The speed of evolution

22 10 2008

The theory of evolution is greater than it looks. It is not just clever. It is not just useful. Its biggest value is as a nail in the coffin of some very destructive ideas. Not just the idea that Europeans are superior to Africans, or the idea that humans are superior to animals, but the idea that we all have some divine purpose – and therewith, the whole idea of good and evil.

The fascinating story of how the the tide of evidence has led to the unravelling of religious explanations for the world is, however, not what I wish to ponder here. No, I would like to ponder an area of evolutionary theory that still holds some uncertainty, some mystery.

Relax, I am not trying to ‘break’ or disprove evolution. I am fairly confident it it largely right, but I still think there are questions about it speed.

The problem…

Anyone who has read on the subject understands the pure cunning of natural selection. Basically put, any replicating ‘creature’, that produces slight mutations in its offspring, will produce some offspring that are better than itself – better at competing for resource, better at surviving. Of course many mutations (indeed perhaps most mutations) may produce ‘worse’ offspring, but if the better offspring survive proportionally more, there will be a generational improvement.

This is the same phenomena that allows us to breed better race-horses, beef-cattle or strawberries.

Now, we can see the effects of selection very quickly in a petri dish of bugs, or perhaps in viruses in the human population, but the evolution of large mammals is a slow affair, not easily observed, and it took the discovery of ‘missing links’ to confirm the theory that we had indeed evolved from primate stock.

I personally have not read widely on evolution, I have simply spent lots of time thinking about it, and also spent some brain cells on pedantic calculations and computer simulations.

What comes up, again and again in the simulations is the question of speed.


Yes, speed. How fast do we evolve, and have we had enough time to do it?


There are two ways to tackle the question of evolutionary speed. One the one hand, you could say: we have only had, say, 5 billion years, to evolve from the basic elements, so we must have evolved fast enough. The calculations must simply be made to fit the data.

Some (not me) have however said, hang on, calculations show that we haven’t had the time to evolve, so the theory must have some massive fault.

The latter argument betrays a misunderstanding of evolution. They assume that as evolutionists claim evolution is ‘true’ and ‘right’, that their models must be right. But if their models suggest we needed 100 billion years to evolve that will prove that evolution is too slow and some other agency is required to square the circle.

However, just because evolution is fairly certain to be right, that doesn’t mean the models are simple, and I hope to give some insight into the challenge that I came across in my own amatuer attempts at the challenge.

Factors that throttle evolutionary change… 

Let’s look at the things that effect the speed of evolution.

  1. the generation gap (time between generations)
  2. the strength of the mutation.
  3. the selection pressures (multiple)
  4. the male/female requirement (and its surprising turbo function)

The first one is obvious – the more generations you get through each year/millennium, the greater potential for evolutionary change.

Mutation strength is more interesting. You could have multiple errors in a DNA sequence, the more errors the stronger the mutation. However, some errors in the DNA may have no particular effect, while other errors could be catastrophic, so that matters too. To keep things simple, lets just focus on the ‘strength’ of the inter-generational change.

If the mutations were very small and subtle, this, I would predict, would slow evolution down. However, if the mutations are too large (remember they are random), they are less likely ‘to be compatible with life’. However, I suspect because they are random, they will come in all shapes and sizes, ranging from untraceably small – to very fatal (resulting in early miscarriage).

However, we have seen in the fossil record evidence that evolution speeds up and slows down. The statistics of mutation ought not to change like that, so there must be more to it.

Selection pressure is the next, and even more interesting, factor.

People have questioned why the world doesn’t have living examples of ‘the missing link’. They must have been ‘viable’ in their own right, so why didn’t they survive?

Some thought on the subject (as well as my own simulations) show that this is not surprising. The speciation event (when one species splits into two) is usually the result of a population becoming subjected to a varying selection pressure (usually geographical). If the population is well mixed, its keeps together, but a mountain range or body or water can reduce the interaction enough to allow the different ‘random walks’ to optimise the two populations for their environments. Allowed to proceed for any length of time, you land up with two separate species, with nothing between. Once separated, they cannot ‘rejoin’ even if they mix once more, so the divergence will continue. Some have argued that ‘spurts’ in evolution augment this speciation process.

So why do these spurts happen? This is most likely selection pressure, but how does it work? Well, putting it simply, the more the environment changes, the more the creatures will need to change to survive. In a static environment, creatures will evolve to suit, but following the law of diminishing returns, once happy, would have no driving force to change any more.

However, you could well argue, that while a quickly changing environment allows faster evolution, it is simply taking its foot off the brake, something else is really controlling the maximum speed of evolution.

What do I mean by maximum speed? Well ask how fast would an environment need to change, such that evolution could not keep up – then you have reached its maximum speed.

There is an example that some folks think is an example of an environment that promoted fast evolution. Theorists have suggested that early man was often the victim of famine, and often needed to move around, which resulted in accelerated evolution. The stronger penalty on the weak, the higher reward for strength and wisdom, meant that potentially positive mutations, that may be lost in stable ‘easy’ environments, were more effective in this environment, thus accelerating change.

There is much written about selection, by people much smarter than myself, so I will not elaborate any more on it. I would simply summarise, that in the course of billions of years, some environments would allow fast evolution, while others would stagnate, and the average speed, while hard to quantify, would not be consistently high enough to be the key to the sort of evolutionary speed we need to gain so many evolved features is so few generations.

So at this stage, I would like to point out the most marvellous thing about evolution, which I think can multiply the effects of natural selection.

The two-sex system and its accelerating effect…

As I grew up, I sometimes wondered why we needed two sexes. Why not just allow all creatures to have offspring, add in a little mutation, and hey presto, it should work. 

This was the form of my very first simulations (some 17 years ago now!). It showed me fairly rapid evolution and increasing fitness, so all looked good. If you set the bifurcation ratio to 2, give each child a random ‘fitness’ and then set the chance of reproduction be proportional to fitness (a very simple algorithm), the population did get fitter. However, when I compared it with the standard model, where you have two sexes, two differences in macro behaviour showed up.

Firstly, you have to add an extra ‘selection’ criteria. It is not just about surviving to reproductive age, it is now about surviving AND finding a mate. And you can forget about monogamy, so a very fit (for sexual selection) male could fertilise several females, at the expense of less fit males. This effect can (in my model) greatly accelerate change. All you need to do to get fast change, is ensure that partners can identify fitness accurately. 

The second interesting effect from having two sexes (and what I found out from my model), is that good genes can spread through the population, which does not happen in the one-sex model. This spread of good genes means that one part of a population could be learning how to deal with sunburn, while another is learning to deal with sickle-cell anemia, and their solutions can be shared by all.

Now we are talking. This, if I have my thinking right, would be a serious turbo-boost for evolution, allowing it to evolve lots of traits in parallel, whereas the single sex model would have to work on one feature at a time – first build an eye, then build a digestion tract, then build a good sense of humour… This buys evolution a lot of time. This makes it far more likely that 5 billion years is enough time to make all the amazing variety we see today.

So I would therefore argue that this makes it more likely we had time to go from the first two-sex replicator to the world of wasps, earwigs and herpes.

That begs my next question: how did the first two-sex replicator come about? I think the computer modelling may be beyond me, but I hold out hope for my children! 





9 responses

23 10 2008

It’s strange you didn’t mention predation as organisms eating each other accelerates the rate of selection. In fact, natural selection for the last 550 million years has been driven by disease and predation during the times of a stable climate.

As for how sexes got their start, take a look at the Y chromosome and compare it to the X. Notice something? The Y chromosome looks like a shriveled little X. There you go. It’s another mutation that allowed animals to have sexes. Before this, all creatures were either sexless or hermaphroditic.

23 10 2008

Thanks gfish, your points are dead right.

I totally agree that disease and predation should be in there, serious oversights on my behalf. I also suspect there are other auto-catalytic or positive feedback mechanisms I have left out…

PS. I am new to blogging, is it rude to improve one’s post thanks to the input of commentators? Credited of course!

Also, the clue you mention to the origin of sexes is really interesting, it looks like I should do some more reading!

21 09 2009

I have recently been pondering an issue that is related to this issue of the “speed” of evolution. More specifically I am thinking through the ethical issues governing genetic modification, which would arguably increase the “speed” of evolution.

It seems to me that most peoples’ knee jerk reaction is to be anti-GM (I am particularly speaking with regard to human GM, not for crop improvements etc). If you do not believe in evolution then I can understand this viewpoint, but it seems even those that believe in evolution tend to be anti-GM and think (feel?) that we shouldn’t “take nature into our own hands”.

I used to think like this but recently I have had something like an epiphany regarding GM. The idea that we should be anti-GM seems to me to inherently treat humans as somehow “different” from other organisms, or that we are somehow “special” and so should be considered outside of evolution. However, I don’t think we are “special” and so I don’t think we (or our actions) should be considered outside of evolution. Let me explain more.

When you consider evolution you don’t think there is anything abnormal when a species undergoes a random mutation that gives it an advantageous adaptation. But suddenly, when we create our own mutations (so that they are no longer random) then most people think this is something we shouldn’t do. I don’t agree. Surely the ability to self modify your genes to improve your species (make your kids cleverer, fitter, healthier etc), and hence accelerate evolution, is the pinnacle of evolution?! If there is one goal of evolution it is to be as “fit” as possible, and if altering your own genes makes you fitter quicker, this must be the holy grail of evolution. For example, if I wanted to play an imaginary game where the goal is to have a species that evolves as fast as possible, so that they are as successful as possible, then surely the best way to do this would be to set your system running so that your series of organisms would develop enough intelligence to start to make significant modifications to themselves per generation? Shouldn’t our adaptation (our intelligence), which allows us to improve our own genes, be taken in a context within evolution, not outside of it?

If that is true then it seems to me that GM is a good thing, and those that are against it think this way because they are worried that them or their children (which of course means their own genes!) get left behind. To me being against GM (if it is because you are consciously or sub-consciously worried about the propagation of your own genes) seems to agree with my argument that GM is a good thing in a strange sort of way! It would be like the organisms who haven’t had the random mutation worrying about being superseded by those that have (but we all agree that is a good thing) – it just so happens that we have got to the holy grail of being able to modify our own.

This is why I am now no longer anti GM, to me that viewpoint is treating humans as outside evolution, whereas if you consider everything we do as part of evolution (which it surely must be unless you are religious), then the ability to modify our own genes and control our own evolution seems a landmark point IN our own evolution, not outside of it. Assuming we make the correct choices of course!

On a loosely related note. Likewise, maybe our ruining of the planet should also not be taken outside of nature. Perhaps this is all part of us being too successful, and if we then kill ourselves off then something better (fitter?) may evolve. After all, as an analogy, when a predator develops a significant adaptation and becomes so successful that it makes its own prey extinct and so eventually dies out itself, we don’t think anything “special” has happened. Maybe our intelligence could be our downfall as well as our reason for success. Of course I hope we are so intelligent that we can sort out our problems and not cause mass extinctions, but on the grander scale of the whole lifetime of the earth (let alone the universe!), we’re not really that important, and controversially perhaps our role in evolution is to do something like that?

21 09 2009

Hi koolherc,
Thanks for some very interesting points. Your logic in undeniable!
Firstly, I agree it is somewhat cavalier to assume that our ability to add some ‘auto-selection’ to our own evolution is somehow ‘outside’ of evolution.
Of course humans are animals, so the idea that we somehow taint nature with our touch doesn’t hold water. How can the formation of pure silica in crystallizing magma, or in the skeletons of algae be considered natural, but when made by man not? So agree on that point.
But doesn’t the issue lie in the (seemingly) common perception that natural evolution is somehow *morally* OK, and it is the morality behind unnatural (GM assisted) evolution that is in doubt (rather than whether or not is part of our evolution or not)?
I personally think that evolution (as currently defined) has no aim or intention, so is neither moral or amoral – but the ‘new’ human-assisted evolution has the potential to have aims: a direction, an intention, a perceived target – complete with moral-assisted design.
So couldn’t GM assisted evolution be notably different?

Following this, your talk of ‘pinnacles’ also troubles me. I think of evolution as a never ending ebb and flow of characteristics trying to keep up with changes in the environment. There is no end point, there is no perfect organism. There are some periods of stability, some or fast change. What is the perfect creature in that picture? Surely it is meaningless as a concept?

So what drives our desire to improve our genes? Of course we all want to give our children every advantage, but rarely do we ask ourselves why.
I suggest the only reason we want our genes to pass on and ‘succeed’, is because wanting our genes to pass on, helps them pass on. That’s all.
All our complex feelings on the subject are part of our evolutionary make-up, just as our eardrums and eyelashes. Our own understanding of why we want to procreate is all illusion.
So this begs the question: if we can control our own evolution, what direction will we take? Do we consciously care about our children’s proliferation, or do we care more about their happiness? I think our evolutionary cares (i.e. those for propagation) are subconscious, but our *conscious* cares may take evolution off on another track…so what will we select for? Longer living? Happiness? Immunity to pain?
Mmmm. We may indeed become a very strange lot. Perhaps we will splinter, as in the Time Machine? I wonder!

28 09 2009

Thank you for your reply, some interesting and thought provoking comments – I certainly hadn’t considered the morality (or lack thereof) of the situation.

Just wanted to clarify the “pinnacle” issue because I agree with the ebb and flow idea. I didn’t necessarily mean that we would reach a pinnacle of evolution and stop, this was probably a poor choice of word and badly explained. I see it more as being able to keep ourselves evolving as fast as possible as our environment ebbs and flows – so I meant a pinnacle in the speed of evolution, not in the organism. Pinnacle is still a poor word as I don’t mean evolution the “normal” way can’t go faster, just that we have accelerated it beyond what is “normal” at the present time, and the ability to accelerate evolution is a land mark point – like sending a human into space is a land mark in space exploration not an end point.

Let me try to explain again. I basically just meant that the ability to accelerate evolution beyond the “normal” way by means of self modification (forgetting for now your interesting points on morality and the contrast between conscious and self-conscious desires) could be seen as a land mark in evolution. This is because we may be able to modify ourselves appropriately, as our environment changes about us, and by being able to do this, we (or whatever we become) may be able to dramatically increase the probability of us (our descendants) being as fit as possible for the given environment we occupy – i.e. to increase the probability of our species/descendants survival beyond what the “normal” way would allow at any given time.

Of course, then there is the not inconsequential question of being able to control our environment to a certain degree as well!

29 09 2009

I think I get what you are saying and it’s a very good point. Perhaps a million years from now, if we look at the ‘tree of life’ the date when we learned how to manipulate genes will stand out as an obvious turning point where the very nature (not only the speed) of evolution will be seen to make a change.

It’s also worth noting that “unnatural selection” can be done without GM – the ability of the human mind to domesticate animals and breed food crops will also show up in the time-line – as would ideas like eugenics (if taken up).

Perhaps we can already see accelerations in the evolution due to man’s intervention – grasses were taking a slow and random walk until humans decided to try increase the size of the seeds and wheat grains have grown dramatically in the last few thousand years – and GM will probably increase that again…

29 09 2009

And your point about controlling the environment is also interesting. We are certainly getting good at that. Perhaps mankind’s unique way of solving problems with a sort of programmable problem solving machine (our brains) will in itself show up as a turning point in evolution? It is the reason we started to control the evolution of other species, it is the reason we learned to manipulate genes, it is the reason we can use so many tools to help us survive the unsurvivable and spread to deserts and the icy tundra.

The question that now comes to my mind is: will our super-powerful brain’s ability to adapt be overtaken by our super-powerful brain’s ability to destroy? Although we are clever enough to make luminous mice, we are also smart enough to rig the world up with thousands of nuclear missiles, each patiently waiting for its day in the sun.

Perhaps this turning point in evolution will also be where it goes unstable, implodes, and has to go back and try and make something from the ooze again…

29 09 2009

I agree, and in a way I find it an oddly comforting thought that if the latter does come true, we won’t be the end of the story of life. You could even argue that wiping ourselves out because of our own success is akin to extinctions that have happened before, where an adaptation has been so successful that a predator has exhausted its supply of food and died out itself. Either way, until the Sun becomes a red giant and engulfs the Earth, life will go on. Furthermore, if you believe the hypothesis that life is a natural result of the increase in entropy (organisms reduce entropy by becoming organised, but overall increase entropy by affecting their surroundings) then it’s almost inevitable that life will go on elsewhere in the universe/multiverse or any of the other hypotheses – assuming life “matters” at all, but lets not get into that!

It has been a pleasure discussing these matters with you.

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