The Man of the Hole

For at least the last 20 years, a solitary indigenous man has been living entirely by himself in the Amazon rain forest. Known as “The Man of the Hole,” he’s believed to be the last surviving member of an uncontacted tribe.

His existence first came to light in 1996, and the Brazilian authorities launched expeditions to ensure his safety and preserved a 31-square-mile area in order to protect him from the encroachments of ranchers and loggers.

His nickname derives from the mysterious hole he digs in the floor of each of his palm thatch huts — more than 5 feet deep, rectangular, and serving no clear purpose. (A village of such huts had apparently been destroyed by settlers in 1996.) He’s been spotted a few times, a naked man with a bow and arrow who would now be in his 50s.

In 2009, gunmen believed to be ranchers attacked the man, but he’s believed to have escaped. Survival International director Stephen Corry told the Guardian, “His tribe has been massacred and now the ‘man of the hole’ faces the same fate. The ranchers must allow this man to live out his last days in peace on his own land, and the authorities must do all they can to protect it.”

(Thanks, Steve.)

July 16, 2017July 15, 2017 | Oddities

Late Again

kendall/thomas railroad puzzle

A problem from P.M.H. Kendall and G.M. Thomas’ Mathematical Puzzles for the Connoisseur, 1962: A road runs parallel to a railway until it bends to cross it, as shown. A man normally cycles to work along the road at a constant speed of 12 mph, and when he reaches the crossing he’s normally overtaken by a train traveling in the same direction. One day he was 25 minutes late for work and found that the train passed him 6 miles before the crossing. What was the speed of the train?

	Select Click for Answer
Suppose the man normally reaches the crossing, B, at 8 a.m. Then on a typical day he’d reach A, 6 miles before the crossing, at 7:30 a.m. When the man is 25 minutes late, he’ll reach B at 8:25 a.m. and A at 7:55 a.m. Hence the train takes 5 minutes to travel the 6 miles from A to B. Therefore its speed is 72 mph.

July 15, 2017July 14, 2017 | Puzzles

Nothing Doing

forest protest

Invited to participate in São Paulo’s biennial art exhibition in 1973, French artist Fred Forest found a unique way to protest the censorship imposed by Brazil’s ruling junto: He organized a group of marchers to carry blank signs through the city. “Instead of calling on dissidents or students who could have been arrested and tortured, Forest hired fifteen men to carry the signs,” writes Karen O’Rourke in Walking and Mapping. “As professional sandwich-board men who work at street corners in the heart of São Paulo, they could not be held responsible for the content of their signs.”

The press published the marchers’ route, and the public understood that the blank signs reflected the government’s repression. Although it was against the law for more than three people to congregate in the street, Forest’s march attracted nearly 2,000 followers, and onlookers showered them with ticker tape from their balconies.

The police arrested Forest for holding up traffic, but he was protected by his status as a foreign artist. After several hours of questioning, they let him go.

July 14, 2017 | Art · Society

In a Word

paranymph
n. at a wedding, a bridesmaid or best man

July 14, 2017July 13, 2017 | Language

A Little Story

IBM nanophysicists have made a stop-motion movie using individual atoms — carbon monoxide molecules arranged on a copper substrate and then magnified 100 million times using a scanning tunneling microscope. The molecules remain stationary because they form a bond with the substrate at this extremely low temperature (-268.15° C); each CO molecule stands “on end” so that only one atom is visible.

The result, “A Boy and His Atom,” holds the Guinness world record for the world’s smallest stop-motion film.

07/16/2017 UPDATE: The day I posted this, news broke that researchers have encoded five frames of an 1870s short film into bacterial DNA. (Thanks, Sharon.)

July 13, 2017July 16, 2017 | Entertainment · Science & Math

Effles

An effle is a grammatical English sentence that no one would ever say — they tend to turn up in textbooks for students learning English as a foreign language:

The farmer kills the duckling.
This is a pencil. This is a boy. Peter is a boy. Peter is not a pencil.
A hat is not food.
A man has a dog.
Is this my finger or your finger?
A tailor sews with a needle.
He’s not very good so I can’t marry him.
One praises a pupil when he works hard.
You can’t go to a restaurant if you don’t have money.
Shall I leave without paying?
These are the people’s lunches.
Ouch! O, foolish bee!

Struck by these absurdities while trying to learn English from a textbook in 1950, Eugene Ionesco wrote a play, The Bald Prima Donna, with the same inane tone:

MARY: I am the maid. I have just spent a very pleasant afternoon. I went to the pictures with a man and saw a film with some women. When we came out of the cinema we went and drank some brandy and some milk, and afterwards we read the newspaper.

MRS. SMITH: I hope you spent a pleasant afternoon. I hope you went to the pictures with a man and drank some brandy and some milk.

Mr. SMITH: And the newspaper.

MARY: Your guests, Mr. and Mrs. Martin, are waiting at the door. They were waiting for me. They were afraid to come in on their own. They were meant to be dining with you this evening.

In his 1973 book The Language Laboratory and Language Learning, linguist Julian Dakin recalls a school textbook for foreign learners in which two children are continually asking one another their names. In Lesson 6 it turns out they’re brother and sister.

See Can You Do Without Soap?

July 13, 2017July 12, 2017 | Language

Never Too Late

Abraham Lincoln had less than a year of formal schooling.

The fifth Lincoln-Douglas debate was held before Knox College in 1858. As he crawled through a second-story window to reach the platform, he said, “At last I have gone through college.”

July 12, 2017 | History

Cheryl’s Birthday

This question appeared in the 2015 Singapore and Asian Schools Math Olympiad, a competition for 14-year-old students from Singapore, Thailand, Vietnam, China, and the U.K. (I’ve amended the language a bit):

Albert and Bernard have just become friends with Cheryl, and they want to know when her birthday is. Cheryl gives them a list of 10 possible dates:

May		15	16			19
June				17	18
July	14		16
August	14	15		17

Cheryl then tells Albert and Bernard separately the month and the day of her birthday, respectively.

Albert: I don’t know when Cheryl’s birthday is, but I know that Bernard doesn’t know it either.

Bernard: At first I didn’t know when Cheryl’s birthday is, but I know now.

Albert: Then I also know when Cheryl’s birthday is.

When is Cheryl’s birthday?

Singapore TV presenter Kenneth Kong posted the question online, and it went viral in a matter of days. The competition organizers had intended it to “sift out the better students” and expected that 40 percent of the competitors would find the solution. What is it?

	Select Click for Answer
Cheryl’s birthday is July 16. Albert’s first statement is unsurprising — he knows only the month of Cheryl’s birthday, and each month on the list includes several possible days. But the fact that he knows that Bernard doesn’t know it is important — it tells us that the month can’t be May or June, because both of those months contain unambiguous dates. For example, if Cheryl’s birthday were May 19, then Bernard would know immediately that she was born in May, as that’s the only month whose 19th day appears on the list. Similarly, if Bernard knew the day of Cheryl’s birthday was the 18th, he’d know immediately that she was born in June. The fact that Albert can exclude these possibilities shows that he knows she wasn’t born in May or June; she must have been born in July or August. Bernard’s statement shows that he’s followed this and now knows that the month must be either July or August. And the fact that he now knows the full birthday shows that Cheryl was born on the 15th, 16th, or 17th — if she’d been born on the 14th then he’d still be uncertain, as both July 14 and August 14 fall on the list. Albert has narrowed the list of possibilities to July 16, August 15, and August 17. As he now declares that he knows the birthday unambiguously, it must be July 16 — if it fell in August he’d have no way to distinguish between August 15 and August 17.

Click for Answer

July 12, 2017 | Puzzles

Patrolling the Palace

A puzzle by James Tanton:

King Tricho lives in a palace in which every room is a triangle:

patrolling the palace

Before retiring for the night he’d like to inspect it. Is there a path that will let him visit each room once and only once? He can start anywhere.

	Select Click for Answer
No, there isn’t. Color the cells as shown: Any path that the king takes must alternate between dark and light rooms, so the king can succeed only if there are an equal number of each (or if their numbers differ by 1). In the diagram there are 12 dark rooms and 10 light rooms, so there’s no way to visit all of them on one connected tour, unless the path travels outside the palace. (From Tanton’s “A Dozen Questions About a Triangle,” Math Horizons 9:4 [April 2002], 23-28.)

Click for Answer

July 11, 2017July 11, 2017 | Puzzles

Monkey See

https://commons.wikimedia.org/wiki/File:Dolphin_Mikurajima_Tokyo_Japan.jpg — Image: Wikimedia Commons

In 1972 biologists Colin Tayler and Graham Saayman were observing a group of Indo-Pacific bottlenose dolphins in a South African aquarium. One of them, a 6-month-old calf named Dolly, began to seek their attention by pressing feathers, stones, seaweed, and fish skins against the glass of the viewing chamber. If they ignored her she swam off and returned with a different object.

At the end of one observation session, one of the investigators blew a cloud of cigarette smoke against the glass as Dolly was looking in. “The observer was astonished when the animal immediately swam off to its mother, returned and released a mouthful of milk which engulfed her head, giving much the same effect as had the cigarette smoke,” the biologists reported. “Dolly subsequently used this behaviour as a regular device to attract attention.”

“Dolly didn’t ‘copy’ (she wasn’t really smoking) or imitate with intent to achieve the same purpose,” argues ecologist Carl Safina in Beyond Words: What Animals Think and Feel. “Somehow Dolly came up with the idea of using milk to represent smoke. Using one thing to represent something else isn’t just mimicking. It is art.”

(C.K. Tayler and G.S. Saayman, “Imitative Behaviour by Indian Ocean Bottlenose Dolphins [Tursiops aduncus] in Captivity,” Behaviour 44:3 [1973], 286-298.)

July 11, 2017July 11, 2017 | Science & Math