Greenhouse effect is nature human activity if has to do with outdoors can help with Mother Nature
While mitosis produces 2 daughter cells from each parent cell, meiosis results in 4 sex cells, or gametes in males and 1 in females. Unlike the cells created by mitosis, gametes are not identical to the parent cells. In males, meiosis is referred to as spermatogenesis because sperm cells are produced.
I think the answer is evolution.