The big bang theory. The big bang theory is the theory that all life started when space; creating all the planets and universe. On our planets, life started in what's called primordial soup. They believe that our planet was originally very volcanic and hot and that we all started as the exact same single-celled organism. We then grew and evolved as the earth cooled down. After that, we evolved into what we are today. That is what most scienctists believe. However, Christianity and many other religions believe that God created the earth. Or in some multiple gods worked.
Muscles can also receive messages from the brain when the body temperature decreases. They respond by shivering. Shivering causes the muscles to contract and relax quickly. This process generates heat.
