I think I first woke up to the potential of ancient DNA (aDNA) research when I was part of the team developing the Evolution for Teaching website. My friend Dave Lambert, who was then with the Allan Wilson Centre at Massey (Albany) was working with aDNA to study microevolution in Adelie penguins in Antarctica, and he gave us some material to put on our site. More recently Dave & his research team applied the same techniques to moa, revealing that in at least some cases what were thought to be pairs of species (one large, one small) were in fact female and male of the same species (Huynen et al. 2003). Now they've turned their focus to kiwi (Shepherd & Lambert, 2008).
September 2008 Archives
For the last of his '10 questions to ask your biology teacher', Jonathan Wells offers:
EVOLUTION A FACT? Why are we told that Darwin's theory of evolution is a scientific fact -- even though many of its claims are based on misrepresentations of the facts?
Way back in 2004, the first of the 'new' Scholarship exams asked students to:
Compare and contrast the ecological and evolutionary outcomes of releasing herbicide tolerant and insect resistant GM plants.
Yesterday I spent some time with year 13 students from Otumoetai High School, over in Tauranga. We were talking about human evolution & at the end of the session one of the students asked me a question about arrowheads. I wasn't able to answer it then, but I've had a bit of time since to come up with a testable hypothesis that might do it. So James - if you're reading this, read on :-)
When Jane Goodall observed chimpanzees making tools, it became clear that here was yet another example of the continuum between humans and non-human primates. Use and manufacture of tools was not something that distinguished humans from their close relatives, & chimps could be said to have a form of culture. Now here's a paper that presents evidence that there are cultural differences between different groups of chimpanzees.
ERV has just put up an excellent post on why genetic diversity is important. She starts off:
Okay, so there are like 20,000 polar bears left.
Meh, who cares, right? I mean, there are still some. 1,600 plus the ones in zoos. 'Endangered' animals are fine! Yeah... No. Minor problem with decreasing population numbers: Its more than just the numbers. It's genetic diversity within those numbers. If those 1,600 pandas are all we have left, and those 1,600 pandas are genetically similar, they are in big trouble.
Easy example? Tasmanian Devils. While there are still 20,000-50,000 Tasmanian Devils left, they are being slaughtered by an infectious tumor. An infectious tumor that is taking advantage of the fact there is very little genetic diversity in the remaining Devil population.
Go over & read the rest - 20,000 polar bears may not be enough.
This one comes directly from the pages of Ben Goldacre's BadScience blog - an excellent example of why media reports on science need to be read (listened to?) carefully and with your critical thinking antennae twitching:
Here is a cautionary tale for anyone working in research. “Captain Cook and Lord Nelson seem unlikely figureheads in the fight against climate change alarmists,” said the Sun. “Lord Nelson and Captain Cook’s ship logs question climate change theories,” announced the Telegraph. Oh that’s handy. So perhaps we can just keep on burning oil regardless then? “The ships’ logs of great maritime figures such as Lord Nelson and Captain Cook have cast new light on climate change by suggesting that global warming may not be an entirely man-made phenomenon.”
So... data from past heroes suggest we don't have to worry about global climate change, then?
Well, no - Ben goes on to talk with the researcher whose work was 'quoted' by these UK papers, & finds out that that's not what was said at all. A cautionary tale for scientists and readers alike.
Almost at the end of Wells' list we come to ourselves:
Q: HUMAN ORIGINS. Why are artists' drawings of ape-like humans used to justify materialistic claims that we are just animals and our existence is a mere accident -- when fossil experts cannot even agree on who our supposed ancestors were or what they looked like?
Excuse my cynicism for a moment, but there's a whole lot of baggage coming to the fore in this one.
Charles Darwin’s 200th birthday may be fast approaching, but this has not stopped him keeping up to date with the latest scientific advances. Yesterday when I visited him at his blog, I found he had written an item on the large hadron collider (LHC) – or, more correctly, a piece on the hysteria that this particular piece of equipment has generated.
Here's an interesting little press release, about a study that purports to show that women find the sound of fast cars (&, by extension, the men driving them) very exciting! Gosh, that'll push up the sales of luxury cars... (And thanks to Orac, where I originally saw the story.)
But does this study really show what's claimed for it?
I see today that Dr Reiss has resigned from his position as director of education at the UK's Royal Society, following the furore over his reported comments on the approach teachers should take to creationism. Having read the original report in the Guardian, and listened to the audio clip of his interview, I have to say that I'm a bit ambivalent over this news. I know that some see the resignation as a victory for truth (or at least, scientific accuracy) - but at the same time, you could say that the worst he was guilty of was a rather sloppy use of words, perhaps reflecting what's been called an 'accommodationist' approach that seeks to avoid offending what you might term the 'moderate creationists'. I said earlier, & still feel, that we don't tread too carefully around other misconceptions & non-scientific worldviews, so why should this particular issue be any different? But having said that, Dr Reiss issued a statement of clarification, and the RS did likewise, so was the resignation really necessary? (You can guarantee that in some circles it will be used as an example of how the evolutionary 'establishment' won't tolerate dissent from the party line - a rare case, perhaps, of this attitude having a small grain of truth at the core of its rhetoric.)
I said the other day that there's always something new to learn, & I love that my job gives me lots of opportunities to do this. Here's a case in point.
In my second-year paper on evolution, I talk a little bit about pseudogenes. I'm not actually a geneticist & so for this part of the paper I've tended to take what I'll admit is the easy way out & be guided by the textbook for the content. (This was always going to come back & bite me one day as textbooks are always behind the primary scientific literature in terms of the details they include.) Anyway, the other day I made a comment on pseudogenes on another blog & one of the other commenters recommended a new paper to me. So I read it, & now I'm sharing it - thanks, Heraclides :-)
Q: MUTANT FRUIT FLIES. Why do textbooks use fruit flies with an extra pair of wings as evidence that DNA mutations can supply raw materials for evolution -- even though the extra wings have no muscles and these disabled mutants cannot survive outside the laboratory?
I don't know that a lot of textbooks actually do this, but let's have a look at Wells' question in more detail anyway.
My brother sent me an e-mail yesterday, saying "This should wind you up..." with a link to an article in the UK's Guardian newspaper. He was right, it wound me up all right.
The black robin (Petroica traversi) is one of the world’s most endangered birds – there are only around 250 or so in existence. But it’s also one of the success stories of NZ’s conservation efforts – brought back from the brink of extinction. However, this has come at a genetic cost to these little black birds.
Naturally, Wells had to include 'Darwin's finches' in his list of evolutionary icons. He asks:
DARWIN'S FINCHES. Why do textbooks claim that beak changes in Galapagos finches during a severe drought can explain the origin of species by natural selection -- even though the changes were reversed after the drought ended, and no net evolution occurred?
One of the things I love about my job is the endless opportunities to learn new things. I have to try to keep up-to-date in the areas of biology that I teach about, & this means a lot of reading & talking with people. But the opportunities are much wider than that - when I was developing the Science on the Farm website, I started learning about technology, soil science, all sorts of stuff (& I loved it). But today it was biology - I found out that E. coli can taste things!
I've just had a quick look at a paper on the likely role of genetic enhancers in the development of human thumbs. Not exactly rocket science has already done an excellent job of commenting on it, so this is really just a heads-up - go over there to read the whole thing.
The paper reports on an experiment that involved the insertion of a human enhancer region, HACNS1, into mouse embryos. The base sequence for HACNS1 is fairly similar in most vertebrates, but it shows rapid, recent divergence in humans & chimpanzees. What does it do? Well, in the mouse embryos it promoted the genetic activity in their paws - or more specifically, the part that will become the first digit: the thumb/big toe. But other primate versions of HACNS1 didn't do this. So maybe - maybe - this enhancer was involved in the evolution of human feet & hands. It's too early to tell for sure: this is a preliminary study after all (though I would bet that the media will present it as 'gene for thumbs discovered!) - but what a fascinating bit of research :-)
One of my readers has pointed out that the most excellent Panda's Thumb had an article on peppered moths, a wee while ago now. It includes a link to a radio interview that is well-worth listening to. Pop over there & tune in.
ERV has just posted an interesting item on the interplay between medicine, genotype, and perceived racial differences. There's a family of genes (CYP450) that produces the cytochrome enzymes involved in drug metabolism. Depending on an individual's particular set of alleles, they may not be able to metabolise a given drug, or might metabolise at a different speed than predicted. The advent of cheaper genotyping techniques has made it possible to tell what variants an individual has, and to tailor drug regimes accordingly. They have also thrown up some interesting findings on 'racial' differences... go over and read the full story.
A while back I sort of promised to post the talk I was going to give on Charles Darwin. Anyway, now I've done the talk (over in Tauranga; may well be repeating it in Hamilton in the fairly near future), & so here are the words. (Sort of. I tend to develop my presentations in terms of a series of powerpoint images - & not a lot of words - & then base the talk round that, rather than writing a set of notes. So this probably isn't quite what I said the other night!)
The duckbilled platypus is such an odd-looking beast that, when the first specimen made it to Europe, it was widely regarded as a fraud. And you can't exactly blame people for thinking that - they had never seen an animal anything like a platypus before. Now a study of the platypus genome, published earlier this year, has reinforced our understanding of just where this odd little animal fits in the mammalian family tree.
You've probably heard about 'peppered moths' in class. They're an example of the ability of natural selection to shape a population in a relatively quick time. But Jonathan Wells asks:
Q: PEPPERED MOTHS. Why do textbooks use pictures of peppered moths camouflaged on tree trunks as evidence for natural selection -- when biologists have known since the 1980s that the moths don't normally rest on tree trunks, and all the pictures have been staged?
Does he have a point?
A little while back I ran a Schol Bio preparation day for Waikato/BoP students (plus some from further afield). Everyone seemed to find the day useful. At the end I asked students to fill out an evaluation form for me, so that I could find out what worked well for them & where I need to improve things. And it occurred to me that it might be useful to highlight here those things that were identified as useful, because you might find some of them relevant in your own preparation.
This one leads us into the concept of transitional fossils (the so-called 'missing links' whose apparent absence is dear to many creationists). Wells asks
Q: ARCHAEOPTERYX. Why do textbooks portray this fossil as the missing link between dinosaurs and modern birds -- even though modern birds are probably not descended from it, and its supposed ancestors do not appear until millions of years after it?