Question

Using the "Checkpoints Section" of your eBook answer the following question:
What types of evidence allow scientists to infer that single-celled life likely existed 3.8 billion years ago?
Select all that apply.
• evidence of extinction events
• transitional fossils in ancient rocks
• fossil evidence, such as stromatolites
• certain forms of carbon in ancient rock

Answer 1

The types of evidence that allow scientists to infer that single-celled life likely existed 3.8 billion years ago include:

- fossil evidence, such as stromatolites
- certain forms of carbon in ancient rock

These pieces of evidence support the presence of early single-celled organisms on Earth during that time.