Common Descent, Uncommon Knowledge
Posted by evanescent on 13 September, 2007
One of my favourite books of all time is A Devil’s Chaplain by Richard Dawkins, and over the next few weeks I hope to share some of my favourite and (in my opinion) most fascinating points from it. The book itself is a collection of Dawkins’ essays over the last few decades. Topics vary between education, science, law, evolution, memes, and religion. What I love most about reading Dawkins is that he makes his writing so engaging and understandable to the non-professional (like myself) without sacrificing the detail, or “dumbing down”.
He almost assumes that you know what he is talking, which is ok since he often explains it so well anyway. This is very satisfying to the reader, and makes your intelligence feel complimented, instead of insulted.
One of the essays in the book is called “The Information Challenge”. I wouldn’t actually put it in the top 5, but whenever I learn something new about the wonder of evolution it increases my awe that I understand it as well as I do. It also makes me feel like shaking certain people by the shoulders and saying “wake up! This is a marvellous wondrous fact about the world! Stop lying about it and hiding from it because it conflicts with your parochial beliefs!” Indeed, that me and many of my friends understand evolution better than most people says nothing about our intelligence, but rather how education and fundamentalists have let the general population down:
Almost everyone from any level of education has heard the formula e=mc2. Slightly fewer will be able to tell you what it represents, and fewer still will be able to explain it. Almost everyone on the planet knows that the earth orbits the sun (despite a few Christian fundamentalists who in the year 2007 reject a heliocentric solar system; it really makes you wonder doesn’t it?). I’d be pretty confident in saying that if you asked anyone in the street how many planets there are in the solar system, at least half of them would tell you 9. Which is fair enough; there are 8, but unless you paid much attention to science news you could be forgiven for overlooking this. But, ask an average member of the public what this expression means: “gene frequencies in a population change over time in response to environmental pressures”, and I will confidently bet a majority wouldn’t understand it. Perhaps I’m being cynical, but I don’t think so.
“Gene frequencies in a population change over time in response to environmental pressures” is the definition of evolution; the very reason we are all here! I don’t think you have to be a scientist or even be interested in science to have a basic knowledge of evolution. But I don’t blame people for their ignorance (I myself spent 23 years of my life hating evolution); I blame education and religion.
That is not to say almost everyone won’t have heard of evolution. But ask an average man (or woman) in the street to explain evolution and they might mutter something about survival of the fittest. Ask a fundamentalist to explain evolution and they might mutter something about fish turning into people.
There is probably something awesome about the natural world to everyone. I personally find a pitch black night and a clear sky, with thousands of stars, a stupefying sight. You know what I also think is just as staggering? The fact that if you look back far enough in time you will find a connection between any two living things on this planet! All species are grouped into genera, which is a subset of Family, which is a subset of Orders. Orders are all subsets of Class, and Class is subset of Phylum, and all Phyla belong to a kingdom. The three kingdoms on earth are Bacteria, Archaea, and Eukarya (of which we belong). This can literally be viewed as a Tree of Life:
The lowest classification is species. It is easy to see that horses are more like camels than they are monkeys. It is easy to see that humans are more like chimps than we are cats. What a creature looks like is called its phenotype. The phenotype is determined by the recipe of genes in a life-form; the genotype. It is yet again easy to see therefore that (most of the time) the closer two life-forms appear, the closer they are genetically, and vice-versa. Just as American English is closer to British English than either are to Russian, and just as you and your siblings are closer to each other than either of you are to me, so animals in the same Genus and Family are more closely related than those of another Genus or Family, and certainly another Phylum!
But, most languages on earth today have a common ancestor. And although it is very unlikely I am related to you, if you back far enough it is certain you will find a connection. Similarly, many words in English are a direct derivation of French or Latin or other languages. We see leftover fragments of ancient languages in today’s languages.
You might have the same colour eyes as me; the phenotype we both share is a result of our genetic recipe for eyes being the same. You aren’t me (leaving aside personality for a moment) because your genetic recipe is different; but you just have the same genes in a different frequency. Identical twins have the exact same genotypes; they are literally clones of each other. All life on earth has the same DNA. Your DNA is no different to a mouse’s, or that of bacteria. By shuffling gene frequencies in a life-form you can produce different forms of life. Nature does this itself (although it takes far longer) by mutation. And if a mutation is favourable to the external world, those changes are selected for, and unfavourable changes are phased out.
Just as we see common words and letters in many languages on earth, from the ancient ancestral languages that bequeathed them, do we see leftover fragments of ancestral life in today’s life? We most certainly do! Humans have tailbones. Humans have atrophied feet muscles that we can’t use, but other modern apes have full dexterity of their toes with this muscle. We both have the muscle because we both share an ancestor that had it. Whales have vestigial hind legs, because their ancestors were land-dwelling mammals. Snakes can be genetically modified to grow legs, and bird beaks can be induced to grow teeth, because their respective ancestors (quadrupeds and dinosaurs respectively) had them, and those genes are still there, dormant.
Wasps are more like bees than they are houseflies. But wasps and houseflies are more closely related than either insect is to a pig. But if you go back far enough, all insects are descended from one organism. Humans are more like chimpanzees than chimpanzees are like gorillas! But we are all primates, and if you go back far enough you will find a common ancestor for humans and chimpanzees. Go further back and you will find one for all primates.
Quoting from The Information Challenge (q.v.):
“Human adult haemoglobin is a composite of four protein chains like globins…Two of them are called alpha globins, and two are beta globins.”
Even these globin genes are ultimately related! They are present in all vertebrates, which further demonstrates that all vertebrates are related to each other.
“The dozen or so different globins inside you are descended from an ancient globin gene which, in a remote ancestor who lived about half a billion years ago, duplicated, after which both copies stayed in the genome.”
After this happened, any descended animal would also have two globin types. One would become the alpha globins and one would become the beta.
Dawkins goes on to call the following a “fascinating point”, and I agree! Since this split took place so long ago (500 million years) it won’t just be human genomes that show the split between alpha and beta, it will be all related species, i.e.: all vertebrates that have evolved since then. Is this what we find? Yes! Every single life-form where we expect to find the split, we do. Proving not just that common descent is undeniable, but also extremely predictive! Can we come at it from another position; find a creature that supposedly predates our shared ancestor (for vertebrates) that doesn’t have the alpha/beta globin split? Yes! As Dawkins says this creature “would be a jawless fish like a lamprey…Sure enough, these jawless fishes are the only known vertebrates that lack the alpha/beta divide.”
Not only is simply knowing our own origins extremely satisfying and illuminating, it forces you to conclude that all life on earth is related. We are cousins with all creatures; some are more distant than others. It also makes you think why so many people are ignorant of this incredible knowledge. Worse, others actively lie about it and/or prefer a boring simplistic creation myth that explains nothing.
Not only is rejecting the fact of evolution provincial and irrational, it is foolish because it’s not as though there is anything to replace it with! A creation account cannot possibly explain nested hierarchy and common descent that we have briefly looked at here. And even if it could, it would require so many mental contortions and apologetics one should just give up and stick to the facts.
Our governments and education boards need to give evolution the time and attention it deserves, and if that upsets or offends a minority of ignoramuses, tough! To those who don’t accept evolution, I say, do yourself a favour! You are better than that! You deserve more than to have a fairy tale fed to you. You should know better than to prefer belief over facts. The history of the world is within your capacity to learn and understand. What are you waiting for?
 Ebon Musings http://ebonmusings.org/atheism/carrot&stick.html
 I used to be a Christian fundamentalist: http://ellis14.wordpress.com/2007/06/20/my-fall-from-grace-wed-20th-jun-07/
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