Evolution of a peeve

I am often peeved at the way evolution is presented and explained. It is bad enough when lay people get it wrong, but it is intolerable when science commentators and scientists explain it sloppily.

First things first, the term evolution comes from the Latin evolutio meaning unrolling. In modern English vernacular is has the generally understood meaning of a progressive change in a particular direction - the general direction being understood as being better or more advanced from the previous form.

This is a horrible term to use for the process Darwin described because it comes with preconceptions that are simply untrue - namely that of a progressive change in a particular direction for good (as opposed to its antonym, devolution).

It also does not help that so many science commentators (all I would say) and scientists (most, I would say) continue to perpetuate this inaccuracy. The say things like, "Plants evolved colourful flowers to attract insects," or "Organisms evolved camouflage to evade predators," or "The species evolved to adapt to its environment."

All three of those statements are totally and completely false and dangerous because they put the cart before the horse and presume some sort of deliberate and intentional progressive development. Using the terms evolution and adaptation are, in my opinion, wrong and dangerous. We should instead be using an expression like, "propagation of advantageous survivability traits", which is a far more accurate description of the process going on.

Every organism has genetic variations from its predecessors, some are simply the result of mixing characteristics (we get half our DNS from our mother and half from our father), there are transcription errors (when a piece of DNA is not properly copied - commonly called a mutation), and finally there are transpositions (this is when a piece of DNA from one strand is grafted onto another. Our DNA contains, not necessarily identical, copies of genes on both strands, but sometimes during the transcription process, a copy of a gene may be moved from one strand to another, thus introducing a change). Most changes are harmless or provide no survival benefit - i.e. there is no reproductive benefit for you to passing on your genes and so those changes simply get lost in the wash of genetic information out there. Some changes are not harmless and severely curtail your survivability - these usually are quickly eliminated from the gene pool. However, there is an interesting class of traits that are fatal (for example sickle cell anemia), which have not been excised from the gene pool. Why? Because having one defective gene and one good gene confers a survivability advantage. People with a single sickle cell anemia gene are more resistant to malaria than people without it.- consequently, they get to live to sexual maturity and reproduce.

Plants did not evolve colourful flowers to attract insects. Plants which had a mutation which gave them colourful flowers attracted more insects. Consequently, the insects preferred to visit the colourful flowers, thus pollinating them, this allowing them to propagate. The plants with dull drab coloured flowers, being ignored by the insects, died out.

Organisms did not evolve camouflage to evade predators. Organisms which were harder for predators to find, had a higher survival rate, consequently they passed their characteristics on to their descendents. Those that did not hide well from predators where soon gobbled up and their genes removed from the gene pool. A rather recent example of camouflage evolution was in Great Britain, where a species of moth came in two colours: grey and black. Before the industrial revolution, the grey moths were the dominant ones, since they blended nicely into the bark of trees as they rested, the black ones stood out and got eaten up. When lots of coal was being burnt and everything was covered in soot, the black ones had the advantage and the grey ones became rare.

A species does not evolve to adapt to its environment. Either the species, or some members of the species are able to survive in the new environment or not. If not, the species dies. Suppose there is an earthquake and a river is diverted as a consequence. All the mice living downstream suddenly find themselves scarce of water. They do not suddenly start changing and learning to live with less water (which would be adaptation). Those who can't live with less water die. Those, assuming there are some, who, perhaps owing to a small genetic variation which permits them to survive with less water, may continue to survive. When water was plentiful, they had no survival advantage over the other mice. Now that water is scarce, they do. The mice did not adapt, those that were able to survive and pass on their genes survived, the others died. Genetic variation and mutation are rarely isolated to a single effect. Typically there is a cascade effect which may include morphological changes as well - for example, Down's Syndrome results when there is excess (duplicated) genetic material on chromosome 21. This results in the over expression of certain genes, resulting in morphological, as well as other consequences.

This is not to say that there are no unanswered questions with evolution, there are plenty, but as a mechanism which describes the transmission of common traits to descendents which confer the ability to survive it works very well.

Darwin's vision of a slow and steady progressive evolution is archaic and is better replaced with Niles Eldrege's and Stephen J. Gould's notion of punctuated equilibrium: for large periods of time, there is little or no change in organisms, however, during times of great environmental or ecological stress, evolution occurs quickly as those who cannot survive die and those that can pass on survivability traits to descendants. Add in some mutations and you have a recipe for rapid change. Which organisms are least likely to survive? Ones which reproduce slowly, they cannot introduce genetic diversity fast enough for natural selection to take place. That is why dinosaurs are extinct. This is why large mammals are dying off, they cannot cope with rapid changes. There is probably some upper limit on how fast change can occur before an organism is unable to cope with the necessary changes and dies off. Also, even if an organism reproduces quickly (say mice), it may still die out if the change is too rapid (for example, if the aforementioned river increased its flow toward the mice and flooded them, I would expect them to drown and not adapt - since I consider it unlikely that there are any mice capable of underwater respiration).

As for unanswered problems? Consider what good a quarter trunk or half trunk is for an elephant. An elephant's trunk is very complex. How it could evolve slowly or in fits and starts is a mystery. Of course, we could always consider the tapir and its elongated snout as a starting point for our question.

The next time someone tells you, "Abc evolved xyz in response to ijk", tell them they are wrong. Tell them that "The selection pressure introduced by ijk caused those abc organisms with the characteristic xyz to survive. Those that did not have characteristic xyz died out."

Image nabbed from here.

[Updated 06-Septemeber-2006 to correct typos (including one caught by Nathalie).]

Comments

Barbara said…
This pretty much turns everything I have ever thought about evolution on its head, but it makes sense. It removes the intentionality from the change and instead puts the emphasis on the result, which probably always has a logical explanation. It casts change over time in a much more global context. I will remember your admonishment the next time I am tempted to give intelligence to evolution!
Richard said…
That is correct, evolution is not about an organism actively directing its process of change. Although, it can be argued that numerous organisms (including humans) actively modify their environments and, consequently, could be argued to be influencing their evolution. Think beavers, they actively modify their environment to make it more hospitable to themselves.

Then there are those who promote "Intelligent Design", which is unsatisfying to me - basically they are looking to see an ever present and continuously active hand of God in everything. As a religious person, I have no problem in accepting that at times God has directly intervened, but I tend to believe He is much more hands off than hands on, letting nature takes its course according to the rules, parameters and boundaries set in motion by Him. (As a side issue, I am also currently thinking about whether free will is real or an illusion.)

Science, in the context I understand it, is about knowing (derived from the Latin scio). I believe it is perfectly reasonable to expect people to learn and to understand how this world and universe works. Understanding, from my religious perspective, does not diminish God. If I did not want to know, then I would choose to be gnostic - a believer in secret and hidden knowledge (a gross simplification, but good enough for my purposes).

Another evolutionary trait: anthocyanins, which give maple leaves (among others) their beautiful red colour in Fall, are quite toxic to many plants. By shedding its leaves, the maple tree poisons the ground around it and gives an advantage to other maples to grow in the neighbourhood. This also happens with pine needles, they make the ground acidic and inhibit the growth of other plants (which would compete for nutrients with the pine tree). Neither of these evolved this things for the express purpose of disadvantaging competitors, rather, it is because they conferred a definite advantage that they stuck around.

Life is a wonderfully complex and rich tapestry of interactions. All too often we try to oversimplify and minimize its beauty. Anything that can take advantage of an ecological niche, will. Even in the pictures of the Paracas National Park I posted a few weeks back, life exists in that very dry area. Even in the Atacama desert in Chile, there are bacteria living in the soil. It is considered to be as close as we can get to environmental conditions on Mars (personally, I think we are arrogant in assuming that life on Mars - if it exists - must follow our biological model).
You know what, your comments make a lot of sense, but seriously, I'm too tired right now to process biology and evolution cohesively.
I liked your cartoon though - Dilbert can be very philosophical sometimes.
P.S. Don't think I'm an idiot based on my comments - I actually did go to college.
Lol ;)
Richard said…
The blog is longer than I wanted. I wanted something much shorter (my general rule is no more than 3 or 4 reasonable paragraphs and no more than 1 post per day). Originally I thought of saying something like, "I am peeved at the colloquial way the term evolution is used and explained – even by those who should know better. Organisms do not evolve characteristics in order to survive, randomly introduced characteristics are selected based on their survival benefit (e.g. plants did not evolve colourful flowers to attract insects, rather insects were attracted to colourful flowers)." or something to that effect. Figuring it was too dense, I added more clarifying verbiage (which just makes it longer and drains people reading).

I think it fails the eye glazing test, much like any text that overwhelms the user with too many graphs, tables, charts, and / or equations.

I am sure you did very well in college :-)
Richard,
Is that really you in the photo?
If so, are you still 12?
Erin
(Do I make you laugh?)
freckled-one said…
Intense reading for a Thursday evening. Haha. It totally makes sense though and I agree that if creators had to wait for the environment to "evolve" than they would be extinct.

And I'd be interested in reading what your take on "free will" is.
b said…
brilliant post, richard. it really challenges and clearly explains something that is so easily misconstrued. "evolution" in itself is a buzz word and people latch on to that without fully knowing the implications of the word. being a word nerd, i so appreciated that you laid out the etymology of the word and broke down your argument in very cohesive and enlightening examples.

this post also is riddled with implications regarding the general human tendency to establish hierarchy. by constantly using the term "evolution," humans attach superiority to the status quo and that assumption that we are so much better ("more evolved") than previous generations or other cultures is a peeve of mine!

thanks for the brain food!
RennyBA said…
Thanks for sharing - I always learn something new and interesting reading your post! I'll tell them next time:-)
Have a great end to your week Richard!
Richard said…
run around paris: yes, that is me in my avatar and no, I am not 12, I am 10 (although, my wife says I am more like 4).

freckled-one: Yeah, it can be a bit heavy. With my friend Tony (a real, honest-to-goodness, bona-fide, environmental scientist (specialization invasive freshwater species) I only needed the abridged version given in my second answer up above. You can read some of my thoughts on free will here, here and there are also some indirect references here - note, this is a thought in progress (and might be classified as heavy reading).

breal: thank you for commenting! The mechanism is fairly easy to understand (although, this is not to say it doesn't have huge unanswered questions) and generally provides a good framework for understanding how change occurs. Humans are pattern matchers and, in my opinion, are always trying to find patterns and meaning in things - we seem to have an inner drive to organize and connect things (although, anyone who has ever seen my workspace or study would beg to differ). You can read some posts on pattern matching and humans (sort of) here and here.

rennyba: I am glad you were able to take something away from this. For me, this blog has become a substitute for long evening walks, drinking coffee and discussions.
Your point is a good one and you articulated it well. You sure put a lot of work into this one!
So do the terms "natural selection" and "survival of the fittest" that we always have heard, still fit into your model? (I'm thinking they do for the most part.)
Richard said…
MOI: of course "natural selection" and "survival of the fittest" fit and are appropriate - however, not in the popular sense.

"Natural selection" simply means that nature applies selective pressure which results in organisms either surviving or dying. If they survuve, then they have ben naturally selected.

"Survival of the fittest" simply means that those organisms best suited to surviving in their environment do. It does not imply the biggest, or fastest, or smartest, or strongest it simply means those that are fit to survive in their environment.

For example, suppose an organism lives in an environment of severely limited resources (like a small island), it would be reasonable to assume that those organism which require a lot of resources to reach reproductive maturity (say large elephants) are going to be under a lot of stress. However, smaller elephants might survive - so the evolutionary pressure would be toward smaller elephants rather than larger ones.
Thanks. I get how it all fits now . I can see why people can get it a little mixed up. The way you presented it makes it more precise and exact even though many would think they mean the same thing.
Nathalie said…
Hi Richard,
Thank you for this brilliant explanation. I remember understanding things exactly that way when evolution was explained to me at school but somehow the improper use of the word had taken over since. Is there any way your paper could be sent to every school teacher in the world ?
However and I will really make you sad, there still was a typo in your paper when I read it this morning : quote
Also, even if an organism reproduces quickly (say mice), it may still dies out ... unquote(dies instead of die)
I tend to be a spelling/typo freak myself !
Cheers
Nathalie
Richard said…
nathalie: Thank you for dropping by and commenting! I certainly am not about ot start bulk mailings to teachers around the world - but thanks for the ego boost.

Also, thanks for pointing out yet another typo. sigh.
carra said…
I feel like an utter idiot. My conception of evolution was, as it was said by the scientists that we all genetically pass down information to our descendants about our environment, thus their bodies adapting to the changes, this concept completely changes my view of thee world, as it is rather than being relating to adapting it is about survival. The strongest (and not necessarily meaning literal strength) are the ones that will be left in the end. I like the way you explained everything, I also like the idea, that sometimes a mutation of one breed can create a completely new breed!
Richard said…
carra: we do pass down our characteristics to each generation. However, we don't all have the same characteristics. Under "normal" circumstances, the differences may not confer any survival advantage. However, sometimes they might - at which point they become significant in driving a difference in the population.

One easy result of this is resistant bacteria. We constantly are touted the benefits fo using anti-bacterials that kill 99.99% of germs. This sounds good, fewer bacteria means less chance of getting sick. However ... those 0.01% that survive are very likely the ones that are resistant to what ever killed of the other 99.99%. So guess what happens? They start to become the dominant strain. Which means the next time, your wonderful anti-bacterial will not be successful in killing off sufficient numbers, since there are resistant (same with insecticide resistant bugs).

I think that widespread use of anti-bacterials is a great way to breed super-bugs.

Mutations can be introduced in a number of different ways: (1) external forces (radiation damages, etc), (2) transcription errors, (3) transpositions.

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