Biology Issues

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James Cameron's Avatar - a biological review

February 3rd 2010 14:31

Avatar is a big budget movie produced with state-of-the-art technology (in fact, Cameron had to wait for several years for the technology to catch up to his vision). Well, the result is stunning. Avatar takes place on Pandora, a moon of a gas giant in the Alpha Centauri system (the moon is fictitious, but the star system is real. At about 4.4 light years away, it is the closest system to our own). Pandora is home to many strange animals and plants. What's great about the film, though, is that these organisms are mechanically feasible, in the sense that such creatures could actually exist and could move the way that they are depicted. Apparently, Cameron hired real biologists to act as consultants for the creature designs, and the effect is wonderful. The plants, too, with their bioluminescence and reaction to physical stimuli. Pandora is utterly believable. Thing is, these organisms might well have evolved on Earth if initial starting conditions had been slightly different. It's not only that the Pandoran organisms are filling niches we would recognise of terrestrial organisms, but are rather similar to the organisms we have on our planet. The Thanator, the giant predator in the film, is quite like a lion, say, except much larger of course (it also has six legs, as do the other animals. I suspect that there's nothing particularly special about the quadruped configuration on Earth; it could well represent a "frozen accident" that was subsequently inherited by thousands of species. And insects, you'll note, do have six legs. Why not four? Or eight - which arachnids have. Or more, which is the case with centipedes and millipedes. We need not suppose that every quadraped was selected to have four legs, only that certain features of embryology constrain them to having four legs. My money is on the number of appendages being relatively variable wherever complex multiceullar life has evolved).

The fearsome Thanator, prime predator on Pandora. Image from www.pandorapedia.com

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Posted By: LuisC - Category: No Category

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Will be back soon, people

December 20th 2009 02:27

Sorry everyone, I've been busy lately. I'll be back soon.

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Posted By: LuisC - Category: No Category

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Are there limits to what evolution can produce?

October 25th 2009 08:53

Evolution has produced some exquisite examples of biological machinery, from bat echolocation to the human brain. But are there things that cannot ever evolve? And why?

To answer this question, we first need to understand a couple of things. The first is that natural selection is about preserving what works, not what is in principle the best "design" for something. We can envisage more efficient designs than those found in nature, but given that evolution is a population phenomenon that compares how well contemporaries do against one another, it will favour those designs that happen to work best, even if they are shoddy solutions (relative to a universal optima that we can imagine) to a problem. Secondly (and related to this first point), is that what gets selected has to be built upon what's already there. This means that selection will result in things that are ad hoc and convoluted. As Richard Dawkins has said about the laryngeal nerve (a nerve that exists in the pharynx or throat region of vertebrates), it is easy to imagine a more efficient, less resource-wasting design that has the nerve pass straight through the pharynx rather than under it and back up again, but the cost in embryological upheaval of such a change would likely be prohibitive because of the negative effects on other morphological arrangements as a side-consequence. The intermediates would never be selected for, and hence the less efficient, sub-optimal version is what gets preserved. Of course, it needn't have been so if organisms had been designed afresh by a deity or some other intelligent agent. What we actually see, though, are solutions to life's problems that clearly show the imprint left behind by history, because the solutions are often a patchwork of prior solutions that are "stuck" at local rather than universal (effectively imaginary) optima. Organisms carry, as Charles Darwin said of human beings (the most exalted of all organisms), the indelible stamp of their origins

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Posted By: LuisC - Category: No Category

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Research update

October 23rd 2009 12:28

My research into the genitalia of seed beetles is coming along nicely. As I've mentioned before, I'm doing a Masters at the University of New South Wales, and my focus is on the evolution of genital components in insects. The seed beetle Callosobruchus maculatus is the model system for two components of the overall program (the third component looks at traumatic insemination in the Heteroptera, a group of bugs). Here are some photos from the study. The genital components I'm looking at include spines on the male aedeagus (intrommitent organ, or penis), spines in the female reproductive tract, the connective tissue composing the reproductive tract, and various other things that are poorly understood. This is a cool approach because most previous studies have focused on one or two genital components, but this one looks at several in both sexes to see how they reacted (or didn't react) to differential life history and sexual selection treatments. This can shed light on how they're used (say, in an antagonistic capacity, or in a more cooperative one).

Spines of the male aedeagus. Source: Luis Cayetano.

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Meet Ardi

October 10th 2009 04:20

The recent stunning unveiling of research on the hominid Ardipithecus ramidus sheds new light on the history of the lineage from which humanity arose. The specimen, which is sure to rob Australopithecus afarensis ("Lucy") of some of its glory now that it has been described, has been especially noted for the anatomical surprises it packs. Ar. ramidus appears to have been well suited to life on the ground as well as in the trees, and was far less like a chimpanzee than we might have anticipated. At 4.4 million years old, "Ardi", a specimen significantly more well preserved than Lucy, is up to several million years younger than the last common ancestor of humans and chimps.

Depiction of Ardi. Source: Scientific American. Illustrated by J. H. Matternes

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Posted By: LuisC - Category: No Category

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Why is biology interesting?

October 6th 2009 10:40

This week, as I'm trying to ease my way back into writing, I thought I'd just write rather than presenting the latest discoveries in biology.

Well, a question I've been asked is why I find biology interesting. First I'd like to say that anyone who thinks that biology is "boring" is a mother-fucker who should immediately go and remove his testicles (I say "he", because only a male would say something so fucking stupid). People from all walks of life find biology fascinating. They might not know a heck of a lot about it, but they're capable of being transfixed by David Attenborough, for example, talking about the wonders of insect reproduction or the dynamics of lion prides. So this is something that people just find interesting, whatever their background. WHAT exactly is it, then, that people find interesting about biology? I suppose that it's the sheer variety of mechanisms, the overwhelming display of ingenuity exhibited by nature, and the intricacy of said mechanisms and ingenuity. Those are exactly the things that fascinate me, with one qualification: these things find their counterpart in the factor that drew me to biology most forcefully - the historical factor. Biology isn't only about things interacting right now; it's about how they got to be the way they are; biology is an historical science. And this historical aspect is half of the fascination. It's where the really interesting questions are, because to know about history is to know about the "why" of something. Why do birds on islands tend to lose their ability to fly? Why did the Jurassic have the greatest explosion of dinosaur diversity? Why don't any birds give birth to live young? In answering these questions, scientists must try to reconstruct the past, and get some clue as to what the environment was like back then. This puts the system being considered - the species, genus, or some higher taxon - into an evolutionary context. Sometimes, we have enough details about the past to be able to test some of our hypotheses. Other times, the details are so sketchy and few and far between that speculations will have to do (until we obtain more evidence). But what's neat is that these things are amenable to human investigation. It's amazing that we can even ask such questions

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Posted By: LuisC - Category: No Category

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Another apology

August 16th 2009 12:41

Sorry folks, I'll be back with more soon. I have no excuse

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Posted By: LuisC - Category: No Category

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Stunning photographs

June 21st 2009 04:44

Check out these stunners over at Wired.com

Eye of a Tokay Gecko Submitted by Alan M

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Posted By: LuisC - Category: No Category

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New books about evolution

May 23rd 2009 04:36

Books like Jerry A. Coyne's "Why Evolution is True" and the upcoming "The Greatest Show on Earth" by Richard Dawkins shouldn't have to exist. In a rational world, there would be no need for books that directly take on the claims of creationists and "intelligent design theorists", because the evidence for evolution, at least in broad outline, would be known to most people, both for the intellectual satisfaction it brings and because it would take a central stage in our culture. Unfortunately, we live in a world where people are still profoundly misinformed about the process that gave rise to us, and as long as that continues, I'll be thankful for books that lay out the case for evolution.

These books are for people who are on the fence about whether to accept the theory. There are many people who simply aren't sure about what the case for it is, whether the "controversy" is a genuine one, and so forth. These folk can be swayed by being shown the evidence; they aren't extremists by any means but have perhaps never taken the time to delve into the issue or maybe have only a vague acquaintance with the theory but aren't sure whether it's as strong as scientists claim it is. Of course, there are people who can't be swayed by evidence, because their reasons for rejecting evolution have nothing at all to do with evidence in the first place. Those people won't have their minds changed by these books. However, if you know someone who is on the fence, or if you yourself aren't sure about the veracity of evolution but feel you could be swayed if shown solid examples of the sorts of things that together clearly demonstrate it, then I implore you to read Coyne's book, because believe me, it's worth it. Dawkins' book is coming out in September of this year, and it can be pre-ordered from his website. It should also make for another sledge hammer of a read, with the wit and elegance that Dawkins is so renowned for

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Posted By: LuisC - Category: No Category

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