Humans evolved 3 billion years ago after the earth was formed.<span />
The answer can be either multicellular organisms or the scientific word of Eukaryotes.
Answer:
The scientific method
:
Make an observation.
Ask a question.
Form a hypothesis, or testable explanation.
Make a prediction based on the hypothesis.
Test the prediction.
Iterate: use the results to make new hypotheses or prediction
Explanation
that's the scientific method but there are many example to how you use it in everyday life i.e the lights went out and you want to find out why, perhaps you didn't pay your bill or maybe the power went out. then you would go through the steps to find out what happened
If you look at this what do you see the earth and when there is the full moon what do you see.
They are used to directly amplify segments of dna