Chemistry and Evolution, Are they universal?

If life is based on the same principles of chemistry whatever is possible here will work any place similar. Is our planet different? Is our planet radically different from other life bearing planets? I don't think so.

The soup required for life is everywhere the same. What can happen here can happen anywhere similar.

The forms created by evolution are also universal.

For example I wouldn't be suprised if there were dolphins on every planet (with our level of life.)

I would be very surprised to find dolphin-like organisms on too many planets. In fact I suspect that if life is anything like on Earth, then multicellular life will be extremely rare. In fact, on Earth, the dominant mode of life for the entire history of life has been unicellular. Even today, despite the seeming dominance of multicellular organism, the predominate mode of life is still unicellular. If one examines the history of life, it becomes apparent that multicellular life is a fairly recent anomaly in the overall pattern of life on Earth. In the long run, say another billion years, it may turn out that this whole multicellular "experiment" of evolution was just a fluke and dead end.

for some more reading on this try this article by Gould:
http://www.brembs.net/gould.html

We and other life on Earth was evolved by the gravity we live under, the atmosphere we must breathe, the light we receive and other conditions. On other Earth type worlds, there could be cosmetic differences in species but regarding eyes (2 for stereoscopic vision, as 2 ears for stero hearing), noses (to warm/cool the air we breathe), mouths, legs, etc all will be the same. Bug-eyed monsters are very unlikely without a different evolutionary inperative.

While probably most of the life in the universe is very primitive, lichens, plants, even a small percentage being advanced mammals would be an incredible number. But that does not mean it would be easy to find. Earth has been around for 4,600,000,000 years and civilised modern man for maybe 10,000 years with the electronic age being very recent. Arriving at the right moment to find beings like us would be incredibly difficult.

On a planet with quite like Earth, with a similar history, then it isn't unreasonable to find similarly formed organisms. However, life may not be confined to quite Earth like, and there's no expectation of a similar history.

Even on Earth alone, the examples of convergent, relay, and parallel evolution speak to some forms being likely.

So finding dolphin like species on a planet quite like earth wouldn't be surprising.

Still, you can't draw trend conclusions from one data point.

As for the soup being the same, I don't see why that would necessarily be the case. And for that, we have 0 data points to consider, so...

What seems to suggest that life is very universal is that life is based on H,C,N and O. This is the stuff that first generation stars can make. Once the atoms appear chemistry is quit conservative with respect to the molecules that will form from various combinations of these four elements. Water will definitely form from any cooling mixture of O and H plasma, maybe 99%. One would also expect CH4, NH3, H2O, CO2, CH2O, HCNO, HCN, etc.. What we have are the basic building blocks appearing almost everywhere, as is demonstrated by meteors. Assembly into life requires some additional elements, such as P, Na, K, S, Ca, Mg, Cl, which appear in second generation stars (if one assumes you need super nova to make higher elements than O).

I disagree with the bit about the bug eyed monsters.
Evolution works with what it's got. Compound eyes are quite efficient, though maybe not so good for detail. Eyes have evolved in several totally different forms, but it is other physical and physiological factors that would determine what life forms become advanced.

I THINK BASICALLY LIFE SUPPORTING PLANETS ARE ALL QUITE SIMILAR. SHOW ME WHERE I AM WRONG. IF YOU CAN.

MITCH RAEMSCH -- LIGHT FELL --

Again, if you look at the overall history of life on Earth, bug eyed monsters are the norm. There are many ways life has achieved sight, some bug eyed critters have far superior vision than humans, just look at mantis shrimp. Also, there is no reason to think that life on other planets would be similar to large vertebrates on Earth except on a biochemical level. As pointed out by Gould in the link I posted, for 5/6 of the history of life on Earth, unicellular life forms dominated. It was only in the past 600 or 700 million years that evolution led to multicellular life. Since multicellular life is still less than a billion years old, it could very well end up that multicellular life forms are just an evolutionary experiment that leads to a dead end.

Nick, on what basis do you conclude that:

This way we can:

I think I have already given evidence to why you may be wrong. If you would provide some reasons why you think this, we can possibly show where you are wrong. It may well be that you convince me you are right, but without any evidence of why you think the way you do, not even an anecdote, there is nothing to show that is wrong.

why travel around the galaxy just to find beings just like us? there are plenty of beings just like us being murdered and starved to death every day right here. perhaps we should look out for them first?


g.

A creature in a similar ecological niche may be similar, in the way that a shark, a tuna, an ichthiosaur and a dolphin are all similar. But if a squid evolved into something that filled this niche, it wouldn't look much like any of the others.

From this point of view, the existence of Nick on every planet seems to be undeniable...
This experiment is by my opinion pretty close to the real origin of life. It describes the simple oily droplets, which are feeding itself by the soap molecules under motion.
Pretty like the slimes feeded by algaes on the aquarium walls.



This post has been edited by Zephir on Feb 19 2007, 03:23 AM

Let's see your data...