There are more people on both sides of the IQ bell curve in the U.S. than there are in Europe. By Europe I am referring to Western Europe. And yes, the U.S. is a lot more diverse which has never been a good thing.
Every bell curve is a graph of how a population behaves or what characteristics it has. It doesn’t matter how many people are in it. It’s always the same—the majoity of the people will always be in the middle no matter which population you are referring to. That’s what a bell curve is. It shows normal distribution and that’s all it shows. There can’t be more people on each side, no matter what you are trying to show. The distribution within any bell curve is always the same.
Yes, the majority will always be in the middle, but that doesn’t imply the bell will be shaped the same way in all occasions. Some bell curves will be taller and narrower than others and their centre will fall in different places on the spectrum.