Mental Floss

Living Root Bridges in India Aren't Built, They're Grown

Hannah Keyser

The United States gets an average of about 28 inches of rain a year. The Cherrapunji region of southeast India, however, receives close to 464 inches—earning it the distinction as one of the wettest places on earth. All this moisture makes wooden structures, like small bridges, highly susceptible to rot. But the local War-Khasis tribe has come up with an ingenious solution to this problem: For at least 500 years, the Khasis people have been training and shaping the growth of roots of the Ficus elastica tree, which grows a secondary root system above ground, to create bridges that can stretch up to 100 feet. It takes about 10 to 15 years for the growth to span a river and take root in the soil on the far bank, but once it does, the living bridges are strong—able to hold up to 50 people at a time—and resistant to rot.

[h/t Atlas Obscura]