As it turns out, however, the Alzarians are actually native to the planet, and are an evolutionary mutation of the Marshmen, which several millennia ago attacked the Terradonian crew and evolved into a new form to replaced them, which ended up looking identical to the Terradonians. Whether horizontal gene transference or some kind of Lamarckian evolution was involved in the process is unknown. When examining them under the microscope, the Doctor noticed that the cells of each Alzarian species (Alzarians, Marshmen and Alzarian Spiders) looked exactly identical, and also determined that they have the same DNA. Due to their origins, the Alzarians are actually far more adapted to their environment than they realize, as they share the Marshmen's abilities to breathe the toxic gases released dur