Dinosaurs in our garden!

February 27, 2010 at 12:57 pm (science) (, , , )

There are dinosaurs in my garden.  They watch me warily with beady eyes as they hunt for food.  Suddenly, a larger dinosaur appears and the smaller ones scatter in a frenzy of activity; it bites some food which dangles helplessly from its mouth.

Luckily for me, these dinosaurs are not about to break through the window and feast on my flesh.  That is because they are about the same size as a crow, because the one I’m looking at is, in fact, crow.

You may have heard that birds evolved from dinosaurs.  Well, according to scientific nomenclature, that means that birds actually are dinosaurs.  The following evolutionary tree from The Loom illustrates why:

The only groups that it makes (evolutionary) sense to give a name to are mono-phylectic: all descendents from a particular organism.  For example, all dinosaurs have a common ancestor, which is the far left of the figure.  If you look at the bottom of the figure, you’ll see that birds share this common ancestor, and therefore are dinosaurs.

The confusion arises because dinosaurs were discovered before we understood their evolutionary relationship to living organisms.  So we called all of the extinct creatures we found fossilised in rocks by the one name, dinosaur (“terrible lizard”).  Once we discovered that birds were direct descendents from dinosaurs, we were already using the name to mean only the scary lizard type dinosaurs, rather than the winged feathered friends we feed seed to.  So now, the correct term for a “dinosaur” is “non-avian dinosaur” (i.e. all the dinosaurs except the birds).

Similarly, birds are descended from reptiles, so they technically are reptiles.  Again, in everyday language it is useful to talk about all reptiles except the birds.  However, turtles turn out to be less related to crocodiles than birds are, for example, so they all have to be technically called reptiles. (Birds, crocodiles and the extinct dinosaurs are all called archosauria together).

Of course, birds changed a lot since the time of the dinosaurs, so they are really very different.  All this just goes to show that technical language is always going to be at odds with everyday language, even though the technical words (technically speaking…) hold more real information.

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Nothing in Biology Makes Sense…

February 21, 2009 at 3:40 pm (Articles, religion) (, , , , , , , , )

Nothing in Biology Makes Sense Except in the Light of Evolution.

These are the words of Theodosius Dobzhansky, one of the founding fathers of the quantitative study of evolution. He wrote an essay about why evolution is so important, and also discussed how he reconciled his Christian faith and the scientific theory of evolution.

The evidence for evolution is overwhelming, if you accept scientific reasoning. There is mathematically no way that evolution could not occur if just three things are true: more creatures are born than get to reproduce; they can vary in new ways; and that these variations are inherited. The first is trivially true as any look in the garden will show, as is the third: for example people take after their parents. The second is more difficult because although all individuals do vary, they mostly do so in an uncreative way by mixing up the traits of their parents. But it does occur: mutations are the source of these creative changes and it has been demonstrated many times that novel abilities (at the microscopic level) can arise.

There is a resurgence recently, particularly in America, to doubt evolution for religious reasons. However, this doesn’t have anything to do with the religion per se, but is a cultural phenomenon. Dobzhansky quite powerfully argues that to deny evolution on religious grounds is verging on blasphemous: it implies that the creator deliberately set out to deceive us. We have the ability to reason about the origins of fossils, or of finches in the Galapogos, and explain why they are there. There is no hole in the theory that has yet been found. To believe that this is some elaborate charade is absurd.

Dobzhansky believed in creation: that god created the world such that we would be here today.  It is a matter of philosophy whether this happened by divine will or by chance.  It is beyond science to answer the question of whether we were “created” in this way, or arose by chance, because there is only one universe from which to draw evidence. But in this Universe, we have surely evolved, and this is not evidencef or or against God in the slightest.

Check out his essay for details of the above discussion.

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