Sebastian Seung could have hired an army of undergraduates to do crucial legwork in his neuroscience lab at MIT. Even with the help of powerful computers that would have taken years. Instead, he and his lab turned it into a game, called it Eyewire, and 10,000 people played it on the first day. Many are still at it. These players hold all conceivable occupations, but in their free time they are neuroscientists: a prime example of scientists partnering with the public in citizen science projects. Collecting or organizing vast amounts of data might take one or two scientists years, but with thousands of people helping, data sets are complete in months or weeks, and discovery accelerates.
The goal of Eyewire is to trace individual neurons in the the tangles of a mouse’s retina. Many people map the same neuron, and results are averaged for better accuracy. Accuracy against the average wins points, though sometimes a player has to be the trailblazer, the first one to map a new neuron, slowly expanding the map. Collectively, the players turn tangles into data, mapping neuron types, connections, and extensions. Seung is hoping to map the retina as a stepping stone to mapping the whole brain, developing a set of connections he thinks may be unique to each person. This connectome, he says, may make each of us who we are. But to map this vast connectome, the pathways of billions neurons in each person’s head, Seung needed help from both a powerful artificial intelligence, the computer game, and thousands of citizen scientists around the world playing it.
If you’re a writer looking for a good symbol, consider the tree. The author of Genesis did, twice: he placed the tree of life and the tree of knowledge front and center in the Garden of Eden. Homer did, too: When his hero Odysseus returned home after twenty years of war and travel, needing to prove his identity to his skeptical wife, Penelope, he used a tree. “Move our bed into the hallway,” Penelope told her servant, laying a trap. (I’m paraphrasing here.) “It can’t be done,” Odysseus protested. “I carved a post of that bed from a living olive tree.” Only then did Penelope believe the strange man was really her husband, as steady as that post.
Trees have long impressed us with their steadfastness; in fact, some trees from Biblical times are still with us today. But a new story I read recently casts trees in a different role. I first came across a version of this story in a paper published in the journal BioScience in 2007. The authors looked at where trees live using a tool known as a “climate envelope,” which is a line drawn on a map around the entire range where a given species is able to survive. The scientists compared climate envelopes for 130 trees under 2007 conditions to those predicted for the end of the century, using the same computer models that the UN’s Intergovernmental Panel on Climate Change bases its forecasts on. On average, they found that trees’ envelopes moved 700 kilometers north, nearly the distance from Memphis to Chicago.
So does that mean our trees will be moving north as things get warmer? Traveling trees can make great stories: Shakespeare’s Macbeth was vanquished when Birnam Wood moved a few miles to his fortress at Dunsinane Hill. And it would be dramatic indeed if future northern woodsmen and women hunt deer among sprawling live oaks and big-leaf magnolias instead of spruce and pine trees. But the scientists who wrote the BioScience paper noted that actual trees are unlikely to track their climate envelopes’ northward migration in the coming years, at least if unassisted by humans. Trees can “move” up to a few miles in a generation, by setting their seeds aloft in the wind or encasing them in a shell so they can survive a trip in the gut of an animal. But tree generations are long, and most seeds land close to home. Sugar maples, for example, lead a chaste adolescence, and don’t start making seeds until the age of 22 or so. They then send out seeds attached to little helicopters, which spin and float at most the length of a football field before touching down. Scientists estimate trees’ maximum migration rate to be around 50 kilometers per century, with many traveling far slower—a tortoise’s pace in this race.