It's interesting to consider whether uncivilized tribes/nations would be more likely to survive than civilized people if civilization collapsed. Does mean civilized people are at an evolutionary disadvantage to those uncivilized? We are indeed less likely to die of animal incidents, infection, exposure, etc. But, our comfortable way of life also makes us weak. Very few know how to live off the land. Our fight or flight instincts are not as sharp because they are not thoroughly being exercised. Our bodies are generally weaker due to not being used as much or in the same ways.
At the same time, civilization gives us the ability to focus on higher mental tasks than basic survival. We work on other projects to obtain currency, this currency being many of our life forces for survival. It's how we get food, shelter, medicine, etc. Most of the time, civilized people have longer lives, often prolonged by medicine. We can focus on solving problems for humanity as a whole rather than smaller groups of our immediate peers.
But, what we CAN do isn't what many CHOOSE to do. We have access to so much information, but many do not take advantage and are stuck in lower mental states. We feed off of technology for bursts of instant gratification, rather than using this tool to work towards something giving us delayed gratification, ultimately more rewarding. Many are dumbed down, disconnected from other people, and confused by conflicting information. Many eat foods lacking nutrition that they barely had to life a finger to get. We waste time in decision paralysis because of all the options we have in many regards.
We have the ability to be so much more...but it seems that civilization has made it so many are weaker and do not work hard towards really making differences in their lives and others. So who's at the evolutionary advantage, civilized or uncivilized people? I don't think the answer isn't as obvious as it may seem.
I am not sure is civilized and uncivilized is the correct labels in this case. I believe I am a fairly civilized person, but compare me to the average person who spends their life trying to "get rich" and I know I have a much better chance of survival than they.
Perhaps, "close to nature" and "not close to nature" would be better labels. I have a degree in computer science and most of my life have been reasonable well off financially, but I have made a conscious choice to learn to understand nature and live within her bounds rather than expecting her to bend to my whims. I can walk out into my yard and find food other people would try to kill off. I have listened to the sounds of nature and can pick out the sounds of most predators and edible animals. I can look at land and see which areas are most apt to flood and can purify water from most any source. Perhaps best of all, I know when to be quiet because one of the best survival tips anyone can learn is you should understand what type of people are around you, long before they know you are there.
I think being more specific by saying close to nature or not close to nature does more suit the idea. Saying uncivilized/civilized is more general, and while they do cover the patterns a lot of people portray, it's not completely accurate since people are on more of a gradient scale. Living in civilization does tend to make people weaker, but not inherently so. Knowing how to live off of the land is crucial for survival, were any sort of catastrophic event to happen. Plus, as you have mentioned, living in civilization doesn't inherently make someone that civilized either, if they're power-hungry and care little about their impact on other life.
A massive amount of death is coming. It will put the estimated 5 million people who died in the Great Depression to shame. The people who can survive off the land on their own and who are better prepared in supplies and skills will have a much greater chance of survival too.