Under a cloudless August sky, I sailed upon an InterCity train from København station to Aarhus, an 8th-century Viking settlement that is now the second largest city in Denmark. After disembarking, I trekked toward the local university to a door marked INSTITUT FOR BIOLOGI. Upon entering, I was greeted by Ian Marshall, a lanky Australian professor with graying hair, who ushered me into his first floor laboratory.Dimly lit, the room was thick with the scent of wet earth. Large plastic buckets lin...