The biological evolution is going on all the time, albeit at a very slow pace. We humans, like all other living things, change over time by natural selection whether we like it or not.
Another type of evolution that is more evident in today's society is the cultural one, how we learn new things and how we use our bodies and interact with each other based on learned information. This is also a type of evolution that affects us greatly.
As I said, we evolve all the time - slowly through biological evolution and incredibly quickly through cultural evolution. But how well can our Stone Age bodies really cope with today's rapid cultural evolution?
I just read an interview with Daniel Lieberman, Professor of Evolutionary Biology at Harvard University. Among other things, he talks about how many of the diseases that exist today could be due to the failure of our Stone Age bodies adapting to today's modern society. He lists everything from asthma and acid reflux to depression, type 2 diabetes and high blood pressure. In his book The Story of the Human Body: Evolution, Health and Disease For example, today we eat large amounts of sugar and/or are physically inactive, as a result of cultural evolution, which often leads to problems such as diabetes and various cardiovascular diseases. This is because we are not living the way we were created to. Remember, it wasn't very long ago that we were hunters, if we look at the biological slow evolution. The sweetest thing we ate was honey and only on certain special occasions and because we were hunters we used our bodies in a completely different way compared to today.
Furthermore, Professor Lieberman talks about the difference between today's and yesterday's type of stress. In Stone Age times we were stressed when we were chased by the big hungry bear, today we are (usually) stressed by completely different factors and in a completely different way. The big hungry bear triggered a surge of stress hormones so that we could quickly outrun it and then the stress levels in the body were back to normal as soon as the danger was over.
The difference with today's stress is that it is more a result of social circumstances - it is our own lives and how we live that stresses us; work, money, thoughts, lots of different activities, internet connectivity etc. The list goes on! This type of stress makes us sick in the long run, as the stress levels in the body become chronically higher and do not return to normal as opposed to how it is actually supposed to work.
I think it's important to try to understand the reasons why people in today's society generally don't feel so well, when on paper things look so incredibly good. I mean, many of us have a roof over our heads, food on the table, money on our bank accounts and the opportunity to explore the world in all sorts of ways, which seems like a good starting point for a healthy and happy life. But somewhere in the rapid cultural evolution, our Stone Age bodies haven't quite caught up and the result is what we see today. Professor Lieberman highlights the problem of evolution which is most interesting to consider in this context. The very best thing, however, is that once you realize what the root cause is, you can also do something about the situation, even though it is a real challenge on many levels for us all to deal with.