The environment at the time life evolved was very, very different from today. In particular, free oxygen was practically non-existent. Metals, particularly iro

The environment at the time life evolved was very, very different from today. In particular, free oxygen was practically non-existent. Metals, particularly iron, and metal complexes were dissolved in the water at high concentration. Processes that spawned the first life had to be compatible with all of that, and may well have depended on many details of it, most of which we can barely imagine. The ancestors of everything alive today survived the arrival of free oxygen a billion or two years later, with the loss of most dissolved metals, leaving no trace of the overwhelming majority that failed to adapt to that. Conditions today, even without competition from existing life, might be wholly unsuitable for biogenesis.