« previous next »

Author Question: Why is it that scientists know less about the first four-fifths of Earth's history than about the ... (Read 126 times)

ap345

  • Hero Member
  • *****
  • Posts: 537
on: Jul 16, 2018
Why is it that scientists know less about the first four-fifths of Earth's history than about the last, most recent one-fifth?
 
  What will be an ideal response?

Question 2

Assuming that humans went extinct today, do you think that they would be good index fossils? Why or why not?
 
  What will be an ideal response?


dyrone

  • Sr. Member
  • ****
  • Posts: 322
Reply #1 on: Jul 16, 2018
Answer to Question 1

Answer: The short answer is that the farther back in time, the fewer the clues that remain because of two major factors: 1) Precambrian rocks (which make up 88 percent of Earth's history) have been intensely deformed, so evidence was destroyed, and 2) the first abundant fossil evidence does not appear until the beginning of the Cambrian period.

Answer to Question 2

Answer: Yes. Modern humans have only existed for 100,000 years and are geographically widespread.


Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
« previous next »
 

Did you know?

One way to reduce acid reflux is to lose two or three pounds. Most people lose weight in the belly area first when they increase exercise, meaning that heartburn can be reduced quickly by this method.

Did you know?

Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.

Did you know?

To prove that stomach ulcers were caused by bacteria and not by stress, a researcher consumed an entire laboratory beaker full of bacterial culture. After this, he did indeed develop stomach ulcers, and won the Nobel Prize for his discovery.

Did you know?

Malaria was not eliminated in the United States until 1951. The term eliminated means that no new cases arise in a country for 3 years.

Did you know?

Computer programs are available that crosscheck a new drug's possible trade name with all other trade names currently available. These programs detect dangerous similarities between names and alert the manufacturer of the drug.

The geological timescale and an overview of the history of life on Earth The geological timescale and an overview of the history of life on Earth
The Sun is the nearest star to Earth. The Sun is the nearest star to Earth.
The health history can be gathered from many sources The health history can be gathered from many sources
Scientists (group photo) Scientists (group photo)
Toussaint L’Ouverture leads a revolt of slaves against the French in Haiti—the first and only major Toussaint L’Ouverture leads a revolt of slaves against the French in Haiti—the first and only major
Earth’s orientation Earth’s orientation
Video: Complement Proteins Animation

For a complete list of videos, visit our video library