SciBlogs

Archive September 2012

how do kids learn about dna? Alison Campbell Sep 30

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My significant other is forever telling me that Facebook is a total time-waster. Sometimes I do tend to agree – but also, one can Find Out Stuff! Like the study I’ve just heard about via Science Alert, on how children get information about genetics and DNA – things we might regard as being in the ‘too hard’ basket & so best left for senior high school students to grapple with. That grappling begins in year 11, when one of the NCEA Level 1 Science standards asks that students be able to “demonstrate understanding of biological ideas relating to genetic variation”.

Is that too late? Jenny Donovan and Grady Venville suggest that it is, arguing that with the rapid growth of knowledge in and applications of molecular biology,

[citizens] of the future will be called upon to make more decisions, from personal to political, regarding the impact of genetics on society. ‘Designer babies’; gene therapy; genetic modification; cloning, and the potential access to and use of personal genetic information are all complex and multifactorial issues. All raise ethical and scientific dilemmas.

They give the example of jury trials, where jurors may hear quite complex information about DNA and be asked to consider this in coming to a verdict, and note that people may have acquired a range of misconceptions around DNA from sources such as the popular program CSI and its various spin-offs.

Children, for example, have a lot of opportunity to hear about genes, DNA, & their uses well before we start formally teaching these concepts at school. Donovan and Venville already knew (from their own previous research) that by the end of their primary schooling many students were already developing misconceptions about genetics; for example, the idea that ‘genes and DNA are two totally separate entities.’ This time, they wanted to examine the impact of the mass media on children’s conceptions (& misconceptions) around this subject. The misconceptions part is particularly important because misconceptions, once formed, can be extremely persistent – affecting learning into the tertiary years.

Using a combination of interviews and questionnaires about media use, the researchers found that their subjects (children aged 10-12) spent around 5 hours a day using various media (TV, radio, print media, movies, & the internet), with most of that being watching television. This included crime shows, and the children felt that they gained most of their ‘knowledge’ of genetics from TV. Donovan & Venville chose to question children from this age group because, with falling numbers of Australian students taking science subjects in upper secondary school, ‘exposure to genetics may be their sole opportunity to develop scientific literacy in this field’ – where ‘scientific literacy’ encompasses literacy both within and about science.

So, what did they find out?

Most children (89%) knew [about] DNA, 60% knew [about] genes, and more was known about uses of DNA outside the body such as crime solving or resolving family relationships than about its biological nature or function. Half believed DNA is only in blood and body parts used for forensics.

Very few – only 6% – knew that DNA and genes were structurally related. Around 50% of the children surveyed felt that DNA & genes are found in only some tissues & organs. (I was half expecting them to say that DNA is found only in genetically-modified organisms – with GMOs in and out of the news, it’s odd that this didn’t come up.) And 80% of them felt that TV was ‘the most frequent source of information about genetics (with teachers confirming that the subject hadn’t been taught at school). As a result of these findings, Donovan & Venville argue very strongly that instruction in genetics should take place much earlier in students’ time in school, noting that other researchers suggest that

giving students opportunities to revisit science ideas and build deeper understanding over time, enables them to grasp and apply concepts that typically are not fully understood until several years later… [and that] students need to be exposed to background knowledge from early ages in order for them to make sense of what they absorb from the world around them.

So, if kids are going to watch programs like NCIS, CSI, and Bones on a regular basis, then maybe early teaching around genetics concepts could use

lively discussions around what they have seen and heard about genetics in the mass media [as this] may ultimately help children to make informed decisions in their future lives.

An interesting suggestion – and one which reinforces yet again how important proper resourcing and support of science teaching are, if we are to develop real literacy in and about science.

J.Donovan & G.Venville (2012) Blood and bones: the influence of the mass media on Australian primary school children’s understandings of genes and DNA. Science & Education (published online 23 June 2012, doi: 10.1007/s11191-012-9491-3

traumatic insemination? ooh that sounds painful! Alison Campbell Sep 26

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Bedbugs. One of the critters that I’d prefer not to encounter on my travels. They come out at night and bite sleeping humans (& other animals), retreating during the day to their dark hideaways, often in cracks in furniture, walls, or floors. This sounds very insanitary but the species that bites humans, Cimex lectularius, isn’t generally regarded as a disease vector, and while a review published in 1963 found that bed bugs can carry a range of pathogens, the author also concluded that there was no scientific evidence of actual transmission of disease. At least one recent research study found that Rickettsia could survive in the insects’ blood for several days after infection, but again noted no evidence that the pathogen was spread in the bugs’ bites.

Now, I know that a bug’s gotta do what a bug’s gotta do. But even when it comes to their love lives, bed bugs are just not that, well, nice. For mating in the African bat bug (a relative of C.lectularius) sounds more like open warfare than a tender meeting of the sexes.

In this, and in other Cimex species (including lectularius), male bugs don’t mess around. Rather than find the female’s genitalia & follow a more normal route, the male simply stabs his penis into his mate’s abdomen. Ouch! Traumatic insemination, indeed. His sperm are injected into her blood-filled body cavity (insects have an open circulatory system) and make their way thence to her ovaries. Not only is the female physically damaged by this act, but it must also open the door to infection by pathogens. It turns out that males are also susceptible to damage as they are not too fussy about who they mate with, and at times another male ‘will do’.

The risk of harm is not trivial, and so individuals with any trait that might minimise the harm is going to be at a selective advantage (& if that trait has a heritable component, the underlying alleles will spread through the population’s gene pool). The result is the evolution of ‘paragenitals’ in both males and females: structures described as ‘extra genital funnel[s]‘ (Dolgin, 2007) that are easy to access and increase the odds that matings will be in that spot rather than randomly all over the abdomen. What’s more, the male’s penis enters a cavity lined with immune cells (like all animals, insects have an innate immune system), which reduces the odds that the mating partner will pick up an infection.

There is, of course, a disadvantage to a male bug in looking like a female – more males may start to hit on him. Consequently males’ paragenitals differ from females’ in that they are more open (their funnel is a different shape). But the story doesn’t stop there. It turns out that at least some female bat bugs’ paragenitals look more like those of the males – and that this deception works: counting the scars on their abdomens, & comparing the results with the scores for more girly girls, showed that male-like females had suffered fewer of those random mating stabbings.

I shall let the reporter at Evolution (on Facebook, where I first spotted this story) have the last word:

If you’re having trouble envisioning this cross-dressing insanity, picture this – the males are dressed like girls, and the girls dressed like guys who are dressed like girls, and everyone’s doing this to avoid sex.

(Avoid it as much as possible. But not completely – for that route would lead to the oblivion of extinction.)
E.Dolgin (2007) Bug sexual warfare drives gender bender: African bat bugs have two types of female genitalia Nature (published online 20 September 2007) doi: 10.1038/news070917-7

 

an ambulant toupee? Alison Campbell Sep 22

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No, it’s a megalopygid moth caterpillar (via Science Alert on Facebook).

Image: Rainforest Expeditions (on Facebook)

Megalopygids are also called ‘flannel moths’ (you can see images of both adults and larvae here - the larvae are quite diverse in appearance). I do wonder, after looking at this adult, if they aren’t related to the poodle moth I shared with you a few posts ago.

Apparently the larvae, which are 2-3cm long, are called ‘puss caterpillars‘, presumably because the long hairs that cover their bodies make them look vaguely (very vaguely!) cat-like**. But you wouldn’t want to stroke them. Hidden in all that seemingly soft fluffiness are spines tipped with venom that causes a burning pain, & inflammation that can last for several days – with the nastiest species, in a worst-case scenario the victim may go into shock. So you’d want to restrain the urge to touch, if you came across one (in the southern US, Mexico, or Central America).

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** I’m afraid I don’t think ‘cat’ when I see that image; it reminds me more of a certain millionaire’s hairpiece…

letting a good story get in the way of a few facts? Alison Campbell Sep 19

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Today in the Herald I learned that eye colour can reflect personality. Apparently

[r]esearchers from the University of Queensland and the University of NSW analysed the eye colour of 336 Australians – most with a northern European background. They answered a series of questionnaires measuring aspects of their personality like agreeableness, conscientiousness and neuroticism.

The story went on to say that blue eyes were linked to competitiveness, and that this would be useful in acquiring a mate during the extreme conditions in northern Europe during the last Ice Age. Along with its own, slightly different version of the story, Medical Daily helpfully provides a link to the original paper (which is a couple of years old). The abstract (Gardiner & Jackson, 2010) tells us that

The current study investigates whether eye color provides a marker of Agreeableness in North Europeans. Extrapolating from Frost’s (2006) research uncovering an unusually diverse range of hair and eye color in northern Europe, we tested the hypothesis that light eyed individuals of North European descent would be less agreeable (a personality marker for competitiveness) when compared to their dark eyed counterparts, whereas there would be no such effect for people of European descent in general. The hypothesis was tested in Australia to provide consistent environmental conditions for both groups of people. Results support the hypothesis. Implications and conclusions are discussed.

My first thought was – in extreme environments, when the whole group has to work together to survive, would a strong competitive streak really be that useful, or would cooperative behaviour be favoured?

The survey participants were university students, & the way they were classified was interesting:

Participants of White UK origin were classified as North European in origin (63.1%) and all other white Europeans were classified as being of Non-UK White European descent. Our designation of participants from the UK as being classified as North European and subject to the effects of the Ice Age is in-line with Frost’s (2006) theoretical account… We chose UK participants as being representative of North Europeans because we thought that its relative isolation as an island would be more likely to have led to less migration than other parts of Europe which might be more commonly defined as being part of North Europe such as the Scandinavian countries.

Yet the British Isles have a long history of migrations from Europe (going well back into prehistoric times).

Respondents self-reported their eye colour, presumably selecting from the categories listed by Gardiner & Jackson (blue, green, hazel, brown, or black). A more objective measure would have seen photographs assessed by a third party. (It would be useful to know whether the participants knew what was being studied, as prior knowledge of the hypothesis, for example, could have biased their choices when completing the surveys.) The researchers found that

light-eyed Europeans are less agreeable than their dark eyed counterparts

who tended to see themselves as more altruistic and helpful. Medical Daily reported that the researchers “believe the link has evolutionary roots”, & the journal article bears this out. Oh goody – evolutionary psychology. I do like a good story. According to the research article,

sexual selection was stronger in ancestral Northern and Eastern Europeans because the steppe-tundra environment of the last ice age skewed the operational sex ratio towards a male shortage. There were two causes for this shortage of males: firstly, men had to hunt over large distances in search for herds thereby often incurring injuries and dying younger; secondly, women had fewer opportunities to gather food and thus required more male provisioning, resulting in less polygyny.

Evidence, please. Evidence that men 20,000 years ago were dying off at a higher rate than women. Are sex ratios skewed, in the skeletal remains we have available from this time period? (Sex ratios tend to be slightly skewed in favour of males in modern hunter-gatherer populations such as Inuit & Australian Aborigines.)

Also, what was that Ice Age environment really like? Up close to the kilometre-thick glaciers that pushed down from the north, conditions would have been severe, but further south? OK, there were periods when the average temperature was rather colder than now: these are the ‘glacial’ periods. And glacial periods were separated by ‘interglacials’, lasting thousands or tens of thousands of years, when things were more temperate & in fact temperatures approximated those we experience now. The ‘Ice Age’ wasn’t one long spell of unremitting cold. Would there really have been sufficiently strong selection, for sufficiently long periods of time, to generate the eye-colour frequencies observed in modern populations? Or are we looking at the result of a bottleneck event, for example?

The article goes on to say that the supposed skewed sex ratio would have generated strong competition between women for the available men, and goes further: that because blue-eyed women are supposedly more competitive, they’d have won out and achieved more matings, spreading their genes around.

Again, evidence, please. If this proposed mechanism shaped our behaviour so strongly, well, we’re only 12,000 years or so out of the last glacial period, so there would presumably still be evidence of similar sexual selection in today’s populations. In fact, Gardiner & Jackson comment that

blue eyes are still much rarer than brown and thus selection based on rare color advantage, even in the present time, may still exist in North Europe.

Somehow I doubt it: 99% of Estonians, 75% of Germans, and 90% of Danes have blue eyes. Rare colour selection, if it exists, should be in favour of brown-eyed people, in those Northern European populations.

E.Gardiner & C.J.Jackson (2010) Eye color predicts disagreeableness in North Europeans: support in favor of Frost (2006) Current Psychology 29: 1-9 doi: 10.1007/s12144-009-9070-1

Quick Personality Survey!<br /><br />
This cat's markings look like:

 

indonesia to host 2014 international biology olympiad Alison Campbell Sep 14

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The dream is over! Dr Poonpipope Kasemsap, the IBO Chairperson, contacted NZIBO chair Dr Angela Sharples last night. The Indonesian government has stepped in to support the organisers and the 25th IBO will be hosted in Bali in either the 1st or 2nd week of July 2014.

As Angela has said to me, on a positive note it will be wonderful to visit Indonesia. They will organise a wonderful event and the Balinese version of manaakitanga is world reknowned. Poon and the IBO steering committee have been incredibly supportive of NZIBO and despite us letting the organisation down it’s great to know we are still able to compete in future IBOs. This really was a major concern for NZIBO, so we were very relieved to hear this.

But we do wish the NZ government understood the importance of consistently supporting excellence in Science education, at all levels. At some point, New Zealand – as a competing nation – will be expected to host the Olympiad. Hopefully the support will be there in the future.

the sir paul callaghan science academy Alison Campbell Sep 13

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Sir Paul Callaghan was a great scientist, a superb science communicator, and a visionary with a very clear idea of the importance of science and science education to New Zealand’s future: a future where our population is ‘science-savvy’ and where students are attracted to study for careers in science, technology and engineering. If that’s to happen, we need to catch students early, nuture their natural curiosity, & maintain their enthusiasm for the sciences throughout their educational trajectories.

And for that to happen, our teachers need to be supported in developing and enhancing their own skills. This is particularly the case for teachers in primary schools, where recent reports have identified quite significant issues with delivery of science programs – due at least in part to a lack of professional development and support for primary science teaching.

Which is where the Sir Paul Callaghan Science Academy comes in to it. It reflects Sir Paul’s belief that

You don’t need to teach a child curiosity. Curiosity is innate. You just have to be careful not to squash it. This is the challenge for the teacher – to foster and guide that curiosity.

Launched today, the Academy aims to

inspire primary teachers to foster and guide the natural curiosity of children; and promote excellence in science teaching through intensive, best practice, inservice training courses.

The intention is that the 24 teachers who attend each Academy session will then be able to become champions of science** in their own school communities. The program’s goals and intended outcomes are praiseworthy, and its success would be a living memorial to a great New Zealander.

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** great to see that they will receive ongoing mentoring; I must hope that their schools will receive the resourcing to allow their champions to fulfill this demanding role.

 

science: 1; society for textbook revise: 0 Alison Campbell Sep 09

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From Nature (& via a commenter at Silly Beliefs): science wins over creationism.

In South Korea, the Society for Textbook Revise, STR [sic] – associated with the Korea Association for Creation Research – has apparently been pushing textbook publishers to remove two examples of evolution from school textbooks. You may be surprised to hear that we’re not in Texas any more, Dorothy, given how similar this sounds to calls in the US for students to learn about the ‘theories’ around the development of life on earth. The STR argued that because scientists were ‘debating’ the two textbook examples (Archaeopteryx, and the evolutionary history of horses), the examples were ‘flawed’ & so shouldn’t be taught. (Which, at the very least, shows a misunderstanding of how science operates.)

Soo Bin Park reports in Nature that, initially, the textbook publishers were going to do as STR wanted; however, following an outcry from scientists, the South Korean government set up an expert panel to look into the issue. The outcome?

A reaffirmation that

the theory of evolution is an essential part of modern science that all students must learn in school

and that Archaeopteryx should be retained in the texts.  Regarding the horse example, the panel commented that the textbooks presented it in ‘too simplistic’ a manner and that it should be revised or replaced, perhaps with an explanation of cetaceans’ evolutionary history. This did make me wonder if perhaps the books’ authors had gone down the route of what the late, great Stephen Jay Gould described as the ‘fox terrier problem’ and the ‘creeping fox terrier clone’.

In other words, had they used the ‘traditional’ iconography where the evolutionary history of modern horses is presented in a fairly linear fashion, from the little Hyracotherium (I still prefer the lovely name Eohippus!) to modern Equus, with only 2-3 intermediaries? We now know that the horse phylogeny is more complex than that. And, had they described Hyracotherium as ‘about the size of a fox terrier’, something that Gould found to be repeated in just about every book he (well, his research assistant) looked at? It turns out that the fox terrier would have been a rather large one: Eohippus/Hyracotherium was about 60cm long & 20cm at the shoulder, and weighed around 22kg – more like a small labrador!

Incidentally, those two names reflect the way this species was named. Hyracotherium was first described – on the basis of an incomplete specimen – by the English anatomist and palaeontologist, Richard Owen. Subsequently the American palaeontologist Othniel Marsh found a complete skeleton and named it Eohippus. Subsequent comparison found the two specimens belonged to the same species, and Owen’s name was applied to both under the rule of priority used in scientific taxonomy. (Brontosaurus went the same way, replaced by the older – but, to me anyway, less euphonious Apatosaurus.)

S.B.Park (2012) Science wins over creationism in South Korea. Nature published on-line): doi: 10.1038/nature.2012.11377

 

if only… Alison Campbell Sep 07

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A nice piece in Nature, by Tony Ballantyne (& hat-tip to PZ Myers, who somehow finds these things first), speculates on how things could be for those who selectively reject the bits of science they don’t like: in this instance, vaccination, but creationism could easily be substituted in this storyline.

T.Ballantyne (2012) If only… Nature 489: 170 doi:10.1038/489170a

 

 

walking on custard Alison Campbell Sep 06

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This is not biology at all :-)

I’ve previously seen (& linked to) videos of people walking on the surface of a mix of cornflour and water. (Marcus will be able to explain the physics behind it.) But now – via PZ Myers – we have:

Walking on Custard!

If my embedding skills fail, follow the link in Custard :-)

more on mosaics Alison Campbell Sep 06

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A couple of days ago I posted a stunning photo of a peacock, and talked a bit about the possible genetic underpinnings of its colour patterns. My friend & blog-buddy Grant then pointed me at the story of a cat that has a similarly amazing colouration. Venus even has her own Facebook page! (I will definitely be using both these images & their stories with my first-year class next week.)

As you can see,  one half of Venus’s face is black, with a yellow eye, while the other half is orange – with a blue eye. What a stunning cat!

The underlying reason for her striking colouration isn’t clear. She could be a chimera, formed from the fusion of two fertilised eggs, so that some of her cell lines would have different DNA from the rest. She could equally well be a particularly impressive example of the results of X-chromosome inactivation in female mammals. In that case, of the two X chromosomes in the cells of the right-hand-side of Venus’s face, the one with the ‘orange’ allele would have been inactivated. That side of her face is black because all cells have functioning X chromosomes that are expressing the ‘black’ allele. The reverse would be true for the orange side of her face.

Which leaves the question: why does she have a blue eye on the orange side?

In the comments thread to my original post, herr doktor bimler noted that

[the] X-chromosome mosaicism of female mammals turned up a lot in colour-vision research, because women carrying a colour-deficiency gene on one X chromosome end up with their retinas being more-or-less coarse patchworks of colour blindness. In the extreme case people can be red-green deficient in one eye and normal in the other**.

This can also be true for haemophilia, where the gene locus involved in the most common form of this disease is found on the X chromosome. (Haemophilia C is not sex-linked.) Heterozygous women, with one normal and one recessive, deleterious allele, are regarded as carriers, unaffected but with the potential to pass the ‘haemophilia’ allele on to some of their children, with damaging effect in those sons who receive it. But – and I must get my class to consider this one next week – such women are mosaics for X chromosome genes. If the ‘haemophilia’ X chromosome is ‘on’ in all the cells of their bone marrow, those women would also be haemophiliac.

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**Being a person with a dry sense of humour, herr doktor concluded that such women “must spend their lives hiding from the colour vision researchers who wish to experiment upon them.”

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