Question

question 1 - 16 scientists once believed that all headaches were caused by factors like loud noises, bright lights or stress. after several studies showed unusual brain activity during headaches, scientists proposed a new explanation: chemical changes in the brain could also cause headaches. these studies were repeated by other scientists with similar results. why did scientists change their explanation? repeated studies provided scientists with new evidence. the original idea was proven to be true by the new evidence. scientists did not believe the original idea so they made up a new one. scientists always update explanations when new ideas are suggested, even without testing.

Explanation:

Scientists base their explanations on evidence. When repeated studies provide new evidence that contradicts the original idea, they change their explanations. They don't stick to un - proven ideas or make up new ones without evidence.

Answer:

Repeated studies provided scientists with new evidence.