"No, it isn't. What separates us from animals is culture. That's it. Without culture, we're just animals. So might as well just go extinct just like hundreds of animal species go extinct every year. Why bother?"
Exactly wrong. It is by expanding the gene pool and cross-breeding more varieties that prevents us from going extinct. For example, the Asians can benefit from the White's tolerance to lactose, while the Whites can benefit from the physical fitness of Blacks, and the Blacks can benefit from the femininity of Asians for their women. Once you blend all of these qualities together for a few generations, you end up with super masculine intelligent men, and super feminine graceful tempered women.