By Chris Spencer and Brent Wells, PhD
Being such a staple of science fiction, Star Wars contains creatures whose evolution ought to be explainable scientifically. So strap in, and come with us as we cast Darwin’s eye over four species from the Star Wars galaxy:
The only wookiee we saw in the original trilogy was the enigmatic Chewbacca, but fortunately enough, we were able to get a glimpse of an entire wookiee community in Revenge of the Sith. These powerfully built furry humanoids are an arboreal race from the planet Kashyyyk. Being tree dwellers, they are well adapted for climbing – having sharp grasping claws, and strong backs and calves. Their characteristic fur has evolved for two purposes: it can be any of a range of earthy brown colours for camouflage whilst hunting terrestrially, and it produces a water repellent oil for swimming. Their sharp teeth and keen sense of smell are hallmarks of a species evolved to be hunters.
According to Wookieepedia, rancors are large, carnivorous reptomammals from the planet Dathomir. Before I move on, a reptomammal, as far as I can tell, is a warm-blooded, oviparous reptile. Rancors grow as tall as 8-10 meters with long, pronounced arms and hands and small, under grown legs, kind of like a reverse T. Rex. This massively unbalanced center of gravity would normally be an evolutionary conundrum, but as a reptomammal, it’s clear the rancor plays by nobody’s rules, including natures, just like Earth’s duck-billed Platypus.
The massive size and top heaviness of rancors can be attributed to the low gravity on Dathomir. Alternatively, their size may be a consequence of the rich, almost unending diet the planet provides or the fact that Rancors, unlike regular mammals, lay eggs; it has been suggested that vivipary could limit the size of land-dwelling mammals. One final factor that could have aided in the evolution of such a large predator is the temperate climate the rancor evolved in. An inverse correlation between temperature and body size has been seen in some warm-blooded mammals, maybe because of overheating issues, maybe as a secondary consequence of higher atmospheric CO2, which would lead to more plant food sources and therefore prey food sources. The rancor’s thick, reptilian skin, large claws and teeth, and powerful jaws are all traits that evolved to aid their predatory abilities and their sense of smell became keen to help them find mates.
Rancors give birth to two young at a time, like polar bears, and following their birth, the young are carried on the body (one clutching to its chest and one to its back) until the young reach maturity. This is no easy feat considering the young are up to three meters tall at birth – this is nearly 50% the size of the adult rancor. As an apex predator, we can assume the rancor hunts and therefore attacks its prey. It would also need to defend its kill from other rancor and top predators roaming Dathomir in search of a free meal. Therefore, we can hypothesize that the evolution of its unnaturally long arms came as a way to do battle while the equivalent of a five-year-old child is strapped to its chest. Without extra-long arms with which to work around the front child, the young would surely perish during the battle, preventing the inheritance of genetic information and fixation of traits in the wild population. By carrying double their own bodyweight around in children, rancors have also found a way to lower infant mortality in the species.
These furry bipeds were used on Hoth by the rebellion in the opening scenes of Empire. Living on an enormous snowball such as Hoth will necessitate adaptations not dissimilar to those displayed by polar bears, including being warm blooded (they are reptomammals not unlike the rancor) – as referenced by Han’s innovative use of the interior of a tauntaun. Their tridactyl feet are furry and with splayed toes to act like snowshoes, with claws to help gain purchase on icier terrain. They also have four nostrils serving to warm air before entering the lungs. The larger pair of nostrils can seal to keep snow out during periods of rest. One key aspect of tauntaun physiology is one shared by many arctic fish: anti-freeze in the bloodstream.
Yoda belongs to a species of small, long-lived creatures with green skin. His longevity is a consequence of a calorically restricted diet and an incredibly slow metabolism, something his species evolved in conjunction with their short stature and slow movement. They live in the wet, dark swamps of an unnamed planet similar to Dagobah, where Yoda was later exiled. Their diet is composed primarily of swamp plants and small insects. Yoda’s species has evolved tough claws on their fingers for prying bark from trees in search of beetles and other insects. Their unusually large ears have evolved as a means to avoid capture by larger, carnivorous animals that would gladly have them for dinner. Hearing predators from a distance is particularly necessary given their slow speed. Their green skin was also evolved as a defensive mechanism to help avoid predation through camouflage; green is the perfect colour for blending in with the large ferns and aquatic plants of their home planet and the creatures of this species are all but invisible among the green swamp gases that persistently hang in the air. Do not confuse Yoda’s bursts of speed during battle with a common trait of all members of his species. He was a Jedi Master, which provided him with special skills. A skill he did not possess, however, was a mastery of the English language.
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