Understanding Fossil Dating

The video explains how scientists determine the age of fossils using carbon dating. It begins by discussing how living organisms incorporate carbon, including carbon-12 and carbon-14, into their bodies. Carbon-14 is unstable and decays over time, allowing scientists to measure the ratio of carbon-14 to carbon-12 to estimate the time since an organism's death. This method is effective for fossils up to 60,000 years old. For older fossils, other elements with longer half-lives are used. The video is presented by Michael Moyer for Scientific American's Instant Egghead series.

What method do scientists use to determine the age of a tree?

• Measuring the height

• Examining the roots

• Counting the rings

• Looking at the leaves

How do animals obtain carbon?

• By absorbing sunlight

• By eating plants

• By drinking water

• By breathing

What is the difference between carbon-12 and carbon-14?

• Carbon-12 has 6 protons and 8 neutrons

• Carbon-14 is stable

• Carbon-12 is radioactive

• Carbon-14 has 6 protons and 8 neutrons

What happens to carbon-14 in an animal's body after it dies?

• It starts to decay

• It increases

• It turns into carbon-12

• It remains the same

What is the half-life of carbon-14?

• 7000 years

• 5000 years

• 6000 years

• 5730 years

After two half-lives, what fraction of the original carbon-14 remains?

• One sixteenth

• One eighth

• One quarter

• One half

How do scientists measure the age of a fossil using carbon dating?

• By measuring the amount of carbon-12

• By measuring the amount of carbon-14

• By measuring the ratio of carbon-14 to carbon-12

• By measuring the amount of nitrogen

Up to how many years old can carbon dating accurately date fossils?

• 10,000 years

• 100,000 years

• 30,000 years

• 60,000 years

What do scientists use to date fossils older than 60,000 years?

• Carbon-14

• Carbon-12

• Unstable elements with longer half-lives

• Stable elements