Egg and sperm cell size evolved from competition

(Northwestern University) Using mathematical modeling, researchers considered a time very early in evolution when primordial species reproduced using external fertilization. In the model, bigger reproductive cells, or gametes, presented a competitive edge because they could hold more nutrients for a potential zygote. Smaller gametes, however, required fewer resources to make, which put less stress on the parent. Organisms evolved to specialize in large or small gametes, precursors to eggs and sp...