How far back does right-handedness go in our evolutionary history?
It goes way back—hundreds of thousands of years. Early stone tools indicate a right-hand preference, and so does paleolithic art. Most prehistoric handprints are of the right hand, while painted hand silhouettes are usually of the left, suggesting they were drawn with the right. Today, about 90 percent of humans are right-handed. A lesser pattern of right-hand dominance has been observed in some other living primate populations, too, such as chimpanzees.
paleo-anthropologist, Human Origins Program, National Museum of Natural History
Black holes: spheres or disks?
West Yarmouth, Massachusetts
Black holes are spheres. But a black hole is generally surrounded by a disk of hot, bright in-falling material. That material is known as an “accretion disk.”
director, Chandra X-ray Center, Harvard-Smithsonian Center for Astrophysics
Why are some lakes designated by “lake” first (e.g., Lake Superior) and others the opposite (e.g., Upper Straits Lake)?
Huntington Woods, Michigan
It seems to depend on who named the lake—or other geographical feature, for that matter—in question. French and Spanish explorers put the noun first and then the adjective; English-speaking explorers put the adjective first. Lake Superior was originally “Lac Supérieur” (or what an English speaker might have called “Upper Lake”). But beware; this pattern is by no means consistent. A number of recent man-made lakes have been christened in the French or Spanish manner—Lake Cumberland in Kentucky is one example that comes to mind. To some ears, that simply sounds more impressive.
geographer, National Museum of the American Indian
Where do urban birds go when they die? We have lots of pigeons, sparrows and other birds where I live, but I’ve never seen a dead one on the street.
Brooklyn, New York
That’s because dead city birds are quickly consumed by rats and feral cats. Even in the city, it’s a jungle out there.
curator of birds, National Museum of Natural History
Is the amount of water on earth finite?
Yes, it is. The water that cycles among the earth’s oceans, atmosphere and land surface can be viewed as a closed system. That means that the total amount of water doesn’t change. How this water originated is the subject of research. Water can be released by volcanic activity (quite a bit of which occurred as the early earth cooled), or it could have been added to the early earth from impacting objects, such as comets.
geographer, Center for Earth and Planetary Studies, National Air and Space Museum