thousands of years before Columbus discovered America (go to answers.com)
Until 1852, Kangchenjunga was assumed to be the highest mountain in the world, but calculations based on various readings and measurements made by the Great Trigonometric Survey of India in 1849 came to the conclusion that Mount Everest, known as Peak XV at the time, was the highest.
The laws of gravity as expressed by Sir Issac Newton were determined before Dr. Louis Pasteur discovered penicillin.
My great uncle Leo Might, my grandma still has a flyer which shows the tallest and shortest marines in World War 2. Her brother was the tallest. Ship captains heard of him before he would board ships and they would come to meet him due to his reputation in size.
Rubber and a number of its uses had already been discovered in the Americas by the native populations long before their countries were colonized. So datewise the only thing we know for sure is that it was discovered (long) before 1492.