Answer:
Scientists used the scientific method of investigation to test this phenomenon. The scientific method consists of these steps:
Make observations: Scientists observed that nerve damage causes severe pain. Scientists knew bone marrow cells seemed to decrease nerve pain, but the reason was unknown.
Ask questions and construct the hypothesis: Would injecting bone marrow cells into the spinal cord decrease pain?
Test the hypothesis: Injected bone marrow cells into the spinal cord of mice that had nerve damage. Observed changes in the cells, and monitored the pain levels in the mice.
Analyze the results and make a conclusion: Determined that the pain decreased because the bone marrow cells released a pain-relieving protein that helps damaged cells.
Test and modify: Make a plan to repeat the test in humans.
Step-by-step explanation: