A One and a Two

In 2013, Georgia Institute of Technology mechanical engineer David Hu and his colleagues discovered a “law of urination”: All mammals weighing more than 1 kilogram empty their full bladders in about 21 seconds (standard deviation 13 seconds).

Last year Hu followed that up with a law of defecation: Despite a rectum length varying from 4 to 40 centimeters, mammals from cats to elephants defecate within a nearly constant duration of 12 ± 7 seconds. A layer of mucus helps feces slide through the large intestine; larger animals have more feces but also thicker layers of mucus, which aids their ejection.

From the journal Soft Matter, whose cover artist deserves some kind of award.

(David L. Hu et al., “Hydrodynamics of Defecation,” Soft Matter 13:29 [August 2017], 4960-4970.) (Thanks, Colin.)

Stare at the cross from a short distance away without moving your eyes. After a few seconds, the colors will fade away.

The effect was discovered by Swiss physician Ignaz Paul Vital Troxler in 1804. The reasons for it aren’t clear — possibly neurons in the visual system adapt to unchanging stimuli and they drop out of our awareness.

Two by Two

In poker, suppose you’re dealt a pair. Is the probability that your opponent also holds a pair higher, lower, or the same as it would be if you held nothing?

Robinson Tiles

Berkeley mathematician Raphael Robinson discovered this remarkable set of aperiodic tiles in 1978. The six shapes will neatly tile a plane, as shown below, and though the pattern cannot be regular, it reliably produces a hierarchical design: Each small orange square sits at the corner of a larger orange square, which sits at the corner of a still larger one, and so on ad infinitum. This is because subgroups of tiles form “supertiles” with similar properties — see here.

(Thanks, Jacob.)

A Prime Square

In 1913 J.N. Muncey of Jessup, Iowa, showed that the first 144 odd prime numbers (counting 1 as prime) can be arranged into a magic square.

Each row, column, and long diagonal totals 4514.

Time and Talk

Speakers of the Kuuk Thaayorre language, spoken by the Thaayorre people in Queensland’s Pormpuraaw settlement, use absolute cardinal directions (north, south, east, west) rather than relative spatial terms (left, right), even at small scales. So, for example, they would say, “The cup is southeast of the plate” or “The boy standing to the south of Mary is my brother.”

In 2010, University of California psychologists Lera Boroditsky and Alice Gaby gave Kuuk Thaayorre speakers sets of cards depicting temporal progressions — a man aging, a crocodile growing, a banana being eaten — and asked them to arrange the shuffled cards on the ground to indicate the correct temporal order.

English speakers arrange the cards from left to right, Hebrew speakers from right to left. But the Kuuk Thaayorre arranged them from east to west, regardless of the direction the subjects themselves were facing.

Among other things, this means that the Kuuk Thaayorre must be constantly aware of their orientation in the world. “We never told anyone which direction they were facing,” Boroditsky wrote later. “The Kuuk Thaayorre knew that already and spontaneously used this spatial orientation to construct their representations of time.”

(Lera Boroditsky, “How Language Shapes Thought,” Scientific American 304:2 [February 2011], 62-65.)

The Big Picture

Give a hundred people a picture of the earth, identify the North Pole for them, and a hundred will hold the photo with the North Pole toward their head and the South Pole toward their feet. Of course, what they are really doing, if they are standing up, is pointing the South Pole at the center of the earth and, if they are standing at the equator, pointing the North Pole at some spot in the sky, which, as the earth turns, traces a circle intersecting the plane of the ecliptic at 23 1/2 degrees. Now why people persist in this foolishness I don’t know. In my living room I have a small framed photograph showing a thin crescent against a black background. Even though the colors are wrong, people always say, ‘Oh, the moon!’; but it is the earth. The earth isn’t ever supposed to be a crescent, I suppose.

— Astronaut Michael Collins, Carrying the Fire, 1975

Priorities

On Sept. 21, 1849, naturalist and explorer Philip Henry Gosse wrote in his diary:

E. delivered of a son. Received green swallow from Jamaica.

The son grew up to be poet, author, and critic Edmund Gosse, who wrote:

“This entry has caused amusement, as showing that he was as much interested in the bird as in the boy. But this does not follow; what the wording exemplifies is my Father’s extreme punctilio.

“The green swallow arrived later in the day than the son, and the earlier visitor was therefore recorded first; my Father was scrupulous in every species of arrangement.”

Good Boy

The esoteric programming language DOGO “heralds a new era of computer-literate pets.” Commands include:

SIT — If the value of the current memory cell is 0, jump to STAY.
STAY — If the value of the current memory cell is not 0, jump to SIT.
ROLL-OVER — Select the next operation in the operation list.
HEEL — Execute the currently selected operation.

This program prints the words HELLO WORLD:

```roll-over roll-over heel roll-over roll-over roll-over roll-over heel heel heel
heel heel heel heel heel heel sit roll-over roll-over roll-over heel roll-over
roll-over roll-over heel heel heel heel heel heel heel heel roll-over roll-over
heel roll-over roll-over roll-over roll-over roll-over heel roll-over roll-over
roll-over roll-over roll-over stay roll-over roll-over roll-over heel roll-over
roll-over heel roll-over roll-over roll-over heel roll-over roll-over roll-over
roll-over heel heel heel heel heel heel heel sit roll-over roll-over roll-over
heel roll-over roll-over roll-over heel heel heel heel roll-over roll-over heel
roll-over roll-over roll-over roll-over roll-over heel roll-over roll-over
roll-over roll-over roll-over stay roll-over roll-over roll-over heel roll-over
roll-over roll-over heel roll-over roll-over roll-over roll-over roll-over heel
roll-over heel heel heel heel heel heel heel roll-over roll-over roll-over
roll-over roll-over heel heel roll-over heel heel heel roll-over roll-over
roll-over roll-over roll-over heel roll-over roll-over roll-over heel heel heel
roll-over roll-over roll-over roll-over heel heel heel heel heel heel heel heel
sit roll-over roll-over roll-over heel roll-over roll-over roll-over heel heel
heel heel roll-over roll-over heel roll-over roll-over roll-over roll-over
roll-over heel roll-over roll-over roll-over roll-over roll-over stay roll-over
roll-over roll-over heel roll-over roll-over heel roll-over roll-over roll-over
heel heel heel roll-over roll-over roll-over roll-over heel heel heel heel heel
heel heel heel heel heel sit roll-over roll-over roll-over heel roll-over
roll-over roll-over heel heel heel heel heel heel heel heel heel roll-over
roll-over heel roll-over roll-over roll-over roll-over roll-over heel roll-over
roll-over roll-over roll-over roll-over stay roll-over roll-over roll-over heel
roll-over roll-over roll-over roll-over heel heel heel roll-over roll-over
roll-over roll-over heel roll-over roll-over roll-over roll-over heel heel heel
heel roll-over roll-over heel roll-over heel heel heel roll-over roll-over
roll-over roll-over roll-over heel roll-over roll-over heel heel heel heel heel
heel roll-over roll-over roll-over roll-over heel roll-over roll-over heel heel
heel heel heel heel heel heel roll-over roll-over roll-over roll-over heel
roll-over roll-over roll-over heel heel roll-over roll-over roll-over roll-over
heel roll-over roll-over roll-over roll-over roll-over heel
```

Here’s a similar program in Blub, which is designed to be readable by fish:

```blub. blub? blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub! blub?
blub? blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub? blub! blub!
blub? blub! blub? blub. blub! blub. blub. blub? blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub.
blub! blub? blub? blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub? blub! blub! blub? blub! blub? blub. blub. blub.
blub! blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub! blub. blub! blub. blub. blub.
blub. blub. blub. blub. blub! blub. blub. blub? blub. blub? blub. blub? blub. blub. blub. blub. blub. blub. blub. blub. blub. blub.
blub. blub. blub. blub. blub. blub. blub! blub? blub? blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub? blub! blub!
blub? blub! blub? blub. blub! blub. blub. blub? blub. blub? blub. blub? blub. blub. blub. blub. blub. blub. blub. blub. blub. blub.
blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub! blub? blub? blub. blub. blub. blub. blub. blub. blub. blub. blub.
blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub. blub? blub! blub! blub? blub! blub? blub. blub! blub! blub! blub!
blub! blub! blub! blub. blub? blub. blub? blub. blub? blub. blub? blub. blub! blub. blub. blub. blub. blub. blub. blub. blub! blub.
blub! blub! blub! blub! blub! blub! blub! blub! blub! blub! blub! blub! blub! blub. blub! blub! blub! blub! blub! blub! blub! blub!
blub! blub! blub! blub! blub! blub! blub! blub! blub! blub. blub. blub? blub. blub? blub. blub. blub! blub.
```

See User Friendly.

Feed Me, Seymour!

Venus flytraps can “count.” When an insect contacts one of the triggering hairs between its hinged leaves, the trap prepares to close, but it won’t do so unless a second contact occurs within about 20 seconds. This spares the plant from wasting energy shutting on raindrops and other nonliving stimuli.

The plant will release a cocktail of prey-decomposing acidic enzymes after five stimuli, enough to “convince” it that it’s caught a creature worth consuming.

(Jennifer Böhm et al., “The Venus Flytrap Dionaea muscipula Counts Prey-Induced Action Potentials to Induce Sodium Uptake,” Current Biology 26:3 [Feb. 8, 2016], 286–295.)