Violence in humans evolved because of fish

Research has claimed that humans have an innate drive for violence. A drive influenced by our territoriality. But why are humans like that? Because of fish


Darwin referred to evolution as a “struggle for survival”. This is often visualised as a struggle between species. However, intraspecies violence is also a key part of evolution. Beating out your competitors can give a huge advantage. So might some species – including humans – evolved a drive for violence?

New research suggests this may be the case. And we might be like this because of our reliance on fish.

Violence evolved

A paper recently published in Nature made a fairly bold claim. Many mammals – including humans – have an innate tendancy towards violence. There’s something bubbling in our subconcious. A drive for death produced by millions of years of evolution.

This dramatic conclusion stems from a massive phylogeny the researchers carried out. Essentially, they put all the animals examined in a family tree. They then looked at the rates of violence within those families. If evolution was at work, closely related species should have similar levels of violence. They’re all part of the same group, after all.

The phylogeny of violence. A family tree of mammals, with more violent ones in red. Note how the more closely related species have similar colours

The phylogeny of violence. A family tree of mammals, with more violent ones in red. Note how the more closely related species have similar colours

As their dramatic claim indicates, they found that this prediction was vindicated. Many groups do have a “baseline” of violence. In most species with this violent tendency, this should result in ~2% of the population being killed by members of the same species.

However, this inherited baseline can’t explain all cases of intraspecies killing. Some groups fought more than their family history would indicate, others less so. It turns out there are certain factors which can amplify or downplay this innate baseline. These key variables are terretoriality and sociality.

The more terratorial a species is, the more likely they are to get into scraps. More social species also tend to wind up in conflict as well.

Why humans?

There seems to be an essential “baseline” of violence that evolved in many species. Including humans. But this net violence is amplified by our territoriality and intense sociality. But it’s not inevitable we turned out that way.

Bonobos are as closely related to us as chimps. Yet they’re far less territorial than their more famous counterparts. As a result, murder is rarely witnessed in bonobos. Yet chimps fight so much that there are Wikipedia pages about their wars. Why do we appear to have fallen closer to the chimp side of the scale? Why are we so much more aggressive about our territoriality?

Fish hold the answer.

They've been plotting to take us down this whole time

They’ve been plotting to take us down this whole time

When you look at all animals a general trend emerges. The hyper-territoriality that can drive human and chimp conflict only appears under certain circumstances. Namely, when the territory contains something within it worth defending.

From that, we can make some inferences about our evolution. At some point in human prehistory, we likely began exploiting a food source that was very valuable. It was rich and predictable, so could be exploited in large quantities. It made life great for those that had it. So naturally, people began fighting over it.

Research has examined the African archaeological record to try and pinpoint that vital resource. The abundant food source that drove humans towards territoriality. It turns out only aquatic resources meet these criteria. People began exploiting rivers, lakes, and coastline from ~160,000 years ago onwards. The food they obtained was rich and predictable, allowing them to exploit it intensley.

Although that might sound like a utopia, it turns out to be a recipie for violence.

Caveats and conclusion

The result of all this research is a comprehensive understanding of why people can be so nasty to each other. Armed with this information, we may be able to improve our conflict resolution. Encourage the better angels of our nature to take hold.

However, before making any dramatic decisions based on this work there are a few caveats. In particular, there are some eyebrow raising issues with the research into our innate level of violence. For example, they predict that most species should kill each other around 2% of the time. Yet they were unable to find a human group that fit that pattern. Modern societies tend to have much lower levels of violence, whilst hunter-gatherers and historical comunities murder each other much more.

The fact this prediction was not vindicated certainly casts some doubt on their claims for an innate “violence baseline”. However, it doesn’t change the fact they show that territoriality influences violence. And that fish made people territoriality.

So whilst the innate nature of human violence might still be up for debate, the fact of the matter is what violence does occur has its roots in the ocean. And those pesky fishy masters.

References

Gómez, J.M., Verdú, M., González-Megías, A. and Méndez, M., 2016. The phylogenetic roots of human lethal violence. Nature.

Marean, C.W., 2016. The transition to foraging for dense and predictable resources and its impact on the evolution of modern humans. Phil. Trans. R. Soc. B, 371(1698), p.20150239.

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5 thoughts on “Violence in humans evolved because of fish”

  1. hari says:

    “At some point in human prehistory, we likely began exploiting a food source that was very valuable.” Any food source that becomes scarce can artificially rise in value. The same effect can be achieved by hoarding food sources out of greed and preventing others access to it. It is this greed that has driven violence in humans right from the day we began moving out in search of greener pastures. The conclusion pointed out by you that fish drove violence seems very strange when we can see right in front of us how greed drives violence everywhere even today. I guess exotic claims are more fancied than the mundane

    1. Adam Benton says:

      You can create value through scarcity (and in turn, greed). However, for that value to influence human behaviour it must pass a certain threshold. For hunter-gatherers to care about a resource, hoarded or not, it must meet certain criteria. Ultimately, only aquatic resources do. Other resources, even if you make them seem valuable by increasing scarcity, still don’t rise to the levels worth fighting over.

      1. hari says:

        I’m sorry but your words certain criteria seems vague to me. Today poverty the biggest cause of violence everywhere is the direct result of hoarding by the rich. This is legitimised through an arbitrary economic system. Acquatic resources play significant part in human interactions only on islands and coastal areas. Terrorism is widespread in the Middle East as the oil resources have been hoarded and the common people left in abject poverty. Where is the role of acquatic resources in this?

        1. Ned Lips says:

          The researchers are not talking about last week. They are talking about how our species evolved millennia ago into a “violent” society. That being said, our modern social structure is not arbitrary. Individuals for whom wealth is important have done and do what it takes to acquire it. Those who are good at doing so, actually acquire it. They then figure out ways to convince others that they should continue to own it. For some reason, the others seem to be OK with characterizations of the elite as gods, etc. Those leaders only need enough followers to create a military stronger than everyone else’s. This is not arbitrary, even today. It is the game. Some play it well. Others do not. That divides the haves and have nots. Always has and always will.

        2. Adam Benton says:

          If you read the article, I go into this criteria. A resource must both be rich and predictable. That way the richness can be reliably exploited. Hunting for meat produces a rich return, but that return is unpredictable as you don’t know when you’ll be able to make a kill. A migrating species might be predictable, but since it only turns up once a year it isn’t too rich. Fish are the long term resource which meet those criteria, and so may have driven past humans to begin defending territory where fish was abundant enough.

Leave your filthy monkey comments here.

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