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All life is connected by the need to pass on genes. Some organisms do this asexually, but many reproduce sexually. Jerry Johnson was looking for a species of lizard with a very strange reproductive strategy. This species consists of only females. Their offspring are exact copies of themselves. He wondered why males are needed at all if females can reproduce on their own. Meredith Small believes that there must be a driving force behind sex. Robert Vrijenhoek, of the Monterey Bay Aquarium Research Institute, also believes that there must be something to cause its need. He regularly went to the desert and studied the minnows he found in the ponds there. 40% of the minnows were affected with a parasite that caused a black spot disease. The asexual reproducers were more parasitized than the sexual reproducers even though both types lived in the same pond. He found that this was a real world demonstration of the value of males. The asexual minnows were not evolving because they were copies of each other. When the sexual minnows reproduced, they made offspring with new combinations of genes. This made them less susceptible to the parasites. Males are needed to keep evolution moving. A drought occurred and the ponds dried up, when th