“A planet where apes evolved from men?”—Charlton Heston’s character wonders whether this is possible in the original 1968 Planet of the Apes. Turns out Heston’s query, and the entire scientific hypothesis on which the Apes moves rests, is bogus. But that doesn’t mean the Planet of the Apes franchise doesn’t raise some fascinating questions about the relationship between human beings and their primate cousins.

In the latest edition of the franchise reboot, Dawn of the Planet of the Apes, the monkeys have become more advanced, with a more developed oral language, family groups, and social structures. Sloan Science and Film spoke with University of Georgia research professor Dr. Irwin Bernstein, a former president of the American Society of Primatologists, about the fundamental differences between humans and monkeys, the intelligence of orangutans, and why monkeys will never rule the Earth.

Sloan Science and Film: First off, can you tell me generally about the links that exist between the species of monkeys in these films and human beings?

Irwin Bernstein: In the Planet of the Apes series, the three types of apes are recognizable as Orangutan, Gorilla and Chimpanzee. None of these are suited to bipedal locomotion anatomically and only humans truly can “walk” bipedally. Aristotle, in fact, defined humans as “the featherless biped.” Note that standing or running is a lot easier than walking bipedally if you have the anatomy of an ape. In addition to the evolution of bipedal adaptations, the Great Apes would need to increase cranial capacity about three fold to come close to Homo sapiens. (I acknowledge that there is no simple correlation between brain size and intelligence.) I do not know what allows for human language systems, but so far all attempts to train apes, dolphins, sea lions, parrots, have failed. Although considerable semantic ability has been demonstrated, syntactic abilities seem limited.

SSF: Is it possible, due to evolution and Natural Selection, that someday, perhaps in millions of years, these other primate species could evolve on the order of Homo sapiens? Is there any scientific reason to believe that the genetic make-up of monkeys would prevent such evolution from taking place?

IB: Evolution is not a “ladder” where some species are simply further along. Each species follows its own path. No monkey or ape will ever evolve into a human being. Each has already diverged in so many ways that it would be necessary to exactly undo the differences in the exact order and then acquire the mutations that characterize the other. Statistically that is as likely as all the molecules in a table synchronously moving upward so that the table levitates. Likewise no living creature, us included, has a prayer of ever changing into another living species. And “a million years” is but the blink of an eye in terms of evolution. The accumulation of enough genetic changes to warrant a new species name generally requires more than that.

SSF: In the film’s sci-fi world, there is a futuristic drug that is inserted into the monkeys to make them smarter. I realize this is totally unbelievable, but are you aware of any research, genetic or otherwise, that has tried to increase the intelligence of apes or chimps?

IB: Of course, lots of people have searched for rearing conditions, drugs, et cetera, to make people (animals) smarter, longer-lived, healthier. We know that early rearing conditions can be very detrimental to the development of intellectual potential, much as they can interfere with longevity and general viability. Many drugs have adverse effects. It seems more profitable at present to avoid those things that we are doing that interfere with developing our potential. To put it another way, genes determine no phenotypic trait, but genes influence every phenotypic trait. They set the limits of potential like height. I undoubtedly could have been a bit taller if my early health and nutritional environments had been better, much as I would certainly have been stunted if they had been worse (within the limits of minimum viability). The environment acts on the genotype to influence the actual phenotype within the limits set as possible by the genotype. (For example I know of no environment that would have caused me to grow wings, but lots of things that could have altered developing ten fingers (or even limbs, witness the tragedy of Thalidomide). This search for a magic pill to increase intelligence is akin to the search for the Fountain of Youth.

SSF: In the film, there is a male orange orangutan with a big rounded face who comes across as particularly intelligent, even before he contracts the DNA-altering drug. Is it true that orangutans are particularly intelligent?

IB: Different apes have different characteristics in regard to how they react to the world. This is true both for individuals and species. Orangutans are less likely than chimpanzees to go off into hyperactive patterns in response to stimuli; whereas a chimp may pant and hoot and drum and race about an orang is more likely to stare quietly before responding and thus seems much more deliberate. Gorillas are also more deliberate than chimps so maybe it is merely that chimps are hyperactive. (They are also the smallest of the three.)

SSF: In the previous film, there is also a silverback gorilla, who seems to embody the stereotype of a more brutish, less intelligent monkey. Are gorillas typically less intelligent and more aggressive than chimps and orangutans?

IB: The short answer is: “No.” Gorillas are very powerful (compared to humans, so are chimps) but the human stereotype linking strong backs with weak minds has no basis in fact. Gorillas are different but not demonstrably less intelligent. I would be sorely pressed to select any one species as smarter than the others. By the way, apes are “the monkeys that have no tails.” Technically, the differences between apes are more with regard to chests, shoulders, the number of lumbar and thoracic vertebrae et cetera, but apes are not monkeys. You will note that since humans have no external tail (we do have five internal coccygeal vertebrae and some apes only three or four) and the same thoracic characteristics as apes, we are all Hominoidea whereas old world monkeys are Cercopithecoidea.

SSF: Can you tell me a bit about how social formations work within groups of monkeys? In the new film, which is a precursor to the original 1968 Planet of the Apes, the chimpanzees begin to form familial units. How much of a scientific leap is it to have chimps pairing for life like married couples?

IB: Chimps are promiscuous with no special bond between any single male and single female. Orangutan males and females usually live independently, but a male may overlap the home ranges of several females and other males may have lesser access to them. Gorilla females usually join a cohesive group (and they are the only one of the three with cohesive social groups; chimps live in fusion-fission societies and orangs are usually just mother and offspring), but there are multiple adult males in such units and no evidence of either monogamy or a single male fathering all of the offspring. Mating systems are generally influenced by multiple factors. The only constant seems to be that the dispersal of one or both sexes at about the time of maturity means that there is little opportunity for inbreeding.

SSF: Ever since at least Gorillas in the Mist, I think movies have represented gorillas and other species of monkey as deserving of our sympathy. What’s your opinion of these popular representations?

IB: The public often sees monkeys and apes as people in little (or big) furry suits and believes that they think as we do and feel the same things that we do. A simple reason why this is not true is revealed in the “mirror test”. So far only humans (at about age 18-24 months), chimpanzees (at about the age of 4 years) and perhaps gorilla and orang have demonstrated that they recognize their reflection as a representation of self. Human infants younger than 18 months regard their reflection as another baby, and monkeys do so all their lives. Put two monkeys together in front of a mirror and each recognizes the other in the mirror (with practice) but each regards its own reflection as that of a stranger and threatens the stranger. They will try to catch the reflection “unawares,” will reach behind the mirror to grab the stranger and enlist their companion to help them to attack the stranger. Note, if they recognize the reflection of their companion as their companion, they are not at all disturbed that their companion is in two places at the same time!

Emotions like guilt, embarrassment and shame require that you know that you are an object and that you can be the object of other people’s attention. First you have to know that you are an object. Perhaps that is why these emotions do not develop in children until after they pass the mirror test and probably are only in animals that also pass the mirror test, despite what well meaning pet owners say about their pets.

Another example: chimpanzees do not seem to understand the difference between “contact” and “connected” and will place a box against a wall and try to climb up on it. They can stack boxes, but only do so by standing on the top one to use their body weight to balance the stack. It immediately crashes down when they get off. They will use a stick to touch a piece of food out of reach and then expect it to come in when they pull the stick in. It takes a long time to teach them how to use a rake to pull things in. If they learn that food in a tube will fall through a hole in the floor of the tube, if you rotate the tube 180 degrees they expect it to fall through the hole in the ceiling.
Humans often think that animals have morality and a sense of justice. However, their world is very much centered on themselves. They avoid unpleasant consequences and seek consequences favorable to themselves. They do have “friends,” individuals that they like to be with, and enemies, individuals that they avoid. They know who comes to the aid of someone that they fight with, but they do not necessarily understand relationships between others that do not influence themselves. Seyfarth and Cheney have commented how strange it is that vervet monkeys that live in fear of pythons do not learn to recognize a python track in the sand and will walk right down the track. Of course they learn alarm calls and threat calls, but they directly impact them. Tracks and signs are not wholly associated with an encounter with the animal and therefore seem not to be associated with who left them.

SSF: There have also been plenty of mainstream movies (the new Planet of the Apes films, included) that have criticized the way in which science experiments on monkeys. What is your response to this?

IB: Scientists are often portrayed as either “mad” or “evil” or “unfeeling.” We are people and people are not all animal lovers or abusers. I personally hold great affection for most animals and am respectful of even snakes and spiders. I have been accused of being a cold uncaring scientist. But then again, I love dogs, but have been told that to “own” a dog is akin to slavery. The Animal Rights movement is extremely broad and does not support a single ethic. We have been muddling with the question of what is our proper relationship to animals for several decades now with no consensus but with lots of strong opinion. I do eat meat (and vegetables). I do use leather. This makes me guilty of “species-ism” to some. I do not hold all living things to be equal. I am presently killing lots of living things without a shred of guilt as I write you. Indeed, I am very grateful that I have a competent immune system. I do swat mosquitos and have little compassion for ticks, leeches and other parasitic invertebrates.