Logic and looking for Life

There have been five mass extinctions on Earth (6 including the one going on right now). Each time many species were killed off, but the survivors repopulated the planet. From volcanic ocean vents, to antartic Ice, to down town NYC there is life. Single celled to complex humans.

At one point in earth history, the world was dominated by single celled organisms. They evolved, and diverged, and spread into macroscopic plants and animals. Five time events whiped out most of the large animals, and yet new ones evolved.

Now, on to Mars...

Mars is virtualy the same age as the earth.

Yet we see no signs of forrest from orbit or tracks of large animals in the rover's view.

So for now, there seems to be no sign of macroscopic life on Mars.

Why? If Mars at any point had life, would it not repopulate, reevolve as the earth has so many times in the past.

With all the evidence rolling in on ancient oceans, people start talking about ancient life. But where is that life now?

Mars has resources! It has regions warmer than our antartic, home to penguins and other macroscopic life. It has regions more harsh than deep see volcanic vents home to tube worms and a huge number of other creatures. It has CO2 and Oxygen in the Air the two main gases of our huge forrest. Why no macroscopic life?

I see two logical options.
1) Mars is currently in a post extinction phase. All the Macro scopic life recently died off and hasn't had time to reevolve (into different things, but still complex and macroscopic again).
2) Mars never had any life to start. If it had life millions or billions of years ago when it had oceans, that life should have addapted to its enviroment by now including macroscopic forms.

And before someone says a constant state of single celled organisms is an option, i'd like to point out that is going beyond the bounds of life as we know it.

The point is, life as we know it evolves. Be it a bacteria becomming drug resistant or a wolf like creature becoming a whale over millions of years, life evolves. If there is place to be, an advantage to be had, levolution will work its magic when given enough organisms to start.

Small shrews will grow bigger and faster to out run preditors until they become hoses, horses will gorw longer necks to reach higher leaves until they are giraffes, and other shrews will grow into lions to eat the girraffes. (Yes, a horrible rendition of possible evolutions, but gets the point across.)

If Mars had oceans with life, at least single celled life, why has it not evolved? Why has it not made that leap the earth has made so many time in size and complexity of life?

Either Mars has no life, something killed it all in a sweeping and (relativly) fast and final extinction, or, it never had life at all.

[Edited on 24-3-2004 by Quest]

Hmmm, no thoughts or a depressing idea since it implies probably no other life in our solar system? (europa being an exception)

My theory is that short wave solar radiation cooked the first little microorganisms on Mars. Without a nice, thick atmosphere to filter out most of those rays, they would have died not long after 'birth'.

Something that may have been overlooked is that if there is, or was life on Mars, who said it had to be above ground? Maybe what you are looking for is beyond our technology.

Mars had a molten core that recently cooled off. I doubt that life would have a chance to begin with such little time.

I think the surface is too extreme for life to adapt too, thin atmosphere, dust storms, extreme high and low temps. Dig below or find caverns and there might be something neato.

Regarding Mars:

Why are we looking for life similiar to our own? We get excited about water, atmospheric conditons etc.. All KNOWN things that support life here on earth. It seems to me obvious that an alien life form would be just that, alien.

As mentioned, there could be life on/in mars underground. There could also be life that is invisible to us, multi-dimensional to us, unrecognizable to us..etc. There may be a life-form that contradicts all known laws of existence.

Is it some form of universal narcissim? Perhaps we're looking for our history. Perhaps we're looking for our future. But we do seem to be looking for ourselves.

You make a good argument and put forth some very good points.

Even if life exists on Mars, what are the chances of us finding it?

How much have we explored? Not much

There are still vast oceans waiting to be explored.

why do cells evolve? because outside influence causes it to. if mars somehow had an organism that did not have to evolve because it was in balance with birth/death cycles and never went to the point where cells started to combine together and eat the single cells perhaps that is why? that is against life as we know it.

that would cause slower development than a what occured at a post extinction development at earth.