# Can You Solve the Pirate Riddle?

iStock / VeraPetruk

In the video riddle below, we explore the distribution of pirates' booty. It gets complicated.

The scenario is this: Amaro is the captain of a pirate ship. His mateys, Bart, Charlotte, Daniel, and Eliza, are the other members of the crew. The group has come upon a bounty of 100 gold coins, and now must divide it up among the group according to "the pirate's code."

The code stipulates that Amaro, as captain, gets to suggest the first plan for distributing the coins among the five pirates. After that proposal, each pirate (including Amaro) votes "yarr" or nay on whether to accept the proposal. If the proposal results in either a tied vote (equal numbers "yarr"/nay) or a majority of "yarrs," it passes and the coins are immediately distributed. If it fails to meet this threshold, Amaro must walk the plank, making Bart the next captain. (Amaro walking the plank removes him from future votes, as well as eligibility for coin disbursals, on account of his death. Yuck.)

This process now repeats with Bart as captain, and the captain's hat will be passed on, in order, to Charlotte, Daniel, and finally Eliza. (If it gets all the way to Eliza without a passing proposal, she gets the booty.)

To make the situation more complex, there are rules governing how the pirates act. First, they each want to stay alive (that's their highest priority), but their next priority is maximizing their personal gold horde. Second, they distrust each other—there are no alliances and they cannot collaborate on a strategy. Third, they are bloodthirsty, and would love to see a fellow pirate walk the plank if they think it won't affect their own gold distribution. Fourth, each pirate has excellent logical deduction skills, and they're aware that everyone has the same skills. For the purposes of the puzzle, we can assume everyone is logical and obeys all the rules.

So we arrive at the key problem for Amaro: What distribution should he propose to ensure he lives and maximizes his own gold return? In order to figure this out, we have to walk through the chain of events and sort it out. Get your scratch paper ready!

The video below explains this puzzle (and its solution); here are the "rules" as stated at the 1:48 freeze-frame:

1. The captain makes a proposal for splitting up the 100 gold coins, which everyone votes on. A proposal that gets a tie or a majority of yarrs passes. A proposal with a majority of nays fails, and the captain has to walk the plank. The new captain then makes a proposal. The order of succession is Amaro, Bart, Charlotte, Daniel, and Eliza.

2. Each pirate's primary objective is to stay alive.

3. Each pirate's secondary objective is to maximize his or her gold.

4. Each pirate will vote to make the others walk the plank, all other results being equal. There are no abstentions.

5. Each pirate knows that the others share the same set of preferences.

6. Pirates cannot collaborate, make promises to each other, or form alliances; there is no communication outside the proposal and the votes, and no other trickery like murder or bribery. Even though they're pirates.

7. Each pirate is a perfect logician and all of them know this about each other.

Think on this a bit, and for the answer, have a look:

For more on the puzzle, check out this TED-Ed page. For a solution (and longer/more complex versions), read this PDF of an article by Ian Stewart.

# It 'Rained' Spiders in Brazil Last Week—and You Can Watch It If You Dare

iStock.com/aury1979

If recent events are anything to go by, you should be less concerned about swallowing spiders in your sleep and more concerned about bird-eating spiders raining down on your head. As The Guardian reports, recent footage from the Brazilian countryside shows thousands of spiders seemingly suspended in mid-air. (Arachnophobes might want to give the video below a miss.)

In reality, they aren’t falling at all. The spiders, which likely belong to a South American species called Parawixia bistriata, are merely crawling on an ultra-fine and nearly invisible web that attaches to two objects, like trees or bushes, to form a canopy.

So why do they do it? To catch prey, naturally. They’re likely to snag a variety of insects and maybe even small birds in their communal web, which can stretch up to 13 feet wide. (And yes, they eat the birds, too.)

Brazilian biology professor Adalberto dos Santos tells The Guardian that P. bistriata are some of the rare “social” spiders that do this. They leave their webs up overnight, hide out in the nearby vegetation, and then return at dawn to feast.

While this natural phenomenon is certainly unsettling, it isn’t exactly rare. Residents of the southeast municipality of Espírito Santo do Dourado, where the video was shot, said these “spider rains” are common when the weather is hot and humid.

Here’s another video from Santo Antônio da Platina in southern Brazil in 2013.

Other species of spider have been known to jump into the wind and "surf" on strands of silk as a means of getting around. They do this to escape threats or get to food or mates in other locations, and cases of "spider flight" have been recorded all over the world. Some especially adventurous spiders have even been known to cross oceans by “ballooning” their way from one land mass to the next.

[h/t The Guardian]

# Watch a Baby Polar Bear Open Its Eyes for the Very First Time

Sometimes, after a long week, all you need is something wholesome to lift your spirits. Here to do just that is the Berlin Zoo's newest resident.

In this polar bear video spotted by Geek.com, a 5-week-old cub can be seen opening its eyes for the very first time as its mom, Tonja (pronounced like Tania), cleans and cuddles it. “While it was previously only able to explore its surroundings by groping and cuddling, the little bear can now see and hear things,” according to a translated version of the zoo’s polar bear video caption.

Like kittens and puppies, polar bears are functionally blind and deaf when they’re born. It takes polar bears several weeks longer to develop their senses compared to puppies or kittens, though—about 30 days total. Their claws come later, too.

The diminutive nature of newborn cubs may also come as a surprise. Although full-grown adults can tip the scale at more than 1300 pounds, newborns weigh just 16 to 24 ounces—about the size of a guinea pig. But they pack on the pounds quickly, and can weigh over 100 pounds by the time they’re 8 months old.

A Berlin Zoo spokesperson reportedly said the cub has a big appetite and ate a lot over the holidays (just like the rest of us, apparently). It’s now attempting to walk, but mom and baby aren’t expected to leave the cave in their enclosure before spring arrives.

According to DW Science, zoo staff don’t know the sex of the cub yet. For its protection, they plan to give mom and baby lots of alone time before they approach. Newborn polar bears are quite vulnerable—especially in the wild, where about 85 percent of the bears die before they’re 2 years old.

Meanwhile, zoo staff are keeping a watchful eye on the cub, courtesy of the infrared cameras they have set up in their den.

[h/t Geek.com]

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