Posts Tagged ‘ Darwin ’

Darwin Day


“Man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his god-like intellect which has penetrated into the movements and constitution of the solar system—with all these exalted powers—Man still bears in his bodily frame the indelible stamp of his lowly origin.”
The Descent of Man, 1871

I was doing so well, you think it would be simple just daily posts for 12 days. Then I drop the ball on the last day and the only one that really mattered. Oh well, it’s still the twelfth somewhere. For this last post in the series I just wanted to briefly look at the writings of Darwin and say you should read them. So far I have not read anything of Darwin’s but I plan to remedy that just as soon as I finish the current book on my list, Daniel Dennett‘s “Breaking the Spell: Religion as a natural phenomenon” which is not a bad read itself. But anyway, in addition to his most famous works “On the Origin of Species” and “The Descent of Man” Darwin also wrote a number of books on a range of topics. Coral reefs, geology, carnivorous plants, worms, volcanic islands as well as a narrative of his time on the “Beagle” and an autobiography are all products of of his pen. Numerous letters have also been collected and published that detail his social contacts and the development of his thinking over time. The website The complete work of Charles Darwin online has a dizzying number of documents boasting 20000 of Darwin’s private papers.

Here’s a quote about Darwins theory:
“[When the theory of creation by evolution] was
first advanced it was met by a storm of dogmatic abuse.
It was ridiculed, pooh-poohed, abused, called the
‘dirt theory,’ and scarcely given a hearing.
Now the tables are completely turned, so that the man who
today opposes it is treated very much the same way as if he
denied the revolution of the earth around the sun.”
These words, rather than being written recently, appeared in the publication “Catholic World”, February, 1882 which contained an article, Evolution, by W.R. Thompson. (reference thanks to The “Popular Press” Responds to Charles Darwin, The Origin of Species and His Other Works Sidney Horenstein published in Evolution: Education and Outreach)

On a geekier note, the Perth Mint has a Darwin Commemorative coin to celebrate the 200 years since Darwin’s birth. Made of 1 ounce of 99.9% pure silver it’s the must have item this year. Be the first Geek on your block to get one. Mine of course arrived several days ago.

Look, it's even in colour!
Look, it’s even in colour!

So, follow my example and read “The Origin of Species” and get a coin to remember your experience by.

Creationists


Quick extra note, Dr. Steven Novella of the Nerurologica blog today posted a great introduction to Creationist arguments and briefly covers the “Cambrian Explosion”, I recommend you pop over there and read this interesting treatise.

Evolution Everywhere


Today I’ve decided to send you away again.

First up is one of the magazine specials that we’ll likely see dozens of this year that centre on Darwin and evolution. It’s from BBC’s Focus magazine and covers topics such as whether humans are still evolving, What Darwin didn’t know, Evolution in action and how to argue with a creationist.

So Check that out, looks like an entertaining read.

Second up is a series of videos featuring one of the greatest popularizers of evolution since Darin himself (Origin of Species was a “best seller“). As well as one of the most controversial and inflammatory, Richard Dawkins. Whatever you think of this now public figure any discussion featuring him is instantly more interesting and his descriptions of evolution are carefully tuned to be understandable by a wide audience without spiraling into condescension. Produced for the National Geographic channel each video is high quality and only a few minutes long. Topic covered in the videos are the importance of Darwin, Fossils & Darwin, Why Darwin Was Right, Creationism then Dawkins’ views on God & the Universe that while in my opinion not strictly relevant to the scientific endeavour of evolution still is one of the first things that many people leap to when considering these ideas.

Again, head over there and consider yourself edified.

Yesterday: Evolutionary “Gems”

Evolutionary “Gems”


As a follow up to yesterday’s post on Transitional Fossils I thought I would highlight another resource put together by the journal “Nature” that brings together 15 short easily read articles on evolutionary evidences along with references and additional resources. Given the name “15 Evolutionary Gems” they have set the stage to showcase some insteresting and foundational topics and they do indeed deliver. A rundown of the contents is as tantalising as I would expect from such a document as you can see below:

Gems from the fossil record
1 Land-living ancestors of whales
2 From water to land
3 The origin of feathers
4 The evolutionary history of teeth
5 The origin of the vertebrate skeleton
Gems from habitats
6 Natural selection in speciation
7 Natural selection in lizards
8 A case of co-evolution
9 Differential dispersal in wild birds
10 Selective survival in wild guppies
11 Evolutionary history matters
Gems from molecular processes
12 Darwin’s Galapagos finches
13 Microevolution meets macroevolution
14 Toxin resistance in snakes and clams
15 Variation versus stability

So from the transition of animals from water to land to the evolution of feathers, the basis of new species to the introduction of sudden changes in animal body plans and everything in between they have it covered. Whether you are just interested in a quick read of a springboard to in depth study this is a great resource. Each topic is covered in less than a single page with usually only two to three paragraphs of text. As such it is a very easy read and certainly does not bludgeon you with overly technical language.

Give it a try, I think you’ll be pleasently surprised.

darwin

Yesterday: Transitional Fossils    Tomorrow: Evolution Everywhere

Transitional Fossils


First lets discuss what fossils are, this is probably redundant but I’ve got to fill my word count somehow. You likely already know the postage stamp version of this, fossils are the mineralized remains of dead animals, but how are they formed and why are there so few of them? Actually the answers to those to questions are the same, the way fossils are formed leads to the natural paucity of the fossil record that those who would dispute evolution decry. Fossils require very particular circumstances in order to be created, the remains of the animal or plant need to be buried quickly in fine sediment such as clay, silt or sand. If the animal is buried fast enough then this may stop scavengers as well as exclude oxygen from the remains and so reduce decomposition. In this case we may get a cast of the exterior features of the animal.

The ever popular Trilobite

The ever popular Trilobite

Once the bones are under a good amount of sediment then the process of fossilization can commence. It’s not a quick process by any means and can happen in several ways. Crystals may develop in the original structure and eventually replace it with a crystallized copy, or the  remains may rot away leaving a hollow that is subsequently filled with rock creating a cast of the original or finally the organic material may be slowly replaced with minerals from the surrounding rock. As I said this process requires that the remains be cover relatively quickly after death and so most fossilization occurs near water where sediments can be washed over the body in a fairly short time. Death inland is usually swiftly followed by the carcass being either torn apart by scavengers, broken and scattered to the wind or decomposition.

Now that we have our fossils what do they tell us? Well the fossil record is a remarkably complete (considering it’s limitations) archive of the gradual change of organisms of the eons for one form to another. The phrase Transitional Fossil is something of a misnomer and gives the wrong impression. As evolution is occurring all the time (visibly or not) every species can be viewed as transitional, including those that survive today. Or to put it another way species can only be viewed as transitional with hind sight and the knowledge that one species preceded another and that was followed by a third. Each species was/is evolved for the environment it live(d)s in and it is only our passion for putting things in order and telling a story that makes it seem natural for us to indulge in the conceit of calling one or another species “transitional”.

Having said that I shall now disregard my own rant and say what are examples of transitional fossils? We one lineage that is now particularly understood is that of horses.There is a list of about 23 intermediate species identified ranging from something like a rodent to deerlike animals and into the modern horse now so familiar. The sequence was first sketched out in the 1800’s and so is now very well understood.

Hyracotherium

Hyracotherium, early horse ancestor

Below is a graphic representation of horse evolution that is quite remarkable and yet does not do the knowledge we have gained justice, as neither does this humble post. But hopefully you will be inspired to look into these examples for yourself.

Horse evolutionary line

Horse Evolution in living colour

Yesterday: Evolution Journal Tomorrow: Evolutionary “Gems”

Evolution Journal


It’s been pretty full on the last few days so I thought I’d take a break and tell you to go check out the (currently) free journal Evolution: Education and Outreach. The first issue of 2009 has just been published and there’s bound to be something of interest for everyone. Actually I especially recommend looking up last year’s fourth issue all about the evolution of eyes and in particular an article written by Dr. Steven Novella on the suboptimal design of the eye, ever popular example of perfection. So browse through it all, the journal has many interesting book reviews, opinion articles and news items. In case you haven’t figured it out yet I highly recommend this journal and think the free period until the end of 2009 should be taken advantage of by everyone who has an interest in science and evolution and everyone else too. Go, go now.

Yesterday: Molecular Evidence Tomorrow: Transitional Fossils

Gene Eye View


The gene centered view of evolutionary change is a useful way to visualize how the processes work and to come up with explanations of why things happen the way they do. I have already mentioned concepts like genetic fitness, genetic lines and goals of an individual and this is where those concepts are grounded. This way of considering things was not originally put forward by Richard Dawkins but he certainly popularized it in 1976 with his book The Selfish Gene.

Gene

Gene

The usefulness of this method becomes apparent when you consider that we are use to thinking of species as individuals, discrete in time and space that act upon the world and are in turn themselves acted upon. But evolution doesn’t happen on the scale of individuals, a particular animal does not evolve the population does, and what produces this change in population characteristics? alterations in the genes. If we reverse our point of view and consider the genes as the primary actors in the evolution games things start to make more sense.

Genes are the true replicators in biological systems, while we may consider reproduction to be about continuing the legacy of an individual into the future in actuality it is the genes that are really being propagated. In addition it is the genes that change over time, not individuals even though in conversation it is useful short hand to refer to, say rabbits, evolving over eons it is really the genes and gene frequencies in the population that we are  discussing.

Given that it is the genes that evolution is really concerned with we can start to put into context the concepts that we have been talking about up until now. In other words when we talk about behaviours or physical characteristics benefiting an individual what we mean is that it helps the individual’s genes survive and replicate and eventually spread through the species. More specifically the gene for that trait is selected by the environment of the individual to continue into the next generation.

In this way when a mutation alters the expression characteristics of a gene (eg making brown eyes blue for instance) it introduces variation in the population of genes and this new variant must compete against the other versions (alleles) in order to continue to exist (be passed on to the next generation). So when we consider how an adaption aids an individual we also need to think in terms of what activity is best for the genes because that is what will be maximized and optimized by nature, that’s just the way it works.

Raphael from TMNT

Raphael from TMNT

Yesterday: Kin Selection Tomorrow: Molecular Evidence

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