'Other life' on Earth

r3nu4l

Read this interesting article on the BBC News today.

Alien life may exist among us

Now 'alien' in this sense does not mean life from outside our planet but more like life-forms we may not yet have discovered. This team of scientists think that it is likely that life may have evolved in different forms on our planet and that remnants of those other life forms may live on today in some of our most inhospitable environments...deep sea vents, deserts etc.

Now we already know that certain bacterial species reside in and on deep-sea vents where most other life on Earth would be unable to survive due to high temperature and sulphur content but could there be other forms of life we haven't yet considered?

The team talk about lifeforms that may or may not be based on DNA/RNA or that utilise different amino acids. Some life forms we already know about use different forms of certain amino acids so that's not too much of a stretch.

What about life that may exist that we haven't recognised as life simply because it doesn't conform to our idea of life? There are some that argue that prions may be a life form. Outside of that he mentions the whole 'silicon' life form from Star Trek and I must admit, I'm one of those geeks that thought of that when I first read the article

So should we abandon SETI and instead spend some money looking closer to home for 'alien' life?

ChocolateSauce

We should totally abandon SETI.

I've often wondered if all life on this earth has only one common ancestor, or if it evolved independently in two or more places and survived? It would of course have to be highly isolated to survive, it is likely competition with our line of DNA would (or already has) destroy it.

biko

I think both are good, looking inwards into the deep oceans as well as the deep space. If the exogenesis theory is correct we'll find the same things.

c4sea

very interesting. I heard some where everything has life.
our body is made from five things - sky, air, water ,earth and fire.
every thing that is made from these five elements is having a life.
very hard to agree but that might be true.

ceegee

c4sea wrote: »

our body is made from five things - sky, air, water ,earth and fire.

wtf??

Capt'n Midnight

ceegee wrote: »

wtf??

ah the fifth element
to the Chinese it's metal
to us it's Boron
it the future it may be Leeloo

kiffer

Boron... I always for get Boron... why is that?

To paraphrase Mr.Pratchett... life turns up where ever it can... and and where it can't it just takes a little longer.

There may be some exotic locations on Earth where life fundamentally different from ours managed to arise... but was then destroyed by invading extremophile 'normal' life...

It would be really funky to find a hidden cache of life isolated somewhere (extreme or otherwise) since antiquity, chemically the same as 'normal' life but with the opposite chirality...

Undergod

c4sea wrote: »

very interesting. I heard some where everything has life.
our body is made from five things - sky, air, water ,earth and fire.
every thing that is made from these five elements is having a life.
very hard to agree but that might be true.

Wouldn't sky and air be the same thing?
Yeah, there was something about this in New Scientist as well I think.

The closest they've come so far is a bacteria in a goldmine in south africa that exists totally independently of the sun, and gets its energy from the decay of uranium in the rocks around it. It's got the same evolutionary heritage as normal life, but is free from the solar energy cycle, and no other known lifeform is.
http://www.newscientist.com/article/dn14906-goldmine-bug-dna-may-be-key-to-alien-life.html

Isn't it widely theorised that life did have a number of seperate origins, but they converged? I remember hearing some time ago that there may once have been a life based on DNA and another on proteins, and the two types grew into the same organisms. And isn't it also suggested that mitochondria are basically descended from another life form that became symbiotically attached to ours?

Kevster

r3nu4l wrote: »

What about life that may exist that we haven't recognised as life simply because it doesn't conform to our idea of life?

I like your thinking... I have considered this for a long time now, but how exactly do you go about defining a new form of life with nothing to base it on... Viruses (like prions) aren't recognised as living at present, but maybe they both should be.

Anyway, I have been taught that less than 1% of the bacterial species on earth have been discovered. The problem is that they mutate into new species so rapidly. It'd be pretty pointless trying to categorise them all, because by the time you finish your list it'd be 99% out of date!

Kevin

nitrogen

ChocolateSauce wrote: »

We should totally abandon SETI.

I've often wondered if all life on this earth has only one common ancestor, or if it evolved independently in two or more places and survived? It would of course have to be highly isolated to survive, it is likely competition with our line of DNA would (or already has) destroy it.

Let me get this straight. Are you more inclined to believe the probability is larger for life to evolve on our planet more than once, than for it to also occur somewhere else in our galaxy?

We should never abandon SETI.

Capt'n Midnight

Kevster wrote: »

Anyway, I have been taught that less than 1% of the bacterial species on earth have been discovered. The problem is that they mutate into new species so rapidly. It'd be pretty pointless trying to categorise them all, because by the time you finish your list it'd be 99% out of date!

Kevin

Don't forget horizontal gene transfer , there may only be one species of bacteria :eek:

r3nu4l

nitrogen wrote: »

Let me get this straight. Are you more inclined to believe the probability is larger for life to evolve on our planet more than once, than for it to also occur somewhere else in our galaxy?

We should never abandon SETI.

On the other hand, we know absolutely that life has evolved on this planet at least once, so what's to stop it happening a second time, whereas we suspect but do not know that life has evolved anywhere else.

That said, I don't think we should abandon SETI just yet

Kevster

Capt'n Midnight wrote: »

Don't forget horizontal gene transfer , there may only be one species of bacteria :eek:

Horizontal gene transfer? I've never heard of this, to be honest. What's your interpretation of it? I'll look it up online later but I imagine that it's to do with the exchange of plasmid DNA? ...just a guess

Timistry

nitrogen wrote: »

We should never abandon SETI.

Yup! There has to be life on other planets according to the drake equation

Capt'n Midnight

Timistry wrote: »

Yup! There has to be life on other planets according to the drake equation

it also proves there is no life elsewhere

just depends on how close to zero you factor the factors

Fermi paradox = where are they ?

Undergod

Timistry wrote: »

Yup! There has to be life on other planets according to the drake equation

No there doesn't. We don't have any way of working out like three of the numbers involved.

Kevster

We can't know for definite if there's life elsewhere unless we physically go out and detect it. You can bring up an equation that predicts life is 99.99% likely to exist elsewhere, but that's still not proof.

Capt'n Midnight

Kevster wrote: »

You can bring up an equation that predicts life is 99.99% likely to exist elsewhere,

actually you can't
sevaral of the terms have probabilities that could be so close to zero that even our own existance is extremely unlikely and may only have happened because there are a nearly infinite number of alternative suitable universes

Kevster

lol, that was just a figure of speech my friend. I actually know that the real equations only give life a minute chance of existing elsewhere. I was just implying that we still need actual evidence/proof after we have done the math.

Capt'n Midnight

proof could be done by doing spectroscopy on the atmosphere of an extra solar planet. If we can detect oxygen that would be very interesting, but if we detected resonable levels of methane even better, but how to prove it wasn't volcanic ???

Undergod

Who's to say that life will use oxygen and methane on other planets? We've gone a bit OT anyway here.

Capt'n Midnight

Undergod wrote: »

Who's to say that life will use oxygen and methane on other planets? We've gone a bit OT anyway here.

it's more that we detect a combination of gases in the atmospheres that would not be naturally stable, which means something is producing it, which might be life

but yeah for lots of life down here oxygen is poisonous

Kevster

Oxygen is poisonous for pretty much all forms of life. We oly breath it in at 21% concentration. If we breathed pure oxygen for too long, then we'd die. Oxygen forms free-radicals in our body which can damage tissue.

Throughout history, life has used Carbon Dioxide, Methane, Oxygen, and also minerals as sources of energy. Think of the Sulphur bacteria, and there are also ones that use Gold. Life always 'finds a way'.