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| Saccharomyces cerevisiae |
After a century discussing about the
origin of life, we are not closer to knowing what did happen. In the mid-twentieth
century, when Stanley Lloyd Miller performed the famous experiment where he
applied energy to a mixture of methane, hydrogen, ammonia and water, and obtained
amino acids, scientists announced the imminent manufacture of artificial life
in the laboratory. Such estimates are often too optimistic. In
this case they were.
The first question to be solved here
is what is meant by being alive. If we consider the problem carefully, we’ll
find beings that are clearly alive and others that definitely are not. Plants,
animals and ourselves are alive. Stones, distilled water, carbon dioxide, are
not. In these cases deciding is no trouble. When Antony van Leeuwenhoek discovered
microorganisms (yeast, infusorians, bacteria, spermatozoa and red blood cells) nobody
doubted that they are alive. But things are not always so simple.
