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The infectious disease trap of animal agriculture


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Infectious diseases originating from animals (zoonotic diseases) have emerged following deforestation from agriculture. Agriculture can reduce its land use through intensification, i.e., improving resource use efficiency. However, intensive management often confines animals and their wastes, which also fosters disease emergence. Therefore, rising demand for animal-sourced foods creates a "trap" of zoonotic disease risks: extensive land use on one hand or intensive animal management on the other. Not all intensification poses disease risks; some methods avoid confinement and improve animal health. However, these "win-win" improvements alone cannot satisfy rising meat demand, particularly for chicken and pork. Intensive poultry and pig production entails greater antibiotic use, confinement, and animal populations than beef production. Shifting from beef to chicken consumption mitigates climate emissions, but this common strategy neglects zoonotic disease risks. Preventing zoonotic diseases requires international coordination to reduce the high demand for animal-sourced foods, improve forest conservation governance, and selectively intensify the lowest-producing ruminant animal systems without confinement.
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Hayek, Sci. Adv. 8, eadd6681 (2022) 2 November 2022
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The infectious disease trap of animal agriculture
Matthew N. Hayek
Infectious diseases originating from animals (zoonotic diseases) have emerged following deforestation from agricul-
ture. Agriculture can reduce its land use through intensification, i.e., improving resource use efficiency. However,
intensive management often confines animals and their wastes, which also fosters disease emergence. Therefore,
rising demand for animal-sourced foods creates a “trap” of zoonotic disease risks: extensive land use on one hand
or intensive animal management on the other. Not all intensification poses disease risks; some methods avoid
confinement and improve animal health. However, these “win-win” improvements alone cannot satisfy rising
meat demand, particularly for chicken and pork. Intensive poultry and pig production entails greater antibiotic
use, confinement, and animal populations than beef production. Shifting from beef to chicken consumption mit-
igates climate emissions, but this common strategy neglects zoonotic disease risks. Preventing zoonotic diseases
requires international coordination to reduce the high demand for animal-sourced foods, improve forest conser-
vation governance, and selectively intensify the lowest-producing ruminant animal systems without confinement.
Despite global advances in prosperity, nutrition, and medical care,
infectious diseases are rising in prevalence (1,2). In the past four
decades, emerging infectious diseases have increased at more than
four times the rate of prior decades (3), most of which have nonhu-
man animal (zoonotic) origins.
Since 1940, an estimated 50% of zoonotic disease emergence has
been associated with agriculture (13). This estimate, however, is
necessarily conservative because only direct agricultural drivers are
considered in the epidemiological literature, i.e., within the farm gate.
Food systems have environmental impacts before and after the farm
gate (4), such as land clearing, food processing, and waste disposal.
Food systems therefore affect zoonotic disease emergence indirectly.
The true contributions of food systems to recently emerged zoonotic
diseases remain poorly characterized.
The increase in zoonosis emergence has been partially attributed
to ongoing deforestation, particularly in the tropics (2,5,6). The
largest driver of deforestation is pasture expansion for ruminants
(e.g., cattle) with another substantial fraction of forest and savanna
clearing for producing feed crops like soy, predominantly fed to
monogastrics (e.g., pigs and chickens) for domestic and export
markets (7), with ongoing debate as to the precise proportions (8).
Land clearing is expected to continue through 2050 due to further
increased meat and dairy demand (912). Deforestation and con-
version to human-dominated systems drive the loss, turnover, and
homogenization of biodiversity and expose adjacent human com-
munities to wildlife harboring microbes that can become zoonotic
pathogens with pandemic potential (5).
To meet the rising global demand for animal-sourced foods, the
most commonly recommended development strategy in the envi-
ronmental literature is “sustainable intensification,” which refers to
increasing production while managing inputs more judiciously
(13,14). Experts recommend this strategy for virtually all low- and
middle-income countries (LMICs). By improving resource use effi-
ciency, sustainable intensification strategies for animal agriculture
can reduce greenhouse gas (GHG) emissions and deforestation
(1517), thereby also reducing zoonotic disease risks.
However, the intensification of animal agricultural production,
in its most common forms, entails the concentration and confine-
ment of animal bodies and their wastes, trading off deforestation for
other multiple well-documented and potentially cascading risks for
zoonotic disease emergence. This creates a paradox for intensifica-
tion that remains unaddressed in the scientific literature: Intensi-
fied animal production, while decreasing marginal land use change
and GHG emissions, can often increase other zoonotic disease risks.
The risks of zoonotic disease emergence from intensive animal ag-
riculture could therefore undermine the “sustainable” nature of sus-
tainable intensification.
This review examines the zoonotic disease paradox inherent to the
sustainable intensification of animal agriculture, exploring whether
food systems can circumvent a “trap” of zoonotic disease risks as
they further develop. The review first aims to characterize interac-
tions between intensification and deforestation while examining
ways that they both contribute to zoonotic disease risk. On the basis
of these interactions, this review provides recommendations to re-
duce the likelihood of zoonotic disease emergence, including (i) se-
lectively intensifying the least productive regions, namely, LMICs,
without resorting to confinement and other common high-risk in-
tensive management techniques; (ii) strengthening and improving
conservation regulations with effective community governance; and
(iii) curbing the high and rising demand for animal-sourced food
products. These three strategies are most likely to succeed if imple-
mented in tandem and via regional and international coordination
to avoid leakage and rebound effects.
A number of intensive animal production methods have been im-
plicated in zoonotic disease emergence in the literature (Table1). The
intensification of animal agriculture through confinement and
industrialization has directly led to the emergence of viruses including
Nipah and H5N1 influenza (“swine flu”) (18) and antibiotic- re si st ant
infectious bacteria including methicillin-resistant Staphylococcus
aureus and Escherichia coli (19,20).
Department of Environmental Studies, New York University, 285 Mercer St., New York,
NY 10012, USA. Email:
Copyright © 2022
The Authors, some
rights reserved;
exclusive licensee
American Association
for the Advancement
of Science. No claim to
original U.S. Government
Works. Distributed
under a Creative
Commons Attribution
License 4.0 (CC BY).
Hayek, Sci. Adv. 8, eadd6681 (2022) 2 November 2022
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Intensified animal agriculture is often, but not always, character-
ized by a shift toward “landless” or “industrialized” systems (as de-
fined by the United Nations Food and Agriculture Organization).
These systems typically restrict animal movement and are oriented
toward rapid weight gain and productivity (21). Monogastric ani-
mals like pigs and chickens are raised indoors in sheds, each animal
with less than twice the space that their bodies occupy, with little or
no room to express natural behaviors (22,23). Many beef cattle
spend the latter part of their lives being “finished” or rapidly fat-
tened to reach their final market weights on enriched feeds in feed-
lots, with stocking densities for cattle on outdoor feedlots of less
than 4m2 per steer/heifer (24). These environments entail physio-
logical and mental stress, close proximity to each other and wastes,
and the routine administration of subtherapeutic (infection-
preventing) and growth-promoting antibiotics (Table1). Zoonotic
diseases from aquatic animals are relatively less common and are
predominantly caused by bacteria rather than viruses (25). However,
aquatic animal bacteria are expected to become more prominent
and potentially infectious among humans as finfish aquaculture
continues to grow to produce a larger share of aquatic foods globally,
and with it are confinement, stress, and antibiotic use, potentially
leading to spillover into humans (26). These intensive systems are
predominant in developed, industrialized countries but are rapidly
proliferating in developing regions (27), with encouragement and
financing from international development organizations including
the World Bank (28).
Relatively more extensive systems include pastoralism, extensive
grazing, and mixed crop-livestock grazing. Extensive systems are
used almost exclusively in developing regions, namely, through the
tropics and semitropics, and among predominantly ruminant live-
stock (e.g., cows, buffalo, sheep, and goats).
Intensification methods sit on a spectrum, with poles of landless,
industrialized production on the high end and highly extensive pas-
toralist grazing on the lowest. The most extensive and inefficient
systems have the potential to be improved using “win-win” forms of
intensification that do not entail a fully industrialized or landless
kind of confined intensification (Table1), but rather a kind of
“meeting in the middle” for the lowest, least productive systems to
improve their performance (15). Thus, intensifying low-production
ruminant systems in a selective manner could confer a neutral or
decreased risk of zoonosis emergence while improving meat and
dairy productivity in the most marginal contexts.
However, there are limitations to this form of intensification.
First, the number of animals raised in extensive systems is already
decreasing while being supplanted by highly industrialized/landless
systems throughout developing regions (11,21). Therefore, there
are regional and global limitations to how much additional food
“semi-intensive” systems can provide. Second, shifts downward
from more highly intensive forms would compromise food produc-
tion or lead to net agricultural expansion. For instance, eliminating
feedlot beef cattle systems in the United States by shifting to inten-
sive grazing would require 64 to 270% greater land use (29), while
eliminating confined indoor broiler chicken systems by shifting to
minimal pasture would require 43.8 to 60.1% greater land use (30).
Industrialized systems are often more productive and resource effi-
cient than semi-intensive methods. Shifting away from industrial-
ized systems therefore entails a GHG and land use penalty or
“sustainability gap” (30). Last, production systems for monogastric
animals, which produce two-thirds of meat globally, lack common
semi-intensive commercial methods (21). Global production and
consumption of beef, pork, and chicken are expected to rise by 39,
55, and 58%, respectively, by 2050, with the majority of additional
production expected to be achieved through intensification systems
(industrial, in the case of monogastrics) (11). Therefore, additional
food system strategies beyond intensification are needed to safely
feed a rising and more affluent global population.
Intensification tends to reduce deforestation directly
Intensification, which aims to make agricultural production more
efficient, is commonly understood to decrease the pressure for de-
forestation within the environmental literature (13,31,32). How-
ever, in many developing tropical regions, both intensification and
deforestation are occurring simultaneously because they share under-
lying drivers (i.e., confounding causes): rising populations, incomes,
and demand for animal-sourced foods (Fig.1). Because the two are
visibly correlated, the epidemiological literature on zoonotic disease
often erroneously links intensification directly to deforestation. A
Table 1. Intensive animal management strategies, by qualitative risk
categories and farmed animal types.
Elevated risks Evidence of zoonotic disease
All farmed animal species
Indoor production and confinement (8385)
Genetic homogenization (86, 87)
Subtherapeutic and growth-
promoting antibiotic use (19, 20, 25, 74, 8890)
Long-distance transportation (91, 92)
Physiological stress from crowding,
confinement, and conflicts (e.g.,
gestation crates, veal crates, and
battery cages)
(22, 23, 26, 93)
Temporary/seasonal and transient
human labor (83, 94)
Concentrated animal wastes (88, 95)
Neutral or reduced risks Evidence of reduced land and
resource needs
All farmed animal species
Improving veterinary care and
reducing mortality (15)
Improving animal husbandry
management (e.g., lower
reproductive age)
(15, 96)
Integrating crop and livestock
production (9799)
Ruminant species only
Optimizing grazing densities (100, 101)
Improving forage quality (15, 102)
Amending and restoring
degraded pastures (15, 102104)
Hayek, Sci. Adv. 8, eadd6681 (2022) 2 November 2022
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number of recent high-profile synthesis reports on zoonoses discuss
intensification and deforestation synonymously and interchange-
ably (6,33,34), sometimes directly implicating intensification as
causing the ongoing deforestation, although the environmental lit-
erature predominantly concludes the opposite. Intensification can
lead directly to reduced deforestation in agriculture-forest fron-
tiers (35,36).
Intensification can indirectly trigger more deforestation
Intensification reduces the marginal resource requirements of animal-
sourced food production; it thus can potentially reduce pressures
for deforestation, a finding that is widely accepted and uncontro-
versial. However, after achieving higher efficiency, intensification can
lower the costs of production and sale prices of final goods, induc-
ing higher demand and production (Fig.1). This greater demand
can then incentivize additional deforestation (37), negating some or
all of the original efficiency improvements. This trade-off is known as
Jevons’ paradox (36,38,39) or “rebound effects,” more commonly.
The occurrence and magnitude of rebound effects in animal-
sourced food production are difficult and controversial to identify
because of confounding factors (4042), leading to ongoing debates
(similarly reflected in the “land sparing versus land sharing” debate
regarding agricultural efficiency). However, some trends and investi-
gations are illuminating. In Sweden and the United States, an in-
creased consumption of chicken over the past two decades, due to
lower prices, resulted in greater aggregate GHG emissions despite
marginal efficiency gains over the same period (43,44). In South
America, beef intensification has triggered further deforestation
due to lower production costs (35,37,45). Sustainable intensifica-
tion can thus spur greater environmental impacts, undermining its
sustainable aims (46,47). Intensification is necessary but insuffi-
cient to reduce pressures for agriculture expansion and land clear-
ing. Escaping this “damned if we do, damned if we don’t” trap of
intensification (Fig.1) requires a more multipronged approach.
Effective forest conservation occurs in tandem with
other strategies
Intensification alone is an insufficient strategy for reducing zoonotic
disease risk (see the “Intensification—Risks, opportunities, and limits
for stemming zoonotic disease” section) and for mitigating and
reversing deforestation (see the previous section). Direct forest
conservation policies and incentives are widely recommended in
environmental and epidemiological literature, e.g., (6,18,33). How-
ever, known trade-offs and pratfalls exist. First, forest and wildlife
habitat conservation policies that are not appropriately designed
and enforced with the involvement of local cultures have backfired
(36,4850). Second, conservation may lead to “leakage” effects: Global-
ization allows production to relocate, along with its deforestation,
to countries where conservation policies are insufficiently adopted
or enforced (51,52). Last, effective forest conservation policies in
the short term can boost intensification but lead to further defor-
estation in the long term and across wider regions (Fig.1) (39). These
effects can vary over space and time, changing with local livelihoods
and culture, price elasticities for agricultural goods, and how con-
nected production regions are to global markets (37).
Conservation policies should be culturally sensitive, rigorously
enforced, and have long-term community buy-in. However, a well-
crafted conservation policy is still insufficient to spare land from
agricultural pressures; additional land for rising populations and diets
richer in animal-sourced foods must come at the expense of clear-
ing native habitats somewhere (11,53).
The largest increases in meat demand and production are occurring
in developing, tropical regions (16). Meat consumption exceeds the
dietary requirements in high-income countries and among increas-
ingly urban and middle-class populations of most middle-income
countries (5456). As demand rises along with affluence in the
coming decades in LMICs and high-income countries continue to
sustain high levels of consumption and exports, additional land
clearing and GHG emissions will occur even with ambitious levels
of intensification (9,12).
Shifting to plant-rich diets mitigates environmental
and zoonotic disease risks
Decreasing meat consumption has cobenefits for environmental pro-
tection and zoonotic disease risks. Global dietary changes are theoret-
ically sufficient to reverse ongoing deforestation trends, providing 5
to 11 GtCO2 per year of natural carbon removal across 5 to 12 million
km2, sequestering approximately a decade worth of anthropogenic
emissions by 2050in natural vegetation (9,5759), which would also
conserve and restore a substantial fraction of lost biodiversity (53,60).
Shifts to plant-rich diets in high-income countries alone would remove
approximately 3 million km2 from agricultural production, including
1 million km2 of natively forested areas (9,56).
To address the emerging zoonotic disease risks of animal agricul-
ture, a multipillared approach is required (Fig.2). This approach in-
cludes reducing demand for animal-sourced foods, semi-intensification
(see the “Intensification—Risks, opportunities, and limits for stem-
ming zoonotic disease” section and Table1), and direct forest con-
servation (see the “Effective forest conservation occurs in tandem
with other strategies” section). Under business-as-usual condi-
tions of rising demand for animal-sourced food, increased land
clearing is inevitable (57,61). Reducing demand can therefore avoid
leakage and rebound effects from focusing exclusively on supply-
side protections like semi-intensification and forest conservation
(Figs.1 and 2).
The zoonosis trap
Fig. 1. Higher incomes are associated with high meat demand that must be
met through intensification or deforestation (or both). Intensification can trigger
higher meat demand through lower prices, because meat demand is elastic with
respect to its cost. Intensification and deforestation are highlighted in orange, as both
have caused recent zoonotic disease emergence and are predicted to continue
doing so. Intensification is colored by a gradient to indicate that intensification strat-
egies lie on a gradient of helpful/neutral to harmful with respect to zoonosis risks.
Hayek, Sci. Adv. 8, eadd6681 (2022) 2 November 2022
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The zoonotic disease risks of rising animal-sourced food pro-
duction and consumption have been underscored by a number of re-
cent major environmental epidemiology synthesis reports (6,33,62).
These reports imply or outright state that high future demand
for animal-sourced foods is an immutable consequence of rising in-
comes, treating this trend as fait accompli rather than a decision
point for policy interventions. This fatalism contradicts behav-
ioral science research on reducing the consumption of meat and
other products with harmful public health impacts (e.g., tobacco
and sugar).
To meaningfully flatten the rising curve of animal-sourced foods,
demand-side interventions should be implemented, tested, and
scaled ambitiously (63). Even gentle changes to dining options and
presentation can create large effects (64). Effective interventions
range from these subtle “nudges” to more blatant rewards and in-
centives, as well as stringent regulations and restrictions (16,55).
This spectrum has been described using the Nuffield intervention
ladder, with lower rungs of “soft” methods or “carrots” (e.g., guid-
ance, suggestions, education, and nudging) to higher rungs of in-
creasingly forceful “hard” interventions or “sticks” at the top (e.g.,
taxes and bans) (65).
Countries lack healthy and sustainable food consumption policies
that are comprehensive and synergistic; most countries only have
education policies (e.g., dietary recommendations), with higher rungs
on the Nuffield ladder—including guiding choices through chang-
ing incentives and defaults or disincentivizing options—completely
missing (66). Promising local policies and corporate initiatives, mean-
while, are aiming to guide consumers toward more sustainable op-
tions using methods of monitoring, goal setting, and verification in
combination with multiple soft behavioral interventions to motivate
change (67).
More targeted dietary change interventions are needed; recom-
mendations for dietary change policies across most scientific litera-
ture are general and vague (16,55). Policies can leverage social,
behavioral, and organizational sciences to change the underlying
motivations and choice environments that drive consumer deci-
sions (64,67). Small successes should also be better communicated to
decision-makers and ambitiously scaled to large populations with
help from community-based advocacy and organizing (68).
Differentiating risks across food animals
Shifting production and consumption from beef to poultry is a com-
mon recommendation in the literature. Such shifts would accomplish
most of the GHG emission mitigation as reducing or eliminating all
meat (6971). These recommendations have shaped national cli-
mate policies: Ethiopia stated plans to shift 30% of their beef pro-
duction to poultry in their 2021 Nationally Determined Contribution
to the United Nations Framework Convention on Climate Change
(72). However, such shifts could maintain or even increase zoonotic
disease risks.
Beef has higher land use and is associated with more tropical
deforestation than any other commodity (73). However, monogas-
tric animals, including pigs and chickens, require higher antibiotic
use and higher animal populations to produce the same quantity of
meat as ruminants such as cattle (Fig.3). Pigs and chickens are fed
more than three times the antibiotics than cattle in intensive sys-
tems (74) due to close confinement of animals and their wastes. It
takes three pigs or 170 chickens to produce the meat of one steer.
Intensive methods of monogastric animal production entail more
marked confinement, including hen laying and pig gestation sys-
tems wherein animals are confined without enough space to spread
their wings or turn around. Now, there are more than 33 billion
chickens on Earth, representing more than 70% of global avian bio-
mass (75). Shifts from beef to even greater chicken consumption
would entail greater confinement and subtherapeutic antibiotic use
for a larger number of animals, elevating multiple risks for zoonotic
disease emergence.
The precise zoonotic disease risks of individual foods and whole
dietary patterns have not previously been quantified. Statistical
analyses are challenging because any predictive metrics would en-
tail creating robust models from only a few (but highly costly) zoo-
notic disease spillover events and outbreaks that have emerged from
agricultural production, often from diverse pathogens and with
sometimes ambiguous origins. The lack of quantitative disease anal-
yses remains a hurdle to assessing the full costs, benefits, and trade-
offs of food system transitions. Despite this, plant-rich diets entail
cost-saving cobenefits (76,77), including environmental outcomes,
human nutrition, and animal welfare, which have been quantified
robustly in previous work (7880).
The coronavirus disease 2019 pandemic has increased the vigilance
of the global community in identifying and monitoring the poten-
tial sources of the next zoonotic disease outbreak. Well-trodden
prevention strategies include suppressing disease in vulnerable ani-
mals, monitoring transmission and spillover events of pathogens
with pandemic potential, and stopping detected outbreaks in do-
mesticated animals through culling (81). These decade-long pursuits
have only tackled pathogens of concern after some initial emer-
gence or spillover. They do not address root causes of transmission,
mutation, spillover, and proliferation of emerging infectious zoonotic
Shifts to
Production is
demand must be
met with
Rebound effects/
Jevons’ paradox—
Lower costs beget more
consumption &
Fewer cobenefits for
emerging economies
(low- & lower-middle
zoonotic disease
Inexpensive land
incentives to
improve marginal
Lack of supportfor low-
income producers and
animals’ health
Fig. 2. A three-pillar approach for preventing zoonotic disease emergence and
reducing environmental impacts from animal agriculture (center). Within indi-
vidual circles and the intersections between the two, limitations of adopting only
one or two strategies are described.
Hayek, Sci. Adv. 8, eadd6681 (2022) 2 November 2022
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pathogens. The high and increasing demand for animal- sourced foods
is one such root cause.
Strategies that prevent infectious diseases at their root sources
are called primary prevention (6,18,33). This work outlines three
pillars for primary prevention that, when combined, constitute
stronger protection against zoonotic diseases from animal agricul-
ture than any one pillar in isolation (Fig2). National governments
should coordinate their support for a wide range of policies and
activities that support these pillars, including expanding veterinary
and extension services for improved animal care in LMICs (18),
phasing out and banning subtherapeutic and growth-promoting anti-
biotic uses (82), forming multilateral commitments among countries
importing and exporting tropical commodities linked to defor-
estation (73), ambitiously scaling community-based approaches to
popularizing plant-rich diets (68), supporting open and public al-
ternative protein research (77), and facilitating sustainable and just
transitions for producers. Commitments should also set quantifi-
able science-based goals and fund ongoing research to monitor and
accelerate progress. Together, the three pillars of primary preven-
tion can guide and empower decision-makers to escape the zoonotic
disease trap of business-as-usual animal agriculture.
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Cattle Pigs Chickens
Hectares (10,000 m
3.93 ha
0.78 ha
0.44 ha
Cattle Pigs Chickens
45 g
172 g
148 g
= 1 animal
3.5 cattle
11.3 pigs
Number of animals
Requirements for 1 metric ton of meat production in OECD countries
Native forest area cleared
592 chickens
Fig. 3. Requirements to produce 1 metric ton of meat (dressed carcass weight), averaged among all OECD countries and weighted by production quantity, base
year 2010. (A) Hectares required for the production of animal feed (crops, pastures, and forages) in natively forested areas, calculated by the author from geospatial
potential vegetation data and agricultural production data in (9) and sources therein. (B) Grams of antibiotics used, derived from (74). (C) Number of animals required for
slaughter, from United Nations FAOSTAT (105). OECD, Organization for Economic Co-operation and Development.
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Acknowledgments: I thank B. Franks, J. Sebo, D. Jamieson, W. Alonso, and N. Mueller as well
as the anonymous reviewers for helpful input regarding the contents and direction of this
article. Funding: The authors acknowledge that they received no funding in support of this
research. Author contributions: M.N.H. authored this report, including all drafts and
revisions, performed the data analysis, and created and designed all figures contained
therein. Competing interests: The author declares that he has no competing interests.
Data and materials availability: All data needed to evaluate the conclusions in the paper are
present in the paper, with the exception of data in Fig. 3, the online sources of which are cited
in the caption.
Submitted 26 June 2022
Accepted 15 September 2022
Published 2 November 2022
... In addition, avoiding factory farmed animal products (esp. from chickens and pigs) may decrease the risk of spreading zoonotic infectious diseases (Karesh et al., 2012;UNEP, 2020;Hayek, 2022) and antibiotic-resistance related illness (Tang et al., 2017;Hayek, 2022). A common motive among people to adopt veg*n diets is to prevent and treat diseases of welfare (e.g., obesity, type 2 diabetes, cardiovascular disease) (Radnitz et al., 2015;Cramer et al., 2017;Costa et al., 2019) and nutritional science indicates that wellplanned veg*n diets may indeed serve this function (Melina et al., 2016;Medawar et al., 2019;Selinger et al., 2022). ...
... In addition, avoiding factory farmed animal products (esp. from chickens and pigs) may decrease the risk of spreading zoonotic infectious diseases (Karesh et al., 2012;UNEP, 2020;Hayek, 2022) and antibiotic-resistance related illness (Tang et al., 2017;Hayek, 2022). A common motive among people to adopt veg*n diets is to prevent and treat diseases of welfare (e.g., obesity, type 2 diabetes, cardiovascular disease) (Radnitz et al., 2015;Cramer et al., 2017;Costa et al., 2019) and nutritional science indicates that wellplanned veg*n diets may indeed serve this function (Melina et al., 2016;Medawar et al., 2019;Selinger et al., 2022). ...
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Animal-based diets in Western countries are increasingly regarded as unsustainable because of their impact on human health, environmental and animal welfare. Promoting shifts toward more plant-based diets seems an effective way to avoid these harms in practice. Nevertheless, claims against the consumption of animal products contradict the ideology of the omnivorous majority known as carnism. Carnism supports animal-product consumption as a cherished social habit that is harmless and unavoidable and invalidates minorities with plant-based diets: vegetarians and vegans (veg*ns). In this theoretical review, we integrate socio-psychological and empirical literature to provide an identity-based motivational account of ideological resistance to veg*n advocacy. Advocates who argue against the consumption of animal products often make claims that it is harmful, and avoidable by making dietary changes toward veg*n diets. In response, omnivores are likely to experience a simultaneous threat to their moral identity and their identity as consumer of animal products, which may arouse motivations to rationalize animal-product consumption and to obscure harms. If omnivores engage in such motivated reasoning and motivated ignorance, this may also inform negative stereotyping and stigmatization of veg*n advocates. These “pro-carnist” and “counter-veg*n” defenses can be linked with various personal and social motivations to eat animal products (e.g., meat attachment, gender, speciesism) and reinforce commitment to and ambivalence about eating animal products. This does not mean, however, that veg*n advocates cannot exert any influence. An apparent resistance may mask indirect and private acceptance of advocates’ claims, priming commitment to change behavior toward veg*n diets often at a later point in time. Based on our theoretical account, we provide directions for future research.
... This transformation involves reintegrating agriculture, livestock and pastoralism into territorial development, developing agroecology and agroforestry approaches to increase resilience to climate change, while ensuring biodiversity conservation and food and health security. As Hayek recently pointed out [75] the prevention of zoonotic diseases requires a comprehensive strategy to reduce the demand for animal protein as well as improved forest conservation [25]. ...
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This study uses the available data to explore the temporal and geographical patterns of infectious diseases and their links between human demography, human-induced land-use change, livestock and poultry expansion, and biodiversity loss. Over the last decades, the number of outbreaks of zoonotic and vector-borne diseases increased mostly in the intertropical zone. The increase in cropland, grassland, tree plantation, livestock, poultry, biodiversity at threat (using the Red List index) mostly occurred in the intertropical zone. Using structural equation modeling, significant relationships were observed between disease outbreaks, human demography, livestock (cattle and pigs), poultry (chickens), tree plantation and artificial land expansion as well as with increasing biodiversity at threat. While agricultural expansion is seen as a driver of biodiversity loss and potentially emerging infectious diseases, here we show that cropland and grassland expansion does not appear to enhance disease outbreaks directly, but indirectly and only for cropland on biodiversity loss. The links observed between infectious disease outbreaks, human demography, agriculture, livestock, urbanization and biodiversity should help rethink the global food system in ways that minimize the risk of infectious diseases while preserving biodiversity and contributing to Sustainable Goals.
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In 2015, the United Nations agreed on 17 Sustainable Development Goals as the central normative framework for sustainable development worldwide. The effectiveness of governing by such broad global goals, however, remains uncertain, and we lack comprehensive meta-studies that assess the political impact of the goals across countries and globally. We present here condensed evidence from an analysis of over 3,000 scientific studies on the Sustainable Development Goals published between 2016 and April 2021. Our findings suggests that the goals have had some political impact on institutions and policies, from local to global governance. This impact has been largely discursive, affecting the way actors understand and communicate about sustainable development. More profound normative and institutional impact, from legislative action to changing resource allocation, remains rare. We conclude that the scientific evidence suggests only limited transformative political impact of the Sustainable Development Goals thus far. The Sustainable Development Goals were launched as a worldwide governance framework, but little is known about their actual political impacts. This study shows evidence that the Sustainable Development Goals have had largely a discursive influence and only limited transformative political impact.
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In 2018, over nine billion chickens were slaughtered in the United States. As the demand for chickens increases, so too have concerns regarding the welfare of the chickens in these systems and the damage such practices cause to the surrounding ecosystems. To address welfare concerns, there is large-scale interest in raising chickens on pasture and switching to slower-growing, higher-welfare breeds as soon as 2024. We created a box model of US chicken demographics to characterize aggregate broiler chicken welfare and land-use consequences at the country scale for US shifts to slower-growing chickens, housing with outdoor access, and pasture management. The US produces roughly 20 million metric tons of chicken meat annually. Maintaining this level of consumption entirely with a slower-growing breed would require a 44.6%–86.8% larger population of chickens and a 19.2%–27.2% higher annual slaughter rate, relative to the current demographics of primarily ‘Ross 308’ chickens that are slaughtered at a rate of 9.25 billion per year. Generating this quantity of slower-growing breeds in conventional concentrated animal feeding operations (CAFO) would require 90 582–98 687 km ² , an increase of 19.9–30.6% over the 75 577 km ² of land used for current production of Ross 308. Housing slower-growing breeds on pasture, the more individually welfare-friendly option, would require 108 642–121 019 km ² , a 43.8–60.1% increase over current land use. Allowing slower-growing breeds occasional outdoor access is an intermediate approach that would require 90 691–98 811 km ² , an increase of 20–30.7% of the current land use, a very minor increase of land relative to managing slower-growing breeds in CAFOs. In sum, without a drastic reduction in consumption, switching to alternative breeds will lead to a substantial increase in the number of individuals killed each year, an untenable increase in land use, and a possible decrease in aggregate chicken welfare at the country-level scale. Pasture-based management requires substantial additional land use. These results demonstrate constraints and trade-offs in animal welfare, environmental conservation and food animal consumption, while highlighting opportunities for policies to mitigate impacts in an integrated manner using a One Health approach.
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Although the role of livestock in future food systems is debated, animal proteins are unlikely to completely disappear from our diet. Grasslands are a key source of primary productivity for livestock, and feed‐food competition is often limited on such land. Previous research on the potential for sustainable grazing has focused on restricted geographical areas or does not consider inter‐annual changes in grazing opportunities. Here, we developed a robust method to estimate trends and interannual variability in global livestock carrying capacity (number of grazing animals a piece of land can support) over 2001–2015, as well as relative stocking density (the reported livestock distribution relative to the estimated carrying capacity) in 2010. We first estimated the aboveground biomass that is available for grazers on global grasslands based on the MODIS Net Primary Production product. This was then utilised to calculate livestock carrying capacities using slopes, forest cover, and animal forage requirements as restrictions. We found that globally, carrying capacity decreased on 27% of total grasslands area, mostly in Europe and southeastern Brazil, while it increased on 15% of grasslands, particularly in Sudano‐Sahel and some parts of South America. In 2010, livestock forage requirements exceeded forage availability in northwestern Europe, and southern and eastern Asia. Although our findings imply some opportunities to increase grazing pressures in cold regions, Central Africa, and Australia, the high interannual variability or low biomass supply might prevent considerable increases in stocking densities. The approach and derived open access datasets can feed into global food system modelling, support conservation efforts to reduce land degradation associated with overgrazing, and help identify undergrazed areas for targeted sustainable intensification efforts or rewilding purposes.
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Significance Livestock supply chains account for 14.5% of global greenhouse gases (GHG) emissions. There is a consensus that approaches that improve cattle productivity while enhancing carbon sequestration can contribute to the multiple goals of improving ranchers’ livelihoods and mitigating climate change. Identifying policies that simultaneously increase productivity and sequestration is therefore critical to promote sustainable growth in the livestock sector. This paper documents the impact of training and technical assistance on pasture restoration and productivity in Brazil. We found that providing technical assistance to previously trained producers promoted pasture restoration, induced farmers to use more inputs, helped them improve their practices, and increased productivity and carbon sequestration. These findings highlight the importance of providing customized information to ranchers to help them sustainably intensify.
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The lives lost and economic costs of viral zoonotic pandemics have steadily increased over the past century. Prominent policymakers have promoted plans that argue the best ways to address future pandemic catastrophes should entail, “detecting and containing emerging zoonotic threats.” In other words, we should take actions only after humans get sick. We sharply disagree. Humans have extensive contact with wildlife known to harbor vast numbers of viruses, many of which have not yet spilled into humans. We compute the annualized damages from emerging viral zoonoses. We explore three practical actions to minimize the impact of future pandemics: better surveillance of pathogen spillover and development of global databases of virus genomics and serology, better management of wildlife trade, and substantial reduction of deforestation. We find that these primary pandemic prevention actions cost less than 1/20th the value of lives lost each year to emerging viral zoonoses and have substantial cobenefits.
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A dietary shift from animal-based foods to plant-based foods in high-income nations could reduce greenhouse gas emissions from direct agricultural production and increase carbon sequestration if resulting spared land was restored to its antecedent natural vegetation. We estimate this double effect by simulating the adoption of the EAT–Lancet planetary health diet by 54 high-income nations representing 68% of global gross domestic product and 17% of population. Our results show that such dietary change could reduce annual agricultural production emissions of high-income nations’ diets by 61% while sequestering as much as 98.3 (55.6–143.7) GtCO2 equivalent, equal to approximately 14 years of current global agricultural emissions until natural vegetation matures. This amount could potentially fulfil high-income nations’ future sum of carbon dioxide removal (CDR) obligations under the principle of equal per capita CDR responsibilities. Linking land, food, climate and public health policy will be vital to harnessing the opportunities of a double climate dividend.
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New estimates of greenhouse gas (GHG) emissions from the food system were developed at the country level, for the period 1990-2018, integrating data from crop and livestock production, on-farm energy use, land use and land use change, domestic food transport and food waste disposal. With these new country-level components in place, and by adding global and regional estimates of energy use in food supply chains, we estimate that total GHG emissions from the food system were about 16 CO 2 eq yr −1 in 2018, or one-third of the global anthropogenic total. Three quarters of these emissions, 13 Gt CO 2 eq yr −1 , were generated either within the farm gate or in pre-and post-production activities, such as manufacturing, transport, processing, and waste disposal. The remainder was generated through land use change at the conversion boundaries of natural ecosystems to agricultural land. Results further indicate that pre-and post-production emissions were proportionally more important in developed than in developing countries, and that during 1990-2018, land use change emissions decreased while pre-and post-production emissions increased. We also report results on a per capita basis, showing world total food systems per capita emissions decreasing during 1990-2018 from 2.9 to 2.2 t CO 2 eq cap −1 , with per capita emissions in developed countries about twice those in developing countries in 2018. Our findings also highlight that conventional IPCC categories, used by countries to report emissions in the National GHG inventory, systematically underestimate the contribution of the food system to total anthropogenic emissions. We provide a comparative mapping of food system categories and activities in order to better quantify food-related emissions in national reporting and identify mitigation opportunities across the entire food system.
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This article argues that governments in countries that currently permit intensive animal agriculture - especially but not exclusively high-income countries - are, in principle, morally justified in taking steps to restrict or even eliminate intensive animal agriculture to protect public health from the risk of zoonotic pandemics. Unlike many extant arguments for restricting, curtailing, or even eliminating intensive animal agriculture which focus on environmental harms, animal welfare, or the link between animal source food (ASF) consumption and noncommunicable disease, the argument in this article appeals to the value of protecting populations from future global health emergencies and their broad social, economic, and health impacts, taking the SARS-CoV-2 virus as a particularly salient example. The article begins by identifying how intensive animal agriculture contributes to the outbreak (and risk of future outbreaks) of zoonotic diseases. Next, we explore three specific policy options: 1. Incentivizing plant-based and cell-based ASF alternatives through government subsidies; 2. Disincentivizing intensive ASF production through the adoption of a “zoonotic tax”; and 3. Eliminating intensive ASF production through a total ban. We argue that all three of these measures are permissible, although we remain agnostic as to whether these measures are obligatory. We argue for this conclusion on the grounds that each measure is justified by the same sorts of considerations that justify other widely accepted public health interventions, and each is compatible with a variety of theories of justice. We then address potential objections. Finally, we discuss how our novel argument relates to extant ethical arguments in favor or curtailing ASF production and consumption.
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The global demand for beef is rapidly increasing (FAO, 2019), raising concern about climate change impacts (Clark et al., 2020; Leip et al., 2015; Springmann et al., 2018). Beef and dairy contribute over 70% of livestock greenhouse gas emissions (GHG), which collectively contribute ~6.3 Gt CO2‐eq/year (Gerber et al., 2013; Herrero et al., 2016) and account for 14%–18% of human GHG emissions (Friedlingstein et al., 2019; Gerber et al., 2013). The utility of beef GHG mitigation strategies, such as land‐based carbon (C) sequestration and increased production efficiency, are actively debated (Garnett et al., 2017). We compiled 292 local comparisons of “improved” versus “conventional” beef production systems across global regions, assessing net GHG emission data from Life Cycle Assessment (LCA) studies. Our results indicate that net beef GHG emissions could be reduced substantially via changes in management. Overall, a 46 % reduction in net GHG emissions per unit of beef was achieved at sites using carbon (C) sequestration management strategies on grazed lands, and an 8% reduction in net GHGs was achieved at sites using growth efficiency strategies. However, net‐zero emissions were only achieved in 2% of studies. Among regions, studies from Brazil had the greatest improvement, with management strategies for C sequestration and efficiency reducing beef GHG emissions by 57%. In the United States, C sequestration strategies reduced beef GHG emissions by over 100% (net‐zero emissions) in a few grazing systems, whereas efficiency strategies were not successful at reducing GHGs, possibly because of high baseline efficiency in the region. This meta‐analysis offers insight into pathways to substantially reduce beef production's global GHG emissions. Nonetheless, even if these improved land‐based and efficiency management strategies could be fully applied globally, the trajectory of growth in beef demand will likely more than offset GHG emissions reductions and lead to further warming unless there is also reduced beef consumption. Global demand for beef is rapidly increasing, raising concern about climate change impacts. We compiled 292 local comparisons of “improved” versus “conventional” beef production systems across global regions, assessing net greenhouse gas (GHG) emission data from Life Cycle Assessments (LCA). Overall, strategies for carbon (C) sequestration on grazed lands reduced net beef GHG emissions by 62%, and growth efficiency strategies reduced net GHG emissions by 30%. Despite these improvements, net‐zero emissions were achieved only in 2% of studies. Brazilian studies had the greatest reductions in beef GHG emissions. This meta‐analysis offers insight into management strategies to reduce beef GHG emissions across global regions.
Wildlife conservation and management (WCM) practices have been historically drawn from a wide variety of academic fields, yet practitioners have been slow to engage with emerging conversations about animals as complex beings, whose individuality and sociality influence their relationships with humans. We propose an explicit acknowledgement of wild, nonhuman animals as active participants in WCM. We examined 190 studies of WCM interventions and outcomes to highlight 3 common assumptions that underpin many present approaches to WCM: animal behaviors are rigid and homogeneous; wildlife exhibit idealized wild behavior and prefer pristine habitats; and human–wildlife relationships are of marginal or secondary importance relative to nonhuman interactions. We found that these management interventions insufficiently considered animal learning, decision‐making, individuality, sociality, and relationships with humans and led to unanticipated detrimental outcomes. To address these shortcomings, we synthesized theoretical advances in animal behavioral sciences, animal geographies, and animal legal theory that may help conservation professionals reconceptualize animals and their relationships with humans. Based on advances in these fields, we constructed the concept of animal agency, which we define as the ability of animals to actively influence conservation and management outcomes through their adaptive, context‐specific, and complex behaviors that are predicated on their sentience, individuality, lived experiences, cognition, sociality, and cultures in ways that shape and reshape shared human–wildlife cultures, spaces, and histories. Conservation practices, such as compassionate conservation, convivial conservation, and ecological justice, incorporate facets of animal agency. Animal agency can be incorporated in conservation problem‐solving by assessing the ways in which agency contributes to species’ survival and by encouraging more adaptive and collaborative decision‐making among human and nonhuman stakeholders. Article impact statement: Incorporating animal agency into wildlife conservation and management can lead to more effective, nuanced, and just outcomes. Aunque las prácticas de gestión y conservación de fauna (GCF) han partido históricamente de una gama amplia de áreas académicas, los practicantes se han visto lentos para participar en las conversaciones emergentes sobre los animales como seres complejos, cuya individualidad y sociabilidad influyen sobre sus relaciones con los humanos. Proponemos un reconocimiento explícito de los animales no humanos silvestres como participantes activos en la GCF. Para esto, examinamos 190 estudios sobre las intervenciones y los resultados de GCF para resaltar tres supuestos comunes que respaldan a muchas estrategias actuales de GCF: el comportamiento animal es rígido y homogéneo, la fauna exhibe un comportamiento silvestre idealizado y prefiere hábitats prístinos, y las relaciones humano‐fauna son de importancia marginal o secundaria en relación con las interacciones no humanas. Descubrimos que estas intervenciones de gestión no consideran lo suficientemente el aprendizaje, toma de decisiones, individualidad, sociabilidad y relaciones con los humanos de los animales, por lo que llevan a resultados imprevistos y perjudiciales. Para lidiar con estas limitaciones, sintetizamos los avances teóricos que han tenido las ciencias dedicadas al comportamiento animal, la geografía animal y la teoría legal animal que pueden ayudar a los profesionales de la conservación a reformular el concepto de animal y sus relaciones con los humanos. Con base en los avances en estas áreas construimos el concepto de agencia animal, el cual definimos como la habilidad que tienen los animales para influir activamente sobre la conservación y los resultados de manejo por medio de su comportamiento adaptativo, complejo y específico al contexto, los cuales están basados en su sensibilidad, individualidad, experiencias vividas, conocimiento, sociabilidad y culturas, de manera que construyen y reconstruyen las culturas, espacios e historias humano‐fauna. Las prácticas de conservación, como la conservación compasiva, la conservación acogedora y la justicia ecológica, incorporan facetas de la agencia animal. La agencia animal puede incorporarse en la solución de los problemas de conservación al evaluar las formas en las que la agencia contribuye a la supervivencia de la especie y al alentar una toma de decisiones más adaptativa y colaborativa entre los actores humanos y los no humanos. 【摘要】野生动物保护和管理的实践历来来自于各种学术领域, 但动物作为复杂生命体, 其个性和社会性影响着它们与人类的关系, 因此实践者很难跟上关于动物不断涌现的讨论。我们建议应明确承认野生非人类动物是野生动物保护和管理的积极参与者。我们调查了关于野生动物保护和管理的干预和结果的190项研究, 并指出目前许多野生动物保护和管理方法的三个常见假设:动物行为是刻板和同质的;野生动物表现出理想化的野生行为, 喜欢原始的栖息地;相比于动物与非人类的互动, 人类与野生动物的关系是边缘或次要的。我们发现这些管理干预措施没有充分考虑到动物的学习、决策、个性、社会性以及与人类的关系, 引起了意想不到的有害结果。为了解决这些缺陷, 我们综合了动物行为科学、动物地理学和动物法律理论方面的理论进展, 这些知识有助于保护专家重新认识动物及其与人类的关系。这些学科深入研究了动物的知觉、适应性、个性、集体决策以及对人类共享环境的参与。基于这些领域的进展, 我们构建了动物能动性的概念, 定义为动物通过其适应性、特定环境和复杂的行为积极影响保护和管理结果的能力, 这些行为是建立在它们的知觉、个性、生活经验、认知、社会性和文化之上的, 其方式塑造和重塑了人类与野生动物共有的文化、空间和历史。保护实践, 如同情心保护、和谐性保护和生态正义, 都包含了动物能动性的各个层面。通过评估动物能动性对物种生存的贡献, 以及鼓励人类和非人类利益相关者之间更多的适应性和合作性决策, 可以将动物能动性纳入到保护问题的解决方案之中。【翻译: 胡怡思; 审校 : 聂永刚】