Co-operative evolution?

[ollypenrice]

I went to the French 'arty documentary' Ocean the other week. It was mesmerzing yet, at some level, curiously depressing - not just because man is bent upon destroying the ocean but because most of the creatures in it are bent upon eating each other. Their fantastic and beautiful forms arise because they are instruments of war, by turns aggressive and defensive. There were, of course, exceptions in which creatures co-operated to their mutual benefit.

And so I wondered - dare we hope for the evolution an all-co-operative ecosystem somewhere in the universe? Do biologists ever give this kind of question their time? Is there a reason, perhaps even a mathematical one, why competition should have come to dominate evolution on earth? Would co-operation be slower in adapting to environmental change? Maybe in a more stable environment co-operation might be more effective than competition?

Darwin's 'survival of the fittest' is now often misunderstood as the term 'fit' has come to mean athletically strong. He meant 'most appropriate.' Maybe somehere co-operation might be just that.

Olly

[michaelmorris]

Olly

This is an interesting question that has been pondered by many.

A characteristic in an individual is controlled by a discreet section of the individual’s DNA This is called a gene. For instance, in humans there is a single gene that determines eye colour. The different versions of this gene (blue, brown, green eye colour) are called alleles.

Natural selection works at the level of the allele, not the individual. If having green eyes makes you most likely to produce more offspring, who themselves reproduce preferentially, you will inevitably eventually end up with more individuals with green eyes in the population than any other colour. Hence the ‘green eye’ allele will have been ‘naturally selected’. The population will thus have evolved into a green-eyed population. This is a rather simplistic example, but I hope it illustrates the point.

Co-operative behaviour in an individual is only an evolutionary advantage if leads to an increased preponderance of the alleles possessed by that individual. So instance, your children will share approximately half their alleles with you. Therefore it may be to your advantage to nurture them to the point where they can reproduce (and hence pass on some of the same alleles).

Similarly, co-operation is an advantage if you it leads to an increased preponderance of alleles possessed by both the individuals co-operating, or at least doesn’t lead to a decrease in the preponderance of their alleles. This is the case in symbiotic relationships.

The best examples of co-operative behaviour can be found in ‘drones’ in the insect community. Worker ants and drone bees will sacrifice their lives to protect the colony. This is counter intuitive until you remember that these animals as clones. Each worker ant or drone bee is genetically identical. Thus if 1000 genetically identical individual ant sacrifice themselves defending the queen, this is an advantage as they are protecting the source of the alleles contained in that population. Simple mathematics determines that such behaviours are selected for.

The problem with this approach is that you end up with populations of very low genetic diversity. If sudden changes comes about, the population does not have the range of characteristics in the popultation (the gene pool) to allow the population to evolve to survive in the new environment. Thus, genetically restricted species are only likely to survive in the long term if they live in a very stable environment.

If you want to get a fuller exploration of these issues, can I suggest three books by Richard Dawkins – The Selfish Gene, The Blind Watchmaker and The Extended Phenotype.

[ollypenrice]

Thanks Michael. Great point about the clones. I hadn't seen the connection with the co-operative model. I have read two of the Dawkins books on your list - excellent. I will get hold of the last one at the earliest opportunity, though I have just received a vast tome alledging that the CIA deliberately poisoned a French village in the early fifties. So much to learn! So much to photograph!

So much to drink...

Olly

[John]

This is fascinating stuff, a little over my head, but fascinating none the less. I'm also going to make a point of reading the Dawkins books mentioned - so far I've only read the God Delusion which is on a different tack I suspect !.

[brianb]

There are large numbers of examples of symbiosis i.e. creatures evolving to depend on each other to their mutual benefit. True, not as many as there are of species being at different ends of the same food chain, but then all living things need to get energy from somewhere, and eating other organisms is a short cut to obtaining nutrients that you don't have the enzymes to synthesise or digest yourself.

You would be terribly ill without a few hundred trillion bacteria which live in your gut ... they make nutrients available to you, and your intestine provides them with a food supply and a shelter from the oxygen-rich atmosphere which is poisonous to them. Symbiosis.

But cooperation only goes so far - resources are limited, and there is usually competition to obtain resources which are becoming scarce due to e.g. overpopulation - a factor which economists with their fondness for unlimited exponential growth tend to ignore, at any rate until it's far too late for any rational controls to be effective.

[vhbelvadi]

Kind of over my head too. Sadly I haven't read Dawkin at all. The three books are next on my list.

Perhaps we are the only ones knowingly being uncooperative. I find there are many organisms being unknowingly cooperative; to en extent, even humans. But that's where it all ends for (most of) us.

[ollypenrice]

I think Brian's point about the consumption of others as a short cut is key to the issue. The best defence would be to be indigestible. In our own ecosystem this evolutionary possibiity is not widespread though I think there are some life forms which are unpalatable as a defence. Not sure about that. However, I wonder if it might be possible to have an ecosystem in which the shortcut did not work. In such an environment co-operation might confer advantage?

Olly

[brianb]

The best defence would be to be indigestible. In our own ecosystem this evolutionary possibiity is not widespread though I think there are some life forms which are unpalatable as a defence.

Indeed ... though mention of "food chains" always brings one particular image to mind ... from "The Simpsons"

I wonder if it might be possible to have an ecosystem in which the shortcut did not work.

Well for a start there are left handed & right handed versions of many molecules - chemically identical but requiring different enzymes to digest. It would be possible for life forms based on left handed & right handed sugars to co-evolve & co-exist ... but it appears to be much more likely that an organism would accidentally (by mutation) acquire both forms of the enzyme, this would give it an obvious evolutionary advantage in being able to exploit both sources of food ... after it has taken over the world, the "spare" enzyme might be useless and would therefore probably be lost.

[michaelmorris]

The best defence would be to be indigestible. In our own ecosystem this evolutionary possibiity is not widespread though I think there are some life forms which are unpalatable as a defence.

Many plants are indigestible due the prescence of thorns, tough outer skins or they contain chemicals called alkaloids. This is the group of chemicals that give many blue/purple plants their bitter taste. The blue colouration is a warning to herbivores - "don't eat me - I taste naff." Of course, by doing so they are creating a niche for creatures to evolve mechanisms whereby they can eat the plant. It's an arms race.

In mammals, a common form of 'food spoilage' is the fact that many mammals will urinate and/or defaecate over themselves when frightened. (the proverbable 'brown trouser' moment!).

[tinvek]

got to be quick, going to work but i did read once that possibly the reason why humans have such a poor sense of smell and hearing was because our "best friends", dogs, have such good versions of these, conversley the poor eye sight of the dog is balanced by our sight and the advantage our higher sight line gives us.

presumably this is also why so many intelegent men are partnered by women of reduced mental facilities

[simon hicks]

Lichens are a great example of cooperative evolution. And I guess all eucaryotic life is a cooperative evolution of a sort, seeing as its incorporated the primitive bits of bacteria i.e mitochodria as a power source.

And Brian is right...if we got rid of all the flaura and fauna in and on our bodies, we would fall down dead very quickly. There's more strands of DNA in and on our bodies that is foriegn than is our own (I find that amazing).

I think all this thinking about creatures as being at war, or offensive or defensive, and therefore by implication good / bad is not very helpful. Things are just the way they are......extremely facinating. C'est la vie.

[ollypenrice]

[quote

presumably this is also why so many intelegent men are partnered by women of reduced mental facilities

Careful now, the ladies on the forum may be quick to point out that the conventional spelling is 'intelligent!' Keep your head down!!

Olly.

[tinvek]

[quote

presumably this is also why so many intelegent men are partnered by women of reduced mental facilities

Careful now, the ladies on the forum may be quick to point out that the conventional spelling is 'intelligent!' Keep your head down!!

Olly.

lol that's probably why i end up with things that make olive from on the buses rank at a 10

oh hello dear........................................ ouch

[Dandobi]

Can I recomend another book? 'The End of Science' by John Horgan. Asking whether we've answered everything that can be answered. Great section on evolutionary biology and arguments on whether competition is beneficial. If computers in the future could invent a 'perfect' universe, would competition be beneficial? The section on chaoplexity was a little over my head tho!

Marc

[ollypenrice]

Thanks, I'll look out for that.

Olly

[Macavity]

I see there are (arguably) other, vertebrate examples:

Remora - Wikipedia, the free encyclopedia (!)

Perhaps we are (unconciously) hitching a ride on something greater?

(The Remora DIET sounds rather less appealing than ours though!)

[Shibby]

w.r.t. symbiosis, my favourite example is the Acacia. Some varieties grow their thorns into swollen ant homes. The ants then live on the tree and defend it from herbivores and neighbouring plants. The tree also feeds the ants by secreting nectar or little ant-sized packets of protein for them to eat.