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

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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

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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

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Many of life's building blocks can be found in the objects bombarding Earth from outer space. Does that mean that life, too, developed elsewhere before arriving here? Mary P. Hrybyk-Keith/NASA hide caption

itoggle caption Mary P. Hrybyk-Keith/NASA

Alcohol: a key babyproofing product for this little mother. Illustration by Daniel M.N. Turner/Photos via istockphoto.com hide caption

itoggle caption Illustration by Daniel M.N. Turner/Photos via istockphoto.com