Even if true, is that really a sign of evolution, or is a sign that our education system can't keep up with population growth? It's not like more babies are being born inherently dumber than other babies, just that they're not being allowed to reach their fullest potential.
The only thing I remember about humans is that we're getting taller, but that is more likely due to better nutrition than evolution.
Regarding the nutrition angle, that still plays into it. As we find better food sources, and better ways to fend off predators, our overall quality of life improves, and that includes the physical benefits from such a change in diet and surroundings.