But just like classical Darwinian evolution, this evolutionary process going on between all stars and planets still is governed by similar rules of change - that is, life evolves to consume, life feeds on life feeds on life.
We evolve to become better consumers. So a small even-toed ungulate grows a long neck, becomes a giraffe - not for mating reasons, not for randomness, but because by doing so, over the span of generations, it grows this neck to access food that is on a higher level than other shorter animals could reach, thus rendering their species the dominate species in that environmental niche.

We evolve lungs to breathe air so we can venture on land. These evolutionary cycles happen over and over again - to get to environmental niches. So the animal evolves a lung to get onto land, then later, evolves a blow-hole and becomes a whale - going back to the ocean. Just think of the changes that it took place of 64 million years in which the dinosaurs evolved into birds. Billions of changes have occurred on this planet over time.

Bats are not related to birds. Bats are closer related to rats. Yet, these animals have evolved wings to compete against environmental food niches. Over hundreds of thousands of years, these vermin evolved flight in order to get at insects which were previously only accessible to a type of bird. Once those types of birds died off, the insect population flourishes (due to no natural predators) - and eventually bats can learn to fly to get at this long-lost source of food.
Convergent evolution says that the environment dictates evolution - geography, competition, sources of food - these factors create seals, dolphins, humans, aliens, etc.
http://en.wikipedia.org/wiki/Convergent_evolution
I think there's something similar to this going on intergalactically - we are all part of a larger ecology. An ecology of suns, planets, moons, stars. We evolve to fit into the niches - for reasons of food, for reasons of territory - and along the way a commonality comes out. life usually evolves with 6 appendages - like a human has 2 legs + 2 arms + 1 head (and 1 vestigal tail).

I was reading some book on the science of dragons, and this author suggested that spines are not capable of evolving the classic 8 appendage form of a dragon (legs, arms, head, tail, and 2 wings) - that we only have to look at our own fossil record (which records over 4 billion years of life, ecology, and evolutionary process. The Pterodactyls didn't grown arms legs head tails and wings - birds didn't bats didn't.
Life has a set pattern. This pattern is defined by physics, by physiology, by organic chemistry. Life anywhere in the multiverse has a set pattern - and that's because the multiverse itself is a hologram.
The holographic principle states that the universe itself is bound by patterns, and that these patterns are echoed down to the tiniest forms from the greatest. This is why the inside of atoms look like solar systems. Everything eventually repeats itself in an infinite loop. And since the universe is a torus - the further in you go, the bigger it gets. Until you end up going so big, that you end up descending back into yourself.

Life has many of these patterns. There are only 64 numbers in the I-Ching, yet it defines everything; the Tarot has 72 cards; zodiac has 12. There are only a finite set of forms which can develop in a universe that has gravity, entropy, and inertia.
So our human forms will definitely see similarities to our alien brethren. As citizens of the multiverse, we are all bound by chemistry, physics and biology. We speak the language of mathematics.
It's time to stop thinking that there is anything that separates yourself from those people and things you perceive as other.
These commonalities serve as a hint - a reminder that we are all one, that we are all illusions of ourselves, that we are the sleeper dreaming of the dreamer.