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Disease outbreak experience alters food safety behaviors in macaque monkeys (opens in a new tab)

news-medical.net · 2026-10-21

Short answerEvidenceSource

Short answer

Mixed

Mixed.

One claim goes further than the study. 3 other points were not covered by the paper.

  • 2 supported
  • 1 overstated
  • 3 not covered

Checked against the study summary. The full text wasn't available, so some details couldn't be settled either way.

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Follow the evidence trail
1
2

NewsLink checks it

Mixed

One claim overstates the study. Two of six check out. Three claims the study doesn't address.

  • 2 supported
  • 1 overstated
  • 3 not covered
Open claim evidence
3
Then inspect each claim

Evidence layer

Claim by claim

Each claim gets a verdict. Expand it to see the evidence directly below.

6 claims in this story

Showing all 6 claimsChoose a verdict to focus the list.

Claim 1 of 6OverstatedResearchers found that macaque monkeys who had lived through a deadly disease outbreak became significantly more cautious about food that appeared contaminated, even though they did not know how the disease had spread.View evidenceHide evidence

Why this verdict

The paper profile supports an association: Japanese macaques from outbreak-exposed groups showed significantly higher avoidance of contaminated substrates than macaques from an unexposed group. However, the story wording that they 'became' more cautious implies a within-animal or causal change after the outbreak, while the profile describes a naturalistic, non-randomized between-group exposure comparison. Details that the outbreak was 'deadly' and that monkeys did not know how disease had spread are not verifiable from the abstract-level profile.

1

Study evidence

Within sanctuary-born Japanese macaques (n = 55 across four groups), individuals from groups that had recently experienced an infectious disease outbreak showed greater avoidance of contaminated substrates in a visual food-choice task than individuals from the unexposed group.

“Our second study tested sanctuary-born Japanese macaques (n = 55) from four groups; three groups had recently experienced an infectious disease outbreak.”
Claim 2 of 6Not coveredThe researchers tested 55 macaques and reported that outbreak-exposed groups ate from the contaminated-looking surface in 47% of trials, compared with 79% of trials for monkeys from the group that had never experienced the outbreak.View evidenceHide evidence

As stated47% vs 79%

Why this verdict

The abstract-level profile verifies that Study 2 tested 55 sanctuary-born Japanese macaques and found higher avoidance in outbreak-exposed groups. It does not report the stated 47% versus 79% trial percentages, so the exact magnitude cannot be verified at abstract depth.

1

Study evidence

Within sanctuary-born Japanese macaques (n = 55 across four groups), individuals from groups that had recently experienced an infectious disease outbreak showed greater avoidance of contaminated substrates in a visual food-choice task than individuals from the unexposed group.

“Our second study tested sanctuary-born Japanese macaques (n = 55) from four groups; three groups had recently experienced an infectious disease outbreak.”
Claim 3 of 6Not coveredThe article says outbreak-exposed monkeys behaved similarly whether or not they themselves had been infected, suggesting the change was associated with living through the outbreak rather than becoming ill.View evidenceHide evidence

Why this verdict

The profile supports a group-level association between recent outbreak exposure and greater avoidance, but the abstract-level evidence does not report analyses comparing monkeys that were personally infected versus not infected. The claim that behavior was similar regardless of individual infection status is therefore not verifiable at this depth.

1

Study evidence

Within sanctuary-born Japanese macaques (n = 55 across four groups), individuals from groups that had recently experienced an infectious disease outbreak showed greater avoidance of contaminated substrates in a visual food-choice task than individuals from the unexposed group.

“Our second study tested sanctuary-born Japanese macaques (n = 55) from four groups; three groups had recently experienced an infectious disease outbreak.”
Claim 4 of 6Not coveredIn a related study described in the same paper, former pet macaques were significantly more likely to eat contaminated food than sanctuary-born macaques raised by their mothers.View evidenceHide evidence

Why this verdict

The abstract-level profile supports the directional finding that sanctuary-born macaques showed greater avoidance of contaminated substrates than former pets. However, it does not provide the statistical details needed to verify the word 'significantly,' nor does it verify the specific description that sanctuary-born macaques were 'raised by their mothers.'

1

Study evidence

In a visual food-choice task (n = 54, seven macaque species), macaques preferred feeding from non-contaminated substrates; sanctuary-born individuals showed greater avoidance of contaminated substrates than former pets.

“Our first study tested macaques (n = 54) from seven different species and four different rearing backgrounds in a visual food-choice task where food was either placed on a substrate with or without pathogenic cues.”
Claim 5 of 6SupportedA new University of California San Diego study suggests that humans may not be alone in changing behavior after experiencing a disease threat.View evidenceHide evidence

Why this verdict

The abstract-level profile supports the hedged idea that nonhuman macaques show altered pathogen-avoidance behavior associated with recent disease exposure, and the authors interpret the findings as relevant to flexible behavioural immune systems with evolutionary relevance to human disgust. The claim is framed cautiously rather than as direct evidence about humans.

1

Study evidence

Within sanctuary-born Japanese macaques (n = 55 across four groups), individuals from groups that had recently experienced an infectious disease outbreak showed greater avoidance of contaminated substrates in a visual food-choice task than individuals from the unexposed group.

“Our second study tested sanctuary-born Japanese macaques (n = 55) from four groups; three groups had recently experienced an infectious disease outbreak.”
2

Study evidence

Early-life rearing background and recent group-level disease exposure are interpreted to shape individual pathogen avoidance sensitivity in macaques, based on the combined results of Study 1 and Study 2.

“Together, our findings suggest that early life rearing experience and recent disease exposure shape pathogen sensitivity in macaques, demonstrating a flexible behavioural immune system in Old World monkeys.”
Claim 6 of 6SupportedThe study, published in Royal Society Open Science, says pathogen-avoidance behavior can be shaped by experience and may offer clues about the evolutionary roots of disgust.View evidenceHide evidence

Why this verdict

This matches the authors' abstract-level synthesis that early-life rearing experience and recent disease exposure shape pathogen sensitivity in macaques, supporting a flexible behavioural immune system and suggesting possible relevance to the evolutionary foundations of human disgust. The claim is appropriately hedged as an implication rather than a directly proven human-evolution result.

1

Study evidence

In a visual food-choice task (n = 54, seven macaque species), macaques preferred feeding from non-contaminated substrates; sanctuary-born individuals showed greater avoidance of contaminated substrates than former pets.

“Our first study tested macaques (n = 54) from seven different species and four different rearing backgrounds in a visual food-choice task where food was either placed on a substrate with or without pathogenic cues.”
2

Study evidence

Within sanctuary-born Japanese macaques (n = 55 across four groups), individuals from groups that had recently experienced an infectious disease outbreak showed greater avoidance of contaminated substrates in a visual food-choice task than individuals from the unexposed group.

“Our second study tested sanctuary-born Japanese macaques (n = 55) from four groups; three groups had recently experienced an infectious disease outbreak.”
Then look for missing context

Context layer

What the story left out

Important study details the story did not include.

  • A key limitation is that recent outbreak exposure in Study 2 was observational and group-level, not experimentally randomized, so causal claims that the outbreak made the monkeys more cautious are limited.

    The story uses mostly associational framing in places, but its lead claim says monkeys who lived through the outbreak 'became' more cautious and the listed caveats do not explicitly acknowledge the non-randomized, between-group exposure limitation.

    From Naturalistic between-group exposure comparison with behavioural food-choice assay

  • At abstract depth, the paper profile does not provide effect sizes, confidence intervals, model details, or the exact percentages for the outbreak-exposed versus unexposed comparison.

    The story reports a precise 47% versus 79% magnitude, but those figures are not present in the abstract-level paper profile and the absence of detailed statistics is not noted as a caveat.

    From Naturalistic between-group exposure comparison with behavioural food-choice assay

  • Study 2’s generalizability is limited because the outbreak comparison involved sanctuary-born Japanese macaques from only four social groups, with three exposed groups and one unexposed group.

    The story mentions that macaque findings cannot directly answer whether humans behave the same way, but it does not reflect the narrower within-macaque sampling limitation described in the profile.

    From Naturalistic between-group exposure comparison with behavioural food-choice assay

3 things the story did carry across
  • Study 1 tested 54 macaques from seven species and four rearing backgrounds in a visual food-choice task with contaminated versus non-contaminated substrates; sanctuary-born individuals showed greater avoidance than former pets.
  • Study 2 tested 55 sanctuary-born Japanese macaques from four social groups, three of which had recently experienced an infectious disease outbreak, and found higher avoidance of contaminated substrates in outbreak-exposed groups.
  • The paper’s broader interpretation is that early-life rearing and recent disease exposure suggest a flexible, context-sensitive behavioural immune system in Old World monkeys, with possible relevance to the evolutionary roots of human disgust.
Then read the study layer

Study layer

Study at a glance

Scan the study first. Expand only the parts you want to inspect.

Pieces of work

3

Evidence read

study summary

Lead result

in vivo animal

1Lead resultin vivo animalEarly-life rearing experience (developmental background) predicts individual differences in pathogen avoidance behaviour across macaque species.cross-species behavioural food-choice experiment (visual contamination-cue manipulation)Expand

In plain English

Study 1 (n = 54) tested seven macaque species from four rearing backgrounds in a visual food-choice task where identical food items were placed on substrates with or without pathogenic cues. Overall, macaques preferred feeding from non-contaminated substrates, and individuals reared in sanctuaries showed stronger avoidance of contaminated substrates than former pet macaques. The authors interpret this as evidence that early-life rearing experience predicts individual differences in pathogen-avoidance behaviour across macaque species.

Key findings

  • In a visual food-choice task (n = 54, seven macaque species), macaques preferred feeding from non-contaminated substrates; sanctuary-born individuals showed greater avoidance of contaminated substrates than former pets.
“Our first study tested macaques (n = 54) from seven different species and four different rearing backgrounds in a visual food-choice task where food was either placed on a substrate with or without pathogenic cues.”
What this piece can’t prove

3 further details could not be confirmed from the summary.

2in vivo animalRecent infectious disease exposure increases pathogen avoidance behaviour within sanctuary-born Japanese macaques.Naturalistic between-group exposure comparison with behavioural food-choice assayExpand

In plain English

Study 2 tested sanctuary-born Japanese macaques (n = 55) from four social groups (three of which recently experienced an infectious disease outbreak) in a visual food-choice task contrasting food placed on substrates with versus without pathogenic cues. Macaques from outbreak-exposed groups showed significantly greater avoidance of contaminated substrates than macaques from the unexposed group.

Key findings

  • Within sanctuary-born Japanese macaques (n = 55 across four groups), individuals from groups that had recently experienced an infectious disease outbreak showed greater avoidance of contaminated substrates in a visual food-choice task than individuals from the unexposed group.
“Our second study tested sanctuary-born Japanese macaques (n = 55) from four groups; three groups had recently experienced an infectious disease outbreak.”
What this piece can’t prove
  • Abstract does not report effect sizes, confidence intervals, or the statistical models used to compare avoidance across groups.
  • Findings are limited to sanctuary-born Japanese macaques sampled from four groups, which may restrict broader generalizability.

2 further details could not be confirmed from the summary.

3otherThese patterns support the existence of a flexible, context-sensitive behavioural immune system in Old World monkeys with evolutionary relevance to human disgust.Narrative synthesis / evolutionary interpretationExpand

In plain English

The authors synthesize results from two studies of macaques to argue that variation in pathogen avoidance is shaped by early-life rearing experience and recent disease exposure, and that these patterns indicate a flexible, context-sensitive behavioural immune system in Old World monkeys with potential relevance for the evolutionary origins of human disgust.

Key findings

  • Early-life rearing background and recent group-level disease exposure are interpreted to shape individual pathogen avoidance sensitivity in macaques, based on the combined results of Study 1 and Study 2.
  • The authors conclude these patterns demonstrate a flexible, context-sensitive behavioural immune system in Old World monkeys and suggest such mechanisms could provide behavioural foundations relevant to the evolution of human disgust.
“Together, our findings suggest that early life rearing experience and recent disease exposure shape pathogen sensitivity in macaques, demonstrating a flexible behavioural immune system in Old World monkeys.”
What this piece can’t prove
  • The unit is an overarching interpretive/conceptual synthesis that extends beyond the individual empirical results reported in the two studies.
  • Evolutionary relevance to human disgust is proposed but not directly tested within the reported studies; it is presented as a theoretical implication.
Finally, the search trail

Method layer

NewsLink found the paper. Tessa takes you deeper.

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Open the paper in Tessa

Early-life experience and disease exposure affect pathogen avoidance behaviour in macaques

Royal Society Open Science · 2026

Source record (opens in a new tab)

Why this one

Near certain

NewsLink found the paper. Tessa is where you inspect it deeply.

Papers considered

The selected paper, plus nearby candidates.

Crossref, PubMed, Europe PMC · 16 candidate papers

Selected

Early-life experience and disease exposure affect pathogen avoidance behaviour in macaques

Royal Society Open Science · 2026 · Crossref

Source (opens in a new tab)
Candidate

Review for "Early-life experience and disease exposure affect pathogen avoidance behaviour in macaques"

2026 · Crossref

Source (opens in a new tab)

And 10 more candidates considered.