The researchers found that the Neanderthal fossil had approximately 0.0078 as much 14C as found originally in the atmosphere. (a) Using the numbers on your graph, determine how many half-lives have passed since the Neanderthal died. (b) Using your 14C calibration on the x-axis, what is the approximate age of the Neanderthal fossil in years (round off to the nearest thousand)? (c) Approximately when did Neanderthals become extinct according to this study? (d) The researchers cite evidence that modern humans (H. sapiens) became established in the same region as the last Neanderthals approximately 39,000 – 42,000 years ago. What does this suggest about the overlap of Neanderthals and modern humans?

Short Answer

Expert verified
  1. Seven half-lives have passed since the Neanderthal died.
  2. The Neanderthal fossil was 40,110 years old.
  3. The Neanderthal became extinct around 40,110 years ago.
  4. Neanderthals and modern humans might have lived for about 2,000 years in the same region.

Step by step solution

01

Explanation for (a)

According to the graph, the Neanderthal fossil had about 0.0078 or 7.8 × 10-3 14C at seven half-lives. This suggests that seven half-lives have passed since the Neanderthal died.

02

Explanation for (b)

According to the graph, the time at seven half-lives is 40,110 years. Therefore, the age of the Neanderthal fossil is about 40,110 years.

03

Explanation for (c)

According to the graph, the age of the Neanderthal fossil is about 40,110 years. Therefore, the Neanderthal must have become extinct around 40,110 years or less than that.

04

Explanation for (d)

According to the researchers, modern humans lived in the same region as Neanderthals did around 39,000-42,000 years ago. This suggests thatNeanderthals and modern humans may have been established in the same region for about 2,000 years.

This is because Neanderthals became extinct around 40,110 years or less than that.

It is also possible that Neanderthals and modern humans may not have overlapped in the past.

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Most popular questions from this chapter

A standard curve of radioactive isotope decay is shown at the top of the right column. The graph line shows the fraction of the radioactive isotope over time (before present) in units of half lives. Recall that a half-life is the amount of time it takes for half of the radioactive isotope to decay. Labeling each data point with the corresponding fractions will help orient you to this graph. Draw an arrow to the data point for half-life = 1 and write the fraction of 14C that will remain after one half life. Calculate the fraction of 14C remaining at each half-life and write the fractions on the graph near arrows pointing to the data points. Convert each fraction to a decimal number and round off to a maximum of three significant digits (zero at the beginning of the number do not count as significant digits). Also write each decimal number in scientific notation.

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