One way in which the study of populations ( human populations - I assume) affects us is that they can help predict the population size in the future and prepare us for it. For example, if we see that the population is decreasing, a country might want to consider supporting child-bearing or immigration to avoid the problem of too many people receiving pensions but not paying taxes.
The big difference between Eastern Europe and Western Europe is that Eastern Europe consists of countries that once belonged to the Soviet block, unlike the Western half. Economically, the Western Europe nations are much more advanced than the Eastern Europe nations. Western Europe outputs a lot more cash due to a larger free trade and more open economy as a whole.
Answer: it can help you (if you observe well) 1) to get to know yourself better, 2) recognize relating patterns adquired from your own family, 3) leave infantile approach to relationships (we all have tendency to look for someone who will unconditionally satisfy our needs and our ego requirements) and learn to relate as adult (respecting, i.e. respect frontiers of the other and require respect, i.e. learn the other respect your boundaries), 4) leave childish, infantile dependency and become responsible for the kind of relationships we make.
Explanation: in our psyche there is always something what is called "kinship libido" that seduces us again and again to regress, to depend on parenting figures. That is why it is no easy to leave family of origin (leave not only physically but also psychologically).
