men were developed
71. ______. efficient short-distance vision and a
sense of color that the animals of the grasslands did not possess. The
ability to see dearly at dose range permitted them to study practical
problems in a way that lay far from the reach of
72. ______. original inhabitants of the
grassland. Good long-distance sight was another matter. Lack of
short-distance vision had not been a problem for forest-
73. ______. dwelling apes and monkeys
because of the higher the viewpoint, the greater
74. ______. the range of sight. So everything they had
to do was climb a tree. But out
75. ______. in the open this simple solution was available. Climbing a hill
would have 76.
______. helped, but in many places the ground was flat. The ape-men had only
77.
______. possible solution. They stood up on their hind limbs (后肢) and began
to walk upright.