The wide variation of gene combination in sexual reproduction can increase the ability of offspring to adapt to natural selection. The random combination of genes in the offspring produced by sexual reproduction may be beneficial or unfavorable to the species, but at least it will increase the chances of a few individuals living in an unpredictable and changing environment, thus benefiting the species. Sexual reproduction can also promote the spread of favorable mutations in the population. If two individuals in a species have favorable mutations at different sites, in an asexual population, the two mutations will compete until one is eliminated, and it is impossible to maintain two favorable mutations at the same time. In a sexually reproductive population, through mating and recombination, these two favorable mutations can enter the genome of the same individual and spread in the population at the same time. In addition, there are diploid stages in the life history of sexually propagated species. Diploid species have two copies of each gene, and one copy is in functional standby state. If this candidate gene mutates and becomes a gene with new functions, there is still potential for new functions at this time. Through spontaneous repetition and gene recombination in sexual reproduction, this new gene can be arranged in sequence with the original gene, thus producing a new gene. Diploid species can enrich their genomes in this way. Based on the above reasons, sexual reproduction has accelerated the process of evolution. In the biological evolution of the earth for more than 3 billion years, the first 2 billion years of life stayed in the stage of asexual reproduction, and the evolution was slow, and the evolution speed was obviously accelerated after 65.438 billion years. In addition to changes in the earth's environment (such as the emergence of an oxygen-containing atmosphere, etc.). ), the occurrence and development of sexual reproduction is also a major reason. In the existing 1.5 million species of organisms, from bacteria to higher animals and plants, more than 98% can have sexual reproduction, which illustrates this point.