Hi Gumboot,
I disagree. Even if the alien world was in fact Earth, the likelihood that another sapient species had matured here instead of us would not dictate that they would resemble us in any particular way. All it takes are relatively minor changes in DNA and the world and ecosystem, and vastly different species evolve and do better and worse. I mean we have everything from bacteria, to tube worms, to fish and birds and terrestrial animals. And when we look at what exists with sufficient brain power that it could one day develop true intelligence, we've got as well as the other hominids, dolphins, whales, and of all things, octopi.
And yet even though all those animals are equally as genetically evolved as us, none of them is even remotely close to "higher intelligence".
Simply put, while some animals display remarkable cognitive abilities (some of them achieving levels of intelligence comparable to young human children in limited areas), they lack the alignment of characteristics necessary to advance beyond this to the higher level of operation seen in humans.
The only way in which you could expect an alien sapient species to be like us, is in their intelligence. Other than that it's fairly much a lottery.
You have it backwards. Our intelligence came
last of all our physiological characteristics, and is a direct result of those characteristics, thus any animal achieving the same sort of intelligence is most likely going to also develop similar physiological characteristics
first.
I mean just consider if the world were slightly wetter, that dry land was a rarity, then the successful species would be more likely to be either amphibian, reptilian or icthian.
I refer you again to the goldilocks concept. The amount of water in the planet, and where it is located, is a fundamental requirement for the evolution of higher forms of life. Indeed, you don't have to go very far outside the earth model at all before a planet ceases to be life-supporting.
And why would any of them have two legs and two arms etc?
The quadrupedal structure is by far and away the most efficient for larger land-based animals. Less than four and you're sacrificing speed and stability, more than four and the extra limbs become a significant drain on resources at no significant extra benefit.
An elephant's nose or an insects mandibles could be just as easily adapted by evolution to make better use of tools etc.
Not really. Evolution doesn't work in a piecemeal way, taking features from random different animals and combining them together. If we take insect mandibles, to illustrate my point, these evolved from legs, but larger numbers of legs are only of benefit to very tiny animals, thus larger animals don't evolve mandibles. Smaller animals lack the size to evolve higher intelligence.
You've got to remember that for any physiological feature to evolve, it has to, at the
bare minimum, not
disadvantage the animal prior to the point where it evolves to becoming a significant advantage.
An elephant's trunk, as example, evolved as a direct result of them being herbivores, yet being predators was an essential part, again, of us developing advanced intelligence (the reason being you don't need to "out smart" a tree to survive).
And both avian and aquatic species would have some serious advantages over us in terms of the mental conceptions of the world. I.e. true three D, since they move in three D, while our conception is better described as two D with a third one tacked on.
No. Just... no.