Some 500 million years ago, an ancient fishlike creature produced at least one offspring with a curious mutation — twice the number of genes. These excess genes began developing in new directions, eventually creating more and more complex brains. Some 150 million years later, human ancestors roamed the land, and their brains continued to grow in complexity. About 2.5 million years ago, hominid brains started growing especially large, although scientists aren’t exactly sure what led to that sudden burst. Yet after millions of years of evolutionary experimentation, the human brain is a biological wonder many times more efficient than any artificial equivalent — in fact, it’s even more efficient than a 60-watt light bulb.

Humans have the world’s largest brain-to-body mass ratio of any mammal.

fact

FIB

Ready to reveal?

Confirm your email to play the next question?

sign up!

Please enter valid email.

Sign up

Oops, incorrect!

It's a fib

Humans rank pretty high among all mammals, with a brain-to-body mass ratio of 1:40. However, when it comes to mammals, tree shrews (Tupaia belangeri) have the biggest ratio of them all, coming in at a ratio of 1:10.

Take, for example, IBM’s Watson, the supercomputer that famously bested Jeopardy! champions on daytime television in 2011. Watson uses around 85,000 watts to electronically outfox a human. Meanwhile, its biological competitors’ brains run at around 20 watts. It’s true that when compared to the rest of the human body, the brain is a greedy customer, requiring about 20% of our energy use. It uses two-thirds of that energy to send signals along its neurons, and the rest for cell-health “housekeeping.” But when it comes to everything our brains do for us — and how efficient they are overall — that seems like energy well spent.

• Share to Facebook
• Share to Twitter
• Share to Email

There are entire websites devoted to whether or not Mercury is in retrograde at any given moment, and all the while Venus is spinning backward (compared to most other planets). As a result, the sun rises in the west and sets in the east on the second rock from the sun. Though no one’s entirely sure why our fiery neighbor rotates to the beat of its own drum, it’s been theorized that it originally spun in the same way as most other planets (counter-clockwise when viewed from above), but at some point flipped its own axis 180 degrees. So while its rotation appears backward from our earthbound perspective, it might be more accurate to say that Venus spins the same way it always has, just upside-down.

A day on Venus is longer than a year there.

fact

FIB

Ready to reveal?

Confirm your email to play the next question?

sign up!

Please enter valid email.

Sign up

Oops, incorrect!

It's a fact

A day — or the length of time it takes for the planet to spin on its axis — lasts 243 Earth days on Venus, while a year (one complete rotation around the sun) lasts 224.7 days. This is by far the longest day in the solar system, with Mercury coming in second (about 59 days).

Some scientists think the flip might have been the result of a situation arising from the planet’s extremely dense atmosphere along with the sun's intense gravitational pull, though the scientific community has yet to reach a consensus. For all that, Venus has often been referred to as Earth’s sister planet — even more so than Mars. We’re the two closest neighbors in the solar system, have similar chemical compositions, and are roughly the same size. One crucial difference: Venus probably cannot support life.

• Share to Facebook
• Share to Twitter
• Share to Email

You may have grown up testing your nerve in front of the mirror by chanting in the dark to see if any spirits would appear. And while this may not summon ghosts, it turns out it can summon illusions. Staring into a dimly lit mirror for an extended period of time can distort your perception of your own face, making it appear to warp, blur, or even morph into someone — or something — else.

This phenomenon, dubbed the “strange-face-in-the-mirror illusion,” was first described in a 2010 study by Italian psychologist Giovanni Caputo. Subjects were placed in a room lit by a 25-watt lamp behind them with a mirror about a foot in front of them. They typically began to perceive the illusion after less than a minute, and after 10 minutes of gazing, many reported eerie changes. 

More than 60% of participants saw “huge deformations” to their own faces, while others saw someone else entirely in their reflection, such as an old woman or a child. Almost 20% described seeing animal faces such as a cat, pig, or lion, and almost half experienced distorted perceptions of monstrous beings.

Ancient mirrors were made of volcanic glass.

fact

FIB

Ready to reveal?

Confirm your email to play the next question?

sign up!

Please enter valid email.

Sign up

Oops, incorrect!

It's a fact

Obsidian, a volcanic glass, has been polished into mirrors since at least as early as 8000 to 6000 BCE in the Anatolian peninsula (modern-day Turkey).

The effect may seem frightening, but it isn’t supernatural — it’s neurological. When the brain is deprived of dynamic visual input, it quickly starts to adapt. Think of the optical illusions you’ve likely tried: In the lilac chaser, for example, a ring of lilac dots seems to vanish and a green dot appears in their place. This happens because of a process called the Troxler effect, in which staring at a fixed point can make surrounding details fade. 

At the same time, because our brains are wired to search for faces, the experiment can also result in subjects seeing the faces of their own parents or other loved ones staring back.

Interestingly, this kind of illusion isn’t limited to mirrors. Caputo found in another study that staring into someone else’s eyes in dim light can trigger similar — or in some cases, even more dramatic — hallucinatory experiences. Many participants saw facial deformities and monsters, but they also reported that colors seemed muted, the volume of surrounding sounds noticeably increased or decreased, time felt stretched, and they felt spacey and dazed.

• Share to Facebook
• Share to Twitter
• Share to Email