Friday Fun: This newly-discovered spider courts by playing peek-a-boo

Watch these spiders seductively waggle their fingers at each other in their search for love. Then go read this paper from the Hoy lab in which they perform the first neural recordings from a jumping spider!

Enjoy your blizzard, Northeasterners.

The not-so frivolous function of play?

We play. Cats play. Dogs play. Horses play. Do fish play? Do cockroaches play? What is the function of play?!

[P]lay is actually at the center of a spectrum of three behavior types: [exploration, play, and stereotypies]. Both exploration and stereotypic behaviors can be easily mistaken for play. Exploration refers to an animal’s reaction to a novel environment or stimuli. For example, if you give a child a new toy, they will generally eagerly take it and examine and manipulate it. However, after thoroughly investigating the new toy, the child may toss it aside and play with their favorite beat-up GI Joe doll…

This doesn’t mean that every species plays, mind you; certainly not every mammal species. Even closely related groups can be vastly different- rats play mountains more than mice do, for example, and some species like aardvarks don’t appear to play at all. Still, almost every major group of mammals has some representatives that show play behavior…

Despite the popular conception that play is practice for later life skills, there is almost zero evidence to back it up. Cats who pounced and batted at objects as kittens were no better at hunting than cats with limited object play;  the same went for coyotes and grasshopper mice. Rats, meerkats, wolves, and many primate species are no better at winning fights based on how often they play fight as youngsters.

Did you know that there is a ‘preeminent play scientist’ and he has five criteria to define play? They are:

  1. The performance of the behavior is not fully functional in the form or context in which it is expressed; that is, it includes elements, or is directed towards stimuli, that do not contribute to current survival.

  2. The behavior is spontaneous, voluntary, intentional, pleasurable, rewarding, reinforcing, or autotelic (done for its own sake).

  3. It differs from the “serious” performance of ethotypic behavior structurally ortemporally in at least one respect: it is incomplete (generally through inhibited or dropped final element), exaggerated, awkward, or precocious; or it involves behavior patterns with modified form, sequencing, or targeting.

  4. The behavior is performed repeatedly in a similar, but not rigidly stereotyped, form during at least a portion of the animal’s ontogeny.

  5. The behavior is initiated when the animal is adequately fed, healthy, relaxed, and free from stress (e. g. predator threat, harsh microclimate, social instability) or intense competing systems (e. g. feeding, mating, predator avoidance).

You have to go read the full article, if for nothing other than all the adorable videos of animals playing.

This is much, much better than that really dumb David Graeber article that science needs to be about play and fun.

Why we need animal models

1. a three-dimensional representation of a person or thing or of a proposed structure, typically on a smaller scale than the original.
2. a system or thing used as an example to follow or imitate.
3. a person, typically a woman, employed to display clothes by wearing them.
4. a particular design or version of a product.
These are all the same:
For the record, I study this courtship. Although I want to say, “We study human dancing as a model system for understanding Drosophila behavior.”

Fight club for flies

I’ve been watching a lot of fly behavior recently and it’s pretty spectacular how easy it is to imagine you’re looking at a mammal (just smaller, smellier, and with more legs.) They wander around, clean themselves off, rub their greedy little hands together, fight, and sing.

Watch the very good video above to see how these guys fight each other. It’s about work from David Anderson’s lab on aggression and tachykinin, aka Substance P.

How do ideas spread?

spread of language on twitter

Cultural transmission is something I’ve written about before. An arXiv paper has a clever way of studying it on twitter: follow the creation of electronic language.

For example, the abbreviation ikr, meaning “I know, right?” occurs six times more frequently in the Detroit area than in the US overall; the phonetic spelling suttin, meaning “something”, occurs five times more frequently in New York City; and the emoticon^-^, meaning nervous or shy and of Korean origin, is four times more common in Southern California.

At the beginning of the study, the abbreviation ctfu, which stands forcracking the fuck up or laughing, appeared mainly in the Cleveland area but by 2012 was being used in Pennsylvania and the mid-Atlantic. However, ctfu is rare in the large cities to the west of Cleveland, such as Detroit and Chicago.

But the team also say that new words tend to be shared between metropolitan areas that have a similar racial mix. In fact, the proportion of African-Americans as the strongest predictor of similar usage. “Examples of linguistically linked city pairs that are geographically distant but demographically similar include Washington D.C. and New Orleans (high proportions of African-Americans), Los Angeles and Miami (high proportions of Hispanics), and Boston and Seattle (relatively few minorities, compared with other large cities),” say Einstein and pals.

On twitter, does the racial mix of two cities predict the likelihood of irl (see what I did there) friends/family? Or is it, thanks to the internet, more about the connection of people with similar interests/culture?

(ht freakonometrics)

Optimal hipster theory

I think people are trying to send me a message. For the last few days, I’ve been getting a steady stream of emails letting me know about a new paper posted on the arXiv – The hipster effect: When anticonformists all look the same (for the record, I have never had an ironic mustache.) It’s definitely because of the math involved. Yeah, that’s it.

Just as I started to write this up, though, I see that someone else has already done a fantastic job at a lay introduction to the paper:

Touboul begins by envisioning a world where people choose between just two styles: Call them punk or normcore. There are two kinds of people in this world: those who like to go with the flow, and those who do the opposite — hipsters, in other words. Over time, people perceive what the mainstream trend is, and either align themselves with it or oppose it.

Here are some examples with a population of three conformists and one hipster. How the world evolves over time depends on who starts off in the majority and who starts off in the minority. Take white to be normcore, and black to be punk (obviously).

What if this world contained equal numbers of conformists and hipsters? No matter how the population starts out, it will end up in some kind of cycle, as the conformists try to catch up to the hipsters, and the hipsters try to differentiate themselves from the conformists.

Essentially, the model assumes that individuals have two states (styles) and they flip between them. The switching rate is determined by the mean-field trend such that mainstream individuals will flip to the mainstream (mean-field) style at a high rate; hipsters will flip at a much lower rate. This can be modeled as a spin-glass system where many analytical results are already known.

Now, spin-glass systems are known from magnetism: they help describe how whole systems can suddenly switch from one macro state to another. For instance, from disorder to sudden order. In the hipster system, near the critical point you get sudden transient alignments of hipsters before switching randomly:

hipster critical point

A lot of flop flop flopping from the nonconformists (hipsters).

A more interesting result is that a time-delay induces a Hopf bifurcation in the system causing systematic hipster alignment:

hipster hopf bifurcations

This immediately suggests that decreased time delays should reduce the coherence of anticonformist trends. Luckily we have a natural experiment – the Internet. I’m not aware enough of fashion to comment on that but I am a pretty big music junky. Thanks to the internet, music genres have split into subgenres which split into microgenres and oh god it’s so hard to even keep track of what is what any more.

Similarly, the paper shows that if you there is a spatial extent to the model, then at low delays you only get hipster synchronization when the spatial extent is not too large or too small (in the figure below, the x-axis a is spatial extent, y-axis tau_0 is temporal delay).

hipster time and area delays

Despite the simplifications in the model – fashion is one-dimensional and everyone exists at unit distance etc – there is insight to be gained.

Additionally, while hipster-hunting is an Internet past-time, distinctiveness is a serious matter in ecology and sociology. This is useful!


Jonathan Touboul (2014). The hipster effect: When anticonformists all look the same arXiv arXiv: 1410.8001v1

Where do people look? Where there’s information

where do people look animation

1. BusinessInsider has a great collection of pictures tracking where people actually look when they see an image. (Big takeaway: men love to look at other people’s groins.)

2. Watch the video above: people generally look at the face of the person talking or the object that someone is pointing at. Why? Because that is where the information resides.

information seeking

3. If you ask someone to look for a hidden target, they will look around in a manner that will give them the most information about where the target may be – this lets them exclude as many locations as possible.

4. But we are social animals, and social animals have a tendency to rely on social information – gathering information from other individuals lets you pass on some of the cost of finding it to others. Humans in crowds will look where other humans are looking – what is going on over there? is it something important? why are so many people looking?

5. Of course, humans in crowds are also wary. Other social creatures are potential threats: you want to look someone else’s face to determine whether they are friendly or not. Many animals (like peacocks!) do this – look at where predators might be hiding. Because what information is more important?

6. One way that the nervous system accomplishes this is by internal reward: it is ‘enjoyable’ to look at social faces (and the more relevant, the more rewarding).

7. Famously, dogs will look at where people are looking while cats will not; one has evolved to understand this social information while the other has not. Which says a lot about the psychology of a cat!

Najemnik, J., & Geisler, W. (2005). Optimal eye movement strategies in visual search Nature, 434 (7031), 387-391 DOI: 10.1038/nature03390
Gallup AC, Hale JJ, Sumpter DJ, Garnier S, Kacelnik A, Krebs JR, & Couzin ID (2012). Visual attention and the acquisition of information in human crowds. Proceedings of the National Academy of Sciences of the United States of America, 109 (19), 7245-50 PMID: 22529369
Gallup AC, Chong A, Kacelnik A, Krebs JR, & Couzin ID (2014). The influence of emotional facial expressions on gaze-following in grouped and solitary pedestrians. Scientific reports, 4 PMID: 25052060
Watson KK, & Platt ML (2012). Social signals in primate orbitofrontal cortex. Current biology : CB, 22 (23), 2268-73 PMID: 23122847
Yorzinski JL, & Platt ML (2014). Selective attention in peacocks during predator detection. Animal cognition, 17 (3), 767-77 PMID: 24253451

Orangutan facts

They’re surprisingly smart:

“They say that if you give a chimpanzee a screwdriver, he’ll break it; if you give a gorilla a screwdriver, he’ll toss it over his shoulder; but if you give an orangutan a screwdriver, he’ll open up his cage and walk away.”

At Camp Leakey, the orangutans had plenty of opportunity to observe and imitate people. They soon developed a habit of stealing canoes, paddling them downriver, and abandoning them at their destinations. Even triple and quadruple knots in the ropes securing the canoes to the dock did not deter the apes. Over the years, they have also learned to brush their teeth, bathe themselves, wash clothes, weed pathways, wield saws and hammers, and soak rags in water in order to cool their foreheads with them. And they have done all of this without any instruction.

They’re also social:

But it turns out that adult female relatives stick together: they have overlapping ranges and periodically interact. “I grew up in rural Saskatchewan,” Russon, who now works and teaches at York University, in Toronto, told me. “And, for me, that is exactly what orangutan social life is like. There are communities, but they are very broadly dispersed. It might be fifteen miles to your cousin’s place, or another twenty miles to the next nearest relative, but everybody knows everybody.” Adolescent orangutans—curious and audacious—regularly make new friends. These wandering youngsters, vaulting from one tree to the next, are likely the torchbearers of orangutan culture.

Here is a paper on social behavior of Orangutans:

As they grew older males increasingly spent less time making physical contact, but the amount of time they spent in proximity (within arm’s length) to others increased. Adult females regularly played with other group members. Contact, allogrooming, and social play showed nonrandom relationships between individuals. Adult females showed the most allogrooming and contact, adolescent and subadult males the most play. There was no obvious dominance hierarchy. One adult male spent about 10% of his time walking around the perimeter of the island. One-year-old infants rarely interacted with other individuals apart from their own and the other infant’s mother. While orangutans lead relatively solitary lives in nature, it was concluded that the opportunities for social contact and play provided by the SZG orangutan island were beneficial to this species in captivity.

[Photo by George]

Tricksy insects sing a song of love and deceit


Beyond a spider snacking on an unfortunate fly, the social lives of insects tend to go unrecognized. Perhaps you notice all the ants marching in a line, or bees heading back to a nest, but it all seems so mechanical, so primal.

In reality, insects have social lives that are more complex than you might imagine. One of the most intriguing is insect courtship. Across many species – such as crickets, fruit flies, moths – males must sing to the female in order to mate. The female will listen, considering, and if the male does well enough? Then he can mate. If he can’t sing well enough? He’s out.

While beautiful and touching, it does make you wonder why? Why should a female care that a male can sing well? There is evidence that song can indicate the fitness of the male – males with better song have offspring that are more likely to survive. However, insects often live in mixed environments that consist of many different species. If you dare, go to a garbage heap buzzing with flies. Chances are that it will have big ones and small ones, many different species competing for the same food. One way to screen out the wrong type of fly is to listen for the right song.

But insects are sneaky and can have alternative motives. Another use of the song lies not just in wooing the ladies, but in scaring off competitors. Males of one species of moth will shout out a string of shrieks that sound like the ultrasonic homing call of the bat. Look at the figure below: while the long, crooning song used to attract females doesn’t scare off other males, bat calls – or the short pulse of other males – will send them packing (capture rate is the probability of a moth making its way to a trap emitting courtship pheromones).

scary song

Insects are tricky creatures, able to sneakily imitate predators in order to scare off competitors before deftly turning to romantic ballads.


Nakano, R., Ihara, F., Mishiro, K., Toyama, M., & Toda, S. (2014). Double meaning of courtship song in a moth Proceedings of the Royal Society B: Biological Sciences, 281 (1789), 20140840-20140840 DOI: 10.1098/rspb.2014.0840

Hoikkala, A., Aspi, J., & Suvanto, L. (1998). Male courtship song frequency as an indicator of male genetic quality in an insect species, Drosophila montana Proceedings of the Royal Society B: Biological Sciences, 265 (1395), 503-508 DOI: 10.1098/rspb.1998.0323

Photo by Johan J.Ingles-Le Nobel

Why do we language?

Aeon has an article on how the genetics that contribute to language are actually part of a much larger system:

But over the years, it became clear that the truth about language origins was not quite as simple as a “language gene” or well-defined language module. Further study revealed that the FOXP2gene is relevant to multiple mental abilities and is not strictly a language gene at all. In a 2009 paper, for example, Max Planck Institute geneticist Wolfgang Enard exploited the fact that just three amino acids distinguish the human version of the FOXP2 protein from that of mice. When he engineered the FOXP2 genes of mice to produce proteins with the two human FOXP2 amino acids, it resulted in functional differences in brain areas critical for carrying out fine motor tasks and controlling muscle movements, as well as altered function in regions involved in sending and receiving reward signals.

The same gene that regulated language so strongly also regulated other mental faculties, so its very existence appeared to contradict rather than strengthen the idea that language commands its own territory separate from other areas of the brain. As Enard points out, the language-as-island idea is also inconsistent with the way evolution typically works. “What I don’t like about the ‘module’ is the idea that it evolved from scratch somehow. In my view, it’s more that existing neural circuits have been adapted for language and speech.”

In a great commentary on mice humanized with FOXP2, Bjoern Brembs has a similar point:

It adds weight to the so-called ‘motor-learning hypothesis’ that came up some time around 2006/7 or thereabout. This hypothesis posits that FoxP2 is mainly involved in the motor, or speech component of language, i.e., learning to control the muscles in the lips, tongue, voice chords, etc. in order to articulate syllables and words. The movements of these organs have to become stereotypic in order to reliably produce understandable language and the main experimental paradigms for this stereotypization of behavior (independent of language) have been procedural learning and habit formation. This work provides further evidence that indeed FoxP2 is an important component of the learning process that leads to automatic, stereotypic behavior.

In particular, it suggests that FoxP2 is involved in the control of the process of stereotypization, i.e., at what point the behavior shifts from being flexible, to becoming more rigid. Until this work, the evidence from vertebrates and invertebrates has pointed to FoxP genes to be involved in the automatization of behavior. Now, this evidence is extended to also – at least in mammals – include the negotiation process, which I don’t think anybody had on the radar thus far.

Besides the genetics, anthropology can help us understand the reasoning behind language. From a perspective article on an exciting article about talking around campfires:

how many hours we need to talk per day

The longstanding assumption, dating back at least a century, has been to assume that language evolved to facilitate the transmission of technical knowledge (“this is how you make an arrowhead”), a view that has been generalized more recently to encompass the social transmission of cultural knowledge (again, mainly with a directly ecological purpose). An alternative view has been that language evolved, at least in the first instance, to facilitate community bonding (to allow more effective communal solutions to ecological problems).

In fact, Wiessner’s data suggest that fire and language may be more closely related than conventional views assume. Whatever may have been the original reason why humans acquired control over fire, it seems that it came to play a central role in two crucial respects. First, it effectively extended the active day…

Stories are important in all societies because they provide the framework that holds the community together: we share this a set of cultural knowledge because we are who we are, and that is why we are different from the folks that live over the hill.

And look at what we talk about during the day vs at night:

what we talk about