Margulis holds a negative view of Neo-Darwinism. She formulated a theory to explain how symbiotic relationships that are taking place in modern day humans and animals are the driving force of evolution. Margulis ''argues that inherited variation, significant in evolution, does not come mainly from random mutations. Rather new tissues, organs, and even new species evolve primarily through the long-lasting intimacy of strangers. The fusion of genomes in symbioses followed by natural selection, she suggests, leads to increasingly complex levels of individuality.''<ref>[http://www.geo.umass.edu/faculty/margulis/ Lynn Margulis] University of Massachusetts, | Margulis holds a negative view of Neo-Darwinism. She formulated a theory to explain how symbiotic relationships that are taking place in modern day humans and animals are the driving force of evolution. Margulis ''argues that inherited variation, significant in evolution, does not come mainly from random mutations. Rather new tissues, organs, and even new species evolve primarily through the long-lasting intimacy of strangers. The fusion of genomes in symbioses followed by natural selection, she suggests, leads to increasingly complex levels of individuality.''<ref>[http://www.geo.umass.edu/faculty/margulis/ Lynn Margulis] University of Massachusetts, |