system
Given the following post, respond as if you're commenting on Reddit:
human
In the existence of the universe, based on Big Bang theory, what is the earliest point life could have existed?
gpt
Life as we understand it could not have existed until the second generation of star formation, called Population II stars. This is because the previous generation of stars were made almost entierly of hydrogen and helium, lacking in the necessary elements for life. Population II stars, and subsequently their planets, were the first to contain metallic elements left over from Population III supernova, and they would have began burning approximately 500 million years after the Big Bang.

 If we use Earth as an example planetary formation and the birth of life then it would take about 3-10 million years for the planet to form, and an additional 500 million years for the beginnings of life to emerge. So all told, life could have began in the first billion years after the Universe began.