-Fitness is the contribution an individual makes to the gene pool of the next generation compared to the contributions of other individuals.
Explanation;
The genetic fitness is the reproductive success of a genotype, usually measured as the number of offspring produced by an individual that survive to reproductive age relative to the average for the population.
-It is the quantitative representation of natural and sexual selection within evolutionary biology. It can be defined either with respect to a genotype or to a phenotype in a given environment. A genotype's fitness depends on the environment in which the organism lives. The fittest genotype during an ice age, for example, is probably not the fittest genotype once the ice age is over.
the structures of our brain stem, in conjunction with our spinal cord (not a part of our brain) is responsible for involuntary action. Not sure if it generate signals, but hey it's better than no answer.
