Hello this is my first post, i hope i ask in right category

I was wondering since how many million or billion years earth is suitable for humans to live ?

Some estimates I've seen assert the Sun will gradually make the Earth uninhabitable as few as 500,000 years, others put it closer to a billion years. 

 

https://en.wikipedia.org/wiki/Future_of_Earth

Future technology may be able to modify those dates; regardless, I expect humanity to migrate to a Dyson swarm orbiting the Sun eventually.

The only answer is how much we care to help keep it suitable.

My dentist tells me to only brush the teeth I want to keep.

I was asking about the past. Not future. Since how many years.....

1 hour ago, Ketanco said:

I was asking about the past. Not future. Since how many years.....

It depends. Physiologically suitable? We can live with less oxygen, but it makes life a lot harder.

Environmentally suitable? If you put us too far back in time without all our tools, the predators become a bit overwhelming.

Probably ideally since only the last 200,000 years ago which corresponds with current theories of Human development..  Even then the Earth may not have been forgiving.  Ideally perhaps the environment developed or "allowed" mankind to flourish only in the last 10.000 years or so when the last large ice age ended.

Future suitability of the Earth?  Harder to figure.  Perhaps as long as several million years.  Perhaps as short as only a few thousand years.  Too variable.  Too dynamic.  Nobody knows for sure.  All it would take is one very large volcano to set mankind way way back.  An asteroid strike may also do the same thing. 

On ‎7‎-‎11‎-‎2017 at 0:50 AM, Ketanco said:

I was wondering since how many million or billion years earth is suitable for humans to live ?

Probably when there was sufficient O2 in our atmosphere...maybe 2.45 billion years ago but the date is not clear.https://en.wikipedia.org/wiki/Great_Oxygenation_Event

Edited November 15, 20178 yr by Itoero