Why is it that women are stronger than men?

Strength can be physical, mental, emotional, or psychological. During the last 50 years, women almost caught up to men in education, jobs, businesses, and many other spheres. But the big difference in physique remains, resulting from the evolution of thousands of years. 

But we wonder, what if women were physically stronger than men? How would the world look with women being the stronger gender?

Interestingly, if we pay attention to the animal kingdom, we see that most species have larger females, for instance, insects, frogs, most fishes, spiders, owls, etc.). They are larger and stronger as they have to carry hundreds of eggs in their bodies. Most terrestrial vertebrates are exceptions to this law, and so are we. So this easily creates the curiosity to think, what if the same natural rules were followed for humans too?