SciBlogs

Archive April 2012

literate primates? Alison Campbell Apr 15

2 Comments

ResearchBlogging.org

A while back now, I wrote a brief piece commenting on the ability of at least some chimpanzees to recognise numbers. So it didn’t come as a huge surprise to hear that members of a baboon troop could distinguish between ‘real’ words and random strings of letters. Yes, really.

A group of psychologists led by Jonathan Grainger (Grainger, Dufaur, Montant, ZIegler & Fagot, 2012) have just published a paper in Science entitled “Orthographic Processing in Baboons (Papio papio)”, where ‘orthography’ is a standardised system for using a particular writing system (script) to write a particular language. The team noted that most research on visual word recognition hasn’t treated words as ‘visual objects’, instead dealing with the relationship between information at the letter level and ‘higher-level linguistic properties including semantics & syntax. But it seems that the ability to recognise words as entities resides in a part of the brain that’s also involved in recognition of objects & faces, and primates are pretty good at faces, so Grainger & his colleagues decided to investigate whether baboons could extend their facial recognition skills to identifying words.

More specifically:

The computation of letter identities and their relative positions is referred to as orthographic processing, and there is a large consensus today that such processing represents the first ’language-specific’ stage of the reading process that follows the operations involved in the control of eye movements (bringing words into the focus of central vision) and early visual processing (enabling visual feature extraction). In the present study, we examined whether the ability to efficiently process orthographic information can operate in the absence of prior linguistic knowledge.

Hence the decision to work with a non-human primate species: baboons don’t use any phonological equivalents of English words (or, most likely, words in any other human language), & so can’t be said to have any prior knowledge of a human linguistic system .

So, what did the researchers do? They worked with a captive social group of baboons that were living in a large enclosure with various climbing structures & sleeping areas, & set things up so that the animals also had free access to a set of test computers that used touch-screen technology & provided operant conditioning: the animals would get a food reward for correctly recognising an English word (as opposed to a string of random letters). The ‘free access’ thing is important – the baboons could get involved, or not, as they chose.

Using that operant conditioning, the baboons learned

to recognize four-letter English words and distinguish them from strings of letters that are not English words.

Each time a letter string (word or non-word) showed on the screen before it, a baboon could touch either a blue cross (for a random set of letters such as DRAN, LONS, TELK, or VIRT) or a green oval (for a four-letter word such as such as DONE, LAND, THEM, or VAST). A correct response was rewarded with a blank computer screen & some food (dry wheat), while an incorrect choice got a green screen for 3 seconds. They began with a single genuine word option & worked up from there (my emphasis):

Words and nonwords were presented randomly in blocks of 100 trials. The 100-trial sessions were composed of 25 presentations of a novel word to learn, 25 presentations of words randomly selected from already learned words, and 50 nonword trials. Each new word was added to the ever-increasing pool of already learned words, once responses to that word exceeded 80% correct within the preceding session. Thus, in terms of explicit information available to the baboons, a word was defined as a string of letters that was repeatedly presented, whereas a nonword was rarely repeated.

During the course of the experiment, individual animals learned to recognise a surprising number of 4-letter English words (from 81 for ‘VIO’ to 308 for ‘DAN’) – correctly distinguishing the words they recognised from a total of 7832 ‘non-word’ combinations.

Obviously the baboons were simply making random choices at the start of the experiment, and in fact they did this in quite a biased way, with each individual tending to go repeatedly for either the green or the blue button. But – after 2000 trials, they became a lot more accurate, correctly identifying words around 75% of the time. And they were doing this on the basis of different frequencies of letter combinations, rather than ‘just’ memorising the real words (although that would be a rather amazing feat in itself). What’s more,

words that were seen for the first time triggered significantly fewer ’nonword’ responses than did the nonword stimuli. This implies that the baboons had extracted knowledge about what statistical properties characterize words and nonwords and used this information to make their word versus nonword decision without having seen the specific examples before.

And:

The more similar a nonword was to a known word, the more false positive responses it produced.

The researchers noted that this mirrors responses in skilled human readers in the same situation – a rather unexpected outcome.

So, are we looking at some feature(s) of the way the primate brain is wired, that could be regarded as exaptations when it comes to processing visual symbols? Grainger & his colleagues certainly think so:

The primate brain might therefore be better prepared than previously thought to process printed words, hence facilitating the initial steps toward mastering one of the most complex of human skills: reading.

Grainger J, Dufau S, Montant M, Ziegler JC, & Fagot J (2012). Orthographic processing in baboons (Papio papio). Science (New York, N.Y.), 336 (6078), 245-8 PMID: 22499949

scientists *do* have a sense of humour :-) Alison Campbell Apr 13

No Comments

Scientists, like everyone else, have a sense of humour. (It’s just that sometimes their ‘in-jokes’ may come across as somewhat incomprehensible.) And taxonomy seems to offer fertile ground to indulge that wit. What else can you think, when there’s a tiny tiny snail with the genus name Ittibittium; a fly called Pieza kake (say it out loud); and a trilobite with the binomial name Han solo (yes, seriously!). And yes, there’s more – you’ll find a more extensive list here (thanks to Mark Willoughby for sending me the link). In fact, such punny names (sorry, couldn’t resist it!) turn out to be surprisingly common.

It’s not just the biologists; chemists seem to have enjoyed coming up with funny names for new chemical compounds. Moronic acid, anyone? You’ll find a lengthy list at Molecules with Silly or Unusual Names – but you may wish to exercise a little discretion as to whether you wish to call some of the names out loud :-)

if evolution is true, why are there still apes Alison Campbell Apr 11

8 Comments

We’ve just come back from a few glorious days in New Plymouth (arriving home before the change in weather). Had a great time tramping, walking the coastal walkway, eating yummy food – all those nice things you do, holidaying with friends. And as some of the party were driving from Paritutu to meet the rest of us at an outdoor cafe on the coastal walkway, they saw the following sign:

why are there still apes.jpg

It’s a variant on the old “if men evolved from monkeys, why are there still monkeys”, only slightly more accurate – in the sense that we are much more closely related to apes than we are to monkeys, lol. But both versions are wrong, based on a misunderstanding on the nature of evolution, and I wonder if the sign’s author would be willing to look at the evidence for the real state of affairs.

For we didn’t evolve ‘from’ modern apes. In taxonomic terms, humans are apes: placed in the primate sub-order Anthropoidea along with gorillas, chimpanzees & bonobos, orangutans, & gibbons. Morphological & DNA evidence indicates that our nearest living relatives are the chimpanzees, with whom we last shared a common ancestor around 6 million years ago. At 4.4 million years old, Ardipithecus ramidus is the oldest known hominin – & it wasn’t particularly chimp-like. Which is hardly surprising, as the ancestors of both humans and chimps/bonobos have been following separate evolutionary trajectories for all that time. As the team who discovered and described ‘Ardi’ have commented (White et al., 2009):

Perhaps the most critical single implication of Ar.ramidus is its reaffirmation of Darwin’s appreciation: humans did not evolve from chimpanzees but rather through a series of progenitors starting from a distant common ancestor that once occupied the ancient forests of the African Miocene.

T.D.White, B.Asfaw, Y.Beyene, Y.Haile-Selassie, C.Owen Lovejoy, G.Suwa & G.WoldeGabriel (2009) Ardipithecus ramidus and the palaeobiology of early hominids. Science 326: 64 (authors’ summary**) & 75-86. doi: 10.1126/science.1175802

** Teachers – the summary would be a good introductory read for your senior students.


cancer – an example of evolution at the cellular level Alison Campbell Apr 10

No Comments

It’s more than 3 years now since a very close friend died of cancer. At the time, I wrote briefly of how cancer cell lines can evolve resistance to chemotherapy. Now Orac has written a much longer essay discussing the same thing. It’s well worth reading & would probably make an excellent resource for working with senior school biology students.

Orac ends his essay with the following quote, an answer to those who ask why we have yet to cure cancer (even when using personalised therapies that in some cases target the genes themselves):

The reason we haven’t cured cancer yet is because we haven’t figured out how to overcome the power of evolution. Right now, cancer seems almost always to find a way. Until we figure out a way how to block all the ways it can find, personalised therapy will be effective in only a small proportion of cases.

in the lecture theatre – but definitely not giving a lecture! Alison Campbell Apr 02

2 Comments

This is a post I first wrote for Talking Teaching – but hey! it’s about teaching science!

Today’s class was a real experiment for me, & although I try lots of different things in my classes, it was also a step outside my normal comfort zone. (But hey! life would be a bit boring if we always stayed safely inside that zone!) Why? Because I put into practice an idea I stole from my friend & colleague Kevin Gould (who also very kindly let me use the resources he’d developed): today was “design-a-plant” day, & probably to anyone looking into the lecture theatre during the first 30 minutes or so it would have looked as if chaos definitely ruled.

Last Friday I gave everyone an information sheet: descriptions of the features of leaf, stem & root that you might see in plants adapted to different environments. Today I trotted off to the lecture room with a box full of overhead transparency sheets, overhead pens, & printed scenarios (descriptions of a particular environment). The lecture theatre was already full — everyone had come ahead of time! This definitely wasn’t usual (it’s not that they normally trickle in late, but we’re talking seriouslyearly); obviously they were expecting something special. Gulp.

So I put up these slides:

then once they’d sorted out their groups I dished out pens, transparencies, scenario sheets (& copies of the info sheet for those who’d forgotten them), & away we went on a mutual journey of discovery. After all, this wasn’t myidea & I had no idea how it would really work out.

Well! The class erupted into happy, productive noise. I know it was productive because while they talked, argued, explained & persuaded, I circulated, listened in, & answered the occasional question. Those with computers had them open – looking up information related to their scenario. (Next time someone asks a question that I can’t answer on the spot, I’m jolly well going to get someone else to google it for me!) They drew, & altered their drawings, & drew some more. The original 20 minutes stretched towards 30, & still they were focused on what they were doing. I was almost sorry to interrupt :-)

Then, I called for volunteers. A hand went up almost immediately, & its owner came down to the overhead projector, not looking too nervous. She picked up the microphone, described her group’s scenario, & showed – & explained – their response. The next speakers followed just as quickly, and each speaker received a round of applause as they finished.

But the proof’s in the pudding – just what sort of plant had they designed? Well, they didn’t necessarily look like plants that my botanical colleagues could have put a name to, but nonetheless, the explanations each group gave for their particular design were sound, & science-based. They’d obviously taken on board not only the info on that fact sheet, but also the material we’d been looking at in lectures & that they’d found on line. And they’d had fun doing it. (I particularly liked the Nepalese Death Vine – the eerie noise of the wind passing through its herbivore-deterring spines apparently puts the locals off harvesting it, lol – and the Serengeti “cactus” that traps water in basin-like leaves, but when there’s a fire the plant’s transpirative water loss is such that its tissues become flaccid and it wilts, spilling that water onto the ground where the dampness keeps the worst of the fire at bay.) Plus – so far, the feedback for this exercise on our Moodle page is all positive: students felt it definitely helped their learning about plants.

Thanks, Kevin — your design-a-plant lesson got an A+ from all of us today!

a bag moth in residence Alison Campbell Apr 01

No Comments

When I took the cover off the barbecue the other day, a tiny insect caught my eye. It was moving in short, fluttering hops so was fairly easy to catch, and once I had it in a jar I could have a better look. It was less than a centimetre long, dark blue with lovely contrasting golden spots on all four of its short wings. The number of wings told me it wasn’t a fly (despite my husband’s protestations to the contrary), as did its long antennae, which were not quite half the length of its body. And I knew ‘it’ was actually ‘she’, because there on the end of her fat little abdomen were two palest gold puffs – her scent glands.

We showed her to friends over dinner (barbecued lamb that had marinated for the day in a delightful mix of soy sauce, garlic, rosemary, lemon zest & lemon juice, with various other dishes on the side), but no-one knew what our little moth might be. And lacking a decent close-up lens on the camera, I couldn’t mount a photo here for other, wiser eyes to identify.

But tonight I’ve just had an e-mail from our dinner guests, who identified her in a book they were browsing through in a second-hand bookstore in Thames. She’s a female bag moth, Cebysa leucotelis, shown here in a photo from the Landcare Research website:

Australian bag moth

This is a strongly dimorphic species, as the male – who is capable of sustained flight, unlike his partner – looks quite different, a dull brown with pale yellow spots on his hind wings & bars of the same colour along the leading edge of each forewing.

The husband was suspicious, lest they be of the same ilk as the pantry moths currently littering the traps in my store cupboard. But no, bag moths apparently eat lichen & algae on the walls of buildings. So our enchanting little house guests can stay, without fear of further disturbance (at least until the next barbecue!).

Network-wide options by YD - Freelance Wordpress Developer