Complex sentence: This is due to the fact that the shikimate pathway is not present in humans and, therefore, is an ideal target for herbicides because chemicals used to inhibit the shikimate pathway should not have an effect on humans.
Split into simpler sentences: This is due to the fact that the shikimate pathway is not present in humans. It is, therefore, an ideal target for herbicides because chemicals used to inhibit the shikimate pathway should not have an effect on humans.