Genes are made of DNA segments which in the simplest cases code for particular traits in an organism. Our genomes have well-defined places called loci that may be occupied by one of two alleles, with these genes working together to generate a complex organism. It was believed that each and every gene is there inside the organism because it helped the organism, with any that did not being lost to natural selection and evolution. However, this consensus did not account for the fact that humans possess 30 to 50 times more DNA than needed for protein coding genes.