History SoYouWantTo / CreateBelievableAliens

6th Nov '17 4:16:47 PM tracer
Is there an issue? Send a Message


Normally, when a single-celled organism (or its zygote) divides, the two daughter cells separate and go on their merry way. But in some circumstances, the daughter cells can stay clumped together -- and sometimes, banding together with your siblings gives you advantages over all the loner organisms out there. Eventually, the group sticking together could evolve so that it ''always'' sticks together, and then the members of that cellular colony have a golden opportunity: They can ''specialize'', so that (for example) a few cells become gametes while others stay "normal" for their entire lifetime. In such a case, where most cells never become gametes, the colony is similar to a beehive: A few reproducing organisms (queens/drones) supported by a non-reproductive mass of organisms with the same genome (workers). Ever-greater cell specialization is possible from this point on, so long as the colony sticks together. The colony can even move and act as a unit, assumining intercellular communication is possible. At that point, the colony has become a ''multicellular organism.'' More than a dozen times in the history of life on Earth, in both eukaryotes and prokaryotes, multicallularity has evolved; even fossilized cyanobacteria shows some evidence of multicellular organization. [[http://www.youtube.com/watch?v=JVqxyYBuI_U This video]] discusses probable ways that it might have evolved.

to:

Normally, when a single-celled organism (or its zygote) divides, the two daughter cells separate and go on their merry way. But in some circumstances, the daughter cells can stay clumped together -- and sometimes, banding together with your siblings gives you advantages over all the loner organisms out there. Eventually, the group sticking together could evolve so that it ''always'' sticks together, and then the members of that cellular colony have a golden opportunity: They can ''specialize'', so that (for example) a few cells become gametes while others stay "normal" for their entire lifetime. In such a case, where most cells never become gametes, the colony is similar to a beehive: A few reproducing organisms (queens/drones) supported by a non-reproductive mass of organisms with the same genome (workers). Ever-greater cell specialization is possible from this point on, so long as the colony sticks together. The colony can even move and act as a unit, assumining intercellular communication is possible. At that point, the colony has become a ''multicellular organism.'' More than a dozen times in the history of life on Earth, in both eukaryotes and prokaryotes, multicallularity multicellularity has evolved; even fossilized cyanobacteria shows some evidence of multicellular organization. [[http://www.youtube.com/watch?v=JVqxyYBuI_U This video]] discusses probable ways that it might have evolved.
6th Nov '17 3:47:11 PM tracer
Is there an issue? Send a Message

Added DiffLines:

Or rather, several disasters all struck at the same time. Land masses slowly drifted together to form the supercontinent of Pangaea, squeezing out oceans that used to harbor life between them. Volcanic activity caused devastating global warming, and exposed underground coal beds which caught fire and caused more global warming; and all this warming melted the frozen methane hydrate under the oceans, which caused even ''more'' global warming. Oxygen levels fell, and hydrogen sulfide levels soared. A giant asteroid may have struck the earth too. With all these catastrophes adding together, 96% of marine species and 70% of land vertebrates vanished. Over half the Earth's taxonomic ''families'' went extinct. This event, known as the Permian-Triassic Mass Extinction, is the worst mass extinction that still survives in the fossil record.

As a result of the Permian mass extinction, the modern-mammal-like domination of the therapsids evaporated. But what if the Permian mass extinction hadn't happened, or had been milder? We still to this day might be living in a world dominated not by furry mammals, but by scaly-skinned warm-blooded lizardlike therapsids.
29th Oct '17 1:07:27 PM Leefan
Is there an issue? Send a Message


You can't make tools without something you can use for "hands". An elephant's trunk, an octopus's tentacles, a monkey's prehensile tail, a dogs's mouth, or even a bird's beak can be used to pick things up, but performing fine work requires either fingers or tools that you can shape to use like fingers.

to:

You can't make tools without something you can use for "hands". An elephant's trunk, an octopus's tentacles, a monkey's prehensile tail, a dogs's dog's mouth, or even a bird's beak can be used to pick things up, but performing fine work requires either fingers or tools that you can shape to use like fingers.
8th Oct '17 9:09:32 PM PaulA
Is there an issue? Send a Message


Perhaps a species of herbivores, such as Creator/LarryNiven's Puppeteers, would be motivated to see what's over the horizon by a simple desire to ensure the safety of the herd -- if they discovered a leopard, they could prepare for it and thus decrease their odds of getting eaten. Or perhaps the grass that the Puppeteers graze on (or whatever ground-covering organism passes for grass on their planet) only grows in random patches that last a few weeks, so they have to find the next grass patch or starve to death.

to:

Perhaps a species of herbivores, such as Creator/LarryNiven's Puppeteers, [[Literature/KnownSpace Puppeteers]], would be motivated to see what's over the horizon by a simple desire to ensure the safety of the herd -- if they discovered a leopard, they could prepare for it and thus decrease their odds of getting eaten. Or perhaps the grass that the Puppeteers graze on (or whatever ground-covering organism passes for grass on their planet) only grows in random patches that last a few weeks, so they have to find the next grass patch or starve to death.
27th Jun '17 5:16:09 PM nombretomado
Is there an issue? Send a Message


Of course, you can't respond to a stimulus unless you can ''detect'' that stimulus, hence the evolution of senses. Of great benefit was the sense of sight. Vision evolved independently no less than ''sixty-four different times'' within different animal classes. The first "eyes" were nothing more than a light-sentitive patch of skin, attached to a nerve that sent different signals depending on how much light was received. Just the ability to detect the difference between being in light and darkness had a huge survival advantage; if the lights suddenly went out, it likely meant that a predator was casting its shadow on you, and by running in a random direction you might be able to escape. TheOtherWiki has an article on [[http://en.wikipedia.org/wiki/Evolution_of_the_eye the evolution of the eye]]. What's important to note is the ''convergence'' of eye evolution in different species. Human and octopus eyes, for example, evolved totally independently of one another, yet their similarity in structure is striking -- in some ways, an octopus eye is ''better'' than a human eye, in that there are no blood vessels cluttering the area in front of the octopus's retina. Many insects have "compound eyes", which are basically a retina turned inside-out -- each facet on a fly's eye can see only one "pixel" of the world around it, and it assembles a vague, low-resolution picture of its surroundings from these pixels.

to:

Of course, you can't respond to a stimulus unless you can ''detect'' that stimulus, hence the evolution of senses. Of great benefit was the sense of sight. Vision evolved independently no less than ''sixty-four different times'' within different animal classes. The first "eyes" were nothing more than a light-sentitive light-sensitive patch of skin, attached to a nerve that sent different signals depending on how much light was received. Just the ability to detect the difference between being in light and darkness had a huge survival advantage; if the lights suddenly went out, it likely meant that a predator was casting its shadow on you, and by running in a random direction you might be able to escape. TheOtherWiki Wiki/TheOtherWiki has an article on [[http://en.wikipedia.org/wiki/Evolution_of_the_eye the evolution of the eye]]. What's important to note is the ''convergence'' of eye evolution in different species. Human and octopus eyes, for example, evolved totally independently of one another, yet their similarity in structure is striking -- in some ways, an octopus eye is ''better'' than a human eye, in that there are no blood vessels cluttering the area in front of the octopus's retina. Many insects have "compound eyes", which are basically a retina turned inside-out -- each facet on a fly's eye can see only one "pixel" of the world around it, and it assembles a vague, low-resolution picture of its surroundings from these pixels.
25th Oct '16 7:04:11 PM nombretomado
Is there an issue? Send a Message


This is not an easy task. GeorgeRRMartin said as much in his 1976 essay "First, Sew On a Tentacle (Recipes for Believable Aliens)". Your alien species will come from a world with its own evolutionary history, its own flora and fauna -- if distinctions like "flora" and "fauna" even make sense in that world's biosphere -- and must occupy some evolutionary niche on that world, or by all rights it shouldn't exist at all.


to:

This is not an easy task. GeorgeRRMartin Creator/GeorgeRRMartin said as much in his 1976 essay "First, Sew On a Tentacle (Recipes for Believable Aliens)". Your alien species will come from a world with its own evolutionary history, its own flora and fauna -- if distinctions like "flora" and "fauna" even make sense in that world's biosphere -- and must occupy some evolutionary niche on that world, or by all rights it shouldn't exist at all.

18th Jun '16 5:47:23 PM evanator66
Is there an issue? Send a Message


Of course, distinctions like "warm blooded" or "cold blooded", and "herbivore" or "carnivore", are ''terrestrial'' ones. The alien biosphere might not have the sharp dichotomy between plants and animals that exists on Earth -- it may have mobile creatures with central nervous systems like animals, who subsist on photosynthesis (and a bit of decaying dead organic matter) like plants. But however they live, there must be ''something'' in their basic survival psychology that pushes them to explore, or they're never going to build space ships in the first place.

to:

Of course, distinctions like "warm blooded" or "cold blooded", and "herbivore" or "carnivore", are ''terrestrial'' ones. The alien biosphere might not have the sharp dichotomy between plants and animals that exists on Earth -- it may have mobile creatures with central nervous systems like animals, who subsist on photosynthesis (and a bit of decaying dead organic matter) like plants. But however they live, there must be ''something'' in their basic survival psychology that pushes them to explore, or they're never going to build space ships in the first place.place.

Once you've got the basics of your species' psychology figured out, consider checking out SoYouWantTo/DesignAnAlienMind to flesh out the rest of the thought processes of your new aliens.
10th May '16 12:21:41 PM hillo315
Is there an issue? Send a Message


But the genetic code we have today -- a mapping of 64 different nucleotide combinations to 20 different amino acids -- is not universal to all life forms on Earth. The mitochondria inside your cells, for example, have their own DNA and replicate themselves according to their own drummer, but their genetic code is slightly different from the genetic code in your cell nuclei. It's ''mostly'' the same, but not ''entirely'' the same. An RNA/DNA using organism that evolved on another planet could --and, indeed, almost certainly ''would'' -- have an entirely different genetic code. Maybe they only make use of 16 amino acids, not 20, and get away with having codons that are only 2 nucleotides long instead of 3. Maybe they don't use amino acids to build their bodies but something else, and that something else has 10,000 variants instead of 20; if they use 4-nucleodite RNA/DNA like we do, each codon would have to be at least 14 nucleotides long.

to:

But the genetic code we have today -- a mapping of 64 different nucleotide combinations to 20 different amino acids -- is not universal to all life forms on Earth. The mitochondria inside your cells, for example, have their own DNA and replicate themselves according to their own drummer, but their genetic code is slightly different from the genetic code in your cell nuclei. It's ''mostly'' the same, but not ''entirely'' the same. An RNA/DNA using organism that evolved on another planet could --and, indeed, almost certainly ''would'' -- have an entirely different genetic code. Maybe they only make use of 16 amino acids, not 20, and get away with having codons that are only 2 nucleotides long instead of 3. Maybe they don't use amino acids to build their bodies but something else, and that something else has 10,000 variants instead of 20; if they use 4-nucleodite 4-nucleotide RNA/DNA like we do, each codon would have to be at least 14 nucleotides long.



Of course, distinctions like "warm blooded" or "cold blooded", and "herbivore" or "carnivore", are ''terrestrial'' ones. The alien biosphere might not have the sharp dichotomy between plants and animals that exists on Earth -- it may have mobile creatures with central nervous systems like animals, who subsist on photosynthesis (and a bit of decaying dead organic matter) like plants. But however they live, there must be ''something'' in their basic survival psychology that pushes them to explore, or they're never going to build space ships in the first place.

to:

Of course, distinctions like "warm blooded" or "cold blooded", and "herbivore" or "carnivore", are ''terrestrial'' ones. The alien biosphere might not have the sharp dichotomy between plants and animals that exists on Earth -- it may have mobile creatures with central nervous systems like animals, who subsist on photosynthesis (and a bit of decaying dead organic matter) like plants. But however they live, there must be ''something'' in their basic survival psychology that pushes them to explore, or they're never going to build space ships in the first place.
20th Nov '14 2:51:31 PM tracer
Is there an issue? Send a Message


But pretty soon, one sub-group of the mammals, called the therapsids, hit upon another strategy for thermal regulation. They produced extra heat ''inside their own bodies'' via chemical reactions. The glucose respiration their cells relied upon for energy also gave off some heat, so by "burning" extra glucose they could keep themselves warm even when the environment got cold. We call it ''endothermy'' (not to be confused with an endothermic chemical reaction, which is a reaction that absorbs heat rather than giving it off; animal endothermy requires exothermic chemical reactions). Endothermy allowed them to keep active on cold nights, when other animals could barely move, and to survive in colder climates.

to:

But pretty soon, one sub-group of the mammals, reptiles, called the therapsids, hit upon another strategy for thermal regulation. They produced extra heat ''inside their own bodies'' via chemical reactions. The glucose respiration their cells relied upon for energy also gave off some heat, so by "burning" extra glucose they could keep themselves warm even when the environment got cold. We call it ''endothermy'' (not to be confused with an endothermic chemical reaction, which is a reaction that absorbs heat rather than giving it off; animal endothermy requires exothermic chemical reactions). Endothermy allowed them to keep active on cold nights, when other animals could barely move, and to survive in colder climates.
19th Nov '14 7:13:31 PM tracer
Is there an issue? Send a Message

Added DiffLines:

By the end of the Paleozoic era, therapsids had diversified until they filled nearly the same ecological niches as the mammals of today. There were great grazing herds that roamed the grasslands, there were predators who fed on the grazing herds, there were tree-dwelling arboreals, there were coastal swimmers; nearly every niche filled by a mammal today had an analog among the therapsids. An alien visitor would find little difference between Earth at the end of the paleozoic and Earth in the modern era.

And then, disaster struck.
This list shows the last 10 events of 45. Show all.
http://tvtropes.org/pmwiki/article_history.php?article=SoYouWantTo.CreateBelievableAliens