Question on evolutionary Rates

Hi ICANT I must admit this is not my field - but I love the question so can't help but butt in before the experts arrive I'm simply in awe of the fact that it took the best part of 2 billion years to go from Pro. to Eukaryotic cell... blows my mind. But it is a mistake to think it was the Pro.s evolving their way towards the Eu.sWhat was changing was the Earth - it was two billion years of 'terra'-forming the atmosphere from a carbon-dioxide rich environment to an oxygen-rich environment by the photo-synthesising prokaryotes.The oxygen was a blessing and a curse - it is highly toxic (something us divers are only too aware - killed my best friend!) and rising levels would have decimated the existing life... but some would have evolved to take advanatge of the huge energy benefit oxygen-use can bring leading the way to multi-cellular and Eurkarotic life.So primitive life itself paved the way for the more advanced life - work of genius if you ask me Anyway, I've embarressed myself enough here already. When you are ready to offer your questions on the beginnings of the universe, fine-tuning, and any other cosmological issues, come and find me. That's my field...