Human Evolution Continued

I was looking at the human population growth over the years and the growth curve is downright scary. There are now about 6.76 billion people living on this planet. 70 000 years ago there were less than 10 000 if the forecasts are correct. It took 60 000 years to get to a million. At 1 A.D., there were 200 million. We reached one billion only 200 years ago and three billion only 50 years ago. According to the human evolutionary tree, we evolved from homo heidelbergensis who existed from 600 000 to 400 000 years. There was a very small group of these human precursors but yet they went through many evolutionary steps in those 200 000 years to get to homo sapiens, us. Why are we not seeing evolution now? Why have we not evolved in complexity in those 400 000 years? There have been more people on earth in the last 200 years than there has been for the entire 400 000 years before this. The more people, the more possibilities for random beneficial mutations and the greater the probability of evolving. Not only that but we have greatly increased the mutation rates. With the production of pollutants, nuclear waste, and hazardous chemicals, our mutation rate should be much higher. Human evolution should be happening at an exponentially accelerated rate in this exponentially growing population.