Logan et al. Journal of Physiological Anthropology (2018) 37:15
https://doi.org/10.1186/s40101-018-0176-8
REVIEW
The importance of the exposome and
allostatic load in the planetary health
paradigm
Alan C. Logan1*, Susan L. Prescott2, Tari Haahtela3 and David L. Katz4
Open Access
Abstract
In 1980, Jonas Salk (1914–1995) encouraged professionals in anthropology and related disciplines to consider the
interconnections between “planetary health,” sociocultural changes associated with technological advances, and the
biology of human health. The concept of planetary health emphasizes that human health is intricately connected
to the health of natural systems within the Earth’s biosphere; experts in physiological anthropology have
illuminated some of the mechanisms by which experiences in natural environments (or the built environment) can
promote or detract from health. For example, shinrin-yoku and related research (which first emerged from Japan in
the 1990s) helped set in motion international studies that have since examined physiological responses to time
spent in natural and/or urban environments. However, in order to advance such findings into planetary health
discourse, it will be necessary to further understand how these biological responses (inflammation and the
collective of allostatic load) are connected to psychological constructs such as nature relatedness, and pro-social/
environmental attitudes and behaviors. The exposome refers to total environmental exposures—detrimental and
beneficial—that can help predict biological responses of the organism to environment over time. Advances in
“omics” techniques—metagenomics, proteomics, metabolomics—and systems biology are allowing researchers to
gain unprecedented insight into the physiological ramifications of human behavior. Objective markers of stress
physiology and microbiome research may help illuminate the personal, public, and planetary health consequences
of “extinction of experience.” At the same time, planetary health as an emerging multidisciplinary concept will be
strengthened by input from the perspectives of physiological anthropology.
Keywords: Allostatic load, Exposome, Nature relatedness, Health disparities, Ecology, Non-communicable diseases,
Dysbiosis, Natural environments
Background
“Sophisticated technology, intended to advantages for
humankind, sometimes has had unforeseen adverse
effects on human health...[environmental degradation]
threatens human and planetary health. The latter
must also be added to the consideration of biological
and sociocultural influences on health throughout the
human life span” [1].
Jonas Salk, MD, 1980
* Correspondence: aclnd@cfs-fm.org
1In-VIVO Global Initiative, Research Group of the Worldwide Universities
Network (WUN), 6010 Park Ave, Suite #4081, West New York, NJ 07093, USA
Full list of author information is available at the end of the article
In the quote above, found within a nearly 40-year-old
medical anthropology textbook, Jonas Salk introduces
the term “planetary health” into multidisciplinary re-
search. Although best known for developing the vaccine
that helped to eradicate polio, Salk spent large portions
of his scientific career championing the idea that human
health is dependent upon biodiversity and healthy eco-
systems. Moreover, he argued that the human body was
an extension of the functioning whole of the external en-
vironments—including its biodiversity, social policies,
and cultural practices: “We must see ourselves as part of
the ecosystem. Where we were once a product of evolu-
tion, we are now part of the process” [2]. In underscor-
ing planetary health in medical anthropology, Salk was
referring to the health of the Earth’s natural systems as
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Logan et al. Journal of Physiological Anthropology (2018) 37:15
Page 2 of 10
an upstream driver of human health and vitality. He em-
phasized the need to study the interconnected biological
(hence, physiological), social, and cultural aspects of
health from the planetary health perspective.
While the term planetary health has since been used
by many different scientific, health, and environmental
advocacy groups—each generally referring to the health
of ecosystems within the biosphere [3]—the 2015 Lancet
Commission on Planetary Health report formally defined
the planetary health paradigm as “the health of human
civilization and the state of the natural systems on which
it depends” [4]. Put simply, there is no human health
without planetary health. Of high-level relevance to
physiological anthropology, the Lancet Commission on
Planetary Health report also emphasizes integration of
biological, social, and cultural aspects of health in the
modern environment. Further, the report “accepts the
complexity and non-linearity of the dynamics of natural
systems” and underscores the need to study potential
health benefits derived from the maintenance and res-
toration of natural systems.
Physiological anthropology will play an important role
in the emergent planetary health paradigm; indeed, for
the last several decades, physiological anthropology has
been a leading contributor in understanding the physio-
logical consequences of modern pressures placed upon
humans. Specifically, physiological anthropology has fo-
cused on the ways in which the modern environment—
with its high technology, dominance of ultra-processed
foods, and diminished human contact with biodiver-
sity—can impact upon normal physiological functioning;
understanding the gulf between the psychological and
physiological requirements of individuals—and the (in)-
ability of the modern environment to help fulfill those
needs—is central to the aims of physiological anthropol-
ogy [5]. Since biological responses are a product of our
ancestral past, signs of metabolic dysregulation can un-
veil an evolutionary mismatch that otherwise contributes
to a global epidemic of NCDs.
an environment formerly rich in biodiversity), and thus,
a “baseline” awareness of the health of nature by succes-
sive generations is reset in a way that underestimates the
full extent of degradation.
Next, we focus on the exposome and recent findings in
the science of allostatic load, underscoring how the total
lived experience of individuals—including missed oppor-
tunities and experiences—influences health at the personal,
public, and planetary scales. Alterations in biological re-
sponses to the modern environment—immune and ner-
vous system functioning in particular—can drive low-grade
inflammation which, in turn, can compromise mental
health. However, under the rubric of “extinction of experi-
ence,” the extent to which humans in westernized and in-
dustrialized nations are aware of connections between
health of self and biodiversity may be increasingly obscured.
Thus, it is our contention that progress toward the goals of
planetary health is predicated upon a greater understanding
of how collected experiences in the natural environment in-
fluence physiology and behavior (Fig. 1).
Extinction of experience
“I would like to say”.
Coyote is forever.
Inside you.
“But it’s not true”.
Gary Snyder, “The Call of the Wild”, 1974
Salk maintained that scientists should look toward the
arts and humanities in order to identify fundamental
questions worthy of scientific pursuit [6]. In this context,
Roadmap to the current review
Here in our narrative review and commentary, we illus-
trate the importance of physiological anthropology in
the context of planetary health. In order to emphasize
this connection, we first discuss “extinction of experi-
ence” with nature, a term which loosely describes the
loss of experiential contact with biodiversity and natural
environments. The term is related to other theories and
phrases such as “shifting baseline syndrome” and “envir-
onmental generational amnesia” which propose that in-
dividuals gauge their perceptions (of, for example,
biodiversity losses or environmental degradation) from
their own experiences in the surrounding environment;
it is difficult to truly appreciate “what once was” (that is,
Fig. 1 How does accumulated experience (or lack thereof) in the
modern environment influence human physiology and help
illuminate the links between personal, public, and planetary health?
Logan et al. Journal of Physiological Anthropology (2018) 37:15
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we highlight the work of scholar, environmentalist, and
Pulitzer-prize-winning poet Gary Snyder; greatly influ-
enced by his many years living in Japan, studying the
rich biodiversity of the land, Snyder’s versification
through the 1950s–1960s celebrated the ways in which
our ancestral experience in natural environments could
reassert itself (in the form of vitality and joy) when
primed. This, according to Snyder, was most obvious
when an individual was once again immersed in nature
[7]. However, in his later Pulitzer-winning book Turtle
Island (1974), Snyder expressed concern about the
trans-generational loss of experience with nature, and
the subsequent ability of nature’s deep (albeit hidden)
resonance—the coyote as a metaphor—to survive in
post-modern humans [8, 9].
Several years later, scientist Robert Pyle coined a term for
this hypothesis—“extinction of experience.” Writing in
Horticulture (1978), Pyle stated that the disappearance of
neighborhood biodiversity was a threat to the “collective
psyche” and that its represented “the loss of opportunities -
the extinction of experience”; in particular, Pyle was con-
cerned about vanishing opportunities for children, “the
ones whose sensibilities must be touched by the magic re-
action with wildlife if biologists, conservationists and con-
cerned citizens are not to become endangered themselves.
What is the extinction the condor to a child who has never
seen a wren?” [10]. The concept of extinction of experience
has been expanded upon, but the primary theme remains
the same—loss of direct, personal, cognitive-emotional con-
tact with wildlife and elements of the natural world could
lead to disaffection, apathy, and irresponsibility in behaviors
toward the environment [11, 12].
At the same time, a related hypothesis was expanding;
the hygiene hypothesis and its variants proposed that
diminishing early life exposures to microbes—due to a
more “sanitized” environment, antibiotic use, smaller fam-
ily sizes, and lower exposure to bacteria in foods and the
overall environment—could compromise normal training
of the immune system. The recent biodiversity hypothesis
updates and unifies this proposal by emphasizing that bio-
diversity losses at the neighborhood scale could translate
into loss of contact with microbiotic diversity. Specifically,
“biodiversity loss leads to reduced interaction between en-
vironmental and human microbiotas. This in turn may
lead to immune dysfunction and impaired tolerance
mechanisms in humans” [13, 14]. However, research in
the more biologically oriented biodiversity hypothesis and
the more psychologically oriented extinction of experience
hypothesis has largely remained separated in silos.
In the twenty-first century, there have been several stud-
ies which support the idea that adults and children in
westernized, industrial, and technologically mature na-
tions are spending more time indoors [15, 16] and less
time in natural environments [17, 18]. There are also hints
that declines in local biodiversity and environmental deg-
radation are associated with greater time spent indoors
[19]; since lack of time spent outdoors is associated with
chronic disease [20], this could present a double burden
of increased risk of NCDs and decreased the awareness of
further threats to local and global biodiversity. The best
evidence of extinction of experience has emerged from
Japanese research; using a range of 21 different neighbor-
hood flowering plants as a measure of interaction with
visible aspects of biodiversity, researchers have shown an
age-related, cross-generational decline in childhood
experiences with nature [21]. International research
demonstrates that such neighborhood changes may be
compounded by cultural changes in media representations
of biodiversity which focus only on a miniscule sliver of
well-known species [22–24].
Extinction of experience is, of course, worrisome from a
conservation perspective; the ability to develop an emo-
tional connection with the natural world (measurable with
the psychological construct of nature-relatedness [25])—
and subsequently develop pro-environmental attitudes
and behaviors—is dependent upon experience [26]. Na-
ture relatedness (see also nature connectivity, nature con-
nectedness) allows researchers to determine individual
levels of awareness of, and fascination with, the natural
world; nature relatedness also captures the degree to
which subjects in research studies have an interest in mak-
ing contact with nature. From the planetary health per-
spective, nature relatedness is positively associated with
empathy, pro-environmental attitudes, and humanitarian-
ism (and negatively with materialism) [27–29]. However,
nature relatedness is also highly relevant to physiological
anthropology, and human biology in general, because a
substantial body of research has linked appreciation of
(and relatedness to) the natural environment with general
health and mental wellbeing [30, 31].
Sitting in parallel to research on the psychology of na-
ture relatedness—unintegrated into the planetary health
paradigm—is a growing body of in vivo research involving
physiological endpoints which demonstrate that time
spent in natural environments might be protective against
allostatic load (described in more detail shortly). While
there are now many studies in this realm, it is perhaps best
exemplified by shinrin-yoku (now generally referred to in
Japanese studies as simply “forest medicine” or “forest
therapy”) research; shinrin-yoku loosely translates from
Japanese as forest-air bathing or “absorbing the forest air”
and places emphasis on the entire forest experience
wherein the individual tales in all the “components emit-
ted from the forest” [32]. Studies under the rubric of shin-
rin-yoku have shown that spending time in a forest
environment can beneficially influence stress physiology,
markers of inflammation, immune defenses, blood pres-
sure, and heart rate variability [33–40].
Logan et al. Journal of Physiological Anthropology (2018) 37:15
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To appreciate the contribution of shinrin-yoku and re-
lated research, consider that a 2018 systematic review
identified a total of 43 studies which measured physio-
logical and psychological stress responses to outdoor en-
vironments—nearly half of the studies were conducted
in Japan [41]. Although limited by small sample sizes,
these and other studies with physiological endpoints
provide potential mechanistic pathways (e.g., immune
activation, oxidative stress, blood pressure, cortisol re-
sponse) for the associative links between green space
and health in large epidemiological studies [42]. More-
over, these studies can be viewed in the context of stud-
ies which link markers of biodiversity with mental and
physical health [43, 44]. On the other hand, relatively
rapid environmental degradation and/or visible losses in
species (e.g., the loss of millions of ash trees due to the
invasive emerald ash borer) are linked to declines in
physical and mental health [45–47].
Extinction of experience research also forces questions
concerning shifting cultural norms and time use; in
other words, if time spent in outdoors in nature is being
displaced, then how specifically is that time displaced?
These are connected conversations. For example, excess
screen time and problematic smartphone use is linked
with lower levels of personal nature relatedness [48]. It
is also important to point out that “extinction of experi-
ence” is not exclusive to psychological losses in contact
with biodiversity (or even biodiversity per se); it could be
argued that for children in westernized nations, the loss
of whole plant foods (relatively unprocessed, high in
fiber) in the dietary and the massive encroachment of
the “invasive species” known as ultra-processed foods
(which now dominate the nutritional landscape, like
weeds, displacing nutrient-dense foods) is also an extinc-
tion of experience [49]. Moreover, from the biological
perspective, urbanization and loss of contact with bio-
diversity [50]—as well as related changes to contact with
diversity of the microbiome [51, 52]—could be viewed as
an “immunological extinction of experience.”
Since the health benefits derived from experiences in
natural environments may be determined by baseline na-
ture relatedness [53], researchers will need to examine
the physiological consequences of the interplay between
the presence (use) of certain technologies and the ab-
sence (disuse) of natural environments and biodiversity.
Thus, the challenge for physiological anthropology in
the context of planetary health is to help bridge the
knowledge gaps between three large, research-based
silos—that is, (1) the psychological and cognitive aspects
of nature relatedness and the loss of experience, (2) the
physiological pathways involved in the risk of NCDs,
and (3) the ways in which human health and wellbeing
are, emotionally and biologically, predicated upon bio-
diversity and the health of the Earth’s natural systems.
It is our contention that an “exposome perspective” will
help break down silos and incorporate the ongoing work
of physiological anthropology into planetary health. The
exposome refers to the science of accumulated “expo-
sures” (meaning both emotional experiences and physical/
sensory exposures) over time. As we explain below, this
view emphasizes that genes alone cannot explain health
disparities and underscores that each individual exposure
(e.g., airborne particulate matter or fast-food, beneficial
microbes, or phytoncides) does not occur independent of
the total environment. Moreover, from the physiological
perspective, the most direct path to understanding the
connections between personal and planetary health—gains
and losses from extinction of certain experiences and the
birth and flourishing of others—may be to examine allo-
static load (the physiology associated with the “wear and
tear” of stress). We will elaborate on this shortly.
Exposome
“Human biology should be primarily concerned with
the responses that the body and the mind make to the
surroundings and ways of life…little effort has been
made to develop methods for investigating
scientifically the interrelatedness of things.
Epidemiological evidence leaves no doubt that many
chronic and degenerative disorders which constitute
the most difficult and costly medical problems of our
societies have their origin in the surroundings and in
the ways of life rather than in the genetic constitution
of the patient. But little is known of these
environmental determinants of disease” [54].
Rene J. Dubos, PhD, 1969
While he did not coin the term “exposome,” micro-
biologist and environmentalist Rene Dubos (1901–1982)
urged scientists to study the response of the “total or-
ganism to the total environment” [55]; Dubos, of course,
not only celebrated the value of single-variable studies
but also warned of their limitations in the context of
chronic diseases, environmental degradations, and the
complexities of the human condition [56, 57]. Today,
the total accumulated environmental exposures (both
detrimental and beneficial) that can help predict the bio-
logical responses of the “total organism to the total en-
vironment” over time are referred to as the exposome
[58]. The temporal aspect of exposome science is im-
portant because the physiological responses of the hu-
man organism are a product of accumulated experiences
and may differ across time depending on shifting envir-
onmental variables. The interpretation of stress physi-
ology in the here-and-now requires an understanding of
the interplay between time scales of stress, including but
Logan et al. Journal of Physiological Anthropology (2018) 37:15
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not limited to early life stress, acute and chronic
stressors, experience of daily hassles, and the aggregate
of life events [59].
The term exposome is now an essential feature of the
planetary health discourse because it helps to demonstrate
why genome-wide association studies cannot explain the
reasons for health disparities; it also helps us understand
why NCDs are increasing over time and in non-random
ways. In particular, the burden of NCDs, especially in
westernized nations, is most often shouldered by disad-
vantaged populations [58]. Furthermore, the exposome
view of total health encompasses the World Health Orga-
nization’s interpretation of the word health; that is, not
simply the absence of specific disease criteria, but rather
the fulfillment of human potential. Although genetics
matter, health includes a state of complete physical, men-
tal, and social wellbeing—it is not a genetic trait.
Rather, the study of physiology related to health promo-
tion and/or risk is better understood when it is placed into
the context of the total exposures experienced by
humans—some positive, some negative—and their interac-
tions with genes over time [60]. From a life-course perspec-
tive, exposome science emphasizes that certain windows of
vulnerability (for disease risk) and opportunity (for health
promotion) are especially important [61]. In the context of
physiological anthropology, this means that socioeconomic
advantage or disadvantage can produce differing biological
responses to specific “beneficial” or “detrimental” expo-
sures—e.g., spending time in nature or consuming a
fast-food meal—depending on many other background
variables.
The interplay of these potentially beneficial and detri-
mental experiences is central to the concept of resili-
ency; as researchers explore how and why positive
adaptation and outcomes occur in the face of adversities,
and why certain individuals (who score high on validated
resiliency scores) seem protected against the negative
health-related consequences of adverse events, it will be
necessary to tease apart the ways in which resiliency is
built in the first place [62]. The available evidence allows
for the hypothesis that exposure to elements of natural
environments—e.g., microbial—can play a role in resili-
ency. Indeed, early-life exposure to diverse microbes
found in natural environments is part of the normal
“training” of the immune system, and it may decrease
vulnerability to later life stress-associated disorders; for
example, researchers have found that urban upbringing
without pets (vs. rural upbringing around animals) is as-
sociated with compromised resolution of systemic im-
mune activation (low-grade inflammation) following an
experimenter-induced social stress [63]. To further ap-
preciate the saliency of how accumulated experiences in-
fluence physiology in the total environment, we can look
to research on allostatic load.
Allostatic load
Human responsiveness to environmental threats has
been shaped by experience over millennia. In particular,
an elegant and active process of allostasis—the normal
initiation, orchestration, and termination of neuroendo-
crine, metabolic, autonomic, and immune “mediators”—
helps ensure a physiological state which supports sur-
vival. Acutely, these multisystem physiological responses
to stress are, under normal circumstances, effectively ini-
tiated, maintained, and extinguished without harm.
However, with repetitive and/or prolonged stimulation
in the modern environment, these compensatory physio-
logical responses can lead to metabolic disturbances and
cellular damage. The collective toll of this physiological
wear and tear—including the associated consequences of
unhealthy lifestyle choices which compound the physio-
logical dysregulation—is known as allostatic load [64].
Over time, the combined disturbances of allostatic load
leads to allostatic overload and contribute to altered be-
havior and disease risk [65].
Epidemiological research indicates that links between
lower socioeconomic position and disease mortality are
mediated by allostatic load [66]. In other words, socio-
economic advantage is associated with lower allostatic
load, which is in turn link to lowered risk of mortality.
Such findings are supported by volumes of research indi-
cating that disadvantage is accompanied by chronic psy-
chosocial stress and daily hassles, lower optimism (an
asset in physical and mental health), and significantly
higher biomarkers of metabolic dysregulation, inflamma-
tion, and oxidative stress [67–74]. Indeed, within
westernized-industrialized nations, allostatic load ap-
pears to bear witness to the ways in which socioeco-
nomic disadvantage “gets under the skin” and “into the
gut,” ultimately decreasing longevity [66, 75].
These links with socioeconomic disadvantage have
been found at the individual and neighborhood levels;
for example, allostatic load persists in low-income
neighborhoods even after adjusting for individual-level
income. Beyond income, anxious arousal is linked to
allostatic load, as well as other lifestyle factors such
as fast-food consumption, exercise habits, and smok-
ing [76]; moreover, neighborhood-level income is as-
sociated with better physical and mental health over
time [77]. Since allostatic load transcends purely gen-
etic influences [78], it reinforces the exposome per-
spective and underscores the need to consider the
context in which exposures are experienced. More-
over, it also allows for the introduction of epigenetic
research and opportunities to determine how expo-
sures (age, diet, physical activity, time in nature, posi-
tive and/or negative emotions, and accumulated
experiences) modify DNA methylation, which in turn,
alters gene expression [79].
Logan et al. Journal of Physiological Anthropology (2018) 37:15
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Putting it all together, future directions
The biological underpinnings of the exposome perspec-
tive indicate that the extent to which an organism can
buffer against the detrimental physiological conse-
quences of particular exposures will determine the risk
of NCDs [58]. Hence, it is essential to understand how
certain psychological “assets”—such as nature related-
ness, positive emotions, mindfulness, and optimism—are
accumulated and employed to act as physiological
buffers in the modern environment. The available re-
search, outlined above, suggests that scientists need to
look more closely at the total lived experience of individ-
uals, and the total environment which surrounds them.
From the planetary health perspective, this means look-
ing at the presence (or absence) of natural environments
and specific features of the built environment that might
offset (or contribute to) allostatic load.
Looking at research from the exposome perspective al-
lows researchers to consider the “big picture” and intercon-
nectivity of humankind’s most pressing problems. For
example, living closer to green space and having greater ac-
cess to safe, local parks, and open space is associated with
health in general and mental health in particular [80]. How-
ever, the presence of green space may be a surrogate marker
for healthier dietary habits, lower density of fast-food out-
lets, and better access to healthy foods [81–83].
Consider also the psychological asset of optimism
which we have alluded to several times; optimism is gen-
erally defined as positive outcome expectancy for future
events across life domains. Optimism has been linked to
lower body mass index and lower rates of chronic dis-
ease and all-cause mortality [84–88]. In the physiological
realm, optimism is linked to optimal metabolic markers
of cardiovascular health, lower inflammatory cytokine
and C-reactive protein levels, and lower inflammatory
response to experimental stress [89–91]. Research sug-
gests that optimism is only about 25% heritable, leaving
plenty of room for the influence of the total lived experi-
ence over time; indeed, higher levels of optimism are as-
sociated with socioeconomic advantage [92, 93]. Since
optimism is malleable [94], experts in physiological an-
thropology might query on biological links between opti-
mism, nature relatedness, and extinction of experience.
For example, higher levels of optimism are associated
with protection against the detrimental effects of envir-
onmental toxins (this appears to operate through epi-
genetic mechanisms) [95].
Scientists are beginning to tie these strands together; for
example, researchers have found that close residential
proximity to vegetated land cover is associated with lower
allostatic load and depression [96]. In addition, researchers
have begun to establish links between residential (or
school) proximity and green vegetation—and degrees of
neighborhood urbanization—with exposure to diverse,
non-harmful microbes that may influence health and be-
havior [97–100]. However, these studies are missing key
bits of information; how do measurements on the psycho-
logical construct of nature relatedness—and responses re-
lated to extinction of experience at the neighborhood
level—match up with the objective markers of allostatic
load, epigenetics and the microbiome? Does the
age-related decline in direct experiences with neighbor-
hood biodiversity manifest physiologically (allostatic load),
and if so, are there connections between allostatic load
and nature relatedness?
These are essential questions for the planetary health
paradigm. So far, the research focus on the human
emotional connections to nature/local lands in the con-
text of planetary health (exemplified by content within
the aforementioned and highly cited Lancet Commis-
sion on Planetary Health report) has been on the real
and potential mental health consequences of environ-
mental degradation. Although there is good research on
the psychological aspects of pro-environmental and
pro-social beliefs and behaviors, its place in the dis-
course of planetary health is minimal. Moreover, the
wealth of information gathered in the field of physio-
logical anthropology (and related disciplines) on differ-
ential physiological responses to natural and built
environments (e.g., shinrin-yoku, forest bathing re-
search) has not penetrated the planetary health dis-
course. In addition to nature relatedness, the inclusion
of other psychological constructs in the literature, espe-
cially those investigating place attachment measure-
ments (e.g., topophilia scales) [101, 102], will help
provide a better understanding of how physiological
endpoints might match individual and community-level
emotional connections to the land.
We suspect that the absence of cohort studies which sim-
ultaneously measure deep aspects of socioeconomic histor-
ies, allostatic load (and other objective markers such as the
microbiome), residential proximity to “assets” (green space)
and “liabilities” (clustering of fast-food outlets), along with
measures of positive psychology/nature-relatedness/envir-
onmental attitudes is a barrier to multidisciplinary break-
throughs in planetary health. Available research indicates
that the loss of experience (especially immunological) can
shape acute biological responses in context over time; as we
have pointed out previously, these are intertwined with in-
come, education, race, immigrant status/segregation, social
cohesion, evaluations of neighborhood esthetic quality, and/
or aspects of neighborhood safety (both real and perceived)
[103]. While constituents of a diet which simultaneously
promotes human and planetary health is generally agreed
upon [104–106], less is known concerning the ways in
which nature relatedness, optimism, and pro-environmental
attitudes/behaviors and allostatic load intersect with adher-
ence to such a diet.
Logan et al. Journal of Physiological Anthropology (2018) 37:15
Page 7 of 10
Macro-scale, multi-factorial, multi-indicator consider-
ations such as the exposome, allostatic load, and planetary
health present enormous challenges; it is easy to criticize
such efforts because they include an essentially unlimited
array of variables. While single-variable studies remain es-
sential to scientific knowledge, large cohort studies are
enjoying remarkable advances in “omics” research; clinic-
ally meaningful data sets are emerging from the analysis
of functional proteins (proteomics), metabolites (metabo-
lomics), gene expression (epigenomics, transcriptomics),
and genetic influences on specific drugs or nutrients
(pharmacogenomics) [107]. For example, large datasets in
the area of the microbiome have provided clinically rele-
vant information which may predict an individual’s
physiological responses to foods [108]. Thus, the ability of
researchers to match environmental attitudes, nature re-
latedness, and other psychological indicators (based on ex-
perience or lack thereof) with important aspects of
physiology at the individual and community-level is on
the horizon [58].
As researchers begin to incorporate research on expo-
sures and experiences into the planetary health perspec-
tive—including studies on physiological endpoints,
resiliency, and allostatic load—we will also learn more
concerning realistic expectations concerning the role of
natural environments and health outcomes; access to
green space is important, but there are many factors that
push health inequalities and social injustices, including
those that may have far more corrosive effects on health.
We may have unwittingly given the impression that the
health implications of experiences, exposures, and allo-
static load are linear—that is, where more of a certain
sort of experience/exposure is better or the more of an-
other sort of experience or load is worse. These are not
aggregate responses with a universal dose-response rela-
tionship; indeed, researchers are already discovering that
the potential benefits of nature are not found along a
neat continuum of benefit [109, 110].
Finally, this entire conversation can be viewed through
an evolutionary lens. What we need to eat—as opposed
to the ultra-processed foods that surround us—is what
we are adapted to eat. The exercise we need is obviously
part-and-parcel of the physical activity to which we are
adapted; corals and mussels need not count steps! So,
too, our requirements for the natural settings to which
we are adapted can be viewed, scientifically, from the
evolutionary perspective and can help guide future re-
search questions. It allows us to ask “why do we humans
need nature to be whole?” in modernity. The answer is
blowing in the wind, complete with microbes, natural
light, and phytoncides, because we are adapted to it as a
part of us, and us as a part of it—for all the same rea-
sons we need to breathe the atmosphere native to the
planet that generated us.
Conclusion
Scientifically, the grand challenges of our time—environ-
mental degradation, a global non-communicable disease
(NCD) epidemic, gross biodiversity losses, climate
change, health and other socioeconomic inequalities—
are adisciplinary. In other words, these challenges are
overlapping, and their causative complexities suggests
that they will not be solved by linear research which
otherwise remains in silos. The extinction of experience
perspective suggests that each generation may accept the
inherited state of their environment with a greater sense
of “normalcy”; while experts in biodiversity conservation
have a keen interest in extinction of experience research,
a greater understanding of its physiological underpin-
nings seem necessary.
In our narrative review and commentary, we have
pointed to research on extinction of experience, nature re-
latedness, and the science of allostatic load to argue for a
stronger presence of physiological anthropology in the
planetary health paradigm. Over time, the burdensome bio-
logical consequences of detrimental exposures (and absence
of beneficial exposures and psychological assets) will press
upon those with higher allostatic load, translating into a
biologically corrosive allostatic overload. While physio-
logical anthropology has made tremendous contributions
to the understanding of mechanisms that help explain the
ways in which experience in natural environments (or ex-
posure to individual constituent parts of nature) promote
health, many gaps remain. In particular, a more persuasive
argument for the connections between personal, public,
and planetary health could be made via more detailed
understanding of the biological pathways between nature
relatedness, changing levels of local biodiversity, and allo-
static load.
The prospect of personalized medicine test results
(based on physiological responses and large datasets)
may provide much-needed incentives to motivate indi-
viduals to change lifestyle behaviors that are in the inter-
est of personal and planetary health. The challenge is to
illuminate the direct links between elements of natural
environments with measurable parameters of human
health; having “lab results” in hand may help individuals,
communities, clinicians, and policy-makers to under-
stand the direct lines between personal, public, and
planetary health. In the meantime, the available evidence
which supports the biodiversity hypothesis is not calling
for a “back to nature” movement, but rather stepping
“forward with nature” in the urbanized environment.
With the momentum initiated by the 2015 Lancet Com-
mission on Planetary Health report (now cited over 300
times on Google Scholar), the counsel of Jonas Salk to
bring planetary health into alignment with the biological
and socio-cultural objectives of anthropology seems wise.
At the same time, the multidisciplinary effort of planetary
Logan et al. Journal of Physiological Anthropology (2018) 37:15
Page 8 of 10
health (adisciplinary in nature, planetary health cannot be
viewed as a single discipline) should draw upon the ex-
pertise of professionals in physiological anthropology. In
the evidence-informed practice, clinicians seek interven-
tion studies (with physiology and controls in mind) to help
guide recommendations; so, too, policy-makers need to
make decisions based on the best available evidence. With
each turn of the Earth, the grand challenges of our time
loom larger—there is no time to waste.
Abbreviation
NCDs : Non-communicable diseases
Authors’ contributions
SLP developed the commentary, project oversight, research analysis, and
approved the final manuscript. TH assisted with research interpretation
and input of early origins, life-course perspectives. ACL provided the
research analysis and developed the manuscript draft. DLK is responsible
for the commentary oversight, research interpretation, critical review of
manuscript, and input of public health perspectives. All authors read and
approved the final manuscript.
Ethics approval and consent to participate
Not applicable
Competing interests
SLP reports the following: Scientific Advisory Board and speakers fees
from Danone Nutricia, Schiphol, Netherlands and Nestlé Nutrition
Institute, Lausanne, Switzerland; consultancy fees from Bayer Dietary
Supplements Division, Whippany, NJ, USA; speakers’ fees from Health
World Inc., Queensland, Australia; and royalties from a trade paperback
which discusses the microbiome. ACL has received consultancy fees
from Genuine Health, Toronto, Canada; speakers’ fees from Health World
Inc., Queensland, Australia; and royalties from a trade paperback which
discusses the microbiome. The other authors declare that they have no
competing interests.
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Author details
1In-VIVO Global Initiative, Research Group of the Worldwide Universities
Network (WUN), 6010 Park Ave, Suite #4081, West New York, NJ 07093, USA.
2School of Medicine, University of Western Australia, Princess Margaret
Hospital, PO Box D184, Perth, WA 6001, Australia. 3Skin and Allergy Hospital,
Helsinki University Central Hospital, PO BOX 160, FI-00029 HUS Helsinki,
Finland. 4Prevention Research Center, Griffin Hospital, Yale University, 130
Division St, Derby, CT 06418, USA.
Received: 23 April 2018 Accepted: 25 May 2018
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