Charles Q. Choi

If a cat kneads on your lap, it's likely because it feels safe around you. But why do they knead in the first place?

Scientists estimate the mass of the 1,084,954 buildings within the five boroughs of New York City is 1.68 trillion pounds.

Modern humans may descend from two or more genetically distinct streams that split but continued to occasionally mix over time in Africa.

The first wave of humans into the Americas during the last ice age may have hailed partly from northern China, according to a DNA study of ancient and modern Indigenous people.

Modern humans migrated into Europe in three waves: 54,000, 45,000 and 42,000 years ago, a new study claims.

The eruption was the most powerful natural explosion in over a century, triggering a tsunami hundreds of feet high.

The moon is slowly creeping away from Earth, but will we actually lose the moon before the sun turns into a red giant and destroys us both?

Here's why hurricanes, also known as tropical cyclones and typhoons, don't form at the equator and why it would be rare for them to cross it.

Dogs commonly tilt their heads, but is it a sign of intelligence, or does it mean something else entirely?

The bottom of the Mariana Trench is about 35,876 feet (10,935 meters) deep, making it deeper than Mount Everest is tall.

Octopuses are odd: They have more than one heart and copper-rich blue blood.

The largest study yet to look at the genetics of ice age hunter-gatherers in Europe has uncovered a previously unknown lineage dubbed the Fournol.

Glassy-winged sharpshooters rapidly fire their pee out of butt catapults.

The first people to enter the Americas may have taken the coastal route along the Bering Strait Land Bridge during these two periods.

An unknown group of hominins crafted more than 500 obsidian hand axes more than 1.2 million years ago in what is now Ethiopia.

A genetic study has revealed the existence of a previously unknown hunter-gatherer group that lived in Siberia upwards of 10,000 years ago.

And do the rodents live in these wooden structures?

It's easy to fold a piece of paper in half once, twice or even three or four times. But what's the highest number of times one piece of paper can be folded in half?

The average life expectancy of a dog is more than 10 years, but life span varies greatly among different breeds.

There are two contenders for the world's largest squid, and both are giants.

The oldest known writing dates back more than 5,000 years. But who was the first author we know by name?

Sometimes dark or milk chocolate gets a white sheen or blotchy white spots on it. What is happening, and is chocolate that has turned white safe to eat?

Cats can squeeze through impossibly small holes, but how does their anatomy enable them to do this?

Shedding fur is useful for cats and dogs. Here's why they do it.

Mother cats nurse kittens, but can older cats safely lap up milk?