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While Earth can no doubt sustain life in the case of humans and every animal alive to date, it is still a question as to whether earth can sustain life or not.
Earth's scientist have not found life on other planets to date.
No planet except the planet Earth is known to sustain life till date.
Most geologists date the Earth at 4.54 billion years and the oldest fossils (of stromatolites) date from around 3.8 billion years, so based on that, the Earth was without life for around 740 million years. However, there may well have been earlier life - there aren't that many sites with rocks dating back that far.
To date there is no direct evidence of life anywhere but Earth, but our capabilities of looking for signs of life are very limited. Many scientists think there is life out there, simply given the number of stars in this galaxy and the discovery that many of these stars have planets.
Pick any date before tomorrow, and Earth existed on that date.
One of the first life forms on Earth are believed to be single-celled microorganisms such as bacteria and archaea. These simple organisms date back billions of years and played a crucial role in shaping Earth's early environment.
Earth is estimated to be around 4.5 billion years old. The earliest signs of life on Earth date back to approximately 3.5 billion years ago, suggesting there was around 1 billion years between Earth's formation and the emergence of life.
So far as is known to date there is no life on any other planet in our solar system or elsewhere. That does not rule out the possibility that life may exist on other planets
Earth is unique because it has the right combination of conditions to support life, such as liquid water, a suitable atmosphere, and a protective magnetosphere. It also has a diverse range of ecosystems and biodiversity. Additionally, Earth's position in the habitable zone of its star allows for stable temperatures conducive to life.
The half-life of the isotope used to date the age of Earth at 4.6 billion years would need to be roughly around 1.5 billion years. This would allow for the gradual decay of the isotope over time, leading to the age estimate of the Earth.
Stromatolites are one of the earliest known life forms; some fossils may date back 3.5 billion years - before Earth had any oxygen in it's atmosphere.