How does natural selection negatively impact humans? use complete sentences to explain with the of an example.

Natural selection is the process by which nature selects organisms or species which fit closely to the environmental conditions. The question of how it can negatively affect humans is thus related to drastic changes in environmental conditions such as climate change. If climate changes become worse in the near future, the criteria for natural selection will also change. It has been argued a lot that changes in climate would not be in favor of currently living organisms, hence, nature will start eliminating humans along with other organisms.

Here is an example: if global warming results into increase in temperature, ice will melt and lead to sea level rise. Most of the continents will be covered with water. On the other hand, terrestrial animals including humans are not able to survive in the water which will result in their elimination.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."