Humans have influenced Earth's history for thousands of years, though some scientists count changes of the last two centuries as especially notable. (Left to right) Universal History Archive/UIG via Getty Images; Hulton Archive/Getty Images; Liszt Collection/Heritage Images/Getty Images; Joint Task Force One/AP hide caption

itoggle caption (Left to right) Universal History Archive/UIG via Getty Images; Hulton Archive/Getty Images; Liszt Collection/Heritage Images/Getty Images; Joint Task Force One/AP

A view of Seattle from the Bullitt Center. Brad Kahn/Flickr hide caption

itoggle caption Brad Kahn/Flickr

Scientists who work for nuclear waste disposal projects in Finland, Canada and Sweden study an ice sheet in western Greenland. Courtesy of Vincent F. Ialenti hide caption

itoggle caption Courtesy of Vincent F. Ialenti

Will the distant future give rise to exhibits of a human past long gone, much as we gawk today at representations of a dinosaur age we can only imagine? Aamir Qureshi/AFP/Getty Images hide caption

itoggle caption Aamir Qureshi/AFP/Getty Images

Coprates Chasma in the Valles Marineris on Mars, photographed by the Mars Express spacecraft. Appearing in the top half of this image, it ranges from 60-100 km wide and drops 8-9 km below the surrounding plains. G. Neukum/ESA/DLR/FU Berlin hide caption

itoggle caption G. Neukum/ESA/DLR/FU Berlin