What are the various speculation on the existance of life or how did life form on earth?

In evolutionary biology, abiogenesis, or informally the origin of life (OoL), is the natural process ... For the oldest life forms, see Earliest known life forms. ... There are several principles and hypotheses for how abiogenesis could have occurred. ... In 2017 scientists found possible evidence of early life on land in 3.48 Gyo

Explanation:

Many scientists favor the RNA world hypothesis, in which RNA, not DNA, was the first genetic molecule of life on Earth. Other ideas include the pre-RNA world hypothesis and the metabolism-first hypothesis. Organic compounds could have been delivered to early Earth by meteorites and other celestial objects. We can only speculate about these questions, since we haven't yet found any life forms that hail from off of Earth. But we can think in a more informed way about whether life might exist on other ... When did life appear on Earth? ... For many millions of years, early Earth was pummeled by asteroids and other celestial objects.

"a.) well–developed vascular system."