SCIENTIFIC AND CRITICAL THINKING QUESTIONS AND ANSWERS

Consider the following passage and answer the questions that follow accordingly.

Humans may have reached northern Europe (including England) 200 000 years earlier than previously thought. Stone tools found in England suggest that early humans were there 700 000 years ago. The stone tools were discovered at a site in Suffolk. The tools have been dated using several methods. Firstly, the magnetic polarity of iron-containing minerals in the sedimentary rocks where the tools were found is aligned north-south, just as it is today. Since the Earth’s magnetic field underwent a polarity reversal 780 000 years ago, the site must be younger than that. The tools were found beneath glacial ice deposits laid down during a period 450 000 years ago when the region was blanketed in ice, so they must be older than this. Also present at the site were fossils of a water vole Mimomys, which was superseded by another vole species called Arvicola around 500 000 years ago. A new amino-acid dating technique gives an estimate of 700 000 years old. The method was used to measure the breakdown of amino acids within shells of a freshwater snail species found with the tools at the site.

1. When were humans previously thought to have reached northern Europe?

a. 450 000 years ago
b. 900 000 years ago
c.  700 000 years ago
d.  500 000 years ago

2. Without the amino acid evidence, which one of the following is the best estimate of the age of the
tools?
a. 500 000 to 780 000 years old
b. 500 000 years old
c.  700 000 years old
d.  450 000 to 500 000 years old

3. Of the following, which best indicates the value of the water vole fossils to the dating of the site?
a. The fossils confirm the date of the glacial deposit.

b. The Mimomys fossils indicate that the site is more than 500 000 years old.
c.  The fossils suggest that the glacial deposits were 50 000 years older than first thought.
d.  The Arvicola fossils indicate that the site is more than 500 000 years old.

4. If found, which one of the following would place the most doubt on the conclusion that early
humans were at the site 700 000 years ago?
a. the freshwater snail species was part of the diet of Mimomys
b. the freshwater snail species did not exist before 500 000 years ago
c.  the freshwater snail species was part of the diet of Arvicola
d.  the freshwater snail species became extinct 500 000 years ago

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