Just to clarify, When I say "us" I mean the western world. True, industrial countries are having fewer kids, and thats an example of a new selective pressure. It's a result of a new environment we've created for ourselves. I'm sure there are many to go along with that. But the sheer number of (potential) selective pressures we've removed through technology doesn't compare: many diseases, muscle size, brain size, vitamin D synthesis (its put in everything now), body hair, skeletal structure, the list goes on. Our interaction with our environment is on such a fundamentally different level that there are many classes of environmental pressures that simply don't affect us anymore.
Think of it this way: we used to be directly reliant our the environment for survival, like animals are. But now, we process our environment to such an extent that small variations in it are overcome by our intellect. Those variations in the past would constantly be exerting selective pressure on us in many different directions. Those pressures are processed out now.