The Belly Button Science Collection

Belly button, navel, umbilicus. Whatever you call it, it’s a source of great scientific inquiry. After reading recently about the Belly Button Biodiversity project, devoted to chronicling the bacterial flora of the belly button, I thought that it’s time to have a repository for the most interesting belly button-related research. Therefore, this post will act as a continuously updated clearinghouse, full of relevant and entertaining navel research. Let’s begin:

– Interested in seeing the diversity of bacteria that grow in your belly button? Then look no further. The Belly Button Biodiversity project (discussed here) has begun compiling data on navel flora, especially for prominent science bloggers.

– Wondering why some belly buttons generate lint and other don’t? Then read The Nature of Navel Fluff by Georg Steinhauser, who explores (using personal experimentation) the hypothesis that abdominal hair increases belly button lint. Here’s the abstract:

Hard facts on a soft matter! In their popular scientific book (Leyner M, Goldberg B. Why do men have nipples – hundreds of questions you’d only ask a doctor after your third martini. New York: Three Rivers Press; 2005), Leyner and Goldberg raised the question why “some belly buttons collect so much lint”. They were, however, not able to come up with a satisfactory answer. The hypothesis presented herein says that abdominal hair is mainly responsible for the accumulation of navel lint, which, therefore, this is a typically male phenomenon. The abdominal hair collects fibers from cotton shirts and directs them into the navel where they are compacted to a felt-like matter. The most abundant individual mass of a piece of lint was found to be between 1.20 and 1.29mg (n=503). However, due to several much larger pieces, the average mass was 1.82mg in this three year study. When the abdominal hair is shaved, no more lint is collected. Old T-shirts or dress shirts produce less navel fuzz than brand new T-shirts. Using elemental analysis, it could be shown that cotton lint contains a certain amount of foreign material, supposedly cutaneous scales, fat or proteins. Incidentally, lint might thus fulfill a cleaning function for the navel.

– Ever thought about why belly buttons appear the way they do? Maybe it’s an evolutionary signal. Or so argues Aki Sinkonnen in the paper Umbilicus as a fitness signal in humans. The author suggests that “the symmetry, shape, and position of umbilicus can be used to estimate the reproductive potential of fertile females.”

Know of more examples? Contact me via email or Twitter and I can add them here. Please feel free to also leave suggestions in the comments.

Why Apollo 12 Was Amazing

Apollo 11 was pretty much one of the most seminal moments in all of human history, so it’s not likely to be forgotten. And everyone knows about Apollo 13. But what about the mission sandwiched in between? On one level, Apollo 12 was extremely important: it showed that our ability to land humans on the Moon was not exceptional. Rather, we could repeat this feat with regularity, doing it twice in less than a single year. But there’s more to that mission. Not many people know the details of Apollo 12. But, simply put, Apollo 12 was awesome.

Here are a few reasons why Apollo 12 was so amazing. First, this mission didn’t just land on the moon. It landed several hundred meters from Surveyor 3, an unmanned probe that landed on the moon in 1967, two years earlier. And this meant that Surveyor 3 was within walking distance from the Apollo 12 landing site! Pete Conrad and Alan Bean actually visited this probe that had been sitting unchanged for years. The camera, retrieved from Surveyor, was initially thought to even contain bacteria that had been dormant for years on the moon, but still alive. However, more recently, this intriguing possibility has encountered some resistance.

But Apollo 12 gets even better. Think the first words of Apollo on the moon had a bit too much gravitas? Then you’ll love what Pete Conrad said. In reference to his height as compared to Neil Armstrong’s, upon jumping down to the landing pad, Conrad uttered the less famous words: “Whoopee! Man, that may have been a small one for Neil, but that’s a long one for me.” And when he set foot on the lunar surface, he said: “Oooh, is that soft and queasy.” Now that feels a bit more properly improvised.

And let’s not forget that Apollo 12 also was the mission of the Moon Museum and playboy centerfolds in the lunar checklists.

But Apollo 12, even upon splashdown, wasn’t done being interesting. In 2002, an amateur astronomer discovered an asteroid. While this is a normal occurrence, he was soon astonished to find that it wasn’t orbiting the sun, like a normal asteroid, but the Earth! This would mean the discovery of a second natural moon of Earth, the only one after our regular moon. Unfortunately, the excitement was short-lived. The actual identity of the minor planet? The third stage of the Saturn V rocket that launched Apollo 12.

While each lunar mission had something special (we can’t forget Alan Shepard’s lunar golf during Apollo 14), Apollo 12 is definitely something to remember.

Geographic Constraints on Social Network Groups

I co-authored a paper in PLoS ONE, published today, entitled Geographic Constraints on Social Network Groups. Essentially, we tried to understand the relationship between position in a social network and physical location by examining social networks at the level of the social group. Here’s a figure from the paper that shows the interplay between the two factors:

And here’s the abstract that gives a sense of our findings:

Social groups are fundamental building blocks of human societies. While our social interactions have always been constrained by geography, it has been impossible, due to practical difficulties, to evaluate the nature of this restriction on social group structure. We construct a social network of individuals whose most frequent geographical locations are also known. We also classify the individuals into groups according to a community detection algorithm. We study the variation of geographical span for social groups of varying sizes, and explore the relationship between topological positions and geographic positions of their members. We find that small social groups are geographically very tight, but become much more clumped when the group size exceeds about 30 members. Also, we find no correlation between the topological positions and geographic positions of individuals within network communities. These results suggest that spreading processes face distinct structural and spatial constraints.

Onnela, J., Arbesman, S., González, M., Barabási, A., & Christakis, N. (2011). Geographic Constraints on Social Network Groups PLoS ONE, 6 (4) DOI: 10.1371/journal.pone.0016939

The First Issue of Nature

Interested in seeing what the very first issue of Nature, published November 4, 1869, looks like? Check it out here. For a bit of scientific context, On the Origin of Species had been published almost exactly ten years ago (November 24, 1859) and the Dinosaur Wars were raging. Evidence of this is even found in one of the articles Triassic Dinosauria by Thomas Huxley.

To give a sense of how scientific writing has changed over the years, here is the first sentence of a report entitled The Recent Total Eclipse of the Sun:

If our American cousins in general hesitate to visit our little island, lest, as some of them have put it, they should fall over the edge; those more astronomically inclined may very fairly decline, on the ground that it is a spot where the sun steadily refuses to be eclipsed.

Unit of Measure: 1 warp = 4 herrings

In the realm of bizarre units of measurement, there is one that takes top prize: the warp, equal to four herring. Really. According to the Encyclopaedia of Scientific Units, Weights and Measures: Their SI Equivalences and Origins, the warp is an “obsolete British unit used by fisherman to measure the number of herrings.”

I recommend the warp be used to measure consumption by old men at shul kiddush.

Rebirth Island and the Sensitivity of Location

The Aral Sea has been shrinking rapidly since the Nineteen Sixties, as I mentioned a while back on the Mesofacts blog. But there’s something I didn’t previously touch upon: the issue of Rebirth Island in its center.

Over the weekend, my wife and I were looking at an old Rand McNally atlas I had first received back when I was in middle school. In it, the Aral Sea is large and liquid and doing just fine. And in its center is the island of Vozrozhdeniya, or Rebirth Island. It stood out to us because there was a national border running directly through its center, dividing it between Kazakhstan and Uzbekistan.

But in recent years, due to the vanishing Aral Sea, the island is no longer an island. It first became a peninsula in 2001, and is now an undifferentiated part of the mainland. The name “Rebirth Island” now rings in one’s ears as a sad taunt about its nonexistence.

But here’s the wrinkle: during the Cold War, the Soviet Union used Rebirth Island as a laboratory for biological warfare. While the lab is now abandoned, it was located there due to its isolated position. And it was indeed perfectly placed, until irrigation decisions “relocated” a carefully isolated highly dangerous base into the middle of a vast open plain.

A lesson from applied complexity: when constructing a top-secret base while also engaging in irrigation projects at the same time, recognize that they can occasionally work at cross-purposes.

Clustering Map of Biomedical Articles

A large team has examined millions of biomedical documents in order to see how various text similarity methods cluster the different articles. These techniques, grouped under the loose banner of machine learning, look at how words appear together in an article, the frequency of words, and more, in order to create a rich picture of how documents are related to each other. Downloading over two million documents from MEDLINE, they tested how PubMed‘s built-in related article methodology compares to a number of other machine learning techniques. The analysis, titled Clustering More than Two Million Biomedical Publications: Comparing the Accuracies of Nine Text-Based Similarity Approaches was published this month in PLoS ONE.

While the result — PubMed is the best — is both gratifying and not entirely earth-shattering, there is a fun figure from the article that looks at the natural document clusters that jump out from the analysis:

These groupings were made by inspection of the 29,000 clusters that the automated methodology found. It’s nice when machine learning yields clear meaning.

Evidence for Fictional Nineteenth Century Science Journalism

Wondering how long scientific journalism has been around? Since at least the Nineteenth Century world of Sherlock Holmes. Holmes, in The Valley of Fear, when referring to a treatise by his nemesis Moriarty, notes that it’s “a book which ascends to such rarefied heights of pure mathematics that it is said that there was no man in the scientific press capable of criticizing it.” Presumably there was also scientific press in the real world.

Cities of Excellent Research

Over on the arXiv there’s a paper–complete with interactive visualization–that determines those cities that produce more highly-cited research than would be expected. The aptly, albeit lengthily, named Which cities produce worldwide more excellent papers than can be expected? A new mapping approach–using Google Maps–based on statistical significance testing uses a fairly straightforward procedure of finding these cities. The authors, Lutz Bornmann and Loet Leydesdorff, control for size to see which cities have higher impact research than would be expected based on their total output in papers. And doing this, they find that many cities in the United States and Europe are better at producing good research than expected by the null hypothesis, and a number of cities in the former Soviet Union that perform less well than expected:

Go here for further information and visualizations.

Cultural Evolution and Diffusion in Basketball

The Wall Street Journal examines the origins and spread of basketball’s “three-point goggles” – this year’s biggest fad among the players:

As you’ll see in the NCAA tournament this week, players on teams from Duke to Kentucky will celebrate three-point buckets by fitting themselves with pantomimed spectacles, the kind your kindergartener might make while pretending to be a superhero.

To make the gesture, players form the ‘A-OK’ sign over both eyes to form “goggles” with their thumbs and forefingers, and (to denote the change in the score) stick the other three fingers up in the air.

And where did this cultural item begin?

The goggles started earlier this season in Portland as a joke. Patty Mills, a guard for the NBA’s Trail Blazers, liked to tease teammate Rudy Fernandez about his poor eyesight. “I’d always give him a little bit—well, not a little bit, but a lot of grief for not being able to see,” Mills said. In the first half of one particular game, Fernandez struggled from long range. Mills said he told Fernandez at halftime that he needed glasses or contact lenses—something.

After halftime, Fernandez hit a few three-pointers. He turned to Mills on the bench and brought his pointer finger and thumb together in a circle over his eyes, with his three other fingers extended upward. “It was like, ‘I don’t need glasses. I’ve got these three goggles that work perfectly,'” Mills said.