The Cathedral Spires in the Black Hills of South Dakota are just one of innumerable formations across the planet that speak to the Earth's ancient history. K. Scott Jackson/Ohio Water Science Center/USGS hide caption

itoggle caption K. Scott Jackson/Ohio Water Science Center/USGS

The plate on the left contains about equal numbers of colonies of two different bacteria. After the bacteria compete and evolve, the lighter ones have taken the lead in the plate on the right. Courtesy of Michael Wiser hide caption

itoggle caption Courtesy of Michael Wiser

The first taste of an olive can be a bit shocking. But eventually, many of us start to enjoy bitter fruits, nuts and beverages. Screenshot from TEDxTalks/Youtube.com hide caption

itoggle caption Screenshot from TEDxTalks/Youtube.com

Human evolution is an unfolding process with chapters yet to be written; no one really knows where we're going. But we can look back to earlier chapters, with ancestors like Australpithecus afarensis, including the individual we call "Lucy" (seen above), for an understanding of how evolution works and what has happened to us over time. Tim Boyle/Getty Images hide caption

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A man reaches for a wooden cross in the sea during an Epiphany ceremony in the Greek port of Thessaloniki on January 6, 2011. Sakis Mitrolidis/AFP/Getty Images hide caption

itoggle caption Sakis Mitrolidis/AFP/Getty Images

Kind of cute. But pretty stupid. A scale model of a baby sauropod in its egg. Tim Boyle/Getty Images hide caption

itoggle caption Tim Boyle/Getty Images

Nom Nom Nom: From left, a cast of teeth from a chimpanzee, Australopithecus afarensis and a modern human. We switched from an ape-like diet of fruits and leaves about 3.5 million years ago, according to fresh research. There's evidence that meat-eating came about a million years or so later. William Kimbel/Institute of Human Origins hide caption

itoggle caption William Kimbel/Institute of Human Origins

British naturalist Alfred Russel Wallace (1823-1913) played a pivotal role in developing the theory of natural selection. But over time, Charles Darwin became almost universally thought of as the father of evolution. Wallace also called for protecting endangered species. Hulton-Deutsch Collection/Corbis hide caption

itoggle caption Hulton-Deutsch Collection/Corbis

An illustration shows how the planet Kepler-36c might look from the surface of the neighboring Kepler-36b. David Aguilar/Harvard-Smithsonian Center for Astrophysics/NASA hide caption

itoggle caption David Aguilar/Harvard-Smithsonian Center for Astrophysics/NASA

Will we need to tread lightly, in deference to the locals, when finally do make it to Mars? Pat Rawlings/SAIC/NASA hide caption

itoggle caption Pat Rawlings/SAIC/NASA

Bonobos at the Lola ya Bonobo sanctuary near Kinshasa in the Democratic Republic of Congo in 2006. Issouf Sanogo/AFP/Getty Images hide caption

itoggle caption Issouf Sanogo/AFP/Getty Images