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Why Humans Prefer Phylogenetically Closer Species: An Evolutionary, Neurocognitive, and Cultural Synthesis
Obstetrics and Gynecology Unit, Sassuolo Hospital, 41049 Sassuolo, Italy
Biology 2025, 14(10), 1438; https://doi.org/10.3390/biology14101438 (registering DOI)
Submission received: 28 August 2025
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Revised: 15 October 2025
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Accepted: 17 October 2025
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Published: 18 October 2025
Simple Summary
Humans often feel more empathy for animals that are evolutionarily closer to us, such as dogs, cats, or horses, than for more distant species like reptiles, fish, or insects. This difference arises from how our brains recognize signals of emotion and intention—faces, eyes, voices, and movements that resemble our own. Shared biology, particularly the hormones that support bonding and care, strengthens these emotional ties. Culture and education also play a role: children’s stories, pets at home, and media images usually focus on mammals, while other animals are less visible or portrayed as dangerous. Yet, this bias can change. When people learn about the intelligence of octopuses, the cooperation of bees, or the parental care of fish, they often feel greater compassion and respect. Understanding why empathy follows evolutionary proximity helps educators and conservationists design ways to extend moral concern to all living beings. Protecting biodiversity then becomes not only a scientific or ethical goal, but also an act of empathy that connects human well-being with the health of the planet.
Abstract
Humans form deep attachments to some nonhuman animals, yet these attachments are unequally distributed across the tree of life. Drawing on evolutionary biology, comparative cognition, neuroscience, and cultural anthropology, this narrative review explains why empathy and affective preference are typically stronger for phylogenetically closer species—especially mammals—than for distant taxa such as reptiles, fish, or arthropods. We synthesize evidence that signal recognizability (faces, gaze, vocal formants, biological motion) and predictive social cognition facilitate mind attribution to mammals; conserved neuroendocrine systems (e.g., oxytocin) further amplify affiliative exchange, particularly in domesticated dyads (e.g., dog–human). Ontogenetic learning and media narratives magnify these effects, while fear modules and disgust shape responses to some distant taxa. Notwithstanding this average gradient, boundary cases—cephalopods, cetaceans, parrots—show that perceived agency, sociality, and communicative transparency can overcome phylogenetic distance. We discuss measurement (behavioral, psychophysiological, neuroimaging), computational accounts in predictive-processing terms, and implications for animal welfare and conservation. Pragmatically, calibrated anthropomorphism, hands-on education, and messaging that highlights agency, parental care, or ecological function reliably broaden concern for under-represented taxa. Recognizing both evolved priors and cultural plasticity enables more equitable and effective science communication and policy. Expanding empathy beyond its ancestral anchors is not only an ethical imperative but a One Health necessity: safeguarding all species means safeguarding the integrity of our shared planetary life.
