Evolution: It’s not difficult

For some reason I keep replying to people who seem to think that evolution doesn’t work and it’s obvious, and they should tell twitter all about it, usually via Richard Dawkins.  Now I think the main reason I reply it is that some seem to be genuinely confused and I feel that nudge in the right direction might help them see the beauty of such a simple idea having such a diverse and complex outcome.

Miniscule variations between generations, plus the filter of life and death that is natural selection, multiplied by the unimaginably large number of iterations that trillions of life forms have cycled through over billions of years, results in ten million species, each suited to its own way of life.

In future, I can just point them to this post and save myself a lot of explaining.  I also have the luxury of unlimited characters here.

The most common assertion, is that there is no evidence for evolution.  Ok, some people suggest that the theory of evolution was personally created by the devil, but I have no intention of replying to that sort, as they can’t be helped if they think the personification of evil is writing peer reviewed articles in order to undermine civilisation.

The theory of evolution by natural selection is the single most supported idea in the history of man.  A bold claim, but I shall explain.

In terms of raw data the great particle accelerators and radio telescopes bury biology.  The LHC and its predecessor, the LEP, have been instrumental in the development of faster and faster computers, and networks, as our technology scrabbles to keep up with the data cascading out of our experiments.

Don’t get me wrong the volume of evidence supporting evolution is immense.  One hundred and fifty four years of research by tens of thousands of scientists has seen to that.  I am simply pointing out that particle physics, or cosmology, is going to be the first discipline to face the problem of where they store a yottabyte of information.  But it doesn’t change my statement about evolution being the most supported idea.  And that is due not to volume, but sheer consistency.

The two great pillars of physics are the Standard Model of particle physics and Relativity.  One is a fantastically detailed and accurate description of the universe at its largest scale, the other at the smallest scale.  Absolutely everything else is built on them.  All of chemistry is really just electromagnetism, as chemical reactions are the interactions of electrons orbiting different nuclei, and the photon is the particle that mediates that interaction.  Biology is a subset of chemistry as it is constrained mainly to carbon based molecules.

But both of these fundamental components of physics are wrong.  Ok, a little headline grabbing; we prefer the phrase incomplete, as the consistent accuracy of their predictions means they are clearly on the right track.

So what’s wrong with them?  Well General Relativity, which is the theory of gravity, doesn’t work at the very small or the very dense.  In other words it doesn’t work at the level of atomic particles or inside black holes, and since we know both particles and black holes exist, a theory that can’t describe them has some short comings.  So far every experiment we have ever done to test General Relativity matches the expected outcome; subtle changes in the precession of orbiting planets that Newtonian gravity cannot account for; time dilation effects on the orbiting atomic clocks of GPS satellites.  We’ve even directly measured frame dragging.  The exception is gravity waves.  The best attempt to detect gravity waves is an experiment called LIGO.  After eight years of operation it did not detect a single event.  The experiment is currently been upgraded to make it more sensitive, and discussions are under way to build a sun orbiting satellite constellation that would be more sensitive still.  If neither of these experiments sees gravity waves after a few years of operation, then Einstein was wrong.  We will need a new theory of gravity; the long sought theory of Quantum Gravity.  Currently we lack enough data to tell us how this theory should look.

The Standard Model, apart from been unable to incorporate gravity, also predicts that there are no particles of any sort in the universe.  That’s not a good start for a theory of particle physics, and it doesn’t help that everything we can directly observe in the universe is made of particles.  It’s a shame, as a component of the Standard Model called Quantum Electro Dynamics, predicted the measured value of the anomalous magnetic moment of the electron to ten digits, which is the most accurate prediction of anything that has ever happened.

You and I and everything else is made of atoms, which contain a nucleus of protons and neutrons, which are in turn made of smaller particles called quarks.  Anti-protons and anti-neutrons are made of the same quarks, just in a different arrangement.  The trouble begins as the universe cools after the Big Bang.  At first it’s too hot for anything but a quark gluon plasma, which we can make at the LHC, but later the universe cools enough for quarks to bond in groups of three.  There is no reason why at this point protons and anti-protons were not made in exactly equal quantities, collided, cancelled each other out, and left the universe as a sea of photons.  This lack of bias is called Charge Parity symmetry.  In order for the universe to exist as it does there must be something breaking the symmetry, and recent experiments involving the decay of B mesons, that I don’t understand, hint at this breaking.

That’s fine, except we have had to apply a fix after the fact.  Charge Parity violation didn’t come built in to the Standard Model.  Then there are the arbitrary values. 

The supremely accurate maths of the Standard Model includes terms whose values are arbitrarily set to make the equations work.  Science hates this, and prefers all the term of an equation to be based on measured values from experiments.

This all hints that something is very wrong with the Standard Model, and that new physics waits to be discovered.  The upgraded LHC may start showing us the way when it comes back on in 2015.

But why did I say at the beginning that evolution is the most supported idea ever?  Because there are no caveats.  No experiment or observation has ever disagreed with it.  Entire fields of biology have sprung up since Darwin’s time, and each gives us greater and greater insight in to the workings of life, and each reveals a mechanism in accordance with evolution.

Embryology basically sewed up evolution on its own.  Every single creature with a spine starts as a ball of cells, in which a hole opens up that goes on to form the anus.  In creatures without spines the hole forms the mouth.  Why is this so?  Because all chordates have a common evolutionary history.  Human embryos form pharyngeal arches, which in fish go on to form gills and in mammals move to form structure within the skull and neck.  This is because our ancestors were fish, and evolution can only work with what it is given.  The first arch forms the jaw in humans and sharks, despite the four hundred million years between us.  Embryonic dolphins have back legs.  They don’t fully develop and are useless internal structures by the time they are born, but their ancestors would have formed fully working back legs as they were land mammals.  The list of developmental features and events shared by wildly divergent creatures, which can only make sense in the context of evolution, is immense

My personal favourite, if I may offer such a preference, is the laryngeal nerve.  This forms from number 6 of the pharyngeal arches.  In fish, these arches, which become gills, each have their own nerve so that this vital structure can be directly controlled by the brain.  In humans this nerve is retained and controls your larynx.  The direct route in early fish is from the brain, round the heart, to the gill.  This is the route taken in humans; from your brain, down your neck, round your heart and back up your neck, even though this involves quite a detour as the heart has moved.  In giraffes the detour is over 5 meters.  This is because evolution can only adapt what is already there, it cannot cut, reroute, and reconnect a nerve so vital to eating and breathing; something a designer would be able to do.

Genomics does sew the argument up.  Every single living thing shares exactly the same genetic mechanism.  There are four letters in the genetic alphabet, which are arranged in groups of three, called triplets.  There are sixty four possible triplets, and they code for the twenty amino acids that all creatures make their proteins from.  Every life from, no matter form or function, uses exactly the same code.  The three letters, CAU and CAC, code for the amino acid histidine in all living things.  Everything shares a single ancestor that used the code we have all inherited.

Everything that evolution requires from hereditability is found in genetics.  There must be a mechanism that can hold an immense amount of information to account for the vast array of species both living and extinct.  It must be capable of copying this information time and time again with almost unbelievable accuracy, and it must be incredibly stable for common features like blood cells or nerves, or jaws, to be retained over hundreds of millions of years.  It can’t be so stable that there is no chance of variations between generations, but neither so unstable that massive changes frequently happen as they would be fatal.  DNA is a molecule that does absolutely all of that, and in the right amounts to produce the evolutionary process we can see around us.

But this doesn’t make the DNA or RNA the magic molecule that must have been created.  The behaviour of the DNA is defined by the laws of physics, and this massive and amazing molecule is made of simpler parts which are themselves generated as a by-product in mundane chemical reactions.

Which brings us to another argument put forward by the doubters.  Evolution cannot explain the origin of life.  No it cannot.  The process that caused life to arise is unknown, but the ideas put forward to explain it come under the subject of abiogenesis, not evolution.  This is an attempt to answer the question how we got from chemistry, to organic chemistry, to biochemistry, to life.  With current technology most of these ideas are untested, but they will be tested because this is still a scientific question, and each will stand or fall on the evidence that is found.

If I’m being complete, then I suppose I should say, if we evolved from monkeys, why are there still monkeys?  We didn’t; we evolved from apes, and that is not a minor technical discrepancy.  Humans and chimpanzees evolved from a common ape ancestor which by the way, is extinct.  Not that extinction is mandated by evolution.  It is quite possible for two populations of a single creature to become isolated in some way and take radically different evolutionary paths.  One may change completely, the other barely at all.

Evolution does not break the second law of thermodynamics; if you don't understand thermodynamics, do not incude it in your argument.

Some other misunderstandings are that creatures must become more complex, or that the subtle interaction of species in an eco-system could not be produced by random chance.

It’s impossible to define complexity, and so is irrelevant as an argument for or against evolution.  Is it the number of chromosomes, the number of bases, the number of different functioning organs?  A human has 46 chromosomes, a chimpanzee 48, a mosquito has 4, and some ferns have nearly 200!

A human has 3 billion base pairs in their genome, a chicken, which evolved from dinosaurs, has 1.2 billion.  A salamander, which predates the dinosaurs has 50 billion, and a trumpet lily, which is just a plant, has 90 billion.  There is no pattern to number of base pairs, or length of genes, or number of genes, based on how long ago a particular species first emerged.  Each has what it was given and what it needs to survive in the habitat it evolved to inhabit.  But how was it given this genetic make-up by random chance events?  In short it was not.  An important and often over looked aspect of natural selection is that it is non-random; it has criteria.

So a cow genome is a 3 billion letter genetic word in an alphabet of 4 letters.  The number of combinations of DNA molecule is therefore 4 to the power of 3 billion.  I’m not going to write the answer to that sum as it would take years.  It’s a massive number!  The chances of the exact molecule that make up one particular cow appearing by accident, in a universe as small and young as ours, is zero.  The only way it could have happened is if there was a guiding force, something shaping the molecule and making something like the one we see more likely.

The mutations that are caused by radiation, or disease, or copy errors, are random, but the filter of natural selection is more likely to remove mutations that cause harm and keep mutations that cause advantage.

If a mouse, in a field of mice has a mutation that causes it to have slightly more fast twitch muscle that the average mouse, so it can dodge a predator ever so slightly quicker than the others, then that mouse is more likely to survive than the population average.  It is more likely to have offspring that survive as some will have the same mutation.  As the generations pass these slightly quicker mice will have slightly more children that in turn go on to have slightly more children, until this mutation is very common in the population.  At this point a mutation in the predators that offsets the advantage in the mice would also most probably be kept.  If a flight control feather was a bit longer making the bird a tiny bit more manoeuvrable, or a minuscule increase in the density of photoreceptors in the eye gave it slightly better vision at night for example.

None of these changes is large, or dramatic, or possibly even visible to us, but they are happening all the time, and while the source of change is random, the filter is not; you have offspring, you do not have offspring.  This is the force that gets us from simple RNA like molecules, to single celled life, to cats and dogs.  And cows.

Its simplicity really does belie its power, and I do see why some people struggle to accept it, but accept it they must, as it is the only mechanism ever suggested that works, and answers every question biology has ever asked.