Yes, I think with the right ruling class and access to weapons, resources and political power it is possible for a third world race to ascend to a first world civilization race. It requires a large centralized government and selecting people that have strength, discipline, martial virtues and intelligence. It would take many centuries and requires a dedicated elite that can plan centuries ahead. Stronger selection pressures will speed up the evolution from a third world race to a first world race but it could lead to social upheaval if the society is too cruel to its people.

If you think this is impossible, I advice you to look at the amazing changes to plants and animals in the agriculture industry. It doesn't take them long to create new plant sub species that are more resistant to extreme temperatures, insects and increased growth rate and yields. If you applied this same methodology to human populations with modern technology the question is not possibility but rather how long. Advances in genetic engineering will only speed up this process and also probably be a huge problem in the not so distant future. The ethnic groups that don't use this technology will be left behind by the groups that use this technology to create designer babies that might have longer life spans, more intelligence, strength and other traits that considered desirable in that given society. There is a pretty horrifying future ahead and there are no easy solutions besides war.