The black spots on old banana peels may unlock a faster, easier diagnosis of human skin cancer, boosting survival chances, scientists said Monday. When bananas ripen, their skin is covered in small, round black spots caused by an enzyme known as tyrosinase. The same enzyme is present in human skin, and in greater quantities in people suffering from melanoma — a potentially deadly form of skin cancer. A team of scientists used this observed commonality to build a cancer scanner, which they then refined and tested at length on banana peels before moving on to human tissue. First, researchers at the Laboratory of Physical and Analytical Electrochemistry in Switzerland concluded that the enzyme is a reliable marker of melanoma growth. In the earliest stage 1 of cancer, the enzyme is not very apparent, becoming widespread and evenly distributed in stage 2, and unevenly distributed in stage 3 — by when the cancer has started spreading to other parts of the body. The earlier the cancer is detected, the greater the chances of survival. Read more at Discovery News.