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Are humans violent by nature? Most of us answer that with a story rather than evidence.
The story goes like this. People snap. We shout, we slam doors, we hold grudges. That is the small version. War is the big version. Same thing, turned up louder.
It is a tidy story. It has been around a long time. And a team of researchers just tested it against 100 species of primates, including us — and it did not survive the test.
The species that squabble most are not the ones that kill
The study was led by Bonaventura Majolo and Samantha Wakes at the University of Lincoln, working with Marcello Ruta, and published in the journal Evolution Letters on 3 March 2026.
Instead of giving each species one overall “aggression score,” they broke aggression into five separate kinds:
- Mild aggression between groups — two troops shoving at a boundary
- Mild aggression within a group — the everyday bickering at home
- Killing of adults between groups
- Killing of adults within a group
- Infanticide — the killing of infants
Then they asked one question. Do these travel together?
Mostly, no. The three lethal kinds were linked to each other, moderately — a species that does one is somewhat more likely to do another. The tightest of those links was between killing adults inside the group and killing adults outside it; nearly the whole range of the model’s estimates pointed the same way.
But the link between everyday fighting and killing was so weak the models could not tell it apart from no link at all.
In plain words: a species can bicker constantly and almost never kill. Another can be calm most of the time and still kill. The temper and the killing are not one trait at two volumes. They are two different traits, with two different histories.
How they worked it out
Only wild primates counted. Group-living, and not fed by people — zoo populations and troops living off human food were left out, because a reliable food supply changes how animals treat each other.
The data came from published research running from 1950 to the middle of 2022, topped up with unpublished observations gathered in a survey of working primatologists. Then they ran it through models that account for the family tree, so that two species behaving alike because they are close cousins does not get mistaken for a pattern. They also controlled for five other things that might explain the behaviour instead: size difference between males and females, the sex ratio inside a group, group size, how much of the diet is leaves, and whether the species defends territory.
One honest wrinkle is worth knowing before you repeat the headline. The write-up describes 100 primate species, while the methods underneath describe a dataset covering 43 genera across 11 families, with a portion of it contributed by a survey of researchers. The paper does not reconcile those two figures. “100 species” is how the finding has travelled; the exact analysed sample is harder to pin to one number than the headline suggests.
The number almost nobody is quoting
Most coverage of this study mentions that adult killing shows up in roughly 20% of the species studied. That is true. It is also the smaller of the two numbers.
Infanticide showed up in about 65%.
That gap is large enough to want an explanation, and the researchers offer two. One is risk: killing an infant is far less dangerous to the attacker than taking on a full-grown adult. The other is simply how science gets done. Infanticide has been studied more systematically, and for longer. Adult killings are rare, fast, and easy to miss unless somebody happens to be watching that group on that day. So the 20% figure is probably a floor, not a ceiling.
Here is the part that runs backwards
Shared ancestry mattered — but not where you would expect.
The family tree explained more of the lethal behaviour than the mild behaviour. The strongest inherited signal of all five categories was male infanticide, where ancestry accounted for roughly 59% of the variation between species.
And the weakest signal of all five? Mild aggression within the group. The everyday squabbling at home.
Read that twice, because it is the reverse of how we talk about ourselves. The thing people excuse most often — that is just how I am, I have a temper, it runs in my family — is the one with the faintest family fingerprint in the entire dataset. The thing that genuinely does run deep in the lineage is the thing nobody would dream of excusing.
Which is a quietly uncomfortable finding, because it removes the most popular excuse for ordinary bad behaviour. Your temper is the least inherited thing about you. It is much closer to something rehearsed than something inherited — and rehearsal can be changed.
The difference is not appetite. It may be planning.
There is one more thread in the paper, and the authors are careful to present it as a suggestion rather than a measurement.
Killing an adult that requires real planning — coordination, patience, intent held over time — may be rare outside chimpanzees and humans. Most adult killing among other primates may simply be opportunistic. The chance appears and the animal takes it.
If that holds up, it moves the question somewhere more interesting. The thing that sets human violence apart might not be that we want it more. It is that we can carry it. We can hold an intention for weeks. We can rehearse a confrontation in the shower, replay it on the walk home, refine it over months. We decide in advance, and then wait.
Which is a strange place for a study of monkeys to arrive, because it lands almost exactly where some very old wisdom started. Long before anyone counted species, there was a claim that the root of killing was never the hand — it was the thing you nurse in private, the contempt you rehearse about someone when nobody can hear you. That old claim did not treat the private version as a harmless miniature of the real thing. It treated them as the same soil. And then it said two things at once, which is the part people usually miss: the capacity is real and it is already in you, and the outcome is not settled. Not denied. Not destiny either. Something you rule rather than something that rules you — and the oldest version of that idea never assumed a person was expected to do that ruling alone, but with God’s help in the part nobody can talk themselves out of.
The study and the old claim are answering different questions, and it is worth being clear about that. One is tracing behaviour through a family tree. The other is talking about something no model has a column for. But they agree on the shape of the thing: the squabble and the killing are not the same trait, and neither one is your fate.
A good place to start:
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What this actually changes for you
Not much, if you were hoping for permission.
The study does not say humans are gentle. It does not say violence is a myth. Majolo’s own caution is the right note to end on: he says “it is biologically inaccurate to rank species on the basis of their general propensity for aggression,” and that “we need a more nuanced approach when discussing whether humans are inherently violent.”
What it does take away is a very specific excuse — the one that says the small stuff and the terrible stuff are the same substance, and both are fixed. On the evidence, they are not the same substance. And the small stuff, the part you actually live with, is the least fixed part of all.
Three things worth doing with that, none of which cost anything:
- Stop filing them together. Losing your temper and wishing real harm on someone are two different problems. Treating them as one keeps you either over-ashamed of the first or strangely relaxed about the second.
- Watch the rehearsals, not the outbursts. The argument you replay while washing up. The reply you have now perfected and will never send. That is the part that compounds, and it is invisible, which is why it goes unchecked for years.
- Break the loop with your body. Walk somewhere. Carry something heavy. Say the thing out loud to an empty room so it stops circling silently. A rehearsal only survives in the quiet.
And if the loop you keep rehearsing has one particular person at the centre of it, that is its own separate knot — worth untangling on purpose rather than waiting for it to fade. Our free Am I Ready to Forgive? assessment is a short, honest way to find out where you actually stand, and what to do when the other person will not forgive you covers the harder direction of that.
The monkeys in that dataset argue all day long and mostly do not kill each other. The distance between those two facts is not luck and it is not nothing.
It is the room you live in too.
What Do You Think?
If everyday anger and real violence are genuinely separate traits, should we stop treating a short temper as a warning sign at all — or is that exactly the kind of thinking that lets the dangerous ones hide in plain sight? Tell us where you land in the comments.
Share This
Researchers compared aggression across 100 primate species. The ones that squabble most are not the ones that kill. Fighting and killing turned out to be two separate traits, not one trait at two volumes. https://bgodinspired.com/index.php/personal-growth-and-life-skills/are-humans-violent-by-nature/
Your temper is the least inherited thing about you. In a study of 100 primate species, everyday squabbling had the weakest family signal of any aggression type measured. https://bgodinspired.com/index.php/personal-growth-and-life-skills/are-humans-violent-by-nature/
Turns out “I have a temper, it runs in my family” is the one part the evidence does not back up. https://bgodinspired.com/index.php/personal-growth-and-life-skills/are-humans-violent-by-nature/
Questions People Are Asking
Are humans violent by nature?
A 2026 study in the journal Evolution Letters, covering 100 primate species including humans, found that mild aggression and lethal violence are not closely linked across species. Species that fight often are not reliably more likely to kill. The study does not conclude that humans are non-violent; lead author Bonaventura Majolo has said it is biologically inaccurate to rank species by a general propensity for aggression, and that a more nuanced approach is needed when asking whether humans are inherently violent.
Is everyday anger the same thing as violence?
Not according to the evolutionary evidence. Researchers at the University of Lincoln split aggression into five types across primate species and found that the lethal types correlated moderately with each other, while mild aggression showed no meaningful statistical relationship with any lethal type. The idea that violence is simply ordinary conflict escalated is not supported by how these behaviours are distributed across species.
How common is lethal aggression among primates?
In the Evolution Letters dataset, infanticide was present in roughly 65% of the species examined, and the killing of adults in roughly 20%. The researchers note the adult figure is likely conservative, because adult killings are rare, difficult to observe, and less systematically studied than infanticide. The study recorded only whether a behaviour was present or absent in a species, not how often it occurs.
Which kind of aggression is most inherited?
Male infanticide had the strongest phylogenetic signal of the five aggression types measured, with shared ancestry accounting for roughly 59% of the variation between species. The weakest signal belonged to mild aggression within a group — everyday squabbling among members of the same troop. In other words, routine conflict showed the least evidence of being shaped by a species’ evolutionary lineage.
Where was this primate aggression study published?
The paper, titled “Origins of violence: evolutionary decoupling between mild and lethal conspecific aggression in primates,” was published in Evolution Letters on 3 March 2026 by Bonaventura Majolo, Samantha J. Wakes and Marcello Ruta of the University of Lincoln. It drew on wild, non-provisioned, group-living primate populations documented between 1950 and mid-2022, plus unpublished survey data from primatologists. The study is available here.
