No, it is impossible for us to "neutralize" the effects of natural selection, because that could only happen if (a) reproduction didn't occur and (b) there was no genetic diversity in the human species. Any changes to the environment that humans create simply become part of the environment that than "selects" for members of the species that are best adapted to that environment. This is true in most species (they shape their environment and the shaped environment than "selects" certain traits).
[WS:] I do not think I would agree with the above interpretation of the natural selection process. In my book, this process involves two analytically separable aspects: (i) the supply aspect i.e. creation of variety and (ii) the process of selective elimination of some of those variety options.
The supply aspect or "creation of variety" is the function of genetic mutation, which in itself may or may not be affected by the environment. That is to say, genes have a propensity to mutate - sometimes randomly, sometimes in response to environmental factors. Those mutations create a variety of organic forms with different morphological and behavioral properties.
In an ideal environment i.e. environment that does not pose any threat to the survival of any life form, all these mutations would continue to exist indefinitely. That is to say, once a genetic mutation creates an organism capable of living on its own and reproducing itself will continue to reproduce itself ad infinitum (at least in theory.) That process is by definition independent of the environment, including the human-created environment aka culture and institutions .
However, ideal environment does not exist. The real environments create pressures that selectively affect different organic forms' chances of survival. As a result of these selective pressures, some organic forms become extinct, while others continue to reproduce themselves or even thrive. This process is quite dependent on the specific nature of the environment.
Since humans have the capacity to manipulate their environment, they can also avert some selective pressures of that environment that jeopardize their chances of survival. In other words, while human can do little to affect the supply process i.e. make a certain genetic mutation available (at least until recently), they can do quite a bit in preventing some of those genetic mutations becoming extinct by shielding them form adverse environmental pressures. That pertains to all organic forms, including humans themselves. Since human capacity to affect the environment is greater than that of other species, it thus follows that humans have a greater capacity to control the natural selection process - or at least its elimination of the 'life unfit for life' aspect. However, with the progress of genetic science, humans are also gaining the capacity to engineer genetic mutations and thus selectively affect the supply process of genetic variation, which gives them even a greater level of control of the natural selection process.
Wojtek