ELAH FEDER: Hey, everyone. We are back again with another episode this week. We're still on the theme of we were wrong about science that we, or some of us used to believe in and how we changed our minds.
ANNIE MINOFF: Here it goes. So Elah, you have seen the opening to 2001, A Space Odyssey.
ELAH FEDER: A long time ago, yes.
ANNIE MINOFF: OK.
ELAH FEDER: Chimps gathered around an obelisk?
ANNIE MINOFF: Monolith?
ELAH FEDER: Monolith?
ANNIE MINOFF: Yeah. All right, so I'm going to refresh your memory. This movie starts on a kind of rocky desert landscape. We're watching an ape. He is squatting in the dirt, kind of snuffling around next to this pile of animal bones. And then suddenly he pauses, cocks his head, looks at the pile of bones, and has a world shattering idea. What if I used one of these bones as a weapon?
And sure enough, in the very next scene, you see this confrontation between two groups of apes. And--
ELAH FEDER: Ooh!
ANNIE MINOFF: --our ape buddy whacks one of those apes in the head with a bone.
ELAH FEDER: Whacking while they're down? They've been neutralized. Stop. This was the flash of insight.
ANNIE MINOFF: Yep.
ELAH FEDER: The earth shattering was I can whack other apes with bones.
ANNIE MINOFF: Indeed.
ELAH FEDER: OK.
ANNIE MINOFF: So this sequence is called the Dawn of Man. It has always made not a ton of sense to me. But recently, I was talking to Erika.
ERIKA MILAM: Erika Milam. I am a historian of science at Princeton University.
ANNIE MINOFF: And Erika told me what we're watching in those first nine minutes of 2001, A Space Odyssey is a dramatization of a scientific theory-- the killer ape theory.
ERIKA MILAM: The killer ape theory is the idea that in the long, deep human past, there has to have been some kind of driver that made the human lineage different from all other great ape species.
ANNIE MINOFF: And according to the killer ape theory, that key difference, the key moment in our evolution that split us off forever from our ape cousins, was when we humans figured out how to kill.
ELAH FEDER: I feel like there should be like a dun, dun, dun.
ERIKA MILAM: Yes, absolutely.
ANNIE MINOFF: I'm Annie.
ELAH FEDER: And I'm Elah.
ANNIE MINOFF: And you're listening to Undiscovered.
ELAH FEDER: And today we present the killer ape theory.
[UPBEAT ELECTRO MUSIC]
ANNIE MINOFF: In the 1960s, a scientist in South Africa and a Hollywood script writer had a ton of people convinced that we humans are natural born killers. That you, you are a murderer at your core. And then just as quickly as this theory rose, it all fell apart.
ELAH FEDER: Coming up, what killed the killer ape?
[UPBEAT ELECTRO MUSIC]
ANNIE MINOFF: So, how does a scientific theory end up in one of the biggest movies of the 20th century? I think the answer to that question basically comes down to one guy, Robert Ardrey. Robert Ardrey is not actually a scientist. He's a writer. It's this talkative guy from Chicago with bad posture and a flair for drama. And as a writer, he kind of does everything. He writes plays. For a while, he carves out a really comfy niche for himself in Hollywood, turning novels into screenplays. So he does stuff like Madam Bovary, The Three Musketeers.
SPEAKER 1: Duels are forbidden. In the name of Prime Minister Richelieu, I arrest you.
SPEAKER 2: Do your best in the king's name.
ANNIE MINOFF: But in the mid '50s, Ardrey is writing magazine pieces. He's actually traveling around Africa, writing pieces about politics. And he gets a tip that is going to completely change his career. A friend tells him, if you want a good story, go down to South Africa and talk to the scientist named Raymond Dart.
So Raymond Dart, a little bit controversial, is kind of a maverick. Three decades earlier, he discovered what he claimed was our oldest human ancestor, this kind of apey creature that he names Australopithecus africanus. Dart also took a lot of flack for suggesting that humans evolved out of Africa-- quite controversial at the time. Of course he turns out to be totally right about this.
And so Ardrey thinks, OK, I'm going to give this guy, Dart, a shot. So one stormy day, Ardrey shows up at Dart's office in Johannesburg. Here's how Ardrey wrote about that meeting later.
CHARLES: A last rare storm of the rainy season darkened Dart's upper floor office at the medical school. Fossil bones of extinct animals piled up before me. Then, I found in my hand what seemed a human jaw.
ERIKA MILAM: When Ardrey first shows up in his office, Dart introduces him to a jawbone.
ANNIE MINOFF: This jawbone belonged to one of these proto humans, Australopithecus africanus. And it's pretty wrecked. Like there's a big crack running down the front of the jaw. The front four teeth are missing.
ERIKA MILAM: And Dart, in the way that Ardrey relates it, Dart takes a very interesting approach, which is, he says, I am going to leave you to your own reasoning as you examine this specimen. And so Ardrey talks about sitting there with this jaw bone, and looking at it, and reasoning through, as a layperson, what could possibly have led to the caved in front part of the jaw and the four missing teeth.
ANNIE MINOFF: So here is Ardrey, the writer's, reasoning. First, he wants to know, OK, when did this jawbone break? Is it possible that maybe it broke 2 million years after this Australopithecine died? You have a bone lying around in a cave.
ELAH FEDER: Someone steps on it.
ANNIE MINOFF: Boom, it's broken. But he figures that probably didn't happen.
CHARLES: For in that case, the fragments would have been scattered about.
ANNIE MINOFF: And they're not.
CHARLES: Flesh must have held the fragments together to be fossilized as a single whole.
ANNIE MINOFF: Ardrey also thinks--
CHARLES: Nor could the blow have resulted in anything but death.
ANNIE MINOFF: He thinks this blow is fatal. Because the bones didn't knit back together. They didn't heal. And then finally, Ardrey thinks that whatever socked this Australopithecine in the jaw and killed him was not an accident.
ELAH FEDER: What? Wait, what? That's a bit of a leap. Like, wait, wait, wait.
ANNIE MINOFF: He's like, who falls on their jaw at precisely this angle? Nobody. For Ardrey, it is perfectly obvious.
CHARLES: One needed nothing but the lay common sense of a jury man to return a verdict that at some terrible moment in ancient times, murder had been done.
ELAH FEDER: That being the voice of our co-worker, Charles, as Ardrey. Nothing but the-- what was it, the lay common sense?
ANNIE MINOFF: Yeah. And apparently, this is the right answer because--
ELAH FEDER: That murder has been done?
ANNIE MINOFF: Yes. Yes. Because Dr. Dart then goes on to share with Ardrey his theory, the killer ape theory. And it goes like this. So, way back in our history, when our ancestors were just small-brained Australopithecines, we learned how to kill. And not only did we learn how to kill, and maim, and murder, but according to Dart, killing is what made us human. Killing is what separated us forever from our peaceable ape cousins and put us on this path to becoming what we are today. Killing was the key to our evolution, which made no sense to me.
ELAH FEDER: Why would it have been beneficial for our ancestor to have invented murder? Like, why is this good evolutionarily?
ERIKA MILAM: It's generally not considered good evolutionarily. The concept of murder was deeply tied for our Ardrey, for Dart to the idea of hunting for meat. Hunting for meat is phenomenally useful.
ANNIE MINOFF: For Dart, killing animals for meat, killing each other, even cannibalism, they're kind of all part of the same phenomenon. And Dart thinks he has really good evidence that Australopithecus was indeed killing other animals for meat. He and his students have been looking at these fossils from South African caves, and Dart notices there seemed to be a whole lot of humerus bones in those caves.
ELAH FEDER: OK.
ANNIE MINOFF: And to him, those humerus bones look a little bit like clubs.
ELAH FEDER: Sure.
ANNIE MINOFF: And then he notices some of these animal skulls have these cracks and dents in them, kind of like they've been bashed in.
ELAH FEDER: With--
ANNIE MINOFF: By clubs.
ELAH FEDER: Right.
ANNIE MINOFF: Yes, and it's like it's all coming together. Our ancestors grabbed some of these bone clubs, whacked each other, just like in the opening of 2001, A Space Odyssey. And they also whacked other animals and ate them. Or as Dart put this slightly more colorfully in a scientific paper, Australopithecus, quote, "battered them to death, tore apart their broken bodies, dismembered them limb from limb," and-- how did he put this? Oh, yeah, "slaked their ravenous thirst with the hot blood of victims."
ELAH FEDER: It's not funny. Ugh.
ANNIE MINOFF: Language like this did not win Raymond Dart a whole lot of scientific support.
ELAH FEDER: Yeah, no kidding.
ANNIE MINOFF: But Robert Ardrey-- dramatist, script writer-- he is very alive to the dramatic possibilities of the killer ape theory. Robert Ardrey writes for pop science books inspired by killer apes. A few of them are bona fide bestsellers. Major newspapers review them. Columnists debate them on TV. NBC airs a primetime documentary featuring Dr. Raymond Dart talking about his killer ape theory.
And then, of course, comes 2001. Stanley Kubrick had gotten a hold of Ardrey's first book, extensively underlines it, and he brings this theory to the big screen with a level of accuracy and attention to detail that is startling. Like, I'd always assumed those apes at the beginning of the movie were just some kind of generic human ancestor ape.
ELAH FEDER: I thought they were chimps.
ERIKA MILAM: No, they are actually recreations of what people really thought Australopithecines would have looked like at the time. They are very specially created masks.
ANNIE MINOFF: Kubrick goes so far as to hire a paleoanthropologist to come on the set and to teach his actors how to move like they think Australopithecines would have moved.
So we asked this question-- how did the killer ape theory get so popular? And I think honestly, Robert Ardrey is a huge reason. But Ardrey's timing is also just really good. Because it's the 1960s, and people are thinking about violence a lot.
SPEAKER 3: Doctors are working feverishly over Senator Kennedy.
ERIKA MILAM: There are a whole series of high profile assassinations.
SPEAKER 3: A gurney has just been brought in. They're lifting Senator Kennedy onto the gurney now.
ERIKA MILAM: The US involvement in Vietnam is really communicating scenes of violence and destruction into American homes through flickering television scenes. Violent acts that would never have been allowed on TV if they were not real.
SPEAKER 4: All right, give me some cover!
ANNIE MINOFF: The assassinations of John F. Kennedy, Martin Luther King Jr, Robert Kennedy, the Tet Offensive, the My Lai Massacre-- like, this is what is coming through your television screen in the '60s and early '70s.
ELAH FEDER: And not that far off from World War II.
ANNIE MINOFF: Right.
ELAH FEDER: Yeah.
ANNIE MINOFF: And so it's really easy to imagine people watching this and thinking like, what is the deal with humans? Like, is this who we are? And then Robert Ardrey comes in with the killer ape theory, and he's like, you know what? Maybe.
SPEAKER 3: People are stunned. They can't believe what's happened. One woman's crying.
ANNIE MINOFF: And then, it all fell apart. Coming up, we were wrong-- the fall of the killer ape theory.
By the late 1960s, the killer ape theory is really big. That doesn't mean that everyone is buying it. From the beginning, Dart and Ardrey's evidence seems shaky.
ERIKA MILAM: There's a lot of assumption built on assumption built on assumption.
ANNIE MINOFF: And starting in the '60s, this paleontologist in South Africa named Bob Brain starts taking down those assumptions. So Dart and Ardrey had read, as you will recall, a whole lot of murder into some dented and cracked fossils. Bob Brain looks at those same fossils and is like, this is just fossil wear and tear. Like, this is what happens when piles of bones are crushed under sediment for thousands of years.
And where Dart and Ardrey had sold us this picture of ancient man as this bloodthirsty bone-wielding predator, Bob Brain sees something a little bit more deflating. He says, maybe Australopithecines were prey. Like, he finds this Australopithecine's skull with two holes in it that perfectly line up with the spacing of a leopard's canines. So maybe it wasn't actually man the hunter. Maybe it was man the hunted.
But this is a debate that's largely happening in the scientific press. None of this is reaching the public, who's still at the theater watching 2001. But then in the 1970s, Jane Goodall discovers something that makes everybody pay attention.
So a decade earlier, Jane Goodall made us all fall in love with chimps. She's on TV in the '60s playing with her chimp friends at the Gombe Stream Reserve in Tanzania.
JANE GOODALL: The chimps gradually came to realize that I was not dangerous after all. And after about 15 months, I was allowed to approach a small group without attempting to hide.
ANNIE MINOFF: This is from a primetime 1965 documentary. And Elah, oh my god, this is the cutest documentary I have ever seen.
ELAH FEDER: Baby chimp. So tiny! It poked her-- it booped her on the nose.
ANNIE MINOFF: Yeah.
ELAH FEDER: Oh, no.
SPEAKER 5: She has made friends of wild animals, and in so doing, has been able to observe them at closer quarters and in more intimate detail than has ever been managed before.
ANNIE MINOFF: And all this chimp cuteness works amazing for the killer ape theory because remember, chimps are supposed to be the path not taken. We are the killer apes. They are the peaceable, cuddly nose boopers. And then in the 1970s, Goodall pulls the rug out from under us.
ERIKA MILAM: When Goodall first goes to Gombe, there is only a single group of chimpanzees. And between 1960 and 1974, that single unitary group has actually split, and there's now two social entities, one in the north and one in the south.
ANNIE MINOFF: And in 1974, the male chimps in the southern group start getting murdered. So one of the first hits in this chimp war, as it comes to be described, is on one of Goodall's favorite chimps. It's an older chimp named Goliath. And he's cornered by a group of five chimps from the northern group, and he's savagely beaten so much that Goodall reports that he can no longer sit up. She later sent some of her assistants out to try to find him to see whether he'd survived, but they never found him again. And the same thing happens to other males in the southern group. So by 1978, there is no southern group of chimps anymore. So that's what's going on with the males circa 1974 in Gombe. What's happening with the females is, actually, in my opinion, more disturbing.
ERIKA MILAM: The main culprit, if you want to use that word, is Passion.
ANNIE MINOFF: So Passion is a female chimp. She has two kids, a female chimp named Pom and a male chimp named Prof. And one day, Goodall gets a call over her radio from Gombe that Passion has been seen eating another chimp's baby.
ERIKA MILAM: Passion goes and kills the infant of [? Glicka ?] and then brings that dead infant back to Pom and Prof and shares the meat as if it is normal prey.
ELAH FEDER: Passion ate another chimp's baby?
ANNIE MINOFF: Yeah.
ELAH FEDER: Ate.
ANNIE MINOFF: Ate. And this keeps happening. Over the next year, Passion and her daughter, they kill and they eat two more baby chimps from their own group. Goodall--
ELAH FEDER: Why is their group still hanging out with them?
ANNIE MINOFF: Good question.
ELAH FEDER: I'm sorry. You were saying something about Goodall.
ANNIE MINOFF: So Goodall describes being out in the field and watching Pom, the daughter chimp, and Passion, the mom. They're sitting next to this other mother from their group called Little B. And Little B is holding her baby.
ELAH FEDER: Oh god.
ANNIE MINOFF: And Goodall describes seeing Pom, the daughter, turn to look at Little B's baby, and reach out her hand towards the infant, and then look back at her mom, like, hey, what about this one? And Goodall actually tries to stop it. She starts yelling, throwing things, trying to make a racket and distract Pom so that Little B and her baby can get away. And they do, but Goodall is horrified.
ERIKA MILAM: One of the things that she says is that her vision of chimpanzee nature was never the same, that this fundamentally changed the way that she thought about chimpanzees as a species and the kinds of social behavior that they were capable of.
ANNIE MINOFF: Chimp violence is a problem for the killer ape theory. Like, if Dart and Ardrey are saying that the key thing that separated us from all the other apes was our ability to kill, explain chimps. It can't be the thing that made the difference. So the killer ape theory died.
And in the end, it wasn't one thing that killed it. There was a whole range of evidence from paleontology, anthropology, evidence from other primates. All of it came together to say, you know what? This theory doesn't really hold up. In fact, we're not even sure that Australopithecus africanus was our direct ancestor, though obviously they were in the family. And frankly, it's kind of a relief. Killer apes, along with whatever other problems it might have, was an incredibly cynical theory.
And these days, it kind of seems like the pendulum is swinging the other way. Like, scientists are looking at the fossil record and they're not seeing a whole lot of evidence of violence. Instead, they find--
AGUSTIN FUENTES: We were really compassionate.
ANNIE MINOFF: That's Agustín Fuentes. He's an anthropologist at Notre Dame.
AGUSTIN FUENTES: We developed not only the ability to hurt one another, but it seems like we spent more time feeding elderly who have lost all their teeth, or caring for a five-year-old Homo erectus who had a congenital defect, or helping individuals with broken legs or limbs. So there's really good evidence in the fossil record that we began to care for one another in ways that go way beyond what other organisms do, well before there's good evidence for us whacking each other over the head on a regular basis.
ELAH FEDER: I mean, yeah. I mean, of course, this is a thing that we do really well-- kindness. Not to discount our horrible violence, but sometimes people obviously do incredible things for each other. Like, we literally give each other body parts. So if I was going to pick something that made us humans special among the apes, I would pick that.
ANNIE MINOFF: Yeah, so scientists are also thinking along these lines. They're thinking that actually what makes us special and different from other apes, it isn't murder. It's cooperation.
ELAH FEDER: Aw.
ANNIE MINOFF: But that can also cut both ways.
AGUSTIN FUENTES: Cooperation allows us to build hospitals, and save lives, and change the world for the better, and to do awful things-- genocides, atrocities, torture, economic inequality, racism. All of that needs cooperation. So I think what we've got to get away from is this idea that we're hardwired to be good or bad. We have the capacity to be the worst thing on the planet and the best thing on the planet simultaneously.
ELAH FEDER: So, Annie, last thing before we go, uh--
ANNIE MINOFF: Yes.
ELAH FEDER: While you were researching this killer ape story, I got curious about who really is the murderiest of all the mammals.
ANNIE MINOFF: The murderiest?
ELAH FEDER: The most murderous. Somebody has, in fact, studied this.
ANNIE MINOFF: Inevitably.
ELAH FEDER: They tried to. They ranked all these different mammal species. And at the very top, at nearly 20%, so one in five deaths in this species they attributed to murder.
ANNIE MINOFF: Please tell me it's not us.
ELAH FEDER: Meerkats.
ANNIE MINOFF: No. Not Timon.
ELAH FEDER: Yeah. According to this one study anyway, one in five meerkat deaths are the result of murder.
ANNIE MINOFF: That is ghastly.
ELAH FEDER: So if murder, as Dart proposed, is the path to world domination-- thankfully you showed that it is not. But if it were, this would not be planet of the apes. It would be planet of the meerkats.
ANNIE MINOFF: Oh, boy.
[MEERKATS CRYING OUT]
Undiscovered was reported and produced by me, Annie Minoff.
ELAH FEDER: And by me, Elah Feder. Our senior editor was Christopher Intagliata, and our composer was Daniel Peterschmidt. This free version of Also Sprach Zarathustra is by Kevin MacLeod.
ANNIE MINOFF: Erika Milam's new book about the killer ape theory is called Creatures of Cain. You can find a link to it plus more info about this episode in our show notes. We are undiscoveredpodcast.org.
ELAH FEDER: Despite that dramatic exit, we're not totally entirely done yet. We're going to be back next week and the week after with two more episodes. These will be interviews that Annie and I did on Science Friday, again on the theme of We Were Wrong. And we hope you like them.