If there was an exact or near-exact copy of the planet Earth and there would also be similar large-scale events (like great volcano eruptions and meteor impacts), I assume the outcome would be surprisingly similar than what we see here on Earth. However, having intelligent species like humans might still not be 100% sure, because there obviously isn’t very high pressure towards intelligence in this kind of environment – after all we’re the only ones.

This being said, it is very unlikely that such a close copy of our planet exists, so I’d assume there might be hugely different outcomes. On most planets, I believe, the life forms would be far less complex due to higher number of planets that have much harsher environment than the Earth has. Of course, there might be also some much more pleasant places and they might have much more complex life forms, who knows 🙂

But at least our closest stars don’t seem to be swarming with high intelligence species, otherwise we would probably have spotted some kind of signal from them, either intentional or unintentional. Radio or such signals at least if nothing else. Although even the way to the nearest star after the Sun is pretty long…

it’s stochastic

First, the question is, whether they would use the same stuff like we do. The DNA, RNA, proteins. Will they have 4 bases or more/less? Will they have 20 amino acids? Will they have ours 20 amino acids? etc. etc. 😉

Goog point, JackBean. But if the rules of natural selection were the same (that whatever the blueprint is, it tries to multiply itself and the fittest ones keep reproducing most) then, in the end, this might not matter!

Although the Cephalotaceae and the Nepenthaceae are not closely related by typical standards, the fact is they are related and share most of their genome. That baggage from heredity and similar physical constaints mean there are only so many solutions to similar problems. An organsim that evolved on another planet would share no ancestry with any on this world. Only similar physical constraints (assuming a similar planet) would serve to produce some form of convergent evolution.

There are plenty of convergent evolution, but also of divergent one 😉

Hmmm. There certainly are plenty of examples of convergent evolution among mammals. Placental mammals and Marsupial mammals from Australia come to mind. However, the physical contraints involved in flight are indeed pretty demanding. There is only so much variation possible with the "design" of a vertebrate flying animal. In addition, terrestrial mammals fill a much wider number of ecological niches than birds do.

In most of these examples, the constraints on the convergence is other organisms (catching insects) or the basic starting structures (birds). If other different starting conditions are possible (is cellularity a necessity?), then it’s tough to know too much about eventual forms.

Yes, you would get things like streamlined swimmers, but we have fish and squid and amphipods, fairly different animals doing similar things. You could predict the existence of streamlined swimmers in an extraterrestrial world, but they wouldn’t necessarily look like fish. Some form of photosynthesis makes sense, which would make sort-of plants, but would convergence produce land plants like ours? Maybe superficially.

Exactly. On other planets, if there was life based on other chemicals, totally other conditions may be favorable for the life and thus the life forms will look differently 😉

that is true to some extent, but i think that even with a world made out of Si instead of C, the same principles of evolution would create creatures that might have some common features

to some extend… they will probably feed on something, divide, but I mean their appearence may be totally different 😉

it’s not certain for now but most likely yes!
I don’t know how I can explain that.I just believe”Somethings’s changing,something will be change..”

not necessarily. I mean think of it. It makes sense to concentrate things, for example control (nervous) organs, which will probably wind up in a sort of brain. brains evolved at least twice independently on earth. It makes sense to have a sort of lens organ (eye) that should be placed in the part that first meets the environment. Eyes have evolved at least 6 or 7 times on Earth. If you want to fly a wing-like organ will most likely be the solution, and wings have evolved 3 or 4 times on earth. Etc etc.

On the sacale of the Universe, with finite construction possibilites, it’s inevitable that biology is constructed on a planet with the same specifications of the Earth. Which is to say, that the emergence of biology is inevitable and exists through-out the Universe.

paradigm

1) why do you think, there are finite construction possibilities?
2) why should be the emergence of life inevitable? 😆

We don’t even know if life actually began on the Earth. Some people have suggested that it may have been carried here e.g. along a meteorite or such. Maybe the early Earth wasn’t suitable for the beginning of life after all, but instead some other place was?