Researchers still don't fully understand why animals, including humans, need sleep.
But we still think they're cute.
Either way, we're dazzled by Heidi's display.
And now it's going to die.
We may have more in common with invertebrates than we thought.
Consider this your end-of-summer reading list.
Warmer isn't always better.
Some scientific explanations for a recent cephalopod invasion.
Tamed and Untamed.
But they're still pretty gloomy.
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