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Nuances and Environments of Hydro-Carbonic Life

 

Hydro-carbonic life may mean the one that, like all life forms that exist on Earth, is based on a specific chemical element Ė the carbon - and develops inside a specific solvent - the water. In our planetary system, apart from our own planet, only on Mars and on three Galilean satellites (Callisto, Ganymede and, above all, Europa) is clearly possible to find traces that those life forms existed or may still exist.

 

Mars and the Galilean Oceans

 

On Mars, itís thought that, in a distant past, liquid water flowed over the surface, which eventually enabled the emergence of primitive living entities.

 

The Meteorite of Antarctica

In 1984 it was found in Antarctica a meteorite (the ALH84001) that was proved to be proceeding from Mars due, for instance, to the fact that its air pockets had a very similar composition to the Martian atmosphere. The meteorite, with an estimated age close to the age of Mars itself, unveils signals of having been enshrouded in a liquid environment and displays chemical and physical properties that possibly denounce an ancient biological activity. Finally, in the meteorite there were found tiny structures whose shape resembles the living being that existed on the primitive Earth. Given its smallness it is, nevertheless, impossible to analyse in detail its initial molecular frame. For instance, it wasnít found any measurable trace of cell membranes. Several factors, like the dimension of the fossils (too small for being able to store the quantity of information required by a living entity, according to some investigators) have awaken some negative reactions about the biological nature of the characteristics that are observed in the meteorite.

 

ALH84001: tubular structures with 1 / 1000 of the thickness of a human hair, which are possible fossils of bacterial life that once existed on Mars (Videnskaben eller Gud - DR Multimedia)

 

Mars Today

Today, Mars is a cold planet (so cold that the existence of liquid water, essential for the development of life, became impossible) with a very rarefied atmosphere, vulnerable to the lethal ultraviolet rays and to the solar wind. The atmospheric composition (95% carbon dioxide and 3% nitrogen) is unsuitable for an animal life as we know it, but it isnít unconformable with life forms that donít need oxygen for their metabolic reactions, as it is the case of the most primitive organisms of Earth. Until today, there were never found any traces of biological activity by the probes that have explored Mars.

 

Galilean Oceans

On the other hand, itís very probable that three galilean satellites (Europa and, not so likely, Ganymede and Callisto) host oceans of liquid water under the icy crusts. Therefore, there is a real chance that life exists in such environments. However, there isnít yet any proof that this hypothesis is correct, because life, if it exists, is hidden under these ice covers.

 

Models of the crust of Europa, one of them proposing the existence of an ocean of liquid water (Josť Antůnio Penas)

 

Oasis of Life in the Universe

 

The life as we know it has the chance of occurring, in the whole Universe, in extremely limited zones, at a determined distance (ecosphere) from simple stars (not multiple), with average dimensions and formed from clouds with a reasonable level of metallicity.

 

Simple Stars vs. Multiple Stars

The double system formed by stars with mutual orbits hardly may harbour a planetary system, because the gravitational disturbance that would result from it would prevent the accumulation of matter in big planets (as it happened, for example, in the region of the asteroids, due to the unstabilizing influence of Jupiter). After some time, even the planets that could eventually form would be thrown out to the interstellar space or would take a collision course with one of the stars.

However, it may happen that stars that are extremely close or extremely far away from each other can be surrounded by relatively stable planetary systems, which would make them possible targets for the search of extraterrestrial life.

 

New Suns

The temperature, diameter, luminosity and life expectancy of a star (characteristics that are all interconnected) also determine the chances for the appearance of life on the planets that eventually exist around them.

The Sun is an average star, with a surface temperature of roughly 6000 ļK, a diameter of about 1,4 million km and a life expectancy of approximately 10 billion (10 000 million) years.

 

Dimensions and Characteristics of the Stars

The life expectancy of the largest stars (hot, blue and very bright) would be excessively short for advanced life forms to have enough time to evolve.

In the case of the much more abundant red dwarfs (small, cold and dim), the planets that would be inside the ecosphere (where the water could exist under a liquid form) would be so close to the star that the powerful tidal forces would end up forcing them to always show the same hemisphere to the star, as it happens in the case of the Moon relation with the Earth. One hemisphere (the enlightened) would be scalding and the other (the dark) would be permanently frozen. This situation would prevent the development of life forms. The global circulation of atmospheric air would, nevertheless, reduce the thermal differences between both hemispheres, to the point of allowing the existence of life.

Itís also important that the star doesnít have a variable brightness, because that would constantly unbalance the temperature of the planets orbiting it.

 

Metallicity

The disk that enshrouds the star shall display a minimum proportion of elements heavier than hydrogen or helium (metals), because life relies on them (carbon, nitrogen, oxygen) and the habitats where life arises are composed by this kind of elements (planets like Earth, composed by elements like iron, magnesium and silicon).

The absence of very heavy elements like iron, nickel, copper or zinc also represents an enormous challenge for the development of a technological civilization. Itís thought that the stars of the Population I, with high metallic content, compose 10% of the stars of our galaxy.

 

Galactic Ecosphere

The position of the star inside the galaxy is also important in what concerns to the chances of life development in a planet orbiting it. The orbital speed around the galactic centre doesnít vary whatever the distance at which they are from the latter, but the orbital speed of the arms is higher in the outer regions of the galaxy, so that they donít disrupt and, therefore, they are kept cohesive and united.

For the existence of proper conditions for the appearance of life itís necessary that the distance at which the planet is from the galactic centre is similar to the one where the orbital speed of the stars and the orbital speed of the spiral arms are equal. The Sun, which is found inside that ďgalactic ecosphereĒ, crossed the arm of Sagitarius 4600 million years ago and only will arrive to the arm of Perseus in 3300 million years from now.

Stars that are placed farther away from the galactic centre orbit the galaxy more slowly than the spiral arms and, therefore, cross them more often. Stars that are placed closer to the centre orbit the galaxy more quickly than the arms, which ends up resulting in similar crossingsí frequencies. When a star crosses a spiral arm, it taker a higher risk of being targeted by radiation emanated from the frequent supernovae that occur there, which may end up becoming lethal. Therefore, itís important to avoid close encounters with the spiral arms and their supernovae.

 

Planets of Life

Since we imagine the existence of a simple star, with average dimensions, reasonable metallicity and revolving around the galactic centre at a suitable distance, it can be conceived that a disk that is formed around it may contain a planet with propitious conditions for the appearance of life as we know it. The planet shall be placed at a suitable distance from the star, in order for the temperature to allow the existence of water under a liquid form.

 

A Moon behind the Scene

Itís quite probable that the existence of a satellite with a dimension comparable to the planetís is a fundamental factor, because it stabilizes the inclination of the rotation axis concerning to the orbit plane (on Earth that inclination is about 23,5ļ). That inclination determines the pattern of the climatic seasons on a planet.

If Earth didnít have a big mass satellite, the inclination of its axis could hugely vary within an interval of a few million years (the Marsí inclination varies between 10ļ and 50ļ), causing dramatic climatic changes. When that inclination would be more pronounced, the seasons would be much more bitter, which would make difficult the evolution of life into more developed forms.

Because the appearance of the Moon was probably caused by a casual event (the collision of a smaller planet with the Earth), itís rational to think that life may, for that reason, be a relatively rare phenomenon in our galaxy.

 

The privilege of having a Moon (Mark S. Robinson)

 

Rotation Speed

Planets with slow rotation, as Mercury and Venus, without satellites, oscillate far less than Mars. But the slowness that characterizes their rotations is also a brake to the process of biological evolution, because it provokes the existence of huge daily thermal amplitudes (because nights and days are both very long). Itís thought that a requisite for the existence of life on a planet is that its rotation lasts less than one week.

 

Gravity

A gravity equivalent to at least one half of the terrestrial gravity is important for retaining a minimally dense atmosphere, so that this one may perform a protective role against the lethal radiations and may assure the existence of a greenhouse effect that keeps the temperature of the planet at levels that are high and stable enough.

 

Orbital Eccentricity

Finally, itís obvious that a planet susceptible of hosting biological activity shall have a nearly circular orbit around its star, so that the seasonal differences of the temperature are not destructive.

 

 

Different Worlds

 

In what different types of planets could happen the existence of life?

 

Low Gravity

In a planet smaller than Earth and with a weaker gravity, the atmosphere would be thinner and dryer, being the greenhouse effect less efficient there. For that reason, the temperatures would vary more strongly between day and night. As the living creatures would weigh less in such a planet, they could grow so much that they would reach very big dimensions when compared with the earthlings.

Just like in the dry regions of Earth, the animal and vegetable life on this hypothetical planet would have to create adaptation mechanisms to low humidity conditions, as the capability for storing water and a reduced body area exposed to evaporation. On Earthís deserts, the leaves of the plants (like the cactuses) assume the shape of spines and the skin properties of the dromedaries make the sweat very difficult.

 

Life on a low gravity planet (Adolf Schaller)

 

High Gravity

On a big planet, one with a stronger gravity than Earthís, the humidity and the density of the atmospheric air would be very high. Given the higher gravity of such planet, the living creatures inhabiting it would necessarily have to be smaller and more muscular, in order to be able to bear their own weight. The gravity would also make improbable the existence of flying animals. Because these organisms live in a so humid biosphere, most inhabitants are adapted to aquatic or swampy conditions. The planet will need to be farther away from its star than the Earth is from the Sun, so that the greenhouse effect caused by the thick atmosphere can be counterbalanced and, therefore, it can be avoided an evolution analogous to the one that occurred on Venus.

 

Life on a high gravity planet (Adolf Schaller)

 

Gas Giants

Itís possible that even in a gaseous planet, like Jupiter, some types of life forms can emerge. There is an intermediate layer in the atmosphere of Jupiter (below the freezing layers and above the scalding depths) that has thermal conditions similar to the ones that exist on Earth. Some of the ingredients essential to life (like the hydrocarbons or the water) are present in the atmosphere of this planet, as well as in the other giant planetsí atmospheres. Therefore, there is some hope that living organisms may eventually live there.

A possible inhabitant of such a planet would be a giant creature that floats as a balloon and that feeds from atmospheric organisms. Smaller animals, with limbs and capabilities for manipulating the environment, could live inside those giant creatures, fit into a symbiotic relationship (the giant creature would serve as a solid holder for the smaller creatures, while the latter would serve the giant by doing jobs inside and outside its body).

 

Life on a gaseous giant planet (Adolf Schaller)

 

 

Genetics and Intelligence

 

The living beings evolve, over the span of several million years, according to what the theorists call as natural selection. The genetic characters, transmitted between succeeding generations through the DNA, explain why are we so similar to what our ancestors were millions of years ago or to what are the inhabitants living is so distant places as Australia (aborigines), Kalahari Desert (khoisan), Peru (amerindians), Japan or Scandinavia: because we share the same genetic inheritance.

 

The double helix of DNA

 

Mutations

The genes are, nevertheless, subjected to casual mutations, so the genetic information of an individual may not be a perfect copy of the information inherited from his parents.

A lot of times, that may end up being negative for the new organism. On other occasions that can be positive for the organisms, providing it some adaptation and/or environmental manipulation capabilities that are superior to their species matesí. They shall have more chances of surviving and living long enough so that they can transmit that new information to a larger number of descendants. As time goes by, these new organisms will end up becoming more numerous and shall be subjected to subsequent mutations that, like the first one, will drive to the improvement of the species. On the contrary, the least adapted species will end up perishing while facing their competitors or predators. To this process is given the name of natural selection.

 

Intelligence

The intelligence is an important characteristic in the self-preservation of an animal. It is, therefore, a key factor in the natural selection of species. The most intelligent creatures have a better capability for thinking about how to avoid or turn the problems around and how to be successful about getting the next meal. That means that the creatures with larger brains tend to survive more easily and tend to dominate the creatures endowed with smaller brains. On Earth, they were the increasingly more intelligent animals those who dominated the environment across the eras: the invertebrates first (specially the arthropods), the fish and the reptiles, then the dinosaurs, the mammals and, finally, the humans.

Life on land, more strongly than life in the sea, may favour the development of the intelligence. The obtainance of food on land demands higher skills than its obtainance in the sea and the climatic variations are more strongly felt on land, which requires higher adaptation capacities.

Besides living on dry land, an animal with an intelligence similar to the humanís will, probably, have an aspect similar to ours. This is called convergent evolution, which is a phenomenon that is, namely, responsible for the similar physical shapes of animals that are genetically very different (like the dolphins and the fish). That happens for the simple fact that they live in the same kind of environment (the water). A humanoid shape brings advantages for the creatures that invest on intelligence, because it sets free the front limbs (arms and hands) for the manipulation and construction of tools and, therefore, for the development of a civilization. Itís also thought that if the head was placed in any space other than above the neck, the body versatility would be inferior to a humanoid creatureís. Itís possible that if the dinosaurs had never become extinct by the catastrophe that occurred 64,7 million years ago, the most intelligent creature on Earth today would be a human-shaped reptile.

 

The Intelligent ET

A civilized alien, no matter how exotic its mind may be revealed, shall share with the humans the following capacities:

1.      Capacity to subdivide complex problems into simple problems;

2.      Capacity to describe a reality or an object based on parts and relations, to perceive and explain the change (cause-effect);

3.      Capacity to accumulate experience about similar problems (memory);

4.      Capacity to employ efficiently the scarce brain resources (economy);

5.      Capacity to organize the work before taking care of the details (planning);

6.      Capacity to solve the problems with the objective of improving its own welfare.

 

The Intelligence on Earth

Although they are not endowed with the intellectual capacities of the human being, animals like the dolphins (which belong to the family of the cetaceans that also includes the whales) seem to have ideas, ethical codes and complex languages, among other brain capabilities. Others, like the chimpanzees, are able to use tools in order to reach their goals (but they are not able to produce them), and they are also able to communicate through gesture language and to discover solutions for complex problems. Itís known the experience where a chimpanzee is faced with the defiance of reaching a banana hanging from the ceiling and, to attain that goal, he piles up a set of boxes, building a tower and climbing to its top.

Dolphins and chimpanzees are, like the humans, endowed with a rational brain, called neo-cortex, responsible for the creative abilities and abstract thinking. Like the superior mammals (which include the humans), all the other mammals and birds are endowed with a limbic system that commands the primary emotions (joy, grief, fear, aversion, surprise, anger), social emotions (love, hate, etc), the feelings resulting from those emotions, as well as some functions related with memory and the stability of the basic conditions of the body. This part of the brain was possibly developed more than 200 million years ago (at the time when the first mammals were emerging).

Because the emotions and the memory are concepts closely related with the emergence of the consciousness, we can tell that it essentially exists in mammals and birds. Itís not very developed in most of these animals (reduced to the core consciousness, centred in the perception of oneís own organism and in the instant moment) and is more developed on superior mammals and birds (which also possess an extended consciousness, able to perceive the involving environment in a past-future perspective). The core consciousness is aimed to favour the attention concerning to determined "objects" (lacto-sensu) that establish relations with the organism, while the extended consciousness is a pre-requisite for the intelligence, which seems to deny the idea that there is some kind of ďintelligenceĒ of the bees, as determined behaviours described ahead could suggest. Itís thought that the consciousness has emerged as a form of manipulation of the images (visual, sound and other) caught by the external and internal senses of the organisms, aiming the forecast and the planning of the actions concerning to an ultimate objective, which would be a trump card for the survival of the conscious creature.

Besides birds and mammals, the reptiles are also endowed with a more primitive component of the brain, called reptilian brain or brain stem, which is responsible for the auto-preservation mechanisms (like retraction) and aggressiveness. The emotions involved on these mechanisms are background emotions (some movements and facial expressions) and not primary or social emotions like love, grief or fear in its strict definition. The brain stem manages the basic biological stability of the body and the basic life support systems, e.g. breathing, heart rate, blood pressure, temperature and sensing of other animals (preys or predators). So, it includes mechanisms that instigate the physical reactions against external tensions.

 

Bodies with Intelligence

On Earth, the most advanced class of animals concerning to intelligence and environmental manipulation are the mammals. However, in other planets where the environmental conditions were different, we could find another type of dominant animals.

In an entirely aquatic planet, the dominating species could be an animal similar to an octopus, which is a cephalopod mollusk, unfurnished of any internal or external skeleton and very agile in the aquatic environment, where it moves using its tentacles or expelling water jets. The development of the intelligence could be, in such species, strongly favoured by the capacity to manipulate the environment, which is granted by the tentacles, just as the progress of the human intelligence was favoured by the bipedism (locomotion on two feet) and liberation of the hands.

 

Cephalopod mollusk (James B. Wood)

 

On the other hand, in hot planets, with a constant temperature (with a so quick rotation that it prevents big daily thermal amplitudes), the reptiles of the actual kind (cold blood vertebrates, unfurnished of hair or feathers) may keep being the dominant animals. The Earth, which is a planet with a relatively slow rotation (cold nights, hot days), is a hostile body for the domination of the reptiles of the actual kind (although many scientists advocate that the dinosaurs, which were also reptiles, were warm blood animals). This kind of animals is condemned to a slow existence, in such an environment.

 

The reptile that could dominate on Earth, today, in the case that the dinosaurs had never become extinct (Dale Russell)

 

On a planet where the land or marine food supply is scarce, the insects or other arthropods (invertebrates endowed with a segmented external skeleton) will tend to become the most intelligent animals. That will happen because the insects can eat any kind of conceivable food and they can live in almost all kinds of environments. Therefore, on a planet that would end up going through a situation of catastrophic scarceness, this group of animals (the most adaptable to the most adverse conditions) would end up assuming the dominating role.

 

The intelligent arthropod (ZetaTalk)

 

 

The Senses

 

How can we imagine the way an alien feels the surrounding environment? What senses does he use, how he does it and with which objectives? Maybe we can find part of the answer in the terrestrial organisms. However, maybe we can go farther than that and try to guess perceptions that are not found in any creature of this planet. Letís do a brief characterization of the known or hypothetical senses that a living creature, terrestrial or not, may or might eventually have in order to be able to manipulate the world.

 

Vision

The vision is the sense through which light patterns are caught and interpreted.

The fact that an animal is endowed with at least two minimally spaced eyes is an advantage, because it provides it with a stereoscopic vision, able to resolve distances and to create, this way, a tri-dimensional image. It provides the predators with the capability for detecting the distance at which they are from their preys and, following that, with the capacity to plan their hunting strategies.

For a complete visual field, useful for the animals that constantly need to have precautions against a predator that may appear from any direction, itís necessary a much larger interval between the eyes (in opposite sides of the head). However, this placement of the eyes leads the animal to lose a great deal of the stereoscopic effect, unless the animal has an even higher quantity of eyes.

For a night vision itís vital to have eyes furnished with large pupils, able to catch bigger quantities of light. A night vision may also be helped by a layer of reflecting cells, that can re-direct the non absorbed light in such a way that it gets a second chance for being caught by the eye (as it happens in the case of the cats).

For a vision focused in a vertical plane or in a horizontal plane (as in an eastern African savanna), itís important that the pupils assume the shape of thin gaps, oriented in the direction in which the animal wants to focus the image.

An animal may also have the need to see colours that are undetectable by the humans, like the ultraviolets (which bees use to detect the nectar of a flower) or the infrareds (which some snakes use to detect the heat emanated by their preys). One possible (but not existent on Earth) vision of microwaves radiation would be useful on a planet enshrouded in a thick and foggy atmosphere.

There are on Earth birds of prey with a visual resolution capacity much higher than the humansí, giving them the capability for detecting preys from a very big distance. The birds also tend to distinguish the colours in a more accurate way than the other animals, because they have eyes containing photo-sensible pigments that react according to the colour that is caught.

A less advanced form of vision than the humanís is, for instance, the vision of the insects, which possess multiple eyes that provide them with low-resolution images, similar to mosaic photos. Itís, nevertheless, a form that gives them a refined capability for detecting movement. Even less advanced is the vision of determined animals that can barely distinguish anything else than variations between light and darkness.

 

The eyes in the animal kingdom (Lani Hardage, Christopher Tyler)

 

 

Mechanical Senses

The mechanical senses are responsible for the detection of tensions, pressures and their variations (waves and vibrations) in the environment.

 

Hearing

The hearing is the most developed mechanical sense in most vertebrates, being characterized by the detection of aerial or aquatic vibrations. Like the vision, the audition of determined animals may also reach more advanced levels than the human audition.

The existence of an ear is an advantage, because it allows focusing the vibrations (sounds) in the channel that leads to the eardrums, or in other words, to the organ that amplifies and transmits them to the brain.

The existence of a pair of ears is also a factor for the success, because it allows detecting where the sounds are coming from (stereophony). This capability results from the analysis that the brain does about the time interval that exists between the arrival of a sound to the left ear and to the right ear.

The bats are specialized on the detection of ultra-sonic frequencies (high frequency sounds), transforming the ears in sonar instruments specialized on the detection of the echoes of the sounds that they emit themselves. That provides them with the capacity to perceive the presence of the preys and objects in dark environments, just as a radar does. Other animals that use the sonar are the dolphins. Itís also possible that an animal specializes its hearing on the act of captivating specific frequencies.

The hearing organs arenít always located at the head. There are insects whose ears are placed in different parts of the body, like the abdomen (grasshoppers) or the front legs (crickets).

Hearing organs that are less advanced than the humansí are, for instance, the simple openings (without ears) leading to the eardrums or, instead, surface membranes or thin hair that vibrate with the flowing of the sound waves. The simplest hearing organ that can be conceived is a primitive structure composed by nerves that are sensitive to the waves proceeding from nearby sounds.

 

Touch

The touch is, like the hearing, a mechanical sense. Itís the only human sense that uses all the bodyís surface as a sense organ, but it can be felt more intensely in specific zones like the hands (humans), the antennas (insects) or sensitive hair (catsí moustaches).

 

Chemical Senses

On the other hand, the smell and the taste are senses that represent the reaction to purely chemical stimulus.

 

Taste

The taste can be found in parts of the body other than the tongue and the smell in parts other than the nose. In many insects, the smell receptors are lodged in the antennas or in mouth prominences.

 

Smell

The moths are among the animals that possess a more accurate sense of smell, which in their specific case has the purpose of detecting the pheromones exhaled by the females. When the males receive them, they fly in the direction of the source with the purpose of coupling. The smell can also be useful for detecting preys, as in the case of the sharks that, this way, catch the smell of blood of the wounded and vulnerable animals.

 

The Two Faces of the Same Coin

The taste frequently acts together with the smell and can be locates in places like trunks or external prominences able to detect the flavour of a meal, even without touching it. Therefore, we can consider the taste as an eventual substitute of the smell. In insects, for instance, this sense exists in organs located in the legs or in the tentacles.

 

Exotic Senses - Detection of Magnetic Fields

A sense that the humans donít have, but that some terrestrial animals like insects, fish and birds use to navigate and to orient themselves (particularly during migration periods), is the detection of magnetic fields (namely, the magnetic poles). In planets with stronger magnetic fields than Earthís, this sense may assume a much higher importance than it does on Earth.

 

Pain

The sense of pain, with a nature that is not exclusively external like the ones previously mentioned, is also a reaction of the nervous system against external or internal pressures. The sensation of pain proceeds from the modified neurons that react to determined substances by emitting electric stimulus.

The ability to feel pain (including the psychological pain, as the anxiety) is an important aid concerning to the survival chances of a living creature, because it leads them to avoid the sources that provoke physical damage on them.

It exists in the superior animals, particularly among the vertebrates and the cephalopod mollusks, but quite doubtfully in animals with a less developed nervous system, like the insects (which miss a system of fibres sensitive to pain analogous to the vertebratesí).

 

Temperature

The sense of the temperature works also through receptors similar to the ones mentioned just above and reacts in a similar way to the neurons that are responsible for the pain. In the cold blood animals like the reptiles (unable to control internally the body temperature) this sense has a particularly important role.

Contrarily to the sense of pain, it is a largely disseminated sense in the animal kingdom, from the most primitive evolution stages.

 

 

Communication

 

The animals can communicate through colours, shapes, movements, smell, touch stimulus and sounds (prevalent among the humans). The signals can be exchanged between two or more individuals of the same species or, more rarely, between individuals of different species.

 

Chemical Communication

The chemical signals, caught by the smell or the taste, are the most ancient and primitive in the animal kingdom. Particularly relevant are the already mentioned pheromones, secreted by some animals to communicate with an eventual receptor of the opposite sex and to awake on them the sexual appetite.

Beyond the attractive signals, there are also tranquillizing signals (for instance, for the purpose of mutual identification of the members of the same community), repelling (which are used to establish limits in what concerns to competitors) and dissuasive (like the ones used by the wounded animals in order to warn their mates about the danger).

 

Visual Communication

The colourations induced by the nervous impulses were essentially developed among the cephalopod mollusks. The emotive state of these animals is transmitted through variations in the skin colour, revealing states of fear, anger or sexual excitement.

Itís possible that some fish, like the candlefish, use their capacities to emit light (from a luminescent organ under each eye) in order to communicate with their speciesí partners.

 

The candlefish, with bioluminescent organs in the head and the body

 

Examples of shapes and movements used for communication purposes are the erection of the feathers (birds), hair (mammals) or extremities (spiders and crabs), inflation of air bags (ballfish), etc. The body expansion reveals the intention to frighten, while its reduction reveals submission. Some birds can display colourful and exuberant plumage, like the peacock that opens its iridescent tail into the shape of a fan, waving and showing it to its potential sexual partners, with the purpose to attract them.

The face and handsí expressions are extensively used by the hominoid primates. The gestures (handsí expressions) are nowadays the base of the deaf humansí language, which is also used to each other hominoids.

Another interesting case is the one about the bees that use a movement (a dance) to communicate to their mates whatís the direction of a food source. Itís remarkable that this form of communication seems to suggest the existence of intelligence in a so primitive organism, as is this insect Ė the bees appear to be able to learn: in one experience a food source was moved every day to a place located at a fixed distance from the previous location. After some time, the bees were already able to fly to the extrapolated direction, instead of flying to the direction where they had found the food during the previous flight.

 

Touch Communication

The touch communication is essentially reserved for the intimate individual relations. They may have the meaning of an appeal (as the child that calls the mother), excitement (in sexual intercourse) or tranquillization.

 

Sound Communication

The most simple sound communication is used by the arthropods (particularly, the insects), that rub structures of the external skeleton in order to produce sounds. Two examples are the crickets and the grasshoppers.

On the other hand, the vertebrates produce sounds through membranes that vibrate with the airflows (as the vocal chords). The sound communication is far less developed among fish and only slightly more among the amphibians (the coaking of the frogs) and the reptiles (whistles, puffs and snores emitted during the period of sexual excitement).

The birds dominate much better the sound communication, emitting their chirps from the internal larynx, located in the lower end of the tracheas (close to the lungs). On the other hand, the mammals emit the sounds from the external larynx, using the air that flows from the interior and that provokes the vibration of the vocal chords. They modulate the sounds in the oral-pharyngeal cavity (in the region of the mouth) and some, like the humans, use their tongues.

On the other hand, the dolphins are even more advanced than the humans over one aspect: since both nasal cavities function as two independent sound organs, they can keep two completely separate conversations at the same time.

 

 

Bizarre Creatures

 

What kind of strange characteristics may we find in an alien species?

 

Number of Sexes

Itís possible that they are hermaphrodites (each individual possesses both sexes, at the same time) or that they can change sex across their lifes, as it happens in some species of fish. There may be more than two sexes, although only two are relevant for procreation, as it happens among some social insects.

 

Psychological Time

They could have a notion of the time flow different from ours, like the insects or other small sized animals that, given their capability for processing fast the images that are transmitted by the eyes, observe the world in a slow motion. The opposite happens with the biggest animals (like the elephants) or with those that are armoured well enough to protect themselves against the natural hazards (like the turtles or the gastropod mollusks). Among the terrestrial animals, the time perception is essentially determined by the temperature of the body and by the adrenalin and the heart activity. The first one conditions the time perception in a direct or inverse relation, so that the animal may inclusively enter a lethargic state (during which that perception is much shortened) when the temperature is excessively low or high. The production of adrenalin and the increase of the heart beat provoke a lengthening of the perceived time, which happens namely in situations when the survival of the organism is challenged, as it happens in the case of a hunt.

 

Brainsí Network

We could know minds connected in a network, like two or more computers. The idea of monitoring the totality of the human brain is already ventured by some scientists. The biggest difficulties about the materialization of that idea are the huge complexity and dimension that characterize this organ. Between monitoring the brain and connecting it to a network there will be only a small step. The dreams, the thoughts, the knowledge, the feelings, all of them could be accurately transmitted among two different brains.

 

Electroencephalography: computerized monitoring of a human brain (BrainMaster)

 

Exotic Capacities

We could even find creatures with powers that we consider exotic (like the extra-sensorial perception or the psychokinesis) or other ones that not even the most advanced imagination can conceive. They may reveal to us completely new ethical patterns as well as new civilization goals or ways of thinking.

 

Conclusion

All the physical, psychological or social nature of the aliens that we may find in the future may be revealed to us as a complete surprise. Maybe even a still unchallenged conjecture may fall: can life be based in elements other than carbon?

 

 

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