- manufacture the amino acids necessary
- produce RNA
- Cell walls
They have yet to produce a cell that is self-replicating. It would seem that something is missing. Though scientists have life in abundance to study, they have yet been unable to ascertain the steps that led to it. I think they are stuck at the point where there was a world within which RNA existed.
It is at this point that the theists would exhort that the scientist to throw up his/her hands and accept that a god did it. Thank goodness that scientists are only about seven percent religious, which is why their work continues.
Much to do has been made about the conditions that prevailed upon the world early in its existence. Scientists so far have tried so hard to manufacture life following guidelines from the information we have about the early earth. So far, it seems, attempts have failed (Though this could change without a moment’s notice).
What if the conditions necessary for the formation of life from the bare constituents was never present on this earth? Suppose instead that the conditions existed at some point that only allowed the formation of life from previously manufactured materials arriving on meteorites? In this case the materials having been formed on some distant site under unknown conditions.
Perhaps it would be better to seek ways that life could have formed under any condition rather than limiting those conditions to what earth might have transiently offered. Scientists might look into the possibility of manufacturing the ingredients and then life in any way they can. Perhaps more than one way is possible. The likelihood of which way it actually occurred can then be derived. Perhaps from this we can also deduce where the process first began.
As far as life on earth, the problem becomes more complex as we cannot be sure what arrived and when, though we do have a pretty good idea when life began. Not only what arrived is a problem to deduce, but also what the conditions were on earth that could at the time carry on from the materials received. At this point it is thought, that anaerobic conditions prevailed at the beginning. Aerobic life, like ourselves, could not have come into being until life forms developed that exhaled the oxygen necessary for respiration. Anaerobic life still exists today deep beneath the soil. Maybe this is what we will find on Mars, Titan, and others.
Anyone out there think, seriously, that we as a species should give up this endeavor? Should we return to a time of accrediting some deity for every thing that is not yet known? It does seem that science generates more questions than answers. It is the questions, however, that is the food of science, not the answers.