Video Aluminum cast of ant nest

One of the most enduringly popular post on this blog is "A cement cast of an entire ant colony", a video of an ant nest cast. Embedded below (direct link) is another video of a beautiful cast, this time made using metal.



(H/T: Mike Breytenbach).

Telegraph Science Journalism Fail: Or, ARRRRGHHHH!!!111!

I was alerted to an absolutely daft article in the Telegraph via Derren Brown's Blog (who, disappointingly, didn't seem to notice it's daft). Basically, the article completely misrepresents a paper, "Bonobos Exhibit Delayed Development of Social Behavior and Cognition Relative to Chimpanzees", in press at Current Biology. The paper showed, roughly and among other things, that both bonobos and chimps are cooperative when they’re young, but then chimps become progressively less cooperative and more competitive with age, whereas bonobos don’t. The authors hypothesize that this may be due to pedomorphosis, that is, evolutionary changes to the developmental pattern such that juvenile characteristics persist into adulthood.

The 'science correspondent' at the Telegraph, one Richard Alleyne, however, would have you believe the researchers involved "now believe that being aggressive, intolerant and short-tempered could be a sign of a more advanced nature." How the hell Alleyne got from the paper to THAT conclusion is utterly beyond me, the researchers never even hinted that there is connection between 'civilization' and their findings. Alleyne goes on to commit a bunch of science howlers: among other things, saying chimps are "more evolved" and that chimps and bonobos are monkeys (ARGH). Anyway, I was going to blog about this in more detail, but luckily Alison Campbell at BioBlog has a most excellent take-down of the article, so go there for more (and more competent) analysis.

By the way, this is not the first time Alleyne has gotten it spectacularly wrong. Ben Goldacre has exposed his breathtaking misinterpretation of climate science (which he refused to correct) and his shameful distortion of a graduate student's MSc thesis which he claimed concluded women who get raped, essentially, were asking for it (at least this was half-heartedly and partially corrected). 

In conclusion: 

Chameleons DO change their color to blend in with their environment

For reasons that are not to hard to fathom, myths about chameleons abound. The Victorians thought they lived entirely on air; a common Zulu superstition is that they're evil (as I confirmed for myself a while back when I tried to show a chameleon I had caught to our gardener); and, more recently, I've been hearing a lot of people say chameleon color changing has nothing to do with camouflage. Even Cracked has got in on the act with an article on "bullshit animals facts", which argues a chameleon's color is determined largely by its mood. I call bullshit on their bullshit.

Thanks to frequent childhood visits to a family farm, I've had lots of encounters with these amazing critters and I've seen them change color to blend in with their environment with my own eyes. Not particularly good evidence, I hear you say. Agreed, so I spent 2 minutes on Wikipedia, followed a link, and found this New Scientist piece, about this study in Biology Letters. And guess what? At least one species of chameleon, Smith's dwarf chameleon (which, incidentally, is South African), does change color to camouflage itself from predators. The paper, "Predator-specific camouflage in chameleons" by Stuart-Fox et. al., demonstrated in several behavioral trials that these chameleons engage in background matching when presented with model predators. In other words, these guys do their best to blend in with their environment when they encounter things that want to eat them. (You can see a clear example of a chameleon matching its background in this YouTube clip [Note: James informs me in the comments that this might be fake]).

So why do people think chameleon camouflage is a myth? It seems other research (also by Stuart-Fox) that concluded color changing evolved for social signalling has been misinterpreted. The conclusion of this second paper was: "our results suggest that selection for conspicuous social signals drives the evolution of colour change in this system, supporting the view that transitory display traits should be under strong selection for signal detectability." In other words, the primary evolutionary 'function' of color changing in chameleons seems to be social signalling. But it does not follow from this that chameleons cannot also use color changing for crypsis -- the ability may have evolved for social signalling, but nothing stops it from being exapted for camouflage. It is such an obvious evolutionary trick that I'm surprised anyone interpreted Stuart-Fox et. al. second paper in this way. If you already have a visual system (to detect background color), you can already change color, you suffer predation and camouflage thus increases fitness, we should positively expect exaptation for crypsis.

As I also pointed out on my fox domistication piece, I'm not a biologist so you should be especially skeptical of my opinions on this (though, I managed to convince biologist Richard Glor over at Dechronization that my interpretation is right). But still... At least some chameleons change their color to blend in with their environment. Obviously.

UPDATE: I emailed Stuart-Fox and asked whether my take is correct. Here is the reply in part (my emphasis):

Yes, your interpretation is correct. Colour change in chameleons serves multiple current functions including camouflage (background matching), thermoregulation and communication (courtship and male-male contests). But we need to distinguish current functions from the selective pressures driving the evolution of the abiltiy to change colours. Some species can change colours much more than others - the question I was trying to answer is why such variation? And it seems that sexual selection for communication (signalling) is the most important selective pressure because the species that change colour the most have the most conspicuous colour patterns that they use to communicate.

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Stuart-Fox D, Moussalli A, & Whiting MJ (2008). Predator-specific camouflage in chameleons. Biology letters, 4 (4), 326-9 PMID: 18492645

Stuart-Fox D, & Moussalli A (2008). Selection for social signalling drives the evolution of chameleon colour change. PLoS biology, 6 (1) PMID: 18232740

Silver fox domestication

I recently linked to an extract from Richard Dawkins’ new book in which he mentions a fascinating long-term experiment on silver foxes. The short version: starting in the late 1950s, the Russian geneticist Dmitry Belyaev selectively bred a population of silver foxes for tameness, and, surprisingly, they acquired a dog-like morphology as a by-product (floppy ears, turned-up tails, and so on). In other words, determining which foxes got to breed based solely on how tame and friendly they were produced not only successively tamer foxes, but dog-like physical traits as well. Belyaev believed (and Dawkins concurs) that the reason for this link is pleiotropy, the phenomenon of a single gene having multiple and seemingly unconnected phenotypic effects. As Lyudmila Trut, Belyaev’s successor as head of the Institute of Cytology and Genetics, explains (pdf):

Behavioral responses, [Belyaev] reasoned, are regulated by a fine balance between neurotransmitters and hormones at the level of the whole organism. The genes that control that balance occupy a high level in the hierarchical system of the genome. Even slight alterations in those regulatory genes can give rise to a wide network of changes in the developmental processes they govern. Thus, selecting animals for behavior may lead to other, far-reaching changes in the animals’ development. Because mammals from widely different taxonomic groups share similar regulatory mechanisms for hormones and neurochemistry, it is reasonable to believe that selecting them for similar behavior—tameness—should alter those mechanisms, and the developmental pathways they govern, in similar ways.

Now, this may be entirely correct but I can think of a fairly obvious alternative explanation: subtle biases in the researchers that meant the foxes were not really selected based purely on tameness. (A bit like Clever Hans in reverse). There is an Olympus Mons-sized literature on how human decision-making is influenced, entirely subconsciously, by a dizzying array of crazy things. To take one random example (also previously linked to), holding a heavier clipboard affects judgments of value and importance. Given the ubiquity of such latent biases, are we really to believe that some mutation (unconnected behavior) that merely made the affected fox look tame – made it look a bit more like a dog, say – didn't influenced judgments of tameness? To flesh this thought out a bit more, consider how the foxes were classified. Trut again:

At seven or eight months, when the foxes reach sexual maturity, they are scored for tameness and assigned to one of three classes. The least domesticated foxes, those that flee from experimenters or bite when stroked or handled, are assigned to Class III… Foxes in Class II let themselves be petted and handled but show no emotionally friendly response to experimenters. Foxes in Class I are friendly toward experimenters, wagging their tails and whining. In the sixth generation bred for tameness we had to add an even higher-scoring category. Members of Class IE, the “domesticated elite,” are eager to establish human contact, whimpering to attract attention and sniffing and licking experimenters like dogs. 

Class III seems unambiguously defined and it’s likely pretty straightforward to spot animals that belong to this category. The differences between the other classes, though, are significantly more subjective, and thus liable to all sorts of subtle biases. What, exactly, is an ‘emotional or friendly response to an experimenter’? What, exactly, is ‘eagerness to establish human contact’? It seems entirely possible – indeed likely – that animals that just looked tamer, had stereotypically domesticated features, were more likely to be assigned to Class I than to class II. If so, the foxes were not really selectively bred for “tameness and tameness alone”. No matter how scrupulous and honest the experimenters tried to be, I find it very hard to believe that they succeeded, continuously and without fail, to assign animals objectively to categories. Indeed, the researchers working on the foxes (including Trut) outlined a new scoring method in a 2007 paper, in which they admitted that a cross-breeding experiment “clearly demonstrates that the traditional scoring systems established for selection of foxes for behavior has limited resolution for measuring behavior as a continuous variable”. Assuming, as seems likely, that tameness-aggressiveness forms a continuous behavioral axis, we cannot be confident that Belyaev and his colleagues invariably selected for tameness alone. If this is correct, the pleiotropy story is somewhat undermined, though by no means refuted, of course. It seems significant, however, that the alternative explanation is more parsimonious: it need not posit nearly infallible experimenters, nor a priori unlikely pleiotropic linkages.

Of course, I’m no expert on this topic, so maybe I’ve misunderstood the protocols, or perhaps the alternative I sketch was been refuted somewhere in the literature. I would, however, be very interested to find out how the researchers ruled out this alternative hypothesis...

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Trut, L. (1999). Early Canid Domestication: The Farm-Fox Experiment American Scientist, 87 (2) DOI: 10.1511/1999.2.160

Kukekova, A., Trut, L., Chase, K., Shepeleva, D., Vladimirova, A., Kharlamova, A., Oskina, I., Stepika, A., Klebanov, S., Erb, H., & Acland, G. (2007). Measurement of Segregating Behaviors in Experimental Silver Fox Pedigrees Behavior Genetics, 38 (2), 185-194 DOI: 10.1007/s10519-007-9180-1

Video: Animal Intelligence

Now this is seriously impressive.

Magpies pass the mirror-test

According to a study published today in PLoS Biology the European magpie (Pica pica), has passed the mirror-test, a widely-used and venerable measure of self-awareness. The magpie thus joins a select group of organisms that have passed the test (including, the Asian elephant, dolphins and all the great apes) and, more importantly, is the first non-mammal to pass. The authors did a bunch of mirror-tests on the birds, but the most convincing involved marking the animal somewhere it could see only with a mirror (like in the picture, left) and then looking for spontaneous self-directed behavior. There are a bunch of videos clearly demonstrating self-awareness in the Supporting Information, I especially recommend having a look at video S5 (3.1mb wmv).

The most exciting bit of the abstract:

In apes, self-directed behavior in response to a mirror has been taken as evidence of self-recognition. We investigated mirror-induced behavior in the magpie, a songbird species from the crow family. As in apes, some individuals behaved in front of the mirror as if they were testing behavioral contingencies. When provided with a mark, magpies showed spontaneous mark-directed behavior. Our findings provide the first evidence of mirror self-recognition in a non-mammalian species. They suggest that essential components of human self-recognition have evolved independently in different vertebrate classes with a separate evolutionary history.

(Via: New Scientist).

Cephalopods are awesome

I'm on record saying cephalopods are amazing and everything I've learnt about them since has confirmed me in this view. The fantastic Carl Zimmer asks in a just-released Slate piece: "How smart is the octopus?" The answer, in short, is 'very smart, if not necessarily in human terms'. Zimmer reports on a paper that even claims octupi are conscious (in a limited or "primary" way). If you haven't seen the TEDTalk I posted earlier, have a look and also check out the YouTube videos Zimmer links to.

Video: A cement cast of an entire ant colony

I just came across probably the single coolest science video I have seen in ages: a six minute excerpt from the documentary Ants: Nature's Secret (which won the special jury prize at the Jackson Hole Wildlife Film Festival in 2005). The documentary itself focuses on the work of Bert Hölldobler (who co-wrote the Pulitzer-prize winning The Ants with E. O. Wilson), but the excerpt (embedded below, or click here to go to YouTube) features Walter Tschinkel's amazing cement cast of an entire ant colony. (The cement technique itself seems to have been pioneered by Moreira et. al.). I highly recommend watching the video - it gets especially interesting after about 2 minutes.



(See also: ABC's article on Tschinkel's work, BLDG Blog's fantastic entry on Nest-Casting, and Ask a Biologist's podcast interview with Hölldobler in which he discusses the documentary [click here for the mp3]).

Interesting research, in brief

Occasionally I will summarize (but not analyze) a handful of attention-grabbing recent research findings and link to the original papers so interested readers can follow up for themselves. Sometimes I might go on to write a more thorough analysis of particular papers mentioned in my “in brief” posts.

Animals...

The first study that caught my eye was that, apparently, elephants stereotype. I'm editorializing, of course, but according to research published in Current Biology, elephants distinguish between different human ethnic groups. In the Amboseli Reserve, in Kenya, elephants sometimes encounter Maasai men who attempt to prove their virility by spearing them. The Kamba ethnic group, on the other hand, are apparently generally nice to the elephants and let them be. As a result, "Elephants showed greater fear when they detected the scent of garments previously worn by Maasai than by Kamba men, and they reacted aggressively to the color associated with Maasai. Elephants are therefore able to classify members of a single species into subgroups that pose different degrees of danger."

The second interesting recent animal study tested a counter-argument to the hypothesis that chimpanzees have culture (or engage in differential "social learning"). Observed behavioral differences between non-interacting chimp troops, so this counter-argument runs, could be due to genetic differences between the groups and therefore may not be attributed to cultural variation. The study, published in PNAS, conducted a cladistic analysis comparing the phylogeny and behavior of different groups. The conclusion? "These findings are inconsistent with the hypothesis that patterns of behavioral differences at the population level are genetically determined. Instead, they are in line with a growing number of studies involving captive groups and wild populations that suggest many chimpanzee behaviors are socially learned and can be considered cultural."

Children...

Far from corrupting the youth, philosophy may in fact be good for children. Research published in Educational Psychology suggests that lessons consisting of a Socratic dialogue between students and a teacher has long term cognitive benefits. This finding is a follow-up on the same authors' earlier study which found 16 months of weekly 1 hour philosophy lessons "showed significant standardized gains in verbal and also in non-verbal and quantitative aspects of reasoning" whereas controls showed no gains. Two years later, the researchers tracked down 96 experimental and 52 control subjects and re-administered the cognitive performance tests. They found that "the significant pre-post cognitive ability gains in the experimental group in primary school were maintained towards the end of their second year of secondary school" whereas "the control group showed an insignificant but persistent deterioration in scores from pre- to post-test to follow-up." As far as I am aware, only the International Baccalaureate curriculum incorporates philosophical training at school-level (and then not early enough). Given these findings, that's quite a shame. (See also BPS Research Digest's report on this research).

In possibly the most interesting study I've seen for a while, Bruce Ellis and Marilyn Essex test a life history model of menarche. In an influential 1991 paper, "Childhood experience, interpersonal development, and reproductive strategy," Belsky, Steinberg and Draper proposed the psychosocial acceleration theory which holds (among other things) that girls adaptively adjust their onset of puberty based on the quality of paternal investment and other factors reflecting their living conditions. Ellis and Essex set out to test this theory comprehensively by following 570 pregnant women and their partners longitudinally and determing the effect of socio-economic status, marital conflict, parental mental illness, parental investment (inter alia) on the age of menarche in their children. Their conclusion is that the "quality of parental investment... is the most important mechanism through which young children receive information about levels of stress and support in their local environments, and that this information provides a basis for adaptively adjusting pubertal timing." (See also ScienceDaily's report on this research).

Infants...

It has been known for some time that "emotion drives attention"; that biologically significant stimuli (snakes and spiders being the classic examples) capture the attention of animals (including humans) much quicker than non-biologically significant stimuli. The focus of this literature, however, has been primarily on threatening biological stimuli; a category arguably much narrower than biologically significant stimuli. Now Tobias Brosch, David Sander, and Klaus Scherer argue in their new study that humans also pay preferential attention to newborn infants. The authors suggest, furthermore, that their "results support the notion that a common evaluative process may be responsible for the emotional modulation of selective attention to both negative and positive affectively arousing stimuli."

According to research just released in Nature, infants as young as 6 months have such a well developed theory of mind that they take individuals' behavior towards others into account when forming preferences. Using a methodology involving an innovative puppet show, the authors show that "infants prefer an individual who helps another to one who hinders another, prefer a helping individual to a neutral individual, and prefer a neutral individual to a hindering individual" and conclude their finding "supports the view that social evaluation is a biological adaptation." (See also Nature News's article on this research).