How does selective breeding support Darwin's hypothesis about evolution?

Over the year of evolution, only the strongest survived and reproduced. So, having this happen over millions of years, species got stronger and stronger. For example, if there were two species of monkey's, one with fangs, one without fangs. The species with fangs would survive, and soon all monkeys would develop fangs because all the monkeys without them would die and not reproduce. That's how the evolved into what animals are today.