Neurotechnology encompasses any method or electronic device which interfaces with the nervous system to monitor or modulate neural activity.
Common design goals for neurotechnologies include using neural activity readings to control external devices such as neuroprosthetics, altering neural activity via neuromodulation to repair or normalize function affected by neurological disorders, or augmenting cognitive abilities. In addition to their therapeutic or commercial uses, neurotechnologies
also constitute powerful research tools to advance fundamental neuroscience knowledge.
The field of neurotechnology has been around for nearly half a
century but has only reached maturity in the last twenty years. Decoding
basic procedures and interactions within the brain's neuronal activity
is essential to integrate machines with the nervous system. This is one of the central steps of the technological revolution based
on a fusion of technologies that is blurring the lines between the
physical, digital, and biological spheres. Integrating an electronic
device with the nervous system enables monitoring and modulating neural
activity as well as managing implemented machines by mental activity.
Further work in this direction would have profound implications for
improving existing and developing new treatments for neurological
disorders and advanced "implantable neurotechnologies" as integrated
artificial implants for various pieces of the nervous system. Advances in these efforts are associated with developing models based
on knowledge about natural processes in bio-systems that monitor and/or
modulate neural activity. One promising direction evolves through
studying the mother-fetus neurocognitive model. According to this model, the innate natural mechanism ensures the embryonic nervous system's correct (balanced) development. Because the mother-fetus interaction enables the child's nervous system
to evolve with adequate biological sentience, similar environmental
conditions can treat the injured nervous system. This means that the
physiological processes of this natural neurostimulation during
gestation underlie any noninvasive artificial neuromodulation technique. This knowledge paves the way for designing and precise tuning
noninvasive brain stimulation devices in treating different nervous
system diseases within the scope of modulating neural activity.
More specialized sectors of the neurotechnology development for
monitoring and modulating neural activity are aimed at creating powerful
concepts as "neuron-like electrodes", "biohybrid electrodes", "planar complementary metal-oxide semiconductor systems", "injectable bioconjugate nanomaterials", "implantable optoelectronic microchips".
The advent of brain imaging
revolutionized the field, allowing researchers to directly monitor the
brain's activities during experiments. Practice in neurotechnology can
be found in fields such as pharmaceutical practices, be it from drugs
for depression, sleep, ADHD, or anti-neurotics to cancer scanning, stroke rehabilitation, etc.
Many in the field aim to control and harness more of what the
brain does and how it influences lifestyles and personalities.
Commonplace technologies already attempt to do this; games like BrainAge, and programs like Fast ForWord that aim to improve brain function, are neurotechnologies.
Currently, modern science can image nearly all aspects of the
brain as well as control a degree of the function of the brain. It can
help control depression, over-activation, sleep deprivation, and many other conditions. Therapeutically it can help improve stroke patients' motor coordination, improve brain function, reduce epileptic episodes (see epilepsy), improve patients with degenerative motor diseases (Parkinson's disease, Huntington's disease, ALS), and can even help alleviate phantom pain perception. Advances in the field promise many new enhancements and rehabilitation
methods for patients with neurological problems. The neurotechnology
revolution has given rise to the Decade of the Mind initiative, which was started in 2007. It also offers the possibility of revealing the mechanisms by which mind and consciousness emerge from the brain.
Types
Neurostimulation
A
wide range of neurostimulation techniques can be divided into four
domains depending on the use of energy stimulation: acoustic wave
energy, electrical energy, electromagnetic radiation, and magnetic
energy. Some of these techniques are presented below:
Deep brain stimulation is currently used in patients with movement disorders to improve the quality of life in patients.
Transcranial ultrasound stimulation
Transcrancial
ultrasound stimulation (TUS) is a technique using ultrasound to
modulate neural activity in the brain. It is an emerging technique that
has shown therapeutic promise in a variety of neurological diseases.
Transcranial magnetic stimulation (TMS) is a technique for applying
magnetic fields to the brain to manipulate electrical activity at
specific loci in the brain. This field of study is currently receiving a large amount of attention
due to the potential benefits that could come out of better
understanding this technology. Transcranial magnetic movement of particles in the brain shows promise
for drug targeting and delivery as studies have demonstrated this to be
noninvasive on brain physiology.
Transcranial magnetic stimulation is a relatively new method of
studying how the brain functions and is used in many research labs
focused on behavioral disorders, epilepsy, PTSD, migraine, hallucinations, and other disorders. Currently, repetitive transcranial magnetic stimulation is being
researched to see if positive behavioral effects of TMS can be made more
permanent. Some techniques combine TMS and another scanning method such
as EEG to get additional information about brain activity such as
cortical response.
Transcranial direct current stimulation (TDCS) is a form of neurostimulation
which uses constant, low current delivered via electrodes placed on the
scalp. The mechanisms underlying TDCS effects are still incompletely
understood, but recent advances in neurotechnology allowing for in vivo assessment of brain electric activity during TDCS promise to advance understanding of these mechanisms. Research into
using TDCS on healthy adults have demonstrated that TDCS can increase
cognitive performance on a variety of tasks, depending on the area of
the brain being stimulated. TDCS has been used to enhance language and
mathematical ability (though one form of TDCS was also found to inhibit
math learning), attention span, problem solving, memory, coordination and relieve depressionand chronic fatigue.
Electrophysiology
Electroencephalography
(EEG) is a method of measuring brainwave activity non-invasively. A
number of electrodes are placed around the head and scalp and electrical
signals are measured. Clinically, EEGs are used to study epilepsy as well as stroke and tumor presence in the brain. Electrocorticography
(ECoG) relies on similar principles but requires invasive implantation
of electrodes on the brain's surface to measure local field potentials
or action potentials more sensitively.
Magnetoencephalography
(MEG) is another method of measuring activity in the brain by measuring
the magnetic fields that arise from electrical currents in the brain. The benefit to using MEG instead of EEG is that these fields are highly
localized and give rise to better understanding of how specific loci
react to stimulation or if these regions over-activate (as in epileptic
seizures).
There are potential uses for EEG and MEG such as charting
rehabilitation and improvement after trauma as well as testing neural
conductivity in specific regions of epileptics or patients with
personality disorders. EEG has been fundamental in understanding the
resting brain during sleep. Real-time EEG has been considered for use in lie detection. Similarly, real-time fMRI is being researched as a method for pain
therapy by altering how people perceive pain if they are made aware of
how their brain is functioning while in pain. By providing direct and
understandable feedback, researchers can help patients with chronic pain
decrease their symptoms.
Neurotechnological implants can be used to record and utilize brain
activity to control other devices which provide feedback to the user or
replace missing biological functions. The most common neurodevices available for clinical use are deep brain stimulators implanted in the subthalamic nucleus for patients with Parkinson's disease.
Pharmaceuticals play a vital role in maintaining stable brain
chemistry, and are the most commonly used neurotechnology by the general
public and medicine. Drugs like sertraline, methylphenidate, and zolpidem
act as chemical modulators in the brain, and they allow for normal
activity in many people whose brains cannot act normally under
physiological conditions. While pharmaceuticals are usually not
mentioned and have their own field, the role of pharmaceuticals is
perhaps the most far-reaching and commonplace in modern society.
Movement of magnetic particles to targeted brain regions for drug
delivery is an emerging field of study and causes no detectable circuit
damage.
Like other disruptive innovations,
neurotechnologies have the potential for profound social and legal
repercussions, and as such their development and introduction to society
raise a series of ethical questions.
Key concerns include the preservation of identity, agency, cognitive liberty and privacy as neurorights.
While experts agree that these core features of the human experience
stand to benefit from the ethical use of neurotechnology, they also make
a point of emphasizing the importance of preventively establishing specific regulatory frameworks and other mechanisms that protect against inappropriate or unauthorized uses.
Identity
Identity in this context refers to personal continuity, described as bodily and mental integrity and their persistence over time. In other words, it is the individual's self-narrative and concept of self.
While disruption of identity is not a common goal for
neurotechnologies, some techniques can create unwanted shifts that range
in severity. For instance, deep brain stimulation is commonly used as
treatment for Parkinson's disease
but can have side effects that touch on the concept of identity, such
as loss of voice modulation, increased impulsivity or feelings of
self-estrangement. In the case of neural prostheses and brain-computer interfaces, the
shift may take the form of an extension of one's sense of self,
potentially incorporating the device as an integral part of oneself or
expanding the range of sensory and cognitive channels available to the
user beyond the traditional senses.
Part of the difficulty in determining which changes constitute a
threat to identity is rooted in its dynamic nature: since one's
personality and concept of self is expected to change with time as a
result of emotional development and lived experience, it is not easy to
identify clear criteria and draw a line between acceptable shifts and
problematic changes. This becomes even harder when dealing with neurotechnologies aimed at
influencing psychological processes—such as those designed to recude the
symptoms of depression or post-traumatic stress disorder (PTSD) by
modulating emotional states or saliency of memories to ease a patient's
pain. Even helping a patient remember, which would seemingly help preserve
identity, can be a delicate question: "Forgetting is also important to
how a person navigates the world, since it allows the opportunity for
both losing track of embarrassing or difficult memories, and focusing on
future-oriented activity. Efforts to enhance identity through memory
preservation thus run the risk of inadvertently damaging a valuable, if
less consciously-driven cognitive process."
Agency
Although the nuances of its definition are debated in philosophy and sociology, agency is commonly understood as the individual's ability to
consciously make and communicate a decision or choice. While identity
and agency are distinct, an impairment in agency can in turn undermine
personal identity: the subject may no longer be able to substantially
modify their own self-narrative, and may therefore lose their ability to
contribute to the dynamic process of identity formation.
The interplay between agency and neurotechnology can have implications for moral responsibility and legal liability. As with identity, devices aimed at treating some psychiatric conditions
like depression or anorexia may work by modulating neural function
linked with desire or motivation, potentially compromising the user's
agency. This can also be the case, paradoxically, for those neurotechnologies
designed to restore agency to patients, such as neural prostheses and
BCI-mediated assistive technology like wheelchairs or computer accessibility tools. Because these devices often operate by interpreting sensory inputs or
the user's neural data in order to estimate the individual's intention
and respond according to it, estimation margins can lead to inaccurate
or undesired responses that may threaten agency: "If the agent's intent
and the device's output can come apart (think of how the auto-correct
function in texting sometimes misinterprets the user's intent and sends
problematic text messages), the user's sense of agency may be
undermined."
Privacy
Finally,
when these technologies are being developed society must understand
that these neurotechnologies could reveal the one thing that people can
always keep secret: what they are thinking. While there are large
amounts of benefits associated with these technologies, it is necessary
for scientists, citizens and policy makers alike to consider
implications for privacy. This term is important in many ethical circles concerned with the state
and goals of progress in the field of neurotechnology (see neuroethics).
Current improvements such as "brain fingerprinting" or lie detection
using EEG or fMRI could give rise to a set fixture of loci/emotional
relationships in the brain, although these technologies are still years
away from full application. It is important to consider how all these neurotechnologies might
affect the future of society, and it is suggested that political,
scientific, and civil debates are heard about the implementation of
these newer technologies that potentially offer a new wealth of
once-private information. Some ethicists are also concerned with the use of TMS and fear that the
technique could be used to alter patients in ways that are undesired by
the patient.
Cognitive liberty
Cognitive liberty refers to a suggested right to self-determination
of individuals to control their own mental processes, cognition, and
consciousness including by the use of various neurotechnologies and
psychoactive substances. This perceived right is relevant for
reformation and development of associated laws.
The invention of electric lights has allowed massive human population centers to be seen from low Earth orbit, demonstrating how humanity's impacts are visible at a global scale.
Twelve candidate sites were selected for the GSSP; the sediments of Crawford Lake (Halton Region),
Canada were finally proposed, in 2023, to mark the lower boundary of
the Anthropocene, starting with the Crawfordian stage/age in 1950.
In 2024, after 15 years of deliberation, the Anthropocene Epoch
proposal of the AWG was voted down by a wide margin by the SQS, owing
largely to its shallow sedimentary record and extremely recent proposed
start date. The ICS and the IUGS later formally confirmed, by a near unanimous
vote, the rejection of the AWG's Anthropocene Epoch proposal for
inclusion in the Geologic Time Scale.The IUGS statement on the rejection concluded: "Despite its rejection
as a formal unit of the Geologic Time Scale, Anthropocene will
nevertheless continue to be used not only by Earth and environmental scientists,
but also by social scientists, politicians and economists, as well as
by the public at large. It will remain an invaluable descriptor of human
impact on the Earth system."
Development of the concept
As early as 1873, the Italian geologist Antonio Stoppani acknowledged the increasing power and effect of humanity on the Earth's systems and referred to an 'anthropozoic era'. From 1877 onward, the term 'Psychozoic' was used by geologists such as Joseph LeConte and Johannes Herman Frederik Umbgrove.
An early concept for the Anthropocene was the Noosphere by Vladimir Vernadsky, who in 1938 wrote of "scientific thought as a geological force". Scientists in the Soviet Union appear to have used the term Anthropocene as early as the 1960s to refer to the Quaternary, the most recent geological period. Ecologist Eugene F. Stoermer subsequently used Anthropocene with a different sense in the 1980s and the term was widely popularised in 2000 by atmospheric chemistPaul J. Crutzen, who regarded the influence of human behavior on Earth's atmosphere in
recent centuries as so significant as to constitute a new geological
epoch.
The pressures we exert on the planet have become so great that
scientists are considering whether the Earth has entered an entirely new
geological epoch: the Anthropocene, or the age of humans. It means that
we are the first people to live in an age defined by human choice, in
which the dominant risk to our survival is ourselves.
The term Anthropocene is informally used in scientific contexts. The Geological Society of America entitled its 2011 annual meeting: Archean to Anthropocene: The past is the key to the future. The new epoch has no agreed start-date, but one proposal, based on atmospheric evidence, is to fix the start with the Industrial Revolution c.1780, with the invention of the steam engine. Other scientists link the new term to earlier events, such as the rise of agriculture and the Neolithic Revolution (around 12,000 years BP).
Evidence of relative human impact – such as the growing human influence on land use, ecosystems, biodiversity, and species extinction – is substantial; scientists think that human impact has significantly changed (or halted) the growth of biodiversity. Those arguing for earlier dates posit that the proposed Anthropocene may have begun as early as 14,000–15,000 years BP,
based on geologic evidence; this has led other scientists to suggest
that "the onset of the Anthropocene should be extended back many
thousand years"; this would make the Anthropocene essentially synonymous with the current term, Holocene.
Anthropocene Working Group
In 2008, the Stratigraphy Commission of the Geological Society of London considered a proposal to make the Anthropocene a formal unit of geological epoch divisions.A majority of the commission decided the proposal had merit and should
be examined further. Independent working groups of scientists from
various geological societies began to determine whether the Anthropocene
will be formally accepted into the Geological Time Scale.
The Trinity test in July 1945 has been proposed as the start of the Anthropocene.
In January 2015, 26 of the 38 members of the International Anthropocene Working Group published a paper suggesting the Trinity test on 16 July 1945 as the starting point of the proposed new epoch. However, a significant minority supported one of several alternative dates. A March 2015 report suggested either 1610 or 1964 as the beginning of the Anthropocene. Other scholars pointed to the diachronous
character of the physical strata of the Anthropocene, arguing that
onset and impact are spread out over time, not reducible to a single
instant or date of start.
A January 2016 report on the climatic, biological, and
geochemical signatures of human activity in sediments and ice cores
suggested the era since the mid-20th century should be recognised as a geological epoch distinct from the Holocene.
The Anthropocene Working Group met in April 2016 to consolidate evidence supporting the argument for the Anthropocene as a true geologic epoch. Evidence was evaluated and the group voted to recommend Anthropocene as the new geological epoch in August 2016.
In April 2019, the Anthropocene Working Group (AWG) announced that they would vote on a formal proposal to the International Commission on Stratigraphy, to continue the process started at the 2016 meeting. In May 2019, 29 members of the 34 person AWG panel voted in favour of
an official proposal to be made by 2021. The AWG also voted with
29 votes in favour of a starting date in the mid 20th century. Ten
candidate sites for a Global boundary Stratotype Section and Point have been identified, one of which will be chosen to be included in the final proposal.Possible markers include microplastics, heavy metals, or radioactive nuclei left by tests from thermonuclear weapons.
In November 2021, an alternative proposal that the Anthropocene is a geological event, not an epoch, was published and later expanded in 2022. This challenged the assumption underlying the case for the Anthropocene
epoch – the idea that it is possible to accurately assign a precise
date of start to highly diachronous processes of human-influenced Earth system change. The argument indicated that finding a single GSSP
would be impractical, given human-induced changes in the Earth system
occurred at different periods, in different places, and spread under
different rates. Under this model, the Anthropocene would have many
events marking human-induced impacts on the planet, including the mass extinction of large vertebrates, the development of early farming, land clearance in the Americas, global-scale industrial transformation during the Industrial Revolution, and the start of the Atomic Age.
The authors are members of the AWG who had voted against the official
proposal of a starting date in the mid-20th century, and sought to
reconcile some of the previous models (including Ruddiman and Maslin proposals). They cited Crutzen's original concept, arguing that the Anthropocene is much better and more usefully
conceived of as an unfolding geological event, like other major
transformations in Earth's history such as the Great Oxidation Event.
In July 2023, the AWG chose Crawford Lake in Ontario, Canada
as a site representing the beginning of the proposed new epoch. The
sediment in that lake shows a spike in levels of plutonium from hydrogen
bomb tests, a key marker the group chose to place the start of the
Anthropocene in the 1950s, along with other elevated markers including
carbon particles and nitrates from the burning of fossil fuels
and widespread application of chemical fertilizers respectively. Had it
been approved, the official declaration of the new Anthropocene epoch
would have taken place in August 2024, and its first age may have been named Crawfordian after the lake.
Rejection in 2024 vote by IUGS
In March 2024, an internal vote was held by the IUGS:
After nearly 15 years of debate, the proposal to ratify the
Anthropocene had been defeated by a 12-to-4 margin, with 2 abstentions. These results were not out of a dismissal of human impact on the
planet, but rather an inability to constrain the Anthropocene in a
geological context. This is because the widely-adopted 1950 start date
was found to be prone to recency bias. It also overshadowed earlier
examples of human impacts, many of which happened in different parts of
the world at different times. Although the proposal could be raised
again, this would require the entire process of debate to start from the
beginning. The results of the vote were officially confirmed by the IUGS and upheld as definitive later that month.
Crutzen proposed the Industrial Revolution as the start of Anthropocene. Lovelock proposes that the Anthropocene began with the first application of the Newcomen steam engine in 1712. The Intergovernmental Panel on Climate Change
takes the pre-industrial era (chosen as the year 1750) as the baseline
related to changes in long-lived, well mixed greenhouse gases. Although it is apparent that the Industrial Revolution ushered in an unprecedented global human impact on the planet, much of Earth's landscape already had been profoundly modified by human activities. The human impact on Earth has grown progressively, with few substantial
slowdowns. A 2024 scientific perspective paper authored by a group of
scientists led by William J. Ripple
proposed the start of the Anthropocene around 1850, stating it is a
"compelling choice ... from a population, fossil fuel, greenhouse
gasses, temperature, and land use perspective."
In May 2019 the twenty-nine members of the Anthropocene Working Group
(AWG) proposed a start date for the Epoch in the mid-20th century, as
that period saw "a rapidly rising human population accelerated the pace
of industrial production, the use of agricultural chemicals
and other human activities. At the same time, the first atomic-bomb
blasts littered the globe with radioactive debris that became embedded
in sediments and glacial ice, becoming part of the geologic record." The
official start-dates, according to the panel, would coincide with
either the radionuclides released into the atmosphere from bomb
detonations in 1945, or with the Limited Nuclear Test Ban Treaty of 1963.
First atomic bomb (1945)
The peak in radionuclides
fallout consequential to atomic bomb testing during the 1950s is
another possible date for the beginning of the Anthropocene (the
detonation of the first atomic bomb in 1945 or the Partial Nuclear Test Ban Treaty in 1963).
Minimum atmospheric methane concentration
On
June 19, 2025, Vincent Gauci proposed that Anthropocene began in 1592.
Ice core records had shown a minimum atmospheric methane concentration
at that time.
Etymology
The name Anthropocene is a combination of anthropo- from the Ancient Greekἄνθρωπος (ánthropos) meaning 'human' and -cene from καινός (kainós) meaning 'new' or 'recent'.
The human impact on biodiversity forms one of the primary attributes of the Anthropocene. Humankind has entered what is sometimes called the Earth's sixth major extinction. Most experts agree that human activities have accelerated the rate of species extinction. The exact rate remains controversial – perhaps 100 to 1000 times the normal background rate of extinction.
Anthropogenic extinctions started as humans migrated out of Africa over 60,000 years ago. Increases in global rates of extinction have been elevated above
background rates since at least 1500, and appear to have accelerated in
the 19th century and further since. Rapid economic growth is considered a primary driver of the contemporary displacement and eradication of other species.
According to the 2021 Economics of Biodiversity review, written by Partha Dasgupta and published by the UK government, "biodiversity is declining faster than at any time in human history." A 2022 scientific review published in Biological Reviews confirms that an anthropogenic sixth mass extinction event is currently underway. A 2022 study published in Frontiers in Ecology and the Environment,
which surveyed more than 3,000 experts, states that the extinction
crisis could be worse than previously thought, and estimates that
roughly 30% of species "have been globally threatened or driven extinct
since the year 1500." According to a 2023 study published in Biological Reviews
some 48% of 70,000 monitored species are experiencing population
declines from human activity, whereas only 3% have increasing
populations.
Summary
of major environmental-change categories that cause biodiversity loss.
The data is expressed as a percentage of human-driven change (in red)
relative to baseline (blue), as of 2021. Red indicates the percentage of
the category that is damaged, lost, or otherwise affected, whereas blue
indicates the percentage that is intact, remaining, or otherwise
unaffected.
Many scientists, along with the Global Assessment Report on Biodiversity and Ecosystem Services, say that the main reason for biodiversity loss is a growing human population because this leads to human overpopulation and excessive consumption.Others disagree, saying that loss of habitat is caused mainly by "the
growth of commodities for export" and that population has very little to
do with overall consumption. More important are wealth disparities
between and within countries. In any case, all contemporary biodiversity loss has been attributed to human activities.
Climate change is another threat to global biodiversity. For example, coral reefs—which are biodiversity hotspots—will be lost by the year 2100 if global warming continues at the current rate. Still, it is the general habitat destruction (often for expansion of
agriculture), not climate change, that is currently the bigger driver of
biodiversity loss. Invasive species and other disturbances have become more common in
forests in the last several decades. These tend to be directly or
indirectly connected to climate change and can cause a deterioration of
forest ecosystems.
Studies of urban evolution
give an indication of how species may respond to stressors such as
temperature change and toxicity. Species display varying abilities to
respond to altered environments through both phenotypic plasticity and genetic evolution. Researchers have documented the movement of many species into regions
formerly too cold for them, often at rates faster than initially
expected.
Permanent changes in the distribution of organisms from human influence will become identifiable in the geologic record.
This has occurred in part as a result of changing climate, but also in
response to farming and fishing, and to the accidental introduction of
non-native species to new areas through global travel. The ecosystem of the entire Black Sea may have changed during the last 2000 years as a result of nutrient and silica input from eroding deforested lands along the Danube River.
Researchers have found that the growth of the human population
and expansion of human activity has resulted in many species of animals
that are normally active during the day, such as elephants, tigers and
boars, becoming nocturnal to avoid contact with humans, who are largely
diurnal.
One geological symptom resulting from human activity is increasing atmospheric carbon dioxide (CO2) content. This signal in the Earth's climate system is especially significant because it is occurring much faster, and to a greater extent, than previously. Most of this increase is due to the combustion of fossil fuels such as coal, oil, and gas.
Changes
in drainage patterns traceable to human activity will persist over
geologic time in large parts of the continents where the geologic regime
is erosional. This involves, for example, the paths of roads and
highways defined by their grading and drainage control. Direct changes
to the form of the Earth's surface by human activities (quarrying and landscaping, for example) also record human impacts.
It has been suggested that the deposition of calthemite
formations exemplify a natural process which has not previously
occurred prior to the human modification of the Earth's surface, and
which therefore represents a unique process of the Anthropocene. Calthemite is a secondary deposit, derived from concrete, lime, mortar or other calcareous material outside the cave environment. Calthemites grow on or under man-made structures (including mines and tunnels) and mimic the shapes and forms of cave speleothems, such as stalactites, stalagmites, flowstone etc.
Stratigraphy
Sedimentological record
Human
activities, including deforestation and road construction, are believed
to have elevated average total sediment fluxes across the Earth's
surface. However, construction of dams on many rivers around the world means the
rates of sediment deposition in any given place do not always appear to
increase in the Anthropocene. For instance, many river deltas
around the world are actually currently starved of sediment by such
dams, and are subsiding and failing to keep up with sea level rise,
rather than growing.
Increases in erosion due to farming and other operations will be
reflected by changes in sediment composition and increases in deposition
rates elsewhere. In land areas with a depositional regime, engineered
structures will tend to be buried and preserved, along with litter and
debris. Litter and debris thrown from boats or carried by rivers and
creeks will accumulate in the marine environment, particularly in
coastal areas, but also in mid-ocean garbage patches. Such human-created artifacts preserved in stratigraphy are known as technofossils.
Twentieth-century technofossils in inundated landfill deposits at East Tilbury on the River Thames estuary
Changes in biodiversity will also be reflected in the fossil record,
as will species introductions. An example cited is the domestic chicken,
originally the red junglefowlGallus gallus,
native to south-east Asia but has since become the world's most common
bird through human breeding and consumption, with over 60 billion
consumed annually and whose bones would become fossilised in landfill
sites. Hence, landfills are important resources to find "technofossils".
Trace elements
In terms of trace elements, there are a range of distinct signatures left by modern societies. For example, in the Upper Fremont Glacier in Wyoming, there is a layer of chlorine present in ice cores from 1960's atomic weapon testing programs, as well as a layer of mercury associated with coal plants in the 1980s.
From the late 1940s, nuclear tests have led to local nuclear fallout and severe contamination of test sites both on land and in the surrounding marine environment. Some of the radionuclides that were released during the tests are 137Cs, 90Sr, 239Pu, 240Pu, 241Am, and 131I. These have been found to have had significant impact on the environment and on human beings. In particular, 137Cs and 90Sr have been found to have been released into the marine environment and led to bioaccumulation over a period through food chain cycles. The carbon isotope 14C, commonly released during nuclear tests, has also been found to be integrated into the atmospheric CO2, and infiltrating the biosphere, through ocean-atmosphere gas exchange. Increase in thyroid cancer rates around the world is also surmised to be correlated with increasing proportions of the 131I radionuclide.
The highest global concentration of radionuclides was estimated
to have been in 1965, one of the dates which has been proposed as a
possible benchmark for the start of the formally defined Anthropocene.
Human burning of fossil fuels
has also left distinctly elevated concentrations of black carbon,
inorganic ash, and spherical carbonaceous particles in recent sediments
across the world. Concentrations of these components increases markedly
and almost simultaneously around the world beginning around 1950.
Anthropocene markers
A
marker that accounts for a substantial global impact of humans on the
total environment, comparable in scale to those associated with
significant perturbations of the geological past, is needed in place of
minor changes in atmosphere composition. A range of markers characterizing the period have been identified, such as silicone or aluminium, but most prominently plastic, with plastic, reminiscent of archaeological ages like the Iron Age, marking an archaeological plastic age or the anthropocene even as a geological plastic epoch.
A useful candidate for holding markers in the geologic time record is the pedosphere. Soils retain information about their climatic and geochemical history with features lasting for centuries or millennia. Human activity is now firmly established as the sixth factor of soil formation. Humanity affects pedogenesis directly by, for example, land levelling, trenching and embankment building, landscape-scale control of fire by early humans,
organic matter enrichment from additions of manure or other waste,
organic matter impoverishment due to continued cultivation and
compaction from overgrazing.
Human activity also affects pedogenesis indirectly by drift of eroded
materials or pollutants. Anthropogenic soils are those markedly affected
by human activities, such as repeated ploughing, the addition of
fertilisers, contamination, sealing, or enrichment with artefacts (in
the World Reference Base for Soil Resources they are classified as Anthrosols and Technosols). An example from archaeology would be dark earth phenomena when long-term human habitation enriches the soil with black carbon.
Anthropogenic soils are recalcitrant repositories of artefacts
and properties that testify to the dominance of the human impact, and
hence appear to be reliable markers for the Anthropocene. Some
anthropogenic soils may be viewed as the 'golden spikes' of geologists (Global Boundary Stratotype Section and Point),
which are locations where there are strata successions with clear
evidences of a worldwide event, including the appearance of distinctive
fossils. Drilling for fossil fuels has also created holes and tubes which are expected to be detectable for millions of years. The astrobiologist David Grinspoon
has proposed that the site of the Apollo 11 Lunar landing, with the
disturbances and artifacts that are so uniquely characteristic of our
species' technological activity and which will survive over geological
time spans could be considered as the 'golden spike' of the
Anthropocene.
An October 2020 study coordinated by University of Colorado at Boulder
found that distinct physical, chemical and biological changes to
Earth's rock layers began around the year 1950. The research revealed
that since about 1950, humans have doubled the amount of fixed nitrogen on the planet through industrial production for agriculture, created a hole in the ozone layer through the industrial scale release of chlorofluorocarbons (CFCs), released enough greenhouse gasses from fossil fuels to cause planetary level climate change, created tens of thousands of synthetic mineral-like compounds that do not naturally occur on Earth, and caused almost one-fifth of river sediment
worldwide to no longer reach the ocean due to dams, reservoirs and
diversions. Humans have produced so many millions of tons of plastic
each year since the early 1950s that microplastics are "forming a near-ubiquitous and unambiguous marker of Anthropocene". The study highlights a strong correlation between global human
population size and growth, global productivity and global energy use
and that the "extraordinary outburst of consumption and productivity
demonstrates how the Earth System has departed from its Holocene state
since c. 1950 CE, forcing abrupt physical, chemical and biological
changes to the Earth's stratigraphic record that can be used to justify
the proposal for naming a new epoch—the Anthropocene."
A December 2020 study published in Nature found that the total anthropogenic mass, or human-made materials, outweighs all the biomass
on earth, and highlighted that "this quantification of the human
enterprise gives a mass-based quantitative and symbolic characterization
of the human-induced epoch of the Anthropocene."
Debates
"While
we often think of ecological damage as a modern problem our impacts
date back millennia to the times in which humans lived as
hunter-gatherers. Our history with wild animals has been a zero-sum
game: either we hunted them to extinction, or we destroyed their
habitats with agricultural land." – Hannah Ritchie for Our World in Data.
Although the validity of Anthropocene as a scientific term
remains disputed, its underlying premise, i.e., that humans have become a
geological force, or rather, the dominant force shaping the Earth's
climate, has found traction among academics and the public. In an
opinion piece for Philosophical Transactions of the Royal Society B, Rodolfo Dirzo, Gerardo Ceballos, and Paul R. Ehrlich
write that the term is "increasingly penetrating the lexicon of not
only the academic socio-sphere, but also society more generally", and is
now included as an entry in the Oxford English Dictionary. The University of Cambridge, as another example, offers a degree in Anthropocene Studies. In the public sphere, the term Anthropocene has become increasingly ubiquitous in activist, pundit, and political discourses. Some who are critical of the term Anthropocene nevertheless concede that "For all its problems, [it] carries power." The popularity and currency of the word has led scholars to label the term a "charismatic meta-category" or "charismatic mega-concept." The term, regardless, has been subject to a variety of criticisms from
social scientists, philosophers, Indigenous scholars, and others.
The anthropologist John Hartigan has argued that due to its status as a charismatic meta-category, the term Anthropocene marginalizes competing, but less visible, concepts such as that of "multispecies." The more salient charge is that the ready acceptance of Anthropocene is due to its conceptual proximity to the status quo – that is, to notions of human individuality and centrality.
Other scholars appreciate the way in which the term Anthropocene
recognizes humanity as a geological force, but take issue with the
indiscriminate way in which it does. Not all humans are equally
responsible for the climate crisis. To that end, scholars such as the
feminist theorist Donna Haraway and sociologist Jason Moore, have suggested naming the Epoch instead as the Capitalocene. Such implies capitalism as the fundamental reason for the ecological crisis, rather than just humans in general. However, according to philosopher Steven Best,
humans have created "hierarchical and growth-addicted societies" and
have demonstrated "ecocidal proclivities" long before the emergence of
capitalism. Hartigan, Bould, and Haraway all critique what Anthropocene
does as a term; however, Hartigan and Bould differ from Haraway in that
they criticize the utility or validity of a geological framing of the
climate crisis, whereas Haraway embraces it.
In addition to "Capitalocene," other terms have also been
proposed by scholars to trace the roots of the Epoch to causes other
than the human species broadly. Janae Davis, for example, has suggested
the "Plantationocene" as a more appropriate term to call attention to
the role that plantation
agriculture has played in the formation of the Epoch, alongside Kathryn
Yusoff's argument that racism as a whole is foundational to the Epoch.
The Plantationocene concept traces "the ways that plantation logics
organize modern economies, environments, bodies, and social relations." In a similar vein, environmental humanities scholars like Heather Davis
and Indigenous studies scholars such as Métis geographer Zoe Todd
have argued that the Epoch must be dated back to the colonization of
the Americas, as this "names the problem of colonialism as responsible
for contemporary environmental crisis." Potawatomi philosopher Kyle Powys Whyte has further argued that the
Anthropocene has been apparent to Indigenous peoples in the Americas
since the inception of colonialism because of "colonialism's role in
environmental change."
Other critiques of Anthropocene have focused on the genealogy of the concept. Todd also provides a phenomenological account, which draws on the work of the philosopher Sara Ahmed,
writing: "When discourses and responses to the Anthropocene are being
generated within institutions and disciplines which are embedded in
broader systems that act as de facto 'white public space,' the academy
and its power dynamics must be challenged." Other aspects which constitute current understandings of the concept of the Anthropocene
such as the ontological split between nature and society, the
assumption of the centrality and individuality of the human, and the
framing of environmental discourse in largely scientific terms have been
criticized by scholars as concepts rooted in colonialism and which
reinforce systems of postcolonial domination. To that end, Todd makes the case that the concept of Anthropocene must be indigenized and decolonized if it is to become a vehicle of justice as opposed to white thought and domination.
Eco-philosopher David Abram, in a book chapter titled
'Interbreathing in the Humilocene', has proposed adoption of the term
'Humilocene' (the Epoch of Humility), which emphasizes an ethical
imperative and ecocultural direction that human societies should take.
The term plays with the etymological roots of the term 'human', thus
connecting it back with terms such as humility, humus (the soil), and
even a corrective sense of humiliation that some human societies should
feel given their collective destructive impact on the earth.
William Ruddiman has argued that the Anthropocene began approximately 8,000 years ago with the development of farming and sedentary cultures. At that point, humans were dispersed across all continents except Antarctica, and the Neolithic Revolution was ongoing. During this period, humans developed agriculture and animal husbandry to supplement or replace hunter-gatherer subsistence. Such innovations were followed by a wave of extinctions, beginning with large mammals
and terrestrial birds. This wave was driven by both the direct activity
of humans (e.g. hunting) and the indirect consequences of land-use change for agriculture. Landscape-scale burning by prehistoric hunter-gathers may have been an additional early source of anthropogenic atmospheric carbon. Ruddiman also claims that the greenhouse gas emissions in-part
responsible for the Anthropocene began 8,000 years ago when ancient
farmers cleared forests to grow crops.
Ruddiman's work has been challenged with data from an earlier
interglaciation ("Stage 11", approximately 400,000 years ago) which
suggests that 16,000 more years must elapse before the current Holocene
interglaciation comes to an end, and thus the early anthropogenic
hypothesis is invalid. Also, the argument that "something" is needed to explain the
differences in the Holocene is challenged by more recent research
showing that all interglacials are different.
Homogenocene
Homogenocene (from old Greek: homo-, same; geno-, kind; kainos-, new;) is a more specific term used to define our current epoch, in which biodiversity is diminishing and biogeography and ecosystems around the globe seem more and more similar to one another mainly due to invasive species
that have been introduced around the globe either on purpose (crops,
livestock) or inadvertently. This is due to the newfound globalism that
humans participate in, as species traveling across the world to another
region was not as easily possible in any point of time in history as it
is today.
The term Homogenocene was first used by Michael Samways in his editorial article in the Journal of Insect Conservation from 1999 titled "Translocating fauna to foreign lands: Here comes the Homogenocene."
The term was used again by John L. Curnutt in the year 2000 in Ecology, in a short list titled "A Guide to the Homogenocene", which reviewed Alien species in North America and Hawaii: impacts on natural ecosystems by George Cox. Charles C. Mann, in his acclaimed book 1493: Uncovering the New World Columbus Created, gives a bird's-eye view of the mechanisms and ongoing implications of the homogenocene.
Society and culture
Humanities
The
concept of the Anthropocene has also been approached via humanities
such as philosophy, literature and art. In the scholarly world, it has
been the subject of increasing attention through special journals, conferences, and disciplinary reports. The Anthropocene, its attendant timescale, and ecological implications
prompt questions about death and the end of civilisation, memory and archives, the scope and methods of humanistic inquiry, and emotional responses to the "end of nature". Some scholars have posited that the realities of the Anthropocene,
including "human-induced biodiversity loss, exponential increases in
per-capita resource consumption, and global climate change," have made the goal of environmental sustainability largely unattainable and obsolete.
Historians have actively engaged the Anthropocene. In 2000, the
same year that Paul Crutzen coined the term, world historian John
McNeill published Something New Under the Sun, tracing the rise of human societies' unprecedented impact on the planet in the twentieth century. In 2001, historian of science Naomi Oreskes revealed the systematic efforts to undermine trust in climate change science and went on to detail the corporate interests delaying action on the environmental challenge. Both McNeill and Oreskes became members of the Anthropocene Working
Group because of their work correlating human activities and planetary
transformation.
Bridie Lonie
has reflected that the Anthropocene has been a theme for art in New
Zealand since the 1970s. Often working outside the art institutions as
societally challenging intervention art also "Interrupting the Automatism" in the activation, decision making and ultimate control of especially urban public space
Popular culture
In 2019, the English musician Nick Mulvey released a music video on YouTube named "In the Anthropocene". In cooperation with Sharp's Brewery, the song was recorded on 105 vinyl
records made of washed-up plastic from the Cornish coast.
The Anthropocene Reviewed is a podcast and book by author John Green, where he "reviews different facets of the human-centered planet on a five-star scale".
Photographer Edward Burtynsky
created "The Anthropocene Project" with Jennifer Baichwal and Nicholas
de Pencier, which is a collection of photographs, exhibitions, a film,
and a book. His photographs focus on landscape photography that captures
the effects human beings have had on the earth.
In 2020, Canadian musician Grimes released her fifth studio album titled Miss Anthropocene. The name is also a pun on the feminine title "Miss" and the words "misanthrope" and "Anthropocene."
.jpg)
_relative_to_baseline_-_fcosc-01-615419-g001.jpg)
