How Do Birds Stay Upright When They Are Sleeping?

You’ve got questions. We’ve got experts

bird illustration
One reader wonders how birds stay balanced on tree branches while they’re asleep. 
  Illustration by Barry Falls

Q: How do birds stay balanced up on tree branches while they’re asleep?

—Gail Singer | Washington, D.C.

Birds can be seen sleeping while perched on a branch, standing on one foot or clinging to bark. Some even sleep while flying. Studies show that birds can let one side of their brains sleep while the other side remains awake. They may also restrict full rapid eye movement (REM) sleep to only a part of the brain at a time, allowing them to maintain a standing posture while grabbing those deep zzz’s. Birds also appear to have an extra balance-sensing organ between their hips, which could help them stay upright while sleeping. Taken together, these features make birds champion sleepers.

Helen James, curator of birds, National Museum of Natural History

Q: If chimpanzees can learn sign language and their anatomy is so similar to ours, why can’t they speak?

—David Cox | Salem, Oregon

For a long time, it was thought that nonhuman primates, including chimpanzees, were unable to speak because they had different vocal anatomy than humans. Recent studies suggest it may have more to do with how their brains are wired. They most likely lack the appropriate neural control over their vocal muscles. So while chimps have proven their ability to learn grammar, they cannot convey this information through speech.

Becky Malinsky, curator of primates, National Zoo

Q: John Hanson was the president of the Confederation Congress before George Washington was elected. Why isn’t Hanson considered the father of our country?

—Yosef S. Jakubowitz | Woodmere, New York

There was a substantial difference between the office John Hanson held starting in 1781 and the office George Washington was elected to in 1789. Under the Articles of Confederation, state delegates met to create and enact policies. When its members chose a “president,” they were choosing someone to moderate their debates and oversee some of their correspondence. Hanson’s role did not matter much to the average American. Compare that with Washington’s role, which was an executive position, set apart from the legislative branch by the U.S. Constitution. Washington had a significant sphere of influence. He was also the ceremonial head of state, symbolizing the unity and power of the nation. Washington, of course, had already been revered as a great leader of the Continental Army during the American Revolution. Hanson held a leadership role in the Confederation Congress, but he did not lead the people of the nation.

Barbara Clark Smith, curator of social history, National Museum of American History

Q: Why didn’t the 13 colonies keep using the same currency as Great Britain?

—Trudy Elardo | Arcadia, California

Colonists began producing their own coins and bank notes in the 17th century, initially motivated by shortages of coins from England and Europe. In the 18th century, each of the colonies produced its own currency in a wide variety of denominations and types. During the Revolutionary War, the Continental Congress issued paper money to fund the war effort. When the U.S. Mint was established in 1792, it was an important marker of American independence.

Ellen Feingold, curator, National Numismatic Collection, National Museum of American History

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