Oxygen is carried by red blood cells, but a specific mutation can cause the cells to take on a sickle shape and make them inefficient at carrying oxygen. This highly adaptive mutation spread through Africa once malaria became a problem there. EM Unit, UCL Medical School, Royal Free Campus/Wellcome Images hide caption
Shaun Parker moved from Menasha, Wis., to Los Angeles to pursue a career in film nearly 20 years after his initial plans were derailed by an illness in the family, but he never lost the determination to craft his own life story. At the end of his life, Parker says, he wants to be able to say, "I was part of something that moved you." Katie Falkenberg for NPR hide caption
Through the lens of evolution, a belief in God serves a very important purpose: Religious belief set us on the path to modern life by stopping cheaters and promoting the social good. iStockphoto.com hide caption
Natural-Born Storyteller? Shaun Parker moved from Menasha, Wis., to Los Angeles nearly 20 years after an illness in his family put his adolescent dreams on hold. "I liked the idea that I was meant to be something more," Parker says. "I always said that we're kind of the sum total of the decisions we make in life, and I just felt like I could very easily make the decisions that lead me away from that path of being more, whatever it is." Katie Falkenberg for NPR hide caption
Lisa Daxer is a biomedical engineering major at Wright State University in Dayton, Ohio. She says her autism has made her feel like an outsider but has also helped her become something of an expert on the social behavior of people she calls "neurotypicals." Skip Peterson for NPR hide caption
A supporter of the Spanish team cries while watching the World Cup final soccer match, which Spain won 1-0. Crying may have evolved as a signal to those who were in close physical proximity to us, but it also adds a powerful dimension to interpersonal communication Dani Pozo/AFP/Getty Images hide caption
Liam, a capuchin monkey, will respond differently to a simple test if another monkey receives a more favorable food reward for performing the same task. Laurent Pretot hide caption
Alex, the famous African gray parrot, learned elements of the English language and shattered the notion that parrots are only capable of mimicking words. Scientists believe human language may have evolved from hand signals and song. NPR hide caption
As humans evolved, our throats got longer and our mouths got smaller -- physiological changes that enabled us to effectively shape and control sound. According to fossils, the first humans who had an anatomy capable of speech patterns appeared about 50,000 years ago. Hulton Archive/Getty Images hide caption
Is This Evolution? This is just one version of the iconic illustration of evolution, but reporter Alix Spiegel believes this type of depiction doesn't tell enough of the story of what truly makes us human. Giovanni Caselli hide caption
The colors in this 3D rendering of a human brain represent different regions of the cortex, the wrinkly outer part of the brain that contains the most evolutionarily advanced regions. Courtesy of the Allen Institute for Brain Science hide caption
Om Nom Nom: As we began to shy away from eating primarily fruit, leaves and nuts and began eating meat, our brains grew. We developed the capacity to use tools, so our need for large, sharp teeth and big grinders waned. From left, a cast of teeth from a chimpanzee, Australopithecus afarensis and a modern human. William Kimbel/Institute of Human Origins hide caption
The human shoulder (above) allows the arm to hang freely and enables us to flex the arm at the elbow and perform tasks in front of us with ease. Because of its location and structure, the human arm is great for throwing. The ape shoulder (below), by contrast, allows for a different range of motion and is more suited to hanging from trees. Maggie Starbard/NPR hide caption
A flint-knapper makes sharp stone flakes by striking a flint "core" with a hammerstone. Human Origins Initiative hide caption
Feet On The Ground: Barefoot runners tend to land on the balls of their feet rather than on their heels the way most shoe-runners do. Rick Roeber went shoeless in 2003 and has clocked more than 13,000 barefoot miles since. Charlie Riedel/AP hide caption
Anthropologist Brian Richmond is trying to determine what the footprints of modern humans can tell us about how we evolved. NPR hide caption
An illustration of what the sea creature Tiktaalik may have looked like. Known as a "fishapod," Tiktaalik bridged the gap between sea living and land living creatures, and played an important evolutionary role on our journey to becoming human. Zina Deretsky/National Science Foundation hide caption
