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How probable is it that life on earth like worlds just look like weird animals? What else could life look like?
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Life on Earth literally looks like a double-helix that creates vehicles for itself to travel in.
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>>13888281
the laws of the universe are universal so some degree of convergence in the physiology and chemistry of alien life will be inevitable. How big of a factor this convergence will be we can not say as the sample data we have for what life on earth like planets looks like is limited to just 1 planet.
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>>13888281
A lot of life on earth doesn't look like animals, anon. Even some of the animals don't really look much like animals.
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>>13888361
We can see that divergent branches evolved exterior apearances that are practicly identical - consider the forest in America, Africa and Australasia are not related in any way, but the whole ecosystems are near identical. Crabs evolved many times. Auks and penguins were extremely alike.Some stumbling blocks can happen, but those may not be the usuallyassumed ones, those like water land transition happened multiple times, at least for plants and animals and back with dolphins. In fact it could have been even more: bony fish may be the result of some organism going back into water, other non vertebrates may have crossed separately.

The life on other planets may be pretty alike, if not necessarily alike biochemically. But even that isn't necessarily the case, and the configuration we see may be the one that works. All life could be as alike that we wouldn't be able to notice an alien species doesn't come from Earth.
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>>13888943
Your general point about convergent evolution isn't wrong, but your specific examples are not very good. Rainforests on different continents are not made up of completely unrelated trees. The species are different because the continents separated millions of years ago, but there are plenty of trees from the same families on every continent. They share common ancestors which were trees in rainforests. They didn't evolve convergently from separate beginnings.
Crabs did not evolve repeatedly. Unless you're thinking horseshoe crabs, which are nothing like crabs, really
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>>13889070
There are several lineages that resulted in "crabs".
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>>13889555
Brachyura and Anomura are probably sister groups, which makes crabs all one lineage with a few divergent members.
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>>13889585
He's referring to the crab bodyplan
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>>13889585
The last common ancestor is several hundred million years in the past, if I remember correctly.
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>>13888281
i'd imagine convergent evolution would be pretty common. certain forms are probably universally selected. a few oddities would probably happen because of sexual selection but that's about it.
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>>13888281
Snaiad is pretty cool
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itt: brainlets prove themselves incapable of imagining anything that they haven't already been shown in the past
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>>13888281
If there are cells theres bound to be clumps of cells. The earliest animals are sponges, a mass of cells that can move around the body and change function, and they are mixed in with random bacteria spread around their cells.
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IMAGINE ALIENS LOOKED LIKE DEAD PEOPLE AHAHAHAHA
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>>13888361
Our world relies on photosynthesis. Rhodopsin is an alternative, and indeed we have the "Purple Earth" theory. In a world that remained purple, things would probably have turned out differently.

Similarly a world without light such as some of our icy moons, will also most likely be very different.
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>>13888287
I wonder if you could make some kind of topological argument that spherical organisms are less evolved than toroidal organisms.

It would mean a more evolved organism is less adaptable to its local environment. Fuck.
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>>13890360
world without light=dead
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>>13890628
That is not given. Are you not aware of the hot sources at the bottom of the oceans?
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>>13892102
Cool so you have hydrothermal vents powered by residual big bang heat and decaying nuclear decay. Many bacteria and 3D cell clumps lifeforms can thrive in such rich environments.
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There's a sea of gasoline on Titan the size of lake superior. It rains gasoline on Titan from gasoline clouds. Would it be possible for a life form to evolve in a world of silicate rocks and gasoline solvents instead of water? If so what would it look like?

>>According to Cassini data from 2008, Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth. These hydrocarbons rain from the sky and collect in vast deposits that form lakes and dunes.[1] "Titan is just covered in carbon-bearing material—it's a giant factory of organic chemicals", said Ralph Lorenz, who leads the study of Titan based on radar data from Cassini. "This vast carbon inventory is an important window into the geology and climate history of Titan." Several hundred lakes and seas have been observed, with several dozen estimated to contain more hydrocarbon liquid than Earth's oil and gas reserves. The dark dunes that run along the equator contain a volume of organics several hundred times larger than Earth's coal reserves.

I could see life forms at the level of diatoms or some kind of creature analogous to bacteria in that environment.
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fuck wrong picrel.
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>>13892323
It's too cold there.
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https://futurism.com/scientists-show-methane-based-life-possible-on-titan-saturns-moon-heres-what-it-would-look-like

A new type of methane-based, oxygen-free life form that can metabolize and reproduce similar to life on Earth has been modeled by a team of Cornell University researchers.

Taking a simultaneously imaginative and rigidly scientific view, chemical engineers and astronomers offer a template for life that could thrive in a harsh, cold world – specifically Titan, the giant moon of Saturn. A planetary body awash with seas not of water, but of liquid methane, Titan could harbor methane-based, oxygen-free cells.

Their theorized cell membrane, composed of small organic nitrogen compounds and capable of functioning in liquid methane temperatures of 292 degrees below zero, is published in Science Advances, Feb. 27. The work is led by chemical molecular dynamics expert Paulette Clancy and first author James Stevenson, a graduate student in chemical engineering. The paper’s co-author is Jonathan Lunine, director for Cornell’s Center for Radiophysics and Space Research.
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https://www.science.org/doi/10.1126/sciadv.1400067

Abstract
The lipid bilayer membrane, which is the foundation of life on Earth, is not viable outside of biology based on liquid water. This fact has caused astronomers who seek conditions suitable for life to search for exoplanets within the “habitable zone,” the narrow band in which liquid water can exist. However, can cell membranes be created and function at temperatures far below those at which water is a liquid? We take a step toward answering this question by proposing a new type of membrane, composed of small organic nitrogen compounds, that is capable of forming and functioning in liquid methane at cryogenic temperatures. Using molecular simulations, we demonstrate that these membranes in cryogenic solvent have an elasticity equal to that of lipid bilayers in water at room temperature. As a proof of concept, we also demonstrate that stable cryogenic membranes could arise from compounds observed in the atmosphere of Saturn’s moon, Titan, known for the existence of seas of liquid methane on its surface.
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>>13892334
Reactions would be slow as treacle but that doesn't mean it would be impossible. Being close to the boiling point of hydrocarbons means it is not entirely impossible.
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Life on Earth, in particular vertebrates, have mirror symmetry. In a sub glacial water world, would there be a selection pressure for that, or would a three way symmetry be equally good?
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>>13889585
This is a fish evolving into a pseudoshrimp. It's armored and walks with spindly legs derived from its fins. Give it a few dozen million years, if it loses its tail, it will literally be a fish crab.
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>>13890628
All a world needs for life is a constant reliable source of energy and heat.
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>>13894292
So we can have an alien civilisation on Europa that worships hot radioactive meteorites. That could be quite the plot.
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>>13894419
I gotta HOT radioactive LUMP in me pants, alien babes.
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>>13889762
i share this sentiment. liquid water oceans will always have some sort of fish like or jellyfish like creature is my guess since being streamlined saves energy while moving. wings will work in other worlds with +/- 1 bar of gases. it heavily depends on the variables involved but there are certain rules that, if alien life also follows natural selection, should result in similar forms we already know, if the conditions are hospitable or even similar to ours.
but there are probably differences in symmetry, 5 appendices from starfish onward are likely just chance, could be more or less.
maybe it's similar even down to the most basic organic chemistry, reduction and oxidation reactions etc.





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