One of the more futile phrases we mutter as teachers in our attempt to squeeze more blood of exam marks out of the stone of pupil indifference is ‘Read the Question’. In the unforgiving heat of the exam glare it is a rare student indeed who is able to consistently keep calm enough to recognise what question is really being asked and provide a thoughtful, well-crafted answer rather than smearing their answer paper with a random collection of half-remembered chemical names and a completely irrelevant aside about enzymes. It is entirely understandable and a feature of exam stress that Continue reading “Read the question: Grammar schools”
You may be wondering why there isn’t much in the course on cryptozoology. This is the study of animals that have not yet been shown to exist, for example unicorns and the Loch Ness monster. This week has seen some attention on the hunt for the Abominable Snowman, or Yeti, and claims from some scientists that they have uncovered evidence for their existence. Unfortunately (and this will explain why we don’t cover cryptozoology in A levels) they have done no such thing.
Science relies on the methodical gathering of evidence, testing and re-testing of hypotheses. The ‘scientists’ involved have gone straight past the boring bit of gathering valid data and gone straight to the headline grabbing phase. Their evidence consists of some hair (unidentified as yet, but it wouldn’t be difficult to do), an alleged nesy made from twigs (Really? Do you have any photos? No? How odd.) and footprints (guess they didn’t get any photos of those either). Science does not get to the truth by making unsubstantiated claims or listening to anecdotes (the Royal Society, probably the oldest scientific society in the world, has for its motto ‘Nulius in verba’, translated as ‘not by words’. This is a good description of the core of science; it is not enough to simply say or assert something, you must back it up with evidence. The evidence must be clearly available to other people to test (it’s no good making special pleading claims that only you can see the evidence, or ‘it did that when I tried it.’
It is possible that the yeti exists, but no valid evidence has been presented to demonstrate this. The scientific position remains that the yeti does not exist. If valid evidence emerges for the existence of these animals, then scientists will change their minds. It is however unlikely to be found. Resorting to boring old things like facts and evidence, creatures of the size proposed (and the same goes for Nessie) would have well understood need for territory, mating groups and reasonably sized gene pools to avoid in-breeding problems. From what we know of comparable sized animals, it is unlikely that something this big would have remained undetected.
New animals are discovered all the time, but it is rare indeed for legendary creatures like bigfoot and Nessie to be found living happily in our world.
Link here to the cell animation from friday’s lesson (you will need youtube so this will not be available in school).
Incredible bit of time lapse video. Now get back to do something productive. We’re back in a week…
I found this on Phil Plait’s superb Bad Astronomy blog. He’s pretty good at picking out this kind of stuff, have a poek around his site. There’s an older cached version you can find through google with soem very good answers to some basic physics questions. Yes, I know you are doing biology but this is science. Embrace your inner nerdiness.
Several newspapers today carry a story about genetic changes in mice. The basic issue is that species of mice common in europe have cross-bred with a species of Algerian mouse. This is of interest because the Algerian mice have a genetic resistance to many types of poison.
A commonly used poison on rodents is warfarin. You may remember it being mentioned in GCSE – it is an anticoagulant; this means it can prevent blood clotting. In high concentrations it kills mice and rats by causing excessive bleeding, but some populations are becoming resistant to it. This was identified back in the 1960s, and is a good example of how rapidly animals can evolve.
Returning to the Algerian mice, the warfarin resistance (and other rodenticides) is common in this species. The interesting part is that two different species of mice have potentially interbred to produce viable offspring. If you remember how we defined species as organisms that can breed to produce fertile offspring, how is it possible that two different species can interbreed? The answer is that our definition of ‘species’ is too simple (for example, what about species that don’t reproduce sexually?) and that genes can be passed between different species quite regularly, known as horizontal gene transfer. It is however more commonly observed in plants and bacteria rather than animals. Some scientists suggest that it may be more common in animals than we suspect, particularly in marine animals. Scientists have identified genes crossing between phyla (e.g. fungi to animals) as well.
What does all this mean for you? Apart from showing evolution in action, it is a nice reminder that very often in biology things are a little more complicated than they may first appear, and things don’t always fit into neat boxes as we may like.