A recent study examined the concept of self-domestication in humans, bonobos, and elephants. The research, led by Limor Raviv, suggests that human evolution, similar to animal domestication, may have favored less aggressive and more prosocial individuals. These traits foster complex community interactions and learning.

Elephants, alongside humans and bonobos, exhibit self-domestication hallmarks such as low aggression, empathy, prosocial behavior, extended juvenility, playfulness, and complex communication. Elephants demonstrate learned behaviors, sophisticated multimodal communication, and signs of grammar in vocalizations. They also show genetic markers associated with domestication.

The study posits that elephants’ large size and strength create a ‘safe environment’, reducing the need for aggression and allowing cognitive development towards communication and exploration. This research offers insights into the evolution of prosocial behavior and convergent evolution across diverse species.

Limor Raviv discussed her research with SCINQ.

Let’s start at the beginning. What made you study elephants and self domestication?

Though I’m not an animal scientist, I’ve studied the evolution of language, and I’m deeply intrigued by various theories that attempt to explain how and why language developed. Particularly fascinating is the question of whether it’s evolution and society that shape language, and in this context, the self-domestication theory has sparked my interest.

I’m curious about how and why human language has evolved to be so distinct, setting us apart from other animals. Among various theories posited, one intriguing idea is the self-domestication hypothesis, a famous concept within human evolution. Recently, in the past five years or so, researchers have started using this theory to explain the emergence of human language. Although I’m not entirely convinced by this hypothesis, I do find it compelling because it generates testable predictions, a rarity in the field of language evolution, which is often shrouded in mystery.

When I first delved into the self-domestication theory, I came across the idea of ‘domestication syndrome.’ To give you a bit of background, Charles Darwin noticed a long time ago that many domesticated animals, despite hailing from different taxa or clades, shared certain traits. These traits were not necessarily expected as a result of domestication, a process where humans selectively breed animals to make them more tame and sociable. For instance, pigs, dogs, sheep, and even fish have undergone this process. Consequently, these domesticated animals share a suite of traits we now refer to as the ‘domestication syndrome.’

A perfect example of this is the famous silver fox experiment, where wild foxes were selectively bred over roughly 13 to 15 generations for their tameness alone. The result was a docile, domesticated fox that also exhibited a range of other traits, such as variations in pigmentation and size, which were not the primary focus of selection.

What’s really intriguing is that humans, too, appear to share many traits associated with domestication. This led to the term ‘self-domestication,’ but it’s important to clarify that this doesn’t mean we actively domesticated ourselves. Rather, it suggests that we may have evolved certain traits naturally, perhaps as a consequence of being selected for more prosocial behavior, similar to domesticated animals.

As I delved into the concept of the domestication syndrome, I was struck by the similarities between humans and certain animals, such as elephants. From my observations, elephants displayed complex social behavior, cooperative tendencies, and sophisticated communication, which, coupled with a lack of aggression, seemed to align with many traits of domestication.

This observation sparked a research endeavor with another scientist, Antonio, who also has a background in linguistics and biology. Despite our lack of expertise in elephant biology, we decided to investigate this hypothesis further. We consulted a group of elephant researchers to ensure we weren’t cherry-picking data or misinterpreting studies due to our unfamiliarity with the field.

Encouraged by their initial reactions, we decided to conduct some preliminary genetic analysis since domestication, at its core, is a process that leaves specific genetic markers. This eventually led to the paper we produced, proposing the idea of elephants as self-domesticated animals.

However, it’s crucial to note that this is just an initial proposal. To firmly establish the self-domestication of elephants, much more research is needed. It’s entirely possible that future studies could refute this hypothesis by revealing, for instance, the absence of specific genetic markers. Nevertheless, this exploration has been a significant first step in our understanding of the self-domestication hypothesis in the context of elephants.

So why is it difficult to test the theory of self-domestication?

This principle likely applies to any theory, especially when we delve into subjects like human evolution or even evolution at large. We understand that evolution is a complex, multifaceted process influenced by various factors, including social and environmental pressures. Many of these cannot be reconstructed, and our understanding of them is often a matter of conjecture and hypothesis. Moreover, piecing together the puzzle of evolution requires the synthesis of a plethora of resources.

It may be tempting to simply sit on your couch and conjure up ideas about how humans evolved, crafting plausible narratives. However, the reality is more complex; we don’t possess a time travel machine to go back and observe what really happened. The process of uncovering the past relies heavily on indirect evidence, on the interpretation of what we have at our disposal.

Testing this theory is no more difficult than testing others. This points to a broader lesson about the field’s inherent challenges and appeal. These processes are complex, spanning multiple generations and influenced by various pressures at different critical junctures.

I emphasize this point not solely in the context of human evolution, but as a challenge faced by anyone studying evolution in general. The evolution of many other species presents similar difficulties. Thus, our task remains to piece together what we can from the evidence at hand, continuously revising our understanding of evolution.

There are certain hallmarks of domestication like low aggression, empathy, and so on. Can you discuss them?

Certainly, let’s delve into the behavioral markers of self-domestication. I believe these are often the ones that garner the most interest. The first marker is reduced aggression, particularly spontaneous or reactive aggression. This doesn’t mean the absence of all aggression; it’s evident that aggression is prevalent in society, especially under certain political climates. However, the type of aggression we often see in human societies is premeditated and requires a degree of cooperation. For example, it takes thousands or millions of people working together to initiate a war.

In contrast, when we speak of reduced aggression in the context of self-domestication, we refer to individual tendencies towards sociality and gentleness, especially towards non-kin. While many animals exhibit social behaviors, they are typically limited to close kin or small social units. Conversely, most animals exhibit aggressive behavior towards strangers. This is typically not the case with humans. In fact, one of the reasons this theory suggests language as a product of self-domestication is because language facilitates communication and negotiation with strangers, helping to deescalate potential violence.

A notable marker in domesticated animals is this reduction of aggression, not only towards their own kind but also towards humans. For instance, a recent study showed that dogs can be aggressive towards other dogs but are usually more gentle towards humans. In self-domesticated species like humans, this is an internal process that fosters more tolerance among individuals and towards offspring.

Another significant aspect is high cooperation, which is different from reduced aggression, although they seem interconnected. Cooperation involves working together in large groups to achieve shared goals, sharing information and resources, as observed in both humans and elephants.

Enhanced play behavior is another characteristic I find interesting. While play is common among young animals, it’s usually limited to a specific period in childhood. Domesticated animals, however, tend to have extended juvenile periods, exhibiting more exploratory behavior and using play to form social bonds. This increased playfulness seems to correlate with an enhanced sociability.

In conclusion, these markers of self-domestication – reduced aggression, increased cooperation, and enhanced playfulness – along with sophisticated communication systems, exemplify the evolutionary pressures that have shaped the self-domesticated species like humans and elephants. We observe not only an increased social responsiveness but also an extension of juvenile behavior patterns and a more sophisticated means of internal communication. The outcome is an unparalleled, incredibly sophisticated, and multimodal language to convey our needs and desires.

So, going from there… Elephants learn from each other and, as you said, they exhibit really sophisticated multimodal communication systems. They even have signs of grammar in how they communicate. Can you elaborate on that?

While the concept of combining different elements in meaningful ways is fascinating, I must clarify that it’s not part of my work and the evidence for this is still preliminary. As such, it might be better for us to steer away from making definitive conclusions as it’s not well-established yet.

Our hope is that our paper will motivate more researchers to delve into the study of elephant communication, as it’s a captivating area with hints of complex behaviors. These behaviors include not just referential communication but also aspects like turn-taking, dialects, and other elements typically associated with human communication.

Unlike many animals, elephants’ communication systems are learned, which is relatively unusual in the animal kingdom. While most communication systems are innate to some degree – for example, different species of chimpanzees around the world emit the same calls for the same contexts – this doesn’t seem to be the case for elephants. Communities of elephants can possess distinct ‘languages’, and there have been reports of two herds needing to ‘converse’ for a while to form a mutual understanding when they first meet.

The study of elephant language has not attracted extensive interest yet, particularly from people who don’t exclusively study elephant communication. We hope that our paper will spark interest in this area, encouraging more research into elephant communication to uncover possible precursors of human language syntax and more. However, it’s important to emphasize that we currently lack sufficient evidence to state these ideas with full confidence.

Can you explain how the creation of a safe environment might promote pro-social behavior?

That’s a great question indeed. Self-domestication can come about in a couple of ways. One is through natural selection favoring more pro-social traits – perhaps something in your environment makes it beneficial to exhibit more social behavior. This is one pathway.

The other route is through a relaxation of the pressure to be aggressive. In the natural world, aggression is often the norm due to the survival-of-the-fittest principle. There’s pressure to be dominant, strong, and to some extent, aggressive. But when this selection pressure for aggression diminishes in a safer environment, it can indirectly foster pro-sociality.

For instance, let’s look at bird domestication. If there’s ample space for all members of a species, adequate shelter, no threats from predators, and an abundance of resources, then the need to compete reduces significantly. In the past, we may have needed to fight over every fruit or grain for survival. In a safe, resource-rich environment without predators, that struggle becomes redundant.

This shift frees up cognitive resources and time, as animals no longer need to constantly be on high alert. Take a gazelle, for example – it spends much of its life being vigilant, anxious, and constantly scanning its surroundings. But over many generations, if the evolutionary pressures for this hyper-awareness were removed, the gazelle could potentially allocate its time, attention, and cognitive resources differently, such as towards exploration. It’s a fascinating concept to consider: what would these creatures do with the mechanisms and time originally dedicated to survival once they no longer need them?

Your paper also discusses potential triggers for self-domestication. Can you elaborate on that? 

Yes, it’s closely connected. What triggers self-domestication can largely depend on environmental factors.

For instance, one scenario could involve an extremely harsh environment where survival becomes increasingly challenging. In such a situation, no single individual can thrive independently, thus necessitating cooperation. This could trigger a process promoting pro-social behavior.

Conversely, in a resource-rich environment devoid of predators, such as the case with bonobos who reportedly found themselves in an island-like area teeming with resources, the need for aggression could significantly reduce. This would pave the way for more cooperative, tolerant, social, and playful behaviors to emerge.

So, depending on the environmental conditions, the triggers for self-domestication can vary, even though it might sound contradictory. A harsh environment may demand cooperation, whereas a resource-abundant, predator-free environment may enable the relaxation of aggressive behavior.

For humans, the prevailing theory suggests that it was harsh conditions during the Paleolithic era that compelled our ancestors to cooperate more. However, for elephants and bonobos, two other species thought to be self-domesticated, the story leans towards an environment of abundance, thereby relaxing pressures.

Perhaps humans went through a similar process as the elephants and bonobos, but determining this is challenging due to a lack of concrete evidence. To clarify our evolutionary history, we would need more archaeological and genetic data to understand the dietary pressures and other factors that characterized our ancestors’ lives.

Can you just explain the genetic findings that seem to support the self-domestication hypothesis?

Okay, I’ll provide a simplified explanation without going too deep into the details. It might not be 100% accurate, but it should give you a sense of our findings.

Across domesticated species, you can find certain genes that appear to have been consistently selected or enriched, as we term it. These genes are shared among different animals if they’re domesticated. This implies that there is a pool of genes associated with the process of domestication, likely because they are enriched in all these different domesticated animals.

We tested these genes to see if they were also enriched in elephants, and indeed some were. However, these results are very preliminary for two reasons. First, we only had the genome for African elephants, not Asian elephants. At this point, there is no sequence typology known for Asian elephants. We only have a genome from one specimen of two African elephants that has been sequenced. Despite this, there seems to be some overlap.

Second, the last common ancestor of humans and all these animals is the lowest common ancestor of all placental mammals. Given this deep ancestry, a lot of changes could have taken place.

We also looked at genes that were positively selected for in elephants. Some of them seemed to be associated with mechanisms and traits that are relevant for domestication, like sociability, or the management of aggression and anxiety. So those are the two different sources of evidence we have, and that is a very broad outline of our study.

IMAGE CREDIT: Tomáš Malík

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