Why we are all so specialized?

"OK, well this was my thought: 50,000 years ago, there are not even a million people on the planet. 10,000 years ago, there's, like, two million people on the planet. Now there's between five and six billion people on the planet, right? Now, if we all have our own, like, individual, unique soul, right, where do they all come from? You know, are modern souls only a fraction of the original souls? 'Cause if they are, that represents a 5,000 to 1 split of each soul in the last 50,000 years, which is, like, a blip in the Earth's time. You know, so at best we're like these tiny fractions of people, you know, walking... I mean, is that why we're so scattered? You know, is that why we're all so specialized?"
– Jesse.