Can we create life from scratch?

[humbleteleskop]

Probably many many times 3.5-4.5 billion years ago... and wait for a long long time ;)

Do we have any reason to believe abiogenesis ever ceased and that is not happening even today?

 

[mfb]

All known species use the same genetic code to translate DNA/RNA to amino acids (sometimes with tiny modifications). If there would have been completely independent evolutions, we would see many different ways.
Life needed a long time to get as competitive as today. I doubt new life would have any chance to survive against current life - it just lacks billions of years of evolution.

 

[humbleteleskop]

All known species use the same genetic code to translate DNA/RNA to amino acids (sometimes with tiny modifications). If there would have been completely independent evolutions, we would see many different ways.
Life needed a long time to get as competitive as today. I doubt new life would have any chance to survive against current life - it just lacks billions of years of evolution.

I would expect abiohenesis of today would be based on the same principles, guided and limited by the same or similar external factors, so I don't think it would be able to produce anything fundamentally different, on this planet.

Simple self-replicating molecules could have an advantage of being more robust and existing in large quantities. I'm not suggesting it would be possible for flying snake to evolve in today's and the world of tomorrow, but perhaps a new virus, very much similar to those that already exist, yet not quite the same. Of course it would be hard or impossible to tell whether this virus is just a mutation or indeed evolved from something simpler than itself.

 

[Ryan_m_b]

Do we have any reason to believe abiogenesis ever ceased and that is not happening even today?

It's unlikely abiogenesis is still ongoing because extant organisms are likely to fill any niche where it could occur.

 

[ChrisJA]

Do we have any reason to believe abiogenesis ever ceased and that is not happening even today?

The theory is that if some new kind of life sprang up it would be VERY poor at competing for resources and in fending off the more advanced microbes that would see it as food.

Also, before there was life on Earth, the Earth was a different place. There was no O2 in the atmosphere and so on. The lifeless Earth was a better place for life to develop but now the air is reactive (with O2) and the nutrient-soup is gone.

Life might have arisen many times only to fail until finally life RNA based on four bases happened and then we had RNA based life for a billion years before DNA came along. The first life to survive and multiply "wins" and would prevent anything else from following. It changes the environment so radically while at the same time adapting to the changes, nothing else can follow it

 

[humbleteleskop]

I agree. However, if something like those self-replicating polymers and fatty acids from Szostak's experiments can occur naturally in large numbers and in an environment sparse or devoid from things that would consume them. Then they could perhaps merge just due to sheer luck and consequently divide like in the experiment.

And then, maybe, just maybe, some of them would turn into something a little bit more robust, something a little bit more likely to merge and divide, and so on... Perhaps at some point external factors would not allow for any further grow in complexity, but it's just a matter of our semantic definition whether we are willing to call those things "alive".