ÜDS-Sosyal 2001-1 Soru=62

We can understand from the passage that, before the ancient trophies of Pedra Furada came to light, ---- .

If you wish to glimpse the ancient trophies of
Pedra Furada, in a difficult, mountainous area of
northeastern Brazil, you must be prepared to face
intense dry heat, treacherous rocky ground,
sudden flooding, boulders falling from cliffs,
aggressive snakes and swarms of mosquitoes. It's
worth it, though, for the archeological treasures to
be found there are exceptionally ancient. Rock
paintings - vivid depictions of prehistoric ways of
life, including dancing, hunting, war and sex rituals
- have been dated at more than 12,000 years old,
while curious pebble structures, primeval bonfires
and early stone tools are up to 50,000 years old.
The discovery of the remains had a profound
effect on our knowledge of American prehistory,
for they suggested that the first people in the New
World arrived not via a bridge of ice from Siberia
but by sea from Africa or possibly even Australia.