Where Did the Term "Pink Slip" Originate?

Pink slip image via Shutterstock

The Short Answer: No one knows, but the search has been interesting.

The Long Answer: Getting a pink slip usually means you're fired. It's not something most people look forward to. Peter Liebhold, then, is an odd guy. He's been searching for a pink slip for years, and he's disappointed he keeps coming up empty.

Liebhold isn't looking to get canned. Rather, finding a pink slip is his job. He's a curator at the Smithsonian Institution's National Museum of American History and Chair of the Division of Work and Industry.

The history of business culture is his business. The pink slip is a mystery he's been chasing for a long time. Almost everyone is familiar with the phrase, but no one seems to know where it originated, or if there's an actual pink slip out there to be had.

The usual line of reasoning is that the phrase was born when one or more companies started the practice of terminating employees by giving them notice on a piece of pink paper. The color was chosen so that the notice would stand out from the rest of the paperwork on the poor guy's desk and he wouldn't miss it. The catch, of course, is that Liebhold and other historians haven't been able to track down an actual slip, or find any companies that actually fired people like this. The most they had to go on for a while was the Oxford English Dictionary citing the phrase's first known appearance in a 1915 pulp novel about baseball.

The most promising lead Liebhold ever had, he told the Baltimore Sun, was the Ford Motor Company. While poring over an obscure history journal, he found a footnote that led him to another article in another journal that talked about the daily evaluations of Ford's assembly line workers. The workers, the article went, all had lockers or cubbies where they kept their things, and at the end of the day they would find a slip of paper from management there. A white paper meant the day's effort was acceptable. A pink slip, though, meant that they weren't wanted back in the morning. 

Liebhold thought he'd finally found his elusive slip, but when he tracked down the source of the story, a California-based management consultant, he learned it was just an anecdote overheard in college. The consultant had been repeating it ever since. Neither the consultant, nor anyone at Ford who Liebhold talked to, had any evidence that the story was true.

Swing and a miss. 

Liebhold's search hasn't been in vain, though. He's found a few other bits of workplace history during the hunt, like the first American filing cabinet and some red twill that secretaries used to use to bundle documents together — apparently, the inspiration for bureaucratic "red tape."

Big Questions
How Are Speed Limits Set?

When driving down a road where speed limits are oppressively low, or high enough to let drivers get away with reckless behavior, it's easy to blame the government for getting it wrong. But you and your fellow drivers play a bigger a role in determining speed limits than you might think.

Before cities can come up with speed limit figures, they first need to look at how fast motorists drive down certain roads when there are no limitations. According to The Sacramento Bee, officials conduct speed surveys on two types of roads: arterial roads (typically four-lane highways) and collector streets (two-lane roads connecting residential areas to arterials). Once the data has been collected, they toss out the fastest 15 percent of drivers. The thinking is that this group is probably going faster than what's safe and isn't representative of the average driver. The sweet spot, according to the state, is the 85th percentile: Drivers in this group are thought to occupy the Goldilocks zone of safety and efficiency.

Officials use whatever speed falls in the 85th percentile to set limits for that street, but they do have some wiggle room. If the average speed is 33 mph, for example, they’d normally round up to 35 or down to 30 to reach the nearest 5-mph increment. Whether they decide to make the number higher or lower depends on other information they know about that area. If there’s a risky turn, they might decide to round down and keep drivers on the slow side.

A road’s crash rate also comes into play: If the number of collisions per million miles traveled for that stretch of road is higher than average, officials might lower the speed limit regardless of the 85th percentile rule. Roads that have a history of accidents might also warrant a special signal or sign to reinforce the new speed limit.

For other types of roads, setting speed limits is more of a cut-and-dry process. Streets that run through school zones, business districts, and residential areas are all assigned standard speed limits that are much lower than what drivers might hit if given free rein.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at

Big Questions
Do Bacteria Have Bacteria?

Drew Smith:

Do bacteria have bacteria? Yes.

We know that bacteria range in size from 0.2 micrometers to nearly one millimeter. That’s more than a thousand-fold difference, easily enough to accommodate a small bacterium inside a larger one.

Nothing forbids bacteria from invading other bacteria, and in biology, that which is not forbidden is inevitable.

We have at least one example: Like many mealybugs, Planococcus citri has a bacterial endosymbiont, in this case the β-proteobacterium Tremblaya princeps. And this endosymbiont in turn has the γ-proteobacterium Moranella endobia living inside it. See for yourself:

Fluorescent In-Situ Hybridization confirming that intrabacterial symbionts reside inside Tremblaya cells in (A) M. hirsutus and (B) P. marginatus mealybugs. Tremblaya cells are in green, and γ-proteobacterial symbionts are in red. (Scale bar: 10 μm.)
Fluorescent In-Situ Hybridization confirming that intrabacterial symbionts reside inside Tremblaya cells in (A) M. hirsutus and (B) P. marginatus mealybugs. Tremblaya cells are in green, and γ-proteobacterial symbionts are in red. (Scale bar: 10 μm.)

I don’t know of examples of free-living bacteria hosting other bacteria within them, but that reflects either my ignorance or the likelihood that we haven’t looked hard enough for them. I’m sure they are out there.

Most (not all) scientists studying the origin of eukaryotic cells believe that they are descended from Archaea.

All scientists accept that the mitochondria which live inside eukaryotic cells are descendants of invasive alpha-proteobacteria. What’s not clear is whether archeal cells became eukaryotic in nature—that is, acquired internal membranes and transport systems—before or after acquiring mitochondria. The two scenarios can be sketched out like this:

The two hypotheses on the origin of eukaryotes:

(A) Archaezoan hypothesis.

(B) Symbiotic hypothesis.

The shapes within the eukaryotic cell denote the nucleus, the endomembrane system, and the cytoskeleton. The irregular gray shape denotes a putative wall-less archaeon that could have been the host of the alpha-proteobacterial endosymbiont, whereas the oblong red shape denotes a typical archaeon with a cell wall. A: archaea; B: bacteria; E: eukaryote; LUCA: last universal common ancestor of cellular life forms; LECA: last eukaryotic common ancestor; E-arch: putative archaezoan (primitive amitochondrial eukaryote); E-mit: primitive mitochondrial eukaryote; alpha:alpha-proteobacterium, ancestor of the mitochondrion.

The Archaezoan hypothesis has been given a bit of a boost by the discovery of Lokiarcheota. This complex Archaean has genes for phagocytosis, intracellular membrane formation and intracellular transport and signaling—hallmark activities of eukaryotic cells. The Lokiarcheotan genes are clearly related to eukaryotic genes, indicating a common origin.

Bacteria-within-bacteria is not only not a crazy idea, it probably accounts for the origin of Eucarya, and thus our own species.

We don’t know how common this arrangement is—we mostly study bacteria these days by sequencing their DNA. This is great for detecting uncultivatable species (which are 99 percent of them), but doesn’t tell us whether they are free-living or are some kind of symbiont. For that, someone would have to spend a lot of time prepping environmental samples for close examination by microscopic methods, a tedious project indeed. But one well worth doing, as it may shed more light on the history of life—which is often a history of conflict turned to cooperation. That’s a story which never gets old or stale.

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