I went to watch War For The Planet Of The Apes recently. It was very good – it made you ponder the questions of who was more human, the apes or the people, and what is it that really makes us human? – as any good sci-fi of that genre should. But, as a good scientist, it also made me think about a couple of questions that the writers probably weren’t intending to pose. Specifically: how are the apes riding horses, and what are the apes eating?
To deal with the first of those: we see repeated shots of Caesar, Rocket (both chimpanzees), Maurice (an orang-utan) and Luca (a gorilla) riding horses. The problem is not mechanical or anything like that, but one of weight. Chimpanzees are fine – they don’t weigh more than a person, and we have plenty of evidence that people can ride horses. Even for Maurice, as a full-grown male orang-utan, it’s entirely plausible – he’d probably weigh in at around the 70-90 kg mark. Maybe on the heavier side, but, given we know you can get horses to carry a full-grown man in full plate armour, weighing something like 100 kg without too much trouble, he could definitely sit on a horse.
Luca, though, is another matter entirely. As an adult male gorilla, he could be tipping the scales at 200 kg, or well over 400 lb, or 30 stone. A fairly cursory bit of googling suggests that the maximum weight for a horse rider is around 20 stone, or, at most, 20% of the weight of the horse. Based on the film, the horse Luca is riding looks fairly normal, which means it probably weighs 500-600 kg. It is possible to get draft horses that weigh in at 1 t or more, but he definitely isn’t riding something of that size. In other words, Luca is either seriously underweight (which his appearance really doesn’t suggest – he looks pretty hench all-round) or his horse has a steel rod instead of a backbone. Because an actual horse of that size with that weight on it would otherwise very quickly become a very dead horse on account of snapping its spine. Instead, it seems quite happy carrying him quite long distances at a fair old speed, on occasion. I am unable to account for this miracle of nature.
The second question concerns the apes’ food supply. A clear idea of the apes’ numbers is never given, but, based on what we get shown in the film, something in the order of several hundreds seems reasonable; a thousand at most. And, at the start of the movie, they seem confined to a relatively small patch of Californian redwood forest. It’s difficult to say what the size of this ‘home territory’ is, but events in the film suggest the apes haven’t generally explored that far in any direction, so a few hundred square kilometres seems reasonable. As much as anything, the remaining extent of mature redwood forests is pretty small. The thing is, your average gorilla, orang-utan or chimpanzee will have a home range of several square kilometres (anything from 3 to 15, depending on species and environment). And that’s in a tropical environment, where appropriate food sources are more easily accessible. Particularly fruit, which is a major dietary component for all three species (though less so for gorillas). It seems unlikely that the temperate redwood forests of California would have quite so much fruit available as your average tropical jungle.
So, even assuming ideal tropical conditions, the apes’ territory seems far too small to sustain them nutritionally. And, redwood forests are not ideal tropical conditions. So, how have the apes not all starved? They must have eaten up all the food available locally pretty quickly, be it animal or vegetable. There’s no sign of them doing any sort of farming or husbandry. So…what are they doing? Short of them being able to live mainly off raiding abandoned human supplies, which would again seem unsatisfactory in the long term for a population of that size, this is another miracle that I am unable to satisfactorily account for.
There you have it: it’s a great film, but watch out for the magic lightweight photosynthesising apes that the main characters seem to have become.
Aiya Helcarda 