TRONDHEIM, NORWAY—Melting snow in Norway’s mountains has revealed a bow and arrows that were probably used to hunt reindeer. The 3,800-year-old bow had been made from elm that grows at lower altitudes. The arrows, the oldest of which was 5,400 years old, were made of different types of wood and tipped in slate. The weapons are similar to those found in other cold climates. Neolithic hunters probably followed the deer into the mountains during the summer months, when the deer would move to cooler pastures. “It’s actually a little bit unnerving that they’re so old and that they’re coming out right now. It tells us that there’s something changing,” said Martin Callanan of the Norwegian University of Science and Technology.