The answer is diminished natural killer cells, or (nk-cell). Cancer patients show diminishing nk-cells activity in the blood. Natural killer cells or Nk-cell for short, is a type of lymphocyte and a part of the immune system of our body. It plays a vital role in host-rejection in both tumors and infected cells. Cancer patients shows a diminishing number of NK-Cells, since the cancer cells spread and defeats the NK-Cell from eradicating the infected cells, wherein the number of NK-cells diminish.
The answer is NO. This is because different environments require different adaptations. A desirable trait in one environment may be inconsequential or detrimental in another environment. This is the reason also why evolution is continuous as natural selection acts on traits of a population to ensure desirable traits are retained with changes in the environment in a dynamic world.
