Which statement describes how the law of superposition supports natural selection?

Which statement describes how the law of superposition supports natural selection?

• A. Deeper layers are younger and contain more complex organisms.
• B. Deeper layers are younger and contain less complex organisms.
• C. Deeper layers are older and contain more basic organisms than the layers above.
• D. Depth has no relation to organism complexity.

Answer: (C)

The law of superposition gives us a time frame for how life changes. In undisturbed sedimentary layers, the oldest rocks and fossils are at the bottom, with progressively younger layers on top. Over long periods, populations change through natural selection, so newer layers tend to show organisms that are more complex or more adapted to their environments than those in older layers. Seeing simpler fossils deeper down and more complex fossils higher up supports the idea that life evolves gradually over time, which is what natural selection explains. So deeper layers being older and containing more basic organisms than the layers above fits best.

The law of superposition gives us a time frame for how life changes. In undisturbed sedimentary layers, the oldest rocks and fossils are at the bottom, with progressively younger layers on top. Over long periods, populations change through natural selection, so newer layers tend to show organisms that are more complex or more adapted to their environments than those in older layers. Seeing simpler fossils deeper down and more complex fossils higher up supports the idea that life evolves gradually over time, which is what natural selection explains. So deeper layers being older and containing more basic organisms than the layers above fits best.