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Elephants say 'hello' to friends by flapping their ears and making little rumbly noisesElephants use ear flaps, rumbles, trunk reaches and other forms of communication to greet peers, new research suggests.
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When were sea levels highest?Sea levels were extraordinarily high during the last period of the dinosaur age. But ocean levels may have been even higher before that.
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Why are insects attracted to artificial lights?Artificial lights can be deadly to the insects that fly around them, so why do these critters do it?
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Which islands will become uninhabitable due to climate change first?Climate change is raising sea levels, and many low-lying islands are at risk. But determining which communities will be first to leave is impossible to answer.
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Could a star ever become a planet?Most scientists say a star can never become a planet, but the boundaries between these stellar objects can sometimes be murky.
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What are the most polluted cities in the world?Cities like Lahore, Pakistan, Hotan China and Delhi, India have consistently poor air quality, but it's impossible to accurately identify the city with the world's worst air pollution.
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Is pee sterile?Here's the science behind urine and whether it's sterile or swimming with bacteria.
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Can hot drinks help you cool down?It may sound counterintuitive, but can a steaming drink cool you down on a scorching day?
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Do the Pacific Ocean and the Atlantic Ocean mix?Photos show what looks like a line between the Atlantic and Pacific with different water colors on either side, but is there some kind of barrier or do the two oceans mix?
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What is the maximum number of biological parents an organism can have?Most organisms have two parents, but not all. Could an individual have three parents, or even more?
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What is the 'ship of Theseus' thought experiment?The Greek writer Plutarch proposed this question: If a ship's planks are replaced over time due to wear and tear until none of the original pieces remain, is it still the same ship?
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Why do cats purr?Cats may purr because they're happy, but also for a slew of other reasons, including getting their owner's attention and stress.
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Which animals have entered the 'Stone Age'?Humans aren't the only species that has entered the Stone Age. Who else is in the club?
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How does coal form?Coal takes tens if not hundreds of millions of years to form; it all starts with living plants that eventually fossilize.
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Which is the largest continent? The smallest?Pangaea was one of the largest continents in world history, but now it's broken up. So which continent today is the largest, and which is the smallest?
