 So why are we so concerned about the fact that our climate might be changing? This graph shows estimates of Earth's temperature way back in time to about 2015 and what's represented here is what we call the temperature anomaly It's the temperature relative to the 30-year average and in this case the 30-year average was taken from 1961 to 1990 Homo sapiens first emerged 195,000 years ago based on skulls that were found in Ethiopia It took us about 185,000 years to become settled in the sense that we were independent of our hunter-gatherer origins and So during this 185 or so thousand years We really were just managing to eke out in existence and survive If you have a look at the graph during this 185,000 years between our emergence and when things started to change You'll see that the temperature has fluctuated significantly So the experience of these hunter-gatherers is one of living in an environment which had no predictability whatsoever Next year would be totally different to this year Which was different to the year before around about 20,000 years ago Temperatures started to settle and by 12,000 years ago We entered into what we now know as the Holocene which is characterized by very stable climate As you can see in that part of the graph