We all know that outdoor time can do wonders for our performance. But there's a surprising new reason: a bacterium called Mycobacterium vaccae
, which lurks in the soil. When biologists Dorothy Matthews and Susan Jenks fed this single-celled bugger to lab mice, the animals became calmer and navigated mazes twice as quickly as those that weren't exposed
—an edge that lasted more than a week. The bacteria, which are often inhaled when we are in contact with dirt (gardening is one potential route), influence the "gut-brain" axis and stimulate neuron growth. (Matthews and Jenks found evidence that the new neurons produce the anti-anxiety neurotransmitter serotonin.) While research is under way on how M. vaccae
may similarly retune our brains, consider trekking
your way to the top.