LO does have a point, the information we have only goes back so far and the data available for this period only covers a miniscule amount of time compared to the life of our planet. Who knows, in the future there could be a massive turn of events which would turn everything on its head and it will be back to the drawing board for a rethink, not that we would necessarily be around to see it! So in hundreds of years: data collection comparisons = yes, now though:data collection comparisons = accurate? or risky in an attempt to be accurate? (if that makes sense?)