I’ve been going to a graduate class in science communication this semester. Doug taught us the rule that if you’re using a bar graph, the y axis must start at 0. Otherwise you end up with trickery like this:
Tag / deception
Cuttlefish strike a pose for 3D camouflage
In the game of hide and seek, cuttlefish have the upper hand. These chameleons of the sea are astonishingly good at disappearing: they can instantaneously change the colour of their skin to blend in with the background, matching even the finicky details like the pattern of coloured rocks on the ocean floor.
Divers have long known that cuttlefish are masters of the 3D camouflage game, too, and new research from the Wood’s Hole Oceanographic Institute has revealed how they do it.
Alexandra Barbosa, a graduate student, and Dr. Roger Hanlon were interested in the way cuttlefish strike a pose when trying to hide. After encountering a predator, these octopus-like animals will flee among the corals, rocks and algae, and freeze with their arms contorted into shapes that mimic nearby objects – a feat made all the more impressive by the fact that cuttlefish arms can bend in any direction. Some birds and insects are also known to camouflage themselves with body posture, but few come close to cuttlefish in shape-shifting flexibility (see photos of cephalopod camouflage in the wild here).
To understand just how they do it, Barbosa and her colleagues in Dr. Hanlon’s lab presented captive cuttlefish with some highly unusual surroundings: jailbird stripes, in black and white. In response, the cuttlefish got theatrical, raising their arms roughly parallel to the angle of the stripes. And when the researchers shifted the angle of the background image, the cuttlefish stretched their arms into a new position in an attempt to stay hidden.
Cuttlefish posing against different backgrounds. Modified from Barbosa et al. 2011 (see Figure 1).
Intriguingly, not all of the ten individuals tested were able to match the angle perfectly all of the time – but these quirks may not be surprising given that cuttlefish camouflage is so complex. After all, in nature cephalopods get to choose their own hiding places, a decision that might involve several different factors. According to the researchers, camouflaged cuttlefish are even known to gently wave their arms to match the movement of the underwater plants they are trying to mimic.
These results are a clear demonstration that cuttlefish use vision to guide their 3D camouflage, since the study animals matched a flat background image. Moreover, Barbosa and Hanlon have shown that shape-shifting cephalopods can easily handle scenarios that would never occur in the environment where these behaviours evolved, and adjust just as flexibly to this artificial environment as they do in their natural habitats.
Captive experiments like this are just the first step in understanding how cuttlefish use visual cues to hide, and some big questions remain. For instance, little is known about how cuttlefish can detect and match colours so well despite the fact that they are, in effect, colourblind – Hanlon has found that giant Australian cuttlefish can take on the colouration of rocks on the ocean floor even in the middle of the night.
These remarkable split-second decisions about where, and how, to hide might also help us understand something bigger. Strategic camouflage is just one aspect of the surprising intelligence of cuttlefish, which have the largest brains for a given body size of any invertebrate – these animals are also able to learn and communicate with one another at a level that rivals many land-based animals. It will be intriguing to see where hide and seek fits in to the history of cephalopod brain evolution.
Further Reading
Barbosa, A. et al. 2011. Proceedings of the Royal Society B. In press.
Groupthink
Which animal would use Facebook most, if it could?
My poll in class last week was a popular one – a fact that I couldn’t properly enjoy, since Charlie came up with it for me in a fit of brain-dead incapacity. Charlie’s Facebook question elicited chirps of excitement, compliments and even a few drawings on the response sheets. Here are the results, ranked by favour among the students:
- Chimpanzees: So they have opposable thumbs, and can “use the spacebar” (is this actually important in Facebook?). A number of students gave bonobos special mention, since they would probably want to keep track of all their casual sexual relationships.
- Dolphins: Highly intelligent, social, and they might also be interested in monitoring multiple sexual conquests. Dolphins and migratory whales could use Facebook to keep in touch while roaming widely over the oceans – the long-distance relationships of the animal kingdom. For some reason, students in different tutorial groups who chose dolphins were inspired to draw them for me as well. Coincidence?
- Parrots and other birds: Especially in species that have high levels of extra-pair paternity, birds could use Facebook as a form of mate-guarding to keep tabs on their social partner1,2. There are other reasons to think that songbirds might easily make the transition to internet gossip. Female black-capped chickadees, for instance, eavesdrop on the outcome of song contests between rival males, and use this information when deciding on a mate3.
- Eusocial animals: Like ants or naked mole rats (the only known eusocial mammal). A couple of students also mentioned highly social meerkats, since living in groups of 10-40 individuals would require them to keep track of a lot of social information.
- Other yappy follower-types: hyenas, seals, lemmings, and Yorkshire terriers all got a mention.
Charlie and I discussed it over dinner at the Iron Duke. My first thought went to ants, for their extreme group lifestyle. The problem is that ants don’t really care about what other ants do or think about each other. Insect sociality is all about the greater good: worker ants toil away for the colony despite having no hope of reproducing on their own. Ok, so maybe the internet isn’t conducive to real reproduction either, but ants just don’t have the ego required. Plus, as one clever student pointed out, a colony of eusocial animals are all very close genetic relatives of one another – and she tends to block family members from Facebook.
Charlie mentioned peacocks for spending so much time on courtship and preening, but I rejected that one too.
Wherefore the mustache?
Ears, palms, toes, neck, and nose. In that order.
These are the grossest places for humans to have hair, according to Queen’s students. Ok, there were a few others that I didn’t mention. The upper lip, however, did not receive a single vote.
Last fall a number of men in the biology department grew competitive mustaches for “Movember” prostate cancer research fundraising. This required mass beard shaving on the first of November. Martin Mallet, known for his thick coat of fur, emphatic hand gestures and all-around intensity, suddenly transformed into a meek imposter. For the first time Martin had no probing questions for the speaker at the EEB seminar. I can’t help but wonder: if he did, would anyone have noticed?
I started to recognize Martin again when the hair on his upper lip attained visibility. Other men of Movember fared less well. It can’t be a good thing when the people who work in the same office as you don’t even notice your new, mustachioed face.
But what, if anything, is it for? My experience suggests that human facial hair serves as a male status signal. Is this why we evolved mustaches in the first place?
Why do mustaches evolve? Inca tern, from Wikimedia Commons.
In class the other week we discussed Stephen Jay Gould and the trouble with adaptationism. Gould famously criticized the proliferation of sloppy adaptive reasoning in his 1979 paper “The Spandrels of San Marco and the Panglossian Paradigm“1. He took aim at scientists who apply adaptive “story-telling” to nearly anything – from the colour of our skin to the size of our noses – in an unverifiable, unfalsifiable way.
It can be easy to jump on the adaptationist bandwagon, since these stories are often quite plausible. This may have been especially true when “Spandrels” was written, due to the rise of some revolutionary ideas about how to apply evolutionary biology to the study of social behaviour. There was plenty of new research to be done. Of course, many of the people doing this research disagreed with Gould’s characterization2. At its worst, adaptationist thinking might lead to some bad science, especially when it comes to human behaviour (where confounds are especially hard to control). But speculation is a necessary part of the scientific method, and adaptive reasoning can be a good place to start.
It is worth noting that Gould’s paper has been enormously influential. “Spandrels” has been cited well over 3500 times. I’m still waiting on citation number 3 for my Master’s research.
And yet, the response of the research community to the “Spandrels” critique has largely been, “That’s well said, but let’s get back to our field work.”2 In that spirit, consider the mustache. Can we speculate about it in a reasonable way, avoiding the big adaptationist pitfalls?
First of all, is this question worth asking?
Science fictions
Fakery is not just for Hollywood films anymore.
Nature documentaries are full of it, from elegant narratives to some downright dirty tricks. This tradition goes back a long way: the myth that lemmings commit mass suicide to save their brethren from overpopulation was spread widely as as result of the 1958 Disney film White Wilderness. This is not trivial. The film won an Oscar for Best Documentary. The lemming story made it as far as a philosophy course I took in university (Science and Society PHIL203), where the instructor used it as an example of why we should doubt evolutionary explanations of human behaviour. The myth just won’t die, even though CBC exposed the lemming scam back in 19821. Journalists on The Fifth Estate proved that the mass suicide scene was actually filmed in downtown Calgary, not in the Arctic as Disney had claimed. The Disney crew used a rotating platform to push captive lemmings into the Bow River.
More recently, the BBC has come under fire for using captive animals to film some of the scenes in the Blue Planet series1. This seems justifiable to me, but some truly ugly practices have also been exposed, like baiting corpses with M&Ms to get footage for an IMAX documentary on wolves2.
Field biology goes to Hollywood
One of the weirder things about my field site is that it is also a Hollywood set. A number of movies, TV shows and commercials have been filmed at the LA Arboretum, going back to Tarzan Escapes in the 1930s.
The Arboretum had a regular appearance in the popular 1970s show Fantasy Island. In the opening credits, a midget rings the bell in the Queen Anne Cottage. This is a historic building on the Arboretum grounds that was built in the by the same wealthy California businessman who started the peafowl population in the area.
You can catch the Arboretum in many other films, since it provides a convenient stand in for the jungle a short drive away from downtown Los Angeles. Examples: The Lord of the Flies, Anaconda, The Lost World, Congo, Terminator 2, The African Queen, and too many campy horror flicks to count (Attack of the Giant Leeches?).
Several things were filmed during my three seasons there, leading me to realize that making a movie is a lot like doing field biology. Here’s how:
1. The hours. Field biologists often have to keep the same hours as their study species, working for as long as the animals are active. For some ornithologists, this can mean starting at 4 am. We were lucky with peafowl. They are late risers, coming down from their roosts around 7-8 am. They also tend to take a long siesta in the middle of the day. This meant that we had to work two shifts, coming in for several hours in the morning and returning after lunch until sunset. It made for some long days.
Film crews also seem to work long hours based on the amount of light, since our schedules would often coincide.
2. Tedium and futility. Most of the time spent watching animal behaviour is watching them do very little. Here’s an example: we saw about 20 mating events in 2010, in 500 man-hours of observation time. That’s over 24 hours of sitting quietly for each copulation.
Catching the beasts can be a little bit more active, but you still feel completely useless 90% of the time. Your main activities include: waiting for the animals to show up, looking for the ones you haven’t caught yet, waiting around for your traps to work, and worrying about all the reasons why they aren’t.
A lot of jobs in Hollywood might not be so far off. When AT&T filmed a commercial at the Arboretum last year, we met a guy whose sole responsibility was to keep the peacocks away from the set. His boss gave him a bag of bird seed. It was the cusp of the breeding season, and the crew had decided to place their set right in the middle of one particularly dedicated male’s territory. The poor guy was literally playing tag with that bird all day.
3. Costumes. Important in Hollywood, but also useful when trying to catch birds. After a few weeks in the field, most tend to settle in to a uniform, wearing the same thing nearly every day. If it works and you’ll just be getting dirty again tomorrow, why change?
Waterproof jackets come in handy when catching large birds. From left: Will Roberts, Myra Burrell and Roz Dakin. Photo by Bonny Chan.
Masters of illusion
It can be easy to see intelligence in the animals we spend a lot of time with. Everyone has their pet example, one of the most common being dogs who can anticipate the precise time of their owners’ return. But what does this really say about the mental life of dogs? Some birds are capable of even more impressive mental stunts – only they often go unnoticed in the wild. Two recent field studies in Africa and Australia provide a nice illustration. The results challenge our notion of limited animal intelligence, but as we will see, the way we interpret them might say more about our own minds than it does about the birds.
Fork-tailed drongos are masters of deception. These small, glossy black birds from southern Africa are known for their ability to mimic the calls of other bird species – much like the mockingbirds found throughout the US and parts of southern Canada. Most of the time, drongos forage alone hunting insects, but occasionally they get other animals to do the hard work for them. Drongos will follow groups of meerkats and pied-babblers – mammals and birds known for their highly social lifestyles – and steal their food, a process known as kleptoparasitism. It might not be a complete loss for the victims, either. Drongo thieves give plenty of alarm calls along the way, and these may help the meerkat and babbler groups avoid predation1.
Perhaps not surprising for an accomplished mimic, the fork-tailed drongo has a diverse alarm call repertoire that includes its own unique warning “chink” as well as the calls of several other bird species. On the savannahs of the Kalahari Desert, birdwatchers noticed that drongos often seem to use these mimicked calls during kleptoparasitism, swooping in to steal food from pied-babblers immediately after sounding a false alarm1. For Tom Flower at the University of Cambridge, this was fascinating anecdotal evidence, so he set out to test whether these alarm calls are used by the drongos in a deceptive way2.
The first thing Flower needed to do was eliminate the possibility that the drongo false alarms are coincidental. If the drongos are truly deceptive, the calls should only occur when the birds are attempting to steal food. Flower also had to establish that the drongos sound the same, regardless of whether they are using their alarm calls in an honest or deceptive context. Finally, he had to show that the meerkats and babblers respond similarly in both cases.
Fork-tailed drongo.