Q: What purpose do mosquitoes serve?

— Lana Carlton | Bradenton, Florida

While they can seem pointless and purely irritating to us humans, mosquitoes do play a substantial role in the ecosystem. Mosquitoes form an important source of biomass in the food chain—serving as food for fish as larvae and for birds, bats and frogs as adult flies—and some species are important pollinators. Mosquitoes don’t deserve such a bad rap, says Yvonne-Marie Linton, research director at the Walter Reed Biosystematics Unit, which curates Smithsonian’s U.S. National Mosquito Collection. Out of the more than 3,500 mosquito species, only around 400 can transmit diseases like malaria and West Nile virus to people, and most don’t feed on humans at all.

Q: I read that a lioness may eat her cubs or let them starve. Is that true? Why would she do that?

— Jeaneth Larsen | Mitchell, South Dakota

If a lioness eats her cub, it’s likely because there’s a problem: Either it was stillborn or died shortly after birth from natural causes. The mother consumes the remains so predators aren’t attracted to it. Think of it more as a survival tactic than a brutal ritual, says Craig Saffoe, curator of Great Cats areas at the National Zoo. A lioness will feed her offspring milk unless she physically stops producing it, which might happen due to low food and water resources and could lead the cubs to perish. If the cubs are old enough to eat solids, they usually eat with the rest of the pride, but have to eat last and are usually the first to die off if resources are low. Grown adults generally eat first; that enables them to breed again as soon as resources return to normal.

Q: What was the origin of ZIP codes?

— Rosanne Levitt | New York City

The U.S. Postal Service introduced the “zone improvement plan” (ZIP) code in 1963. The nationwide system mechanized more of the work of mail sorting, which had previously been done by hand, says Lynn Heidelbaugh, curator at the National Postal Museum. The idea dates to 1944, when postal inspector Robert Moon proposed adding a three-digit code to addresses; the first number referred to a region and the next two to a mail processing center. Two decades later, after mail volumes had grown exponentially, Postmaster J. Edward Day adopted a version of that plan, adding a fourth and fifth digit designating a specific post office. The Zip code has been expanded twice: Four additional numbers indicate what side of the street, or even hallway, the destination is on. Two more numbers sequence the carrier’s route to make it more efficient.

Q : Why is the Republican Party represented by an elephant and the Democratic a donkey?

— Anonymous | Washington, D.C.

President Andrew Jackson, who was supported by the Democrats in 1828, earned the nickname “Jackass” for his stubbornness, says Jon Grinspan, curator of political history at the National Museum of American History. The image stuck to the Democrats and took off after the Civil War, when they were seen as the defeated party that wouldn’t accept its loss. Around the same time, cartoonist Thomas Nast started drawing a stumbling elephant to represent the Republican Party, once united by its abolitionist goal but struggling in the postwar years. Originally somewhat insulting, the two symbols were embraced in the early 20th century.

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