Some almost random thoughts..

Wednesday, October 1, 2008

Life from the Perspective of the Single Genome per Species.

Life is a replicating molecule called the genome. To understand every aspect of life, we only need to look at the effect it has on the replication of this single genome per species.

What makes life possible is replication. To a genome, the choice between change or no change is literally a no-brainer. Only those genomes that achieve a high degree of error-free replication manage to stay around, all others will have perished a long time ago.

The genome under perfect replication:
The genome has no number dimension.
Whether it codes for 100 or 100 million organisms, it is still the same genome in every organism. There is only ONE genome per species. It either exists, or it doesn't. The number of organisms is only relevant when there is safety in numbers, because whenever the organism count hits 0 the genome is gone.

The genome has no time dimension.
The genome codes for an organism that replicates itself, bringing the genome back to where it was before the life of the organism started. So while the organism lives and changes over time, the genome does not. To the genome, time makes a perfect circle every generation.

All the organisms the genome ever codes for have one use only, and that is the replication of this single genome per species. So the fortunes of all the organisms from the genome's perspective are interchangeable. A benefit the genome gets in replication from one organism can be covered by a cost to any other organism it codes for. Because there is no time or number dimension, cost and benefits in terms of replication can be collapsed over all generations and individuals, as long as the organism count always stays positive.

The genome with imperfect replication.
Life is all about replication of the single genome per species. The replication process is imperfect, so every now and then the genome encounters a change in an individual organism it codes for. This change usually stops the organism from replicating. Sometimes the mutation improves replication in the short run and the mutated genome in the single organism can spread and make it to become the species standard. This is evolution. Evolution happens when replication fails.

The circular cost-benefit analysis from the genome's perspective show the weaknesses in its replication. A mutation in the direction of a profit could overtake it. Mutations that benefit others at a loss to the organism can evolve if they can make it to the position where the organism also gets to be on the receiving end of the deal. A subsequent cheater may get a profit at first, but soon it will find itself surrounded by cheaters and it loses the benefit it was after. So the circular cost-benefit is the overriding constraint to possible change in the genome by failures in replication.

All aspects of life can be explained by looking at the perspective of the single genome per species.
The genome needs to do only one thing: stay alive and replicating in at least one organism. To look at the effect of specific behaviours of the organism the genome codes for, we must also remember that life from the genome's perspective is circular over all individuals and generations.

Parental care.
The genome can code for an organism to take care of its young at great cost, and recover the cost by having the organism taken care of when it is young. If the net benefit on replication is positive, this makes sense from the single genome's perspective. Family ties are common in the animal world because they are fairly easy to program in and reliably lead to a net benefit in reproduction of the single genome.

This means that from the genome's perspective, you do not take care of your children because they take 'your genes' into the future. You take care of your children because the genome that codes for it also makes your parents take care of you. And the net benefit in terms of replication is positive to the genome. The specific genetic combination that makes up an individual human gets shuffled up in the gene pool in no-time and is not a lasting entity.

Sexual reproduction.
Sexual reproduction is all about replication error prevention and correction.

The first stage of sexual reproduction is swapping individual pieces of code (genes) before reproducing while keeping both copies in the organism. When one gene fails in building the organism, it can fall back on the other. This increases the reliability in copying the entire genome and improves the security of reproducing the single genome per species. This improved copying is beneficial to the genome from the start and can increase right up to swapping 50% of the code in small functional pieces.

The second stage is male/female specialisation. This allows more distance between the fertilizing male and the reproducing female and lowers the chance of encountering the same errors in a code swap. This further increases the reliability in the copying of the genome and makes it more likely for the single genome per species to continue.

The third stage is male competition. The female side gets to select the least damaged code from the males. This can act as a circuit breaker stopping damaged pieces of code from continuing in the circle of life. Damaged genes will be present in both females and males, but they can be filtered out on the male side improving the integrity of the single genome and improving its long term chances.

Sexual reproduction is a copy control mechanism in the replication of the single genome per species. Because it allows for some males to out-reproduce others, it can accelerate the spread of a changed genome. But while sexual selection can speed up evolutionary change, its function is only to improve the reliability in the copying of the single genome per species.

The 'species genome' is the narrow band of genetic variation you find within a single species. Pulled apart by viable failures in replication(evolution) and pulled together by sexual reproduction. Sexual reproduction could evolve because at every step it provided a benefit in the error free copying of the genome. And since the vast majority of mutations hurt rather than help in replication, that is a tremendous advantage.

The difference between replication and evolution is a major cause of confusion. Replication is about keeping the single genome per species alive. Evolution is the change of the genome which can start with a single gene in a single organism out competing others and becoming the species standard. Evolution of life is about changes to the genome, life is about replication of the genome. 'Sexual selection' is a part of replication, 'natural selection' belongs to evolution.

Cooperation and competition in humans.
The single genome per species can improve on its replication by having the organism it codes for cooperate. Even though humans share practically 100% of the genome with each other, the genome has coded in a tolerance for diverging face structures. This is our individual signature that enables us to recognize each other and cooperate. Just like the cat genome uses differing scents and the bird genome uses differing vocal calls, the human genome uses variable face structure to improve its replication by enabling cooperation.

Humans are practically clones, they only differ for as much as it helps the single human genome to improve its replication by enabling humans to cooperate. You would never get your bike back if you couldn't tell who you gave it to.

Competition in humans comes from the sexual selection mechanism. For individual males to make it through it helps to outperform other males. Because of the high parental investment by both sides in humans, the mechanism of sexual selection to maintain gene quality can be used in both males and females by the single human genome.

Cainism among raptors.
Some birds have the elder chick throw the younger one from the nest. This makes sense from the single genome per species perspective because it increases the likelihood of the genome to make it into the next generation in at least one organism.

Short term view of evolution.
For a change in the genome to make it as the species standard, all it has to do is crowd out the alternative. So even though a single gene change can be beneficial in replication in the beginning, that says nothing about its effect in the long run. Language may have evolved in humans as a result of a changing muscle structure releasing the jaws and improving humans ability to speak and think. In the short run this changed genome managed to make it as the species standard. In the longer run it has led to humans exhausting their environment. So while the benefit to the reproduction of the genome is there, the cost is yet to come.

To a nomadic species like humans, exhausting the environment before moving on is a matter of efficiency. Only this time there is nowhere left to go.

Punctuated Equilibrium.
Life from the perspective of the single genome per species is entirely circular. This often causes balancing acts in life, such as for the level of parental care in animals. When parental care evolved this must have been beneficial to the replication of the genome. In humans, it could then evolve further by chance mutations over many generations to the level of almost two decades. So qualitative changes in the building plan of the organism can open up long avenues of further quantitative evolution.

Life falling apart.
Many people see life as building ever more complicated structures, somehow improving on complexity and diversity. But from the perspective of the single replicating genome, evolution is about breaking down. The genome was alive, brakes and is rescued by more complicated way of replicating. Every mutation leads to a more complicated way to hang on to life, while closing off the way back.

From the single genome's perspective, the evolutionary change in the organism it codes for is due to a succession of failures in replication. These changes usually make the genome more instable as can be seen by the accelerating speciation once a genome diverges from its simplest and safest form. It is pushed in an ever tighter corner and generally dies out due to the increased vulnerability. A mutation profit in the circular cost-benefit in terms of reproduction shows where the genome's weaknesses are.

Hamilton's rule.
Hamilton's rule states that the effort an organism spends on another organism can improve genetic fitness for as long as the cost is lower that the benefit adjusted by its degree of genetic relatedness. While this makes a difference for a gene that isn't the species standard, to a standard gene all organisms within the species are 100% related and Hamilton's rule is the same as the circular cost-benefit view from the perspective of the single genome per species.

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Laughter and storytelling:

All humans are equipped with the ability to experience the same social emotions like shame, pride, envy and respect. But the applicability of these emotions can vary strongly from group to group and over time. So the brain needs us to constantly calibrate our social morals with those of our group. The most efficient way to do this is through storytelling. We evolved a love of listening to stories, because in a stone age setting that would expose us to the reactions of our group to the story. We slowly but surely mirror the reactions we hear around us, like laughter and outrage, so that we end up in sync with the social morals of the group. This shows why watching comedy without the studio laughter is difficult. Not only can't you laugh with others, you actually get the message that what you hear shouldn't be deemed funny, because nobody else is laughing.

Laughter and storytelling combine to make us compatible in behaviour, because when it comes to social morals, it did not pay to be different. In the modern world, we have automated the storyteller in the middle of the group, into the TV-set we mostly watch on our own. But without the vocal reactions of our group, it might have become a waste of time.

Hunting and gathering.

As humans we solved our basic food problem. Getting the calories we need to survive is easy. But like animals in the zoo that get fed, we have kept much of the display behaviour related to our feeding methods throughout our evolution.

The gatherer into gossip and fashion.
The success in gathering partly depends on the quality of your information network. You need to hear in time where the latest fruiting tree is. There may be more than enough for the person that finds it, but not enough for everyone. A gatherer that finds food will share the information with someone that seems likely to be able to return the favour another time. So gatherers have evolved a need to signal having a quality social network and being 'up to date'.

Gossip and keeping up with fashion trends are modern display behaviours linked to the innate need to be up to date and to be seen to be up to date. With gossip, a gatherer has a special interest in being the first in relaying otherwise useful bits of information.

The hunter into sports and career.
Stone-age hunting is a team effort needing diverse skills. You are better off hunting with a few others. But you do not want to bring anyone along who can't pull his own weight. You do not want to share the meat and the glory with a slacker. So the hunter has evolved a constant need to show they will make a valuable team member to other hunters. That is what gets you on the best hunting party and that gets you the best food and possibly 'extra' mating opportunities.

Every opportunity you have to compete with others to show off your skills can help you get picked by the best. Modern sports and even career are behaviours linked to the need to show you are a valuable team member and you deserve your spot in the highest league. The displays needed to establish and keep your deserved rank would settle down in a small group. In our modern large group the hunter has become stuck in this display behaviour because there is always a higher league to get into. And people's social circle has become more homogeneous through the sorting that happens in school, housing and work arrangements. So there is always someone close ahead or behind. This may be an important driver behind the 'never enough' economy.

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