By Luke Kristopher Davis
Life on other planets
There is little doubt that there is a finite chance of biological life existing anywhere else in the universe be it in our own solar system or galaxy. A more interesting question to think about is whether the life that does exist elsewhere, arising independently from ours, follows natural selection via the differential selection of genetic material. Basically will it evolve in a similar manner to how life on planet earth has?
We do not yet know precisely the mechanism or all the ingredients for life to emerge from pools of basic chemistry and physics. However we are pretty confident, we meaning the scientific community, that life arises through the thermodynamic building of complex molecules which then have the special property of replicating themselves. This could arise from special symmetries of the molecular lattice such that when this special molecule is bombarded with other basic ones or after some chemical reaction it splits in two, each being copies of each other and of its parent. Though this is mere speculation on my behalf. Life that could arise on other planets will probably originate through this same process, the building of replicators, and as soon as replicators are built Darwinian natural selection starts to exert itself on these extremely basic forms of life. I only say that life will 'probably' start this way because we do not know any other way that it could arise from basic matter within the confines of our established science.
So we are assuming with good reason that life can and probably does exist independently and that it would have emerged from the molecular building of replicators.
How does evolution work again?
Charles Darwin - Proposed natural selection and evolution
Let's continue the story on from our basic replicator molecule which copies itself due to some physical mechanism. This copying process is not perfect, there is a probability that some part of the molecular structure will change slightly after replication therefore a daughter molecule will differ from its parent. These molecules will probably exist in a pool of other molecular compounds and elements and the different daughter replicator will change how it reacts with other molecules or how it bonds with other compounds. If the new daughter molecule speeds up the replication process somehow or can breakdown a new source of energy to fuel reactions its type will no doubt out replicate its mother. So then we already see how a slight change in structure can offer advantages for out replicating the parent or other 'mutated' siblings. Over a great expanse of time molecules would be able to build, through chemical means and interacting with other replicators, bodies which are capable of moving and sensing the environment (a basic example is plankton). The replicator molecules would chemically instruct their bodies to carry out certain physical actions. In certain environments there are selection criteria which select those replicators which build more advantageous bodies, these bodies are called phenotypes and the selection criteria of the environment impresses itself on the phenotypes which increases or decreases the chance of future replication. The replicator body which is more 'adapted' to the selection criteria will increase its chances compared to other replicator bodies.
Replicators are known as genes and replicator bodies are known as organisms. Over time and with the statistical spreading of organisms into different environments (or the statistical emergence of separate life on the same planet) they will branch out into species and evolve complexity. The evolution of all the organisms follow from the differential selection of genes which produce more advantageous phenotypes.
Nature has universal tricks for varying environments
What sort of environment can we expect on other planets ? Well I will not go to the expense of describing them because the range of possible environments that could foster life is great, and it is not key to the point of this article. All I can say is that in general there will be environments which contain molecules for phenotypic structure and metabolism, a solvent and a replicating molecule which does not necessarily have to look like DNA but may well be very similar to.
Even if different planets have different atmospheric pressures, different concoctions of gaseous elements or different amounts of solar radiation and light coming through the sky etc. there will be strong selection criteria which will form similar phenotypic solutions which occured on our planet. For example: the need to move the body through a medium or along it will require limbs or jet propulsion, assuming a wing is a limb. On earth the independent evolution of the wing occurred in birds, insects and bats which resulted in varying wings but similar in function (creating lift). The independent evolution of a particular phenotype tool is called homoplasy in cladistics, in general we call it convergent evolution i.e. similar selection criteria causes a convergence to the same structure. So nature seems to re-use solutions for similar problems.
On other planets the need to fly, even if it is through more dense air, will lead to something like the wing. There may even be other ingenious ways for organisms to move through air which us humans cannot imagine but in the unique environment natural selection will carve it out.
One thing which I would bet a large amount of money on is the evolution of social behavior and sexual reproduction on life on other planets. Scientists do not completely know how sexual reproduction evolved but because nearly all organisms take part in it sexual reproduction must somehow ultimately bring survival advantages for the genes that instruct them. If this is true, which I assume is, mating dynamics will play out which will cause the evolution of social behavior. Altruism in some species will most likely evolve, either by hunting in a group or living in close proximity to offer protection, warmth, help with rearing young etc. the point is it will offer some sort of advantage to survival or reproductive power. With the existence of social organisms there are advantages to manipulation either of individuals belonging to their own species or organisms from a different species. This manipulation exists as language: the organism exerts some force on the environment which another organism registers and carries out an interpretation or action. As we see in bees, dolphins and us use a fairly complex language which arises from manipulation. This evolution in language must first start with the evolution of a complex brain.
Convergent evolution of intelligence
Simulation of the world is a process which many animals do, it is more cost-effective in terms of time, energy and risk to simulate an event in the world than to try it out for yourself. Young animals with little experience of the world and 'no data' in their memory can have instincts programmed by their genes to get them to make the right choices in early life, and they can have their parents to teach them certain things which they have learnt in their lives. Brains capable of guessing what would happen if an action is taken and choosing the optimal choice based on simulation will be favored by natural selection and an organism which simulates more accurately or records more accurate data will be more favored.
Going back to manipulation of other organisms and social behavior it seems simulating brains of other organisms is a much more complicated matter than simulating the seemingly deterministic physical world. So with the evolution of language and simulation mechanism would lead to a very sophisticated control center of an organism. With phenotypic tools which can adequately alter the environment (would have been advantageous in many environments: see Beavers, our ancestors and even ants) and an ability to somehow infer the causal nature of things, which amounts to an innate genetic proficiency of physics, then organisms could somehow manipulate the environment to reduce the exertion of selection criteria. They could build weapons or defenses to fight off predators, herd prey into groups and cultivate them all this arising from rules and language passed down from generations.
Using the environment to increase an individuals survival or even group survival (dependent on genes shared) is obviously beneficial to the genes which reside in them. However using rules and tricks passed down by the generations through linguistic means or means other than genetic change, results in a reduction of the power of selection criteria without further genetic selection. Normally a reduction in the power of selection criteria comes with better adapted phenotypes from selecting better genes. If an intelligent organism can even restrict the power of future selection criteria be it disease, food shortages or a new predator by using sufficient intelligence as to remove it or constrain it then this organism will not evolve anymore. Evolution needs selection criteria.
I say 'will not evolve anymore' but of course some evolution will gradually take place. Sexual selection will place selection criteria on the organisms but of course in principle this criteria can be reduced through more manipulation of the environment and even the phenotypes themselves without genetic changes. Also a moderately intelligent organism like ourselves has not completely outdone natural selection as poverty in some parts, disease and smaller environmental effects which we have not yet seen could be still placing selection criteria on gene pools.
The point is this, with sufficient intelligence and sufficient ability in manipulating the environment, natural selection will have dwindled. This is because the intelligent organism solves the problem before natural selection will. Natural selection occurs in much greater spells of time then say the time between future generations.
With a great intelligent organism which reduces all selection criteria by manipulation of the environment then evolution, in the sense of differential selection of genetic material, will have ended. It could happen that such an intelligent organism will modify its genes as to increase its manipulative power over the environment, selecting pre-existing genes from other organisms or cutting some genes out or even inventing new ones. However would we still call this evolution?
Would such an organism become victim of another evolution?
Such an organism whose body of accumulated information from generation to generation may become a vehicle for another selfish molecule which is not the gene but a unit of the body of information. So another form of evolution could take place.
In the collected body of information which we call culture in human terms, has selection criteria for certain types of information in certain types of departments. Say the department of finding another energy resource will have the selection criteria of ideas which seem feasible, then there is selection criteria for those which can be implemented sooner or with less energy. This environment provides selection mechanisms for units of information, surely this resembles the differential selection of genetic material? Surely genes are fundamentally just bits of information however complex.
If this scheme were to actually happen the selection criteria would come from the organism itself so it could be argued that the units of this evolution would always be products of the organism and hence the organism is not the one being played in this case it is the player. However it does not seem impossible that the units of evolution in this new scheme could manipulate the organisms for their own survival in the body of accumulated information.
This of course is not established science so I cannot assign any validity to it as an empirically or mathematically sound idea. However with what we witness within our culture, the control of humans by hostile ideas to kill others and themselves seems to not benefit them but the continuation of the idea itself and its future copies. I think there is some value in this proposed idea and something which needs further study.