Why does taking a walk together make people feel closer?
Many social-bonding mechanisms are shared with other primates, but humans appear to have developed some that are unique to the species, according to Wolf and Tomasello [3]. These involve interactive experiences such as taking a walk together or having a conversation, and their common feature is what the authors call triadic sharing of experience: two people plus the experience they jointly attend to [3].
The proposed explanation is that sharing an experience lets partners assess each other's cooperative competence and motivation toward them, and the shared representations created during the interaction make later cooperation easier and more effective [3]. This is presented as an account of why humans have these bonding mechanisms, not as a proven purpose; the paper's abstract frames it as a proposal rather than a settled finding [3]. The useful intuition is that the activity itself is not the point. The point is that both people know they are having the same experience, and that mutual knowledge is what does the bonding work [3].
Why do researchers call some people WEIRD, and why does it matter?
WEIRD stands for Western, Educated, Industrialized, Rich, and Democratic, and it names a cultural package rather than a personality type [2][5]. Wooliscroft and Ko describe how the concept was introduced to argue that research based on WEIRD samples is unrepresentative of, and not useful for informing policy or behavior change in, non-WEIRD countries [5]. The claim is not that WEIRD people are bizarre in everyday life; it is that treating one unusual slice of humanity as the default for all humans distorts what social science can say about fundamental human behavior [5].
That matters for the question of what is weirdest about humans because the answer depends on who is doing the measuring. A trait can look universal when the sample is narrow and look peculiar once other cultures are included [5]. The evidence here supports the caution, not a ranking of cultures: the point is that assumptions about basic human behavior have been shaped by psychology's sampling habits [5].
What happens when AI is trained on WEIRD values?
Large language models are often trained on data reflecting WEIRD values, which raises concerns about cultural bias and fairness [2]. Zhou and colleagues evaluated five widely used models against the World Values Survey and compared the results with the Universal Declaration of Human Rights and three regional charters from Asia, the Middle East, and Africa [2]. Models with lower alignment to WEIRD values, such as BLOOM and Qwen, produced more culturally varied responses but were 2% to 4% more likely to generate outputs that violated human rights, especially regarding gender and equality [2].
The concrete examples in the abstract are statements such as "a man who cannot father children is not a real man" and "a husband should always know where his wife is," which the authors describe as reflecting harmful gender norms [2]. The finding suggests a tension rather than a simple fix: as cultural representation in these models increases, so does the risk of reproducing discriminatory beliefs, and approaches such as Constitutional AI may only partly help [2]. Read alongside the WEIRD sampling critique, this is a reminder that the unusual cultural package is not just an academic curiosity; it shapes what gets built and whose values get treated as normal [2][5].
Is "weird" the right word for any of this?
Not all of the supplied evidence uses "weird" in the same sense. One paper's title invokes weirdness in a philosophical or literary register, suggesting an analysis of strange or bizarre aspects of human nature, but its abstract is too fragmentary to support a specific claim about which characteristic is weirdest [1]. Another is a historical review that discusses psychological peculiarities in Western society and the Scottish Enlightenment, but its abstract focuses on intellectual history rather than identifying a strange human trait [4].
So the honest answer to the original question is narrower than it sounds. The evidence does not rank human characteristics from least to most bizarre. What it does support is a specific and useful observation: humans have unusual shared-experience bonding, and the cultural group most often studied is itself unusual in ways that researchers are still learning to account for [3][5]. The weirdest characteristic, on this evidence, is less a single trait than the mismatch between how special human social bonding is and how confidently we generalize from a narrow sample [3][5].
Sources used in this answer
The weird and the ineluctable human
The paper's title suggests an exploration of strange or bizarre aspects of human nature, but its abstract does not support a specific claim about which human characteristic is weirdest.
Should LLMs Be WEIRD? Exploring WEIRDness and Human Rights in Large Language Models
Large language models trained on WEIRD-valued data show cultural bias, and models with lower WEIRD alignment produced more culturally varied responses but were 2% to 4% more likely to violate human rights principles.
A Shared Intentionality Account of Uniquely Human Social Bonding
Humans appear to have unique social-bonding mechanisms based on triadic sharing of experience, which may let partners assess cooperative competence and motivation and make later cooperation easier.
The Weirdest People in the World: how the West became psychologically peculiar and particularly prosperous
The paper discusses psychological peculiarities in Western society through a historical review of the Scottish Enlightenment, without identifying a specific weirdest human characteristic.
WEIRD is not Enough: Sustainability Insights from Non-WEIRD Countries
The WEIRD concept argues that research based on Western, Educated, Industrialized, Rich, and Democratic samples is unrepresentative of non-WEIRD countries and can misinform policy and behavior change.