Evolution occurs when<span>these heritable differences become more common or rare in a population, either non-randomly through natural selection or randomly through genetic drift
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Answer:
Humans have 23 pairs of chromosomes--22 pairs of numbered chromosomes, called autosomes, and one pair of sex chromosomes, X and Y. Each parent contributes one chromosome to each pair so that offspring get half of their chromosomes from their mother and half from their father.
Explanation:
(Sorry, I'm not sure)
