Because natural selection can only increase or decrease frequency of alleles that already exist in the population
If a pathogen penetrates the first line of defense, the nonspecific internal defenses (as part of the second line of defense) it will possibly encounter are: an inflammatory response and neutrophils.
If a pathogen able to somehow pass through the the barriers shielding the body, one of the first active responses of the innate immune system is triggered. It is termed as an inflammatory response.
The major role of an inflammatory response is to set up a physical barrier against the spread of an infection.
Neutrophils are the phagocytic cells which move throughout the body in the blood. They are generally the first immune cells to show up at the site of an infection.
To learn more about neutrophils here
brainly.com/question/27960149
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