The (sadly extinct) Tasmanian Tiger and living wolves provide an excellent example of convergent evolution. They have the same ecological niche, with the Tiger filling the role of a top predator in Australia, while wolves are found throughout the northern hemisphere. But the Tiger is a marsupial, while wolves are placental mammals.
May 2008 Archives
I've been following a developing discussion about what characterises scientists (and what happens when some of them go to the 'dark side' of pseudoscience...) and I've just found a posting on Respectful Insolence that I want to share with you. (Follow this link to read the whole thing. And many thanks to Orac for writing it.) The proposition here is that scientists are frequently wrong...
I was talking about evolution with some students the other day and one of them said, 'But to get new features in an organism you have to have new genes, and mutation can't do that." We talked a bit about transposons and other means of gene duplication, & I also pointed out that changes in the control regions for a gene - & not the gene itself - could also have far-reaching consequences in terms of form and function. But I didn't have a specific example to hand. Until today.
This is an item that's been in my 'how cool is that?' folder for a while - a very large dinosaur-eating frog!
Another in the occasional series of 'what I'm reading'. This time it's a modern biography of Leonardo da Vinci: The Science of Leonardo, by Fritjof Capra (2007). It's a beautiful book, from the cover, to the sepia-toned type, to the writing itself. And the author does a beautiful job of making 'the great genius of the Renaissance' come alive.
I'm a bit pressed for time at the moment & thought I'd re-post this one - although it probably reiterates what your teachers have already told you about doing lots of reading around the subject!
You've probably found by now that preparing for Scholarship exams involves (among other things) an awful lot of reading. I was reading an on-line article just now and came across a statement by an English professor which I think is just as relevant to biology. He's commenting on what he perceives as pressure to increase the amount of computer-based learning in the classroom.
There was an article in the Herald last week (I think) which set my pseudoscience detector ringing... it had a title something like "Pixie dust helps man regrow finger". The article itself gushed on about how this guy had lost part of his finger to a bit of sharp-edged machinery, but the missing bit - including even the nail & fingerprint, raved the article's author - had regrown following application of a non-cellular matrix whimsically called 'pixie dust'...
I mentioned my reading list in the last post - so this time round I'll let you in on what excites me about one of the books I'm reading at the moment. (I tend to have several on the go at once, so I can dip into whatever matches with what I'm thinking about at the time.) This time it's (drumroll) Charles Darwin's autobiography. Darwin wrote this towards the end of his life, and the edition I'm reading was edited by his grand-daughter, Nora Barlow.
There's been quite a lot of conjecture, over the years, about what our early ancestors ate. Much of the evidence has been indirect: size of teeth, size of chewing muscles (which can be estimated from measurements of the places where muscles attach to the skull), ridges & crests on the skull, & so on. Teeth are very informative - as well as their size & shape, we can gain information from the tiny patterns of wear left from chewing food. (Or cleaning your teeth - my old dentist used to say he could tell if people followed the recommended brushing pattern by looking at wear on their teeth...)