My three-year-old knows something about gravity but that’s not what makes him special. Even babies grasp the fact that unsupported objects tend to fall downward. Endless experimentation launching sippy cups off high chairs and dropping balls to the floor teaches youngsters how gravity works. But it’s just this experience that makes it hard for them to believe that the earth is a sphere, according to a recent article in Science Magazine (May 18, 2007) about the childhood origins of adult resistance to science. Until about age nine, children have difficulty comprehending a spherical earth because they can’t understand why people on the other side don’t fall off.

Eventually kids accept earth’s shape, in large part because trusted information sources, such as teachers and parents, confidently tell them so. They might also see space photographs of the “blue marble” earth, evidence that helps reinforce the concept. Eventually most students develop a more sophisticated understanding about the gravitational attraction of large objects that reconciles experience with learned knowledge.

Other scientific concepts that are complex or that go against common sense are more difficult to dislodge, especially in a society where debate about these topics create uncertainty. Young children are especially susceptible to believing that things have a purpose and a design, a belief system that is clearly not based on evidence or scientific understanding. The Science article, written by Yale psychologists Paul Bloom and Deena Weisberg, describes children’s propensity for “promiscuous teleology” as the belief, for example, that clouds are for raining and lions are for going to the zoo.

We run into problems as a society when these misconceptions about science persist into adulthood. For children, the simplest explanation for the origins of plants and animals is a creationist belief. Good science education should supplant this belief with an understanding of how natural selection and evolution works, but the Science authors make the point that the current debate over teaching evolution gives the public, and students, an easy out. Rather than go through the hard work of evaluating the strong, deep and complex evidence of how mutations over time lead to new species, they can rely on non-science information sources, such as clergy, politicians, media personalities, or other authority figures, to come to a simpler concept that God (i.e. an intelligent designer) created all species on earth.

We hope to give folks a different way of answering the question: how do we know what we know? I’m on an NSF-funded project team at the Exploratorium that is digging into the ways that scientists use evidence, data and observations to understand the natural world. We’ve spent some time with scientists in Kamchatka investigating organisms that live in extreme environments, which might eventually provide clues about the early history, if not the origin, of life on earth. Later this year, we’ll launch an interactive Evidence Website that highlights the work of scientists at the Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany. Max Planck geneticists, anthropologists, linguists, cognitive psychologists, and primatologists use multiple lines of evidence, from DNA, to research on Great Apes, to fossilized skulls, bones and teeth, to investigate what makes us human and different from our primate relatives.

We’ll show the experiments, data and video interviews with scientists and will also include an interactive section that will allow online visitors to investigate the ways that they as individuals arrive at their knowledge and compare their belief systems to others. Rather than just rely on authority figures, including scientists, visitors can investigate the evidence and the methods that scientists use to understand nature, including human nature. If we are going to “believe” in anything, maybe it should be in the cumulative and self-correcting process of evidence-based science.