Life Keeps Us Alive: The Startling Biochemical Ties That Bind Human Bodies to the Living Planet

Take a breath. In the span of a single second, oxygen enters your lungs, crosses into your bloodstream, and powers the metabolic machinery of trillions of cells. Most of that oxygen was not made by the forest at your window or the crops in a nearby field. According to a sweeping new synthesis published in the journal Ambio, more than six out of every seven breaths you take is drawn from oxygen generated in the ocean, accumulated in the atmosphere over hundreds of millions of years through the slow burial of organic matter in marine sediments. The finding is one of many in a landmark perspective paper that reframes what it means to be human in the Anthropocene: not as a species acting upon the biosphere from the outside, but as a physical, embodied component of it.

The article, led by Carl Folke of the Anthropocene Laboratory at the Royal Swedish Academy of Sciences and co-authored by an international team spanning ecology, microbiology, hydrology, economics and the arts, argues that the notion of ‘people and nature’ being intertwined is not merely a philosophical or ethical stance. It is a hard biochemical reality. The human body, the authors contend, is an open living system in continuous exchange with the chemical elements of the Earth, and the movement of those elements into and out of our bodies is mediated at every step by living organisms: bacteria, fungi, plants, plankton, insects, birds, fish and mammals. To be alive, in the most literal sense, is to be threaded through with the web of life.

The evidence begins with the periodic table itself. The human body contains at least sixty detectable chemical elements, of which roughly twenty are essential for basic metabolism. Six elements—oxygen, hydrogen, nitrogen, carbon, calcium and phosphorus—constitute ninety-nine percent of body mass, forming the scaffolding of bones, tissues and cells. Five more—sulphur, potassium, sodium, chlorine and magnesium—are critical for nerve conduction, muscle contraction and fluid balance. Trace elements such as iron, zinc, copper, iodine, selenium and cobalt act as cofactors in enzymes, enable oxygen transport, support immune defence and drive DNA transcription. Crucially, the body cannot manufacture any of these from scratch; they must be acquired from external sources, which means from the biosphere.

But the acquisition is rarely direct, and this is where the paper’s technical depth becomes remarkable. Consider the gut microbiome. Over half the cells in a healthy human body belong to microbes, and these communities perform functions integral to whole-organism health. The gut is dominated by obligate anaerobic bacteria whose metabolisms mirror those of Earth’s earliest life forms, which emerged some 3.7 billion years ago in oxygen-poor environments using sulphur and nitrate as electron acceptors. In our large intestine today, their descendants ferment dietary fibre into short-chain fatty acids such as butyrate, a primary energy source for intestinal epithelial cells and a signalling molecule in the gut-brain axis. These metabolites influence immune responses, hypothalamic–pituitary–adrenal axis activity and even the synthesis of serotonin. In parallel, gut microbes synthesise B vitamins—including up to thirty-seven percent of a healthy adult’s daily folate requirement—and mediate the bioavailability of minerals such as calcium, magnesium, iron and phosphorus, competing with our own cells for limiting metals in a dynamic the authors call the human-microbiome-element symbiosis.

Extending outward, the paper traces how planetary-scale biogeochemical cycles deliver those essential elements to the human body through air, water and food. Roughly half of the oxygen in every breath is produced by oceanic photosynthesis, much of it by microscopic phytoplankton such as diatoms and the cyanobacterium Prochlorococcus marinus, a single species responsible for as much as five percent of global photosynthesis. On land, tropical forests account for about thirty-four percent of terrestrial oxygen production. Yet the authors stress that current biomes collectively produce and consume approximately the same amount of oxygen, meaning today’s atmospheric oxygen is a legacy of geological burial processes, predominantly in the ocean, accumulated over millions of years. In this sense, humanity is entangled not only with contemporary ecosystems but with the metabolic work of life across deep time.

Water, described by the authors as the ‘flowing bloodstream’ of the biosphere, offers another vivid illustration. Humans require a continuous turnover of one to six litres of water daily, and the patterns of freshwater circulation that make this possible are not simply physical. Terrestrial ecosystems store soil moisture, sustain evaporation and generate downwind rainfall. Around forty to fifty percent of precipitation over land is recycled by evapotranspiration from plants and soil, and a barren planet would generate less than a third of that moisture flux. The freshwater we drink dissolves calcium, magnesium and iron from rocks and soils, delivering them into the body. Meanwhile, food production depends on even larger volumes of green water: an adequate daily diet requires three thousand to four thousand litres of evapotranspiration per person, with croplands in as many as 155 countries receiving up to forty percent of their annual precipitation from forests located in other nations through atmospheric moisture transport.

Soil and marine ecosystems complete the picture. Soil organisms, representing nearly sixty percent of Earth’s species, decompose organic matter and mineralise bound nutrients into plant-available forms. A single gram of soil can contain up to ten billion microorganisms. Earthworms deepen rooting zones, nematodes stimulate bacterial mineralisation, and mycorrhizal fungi extend the foraging reach of plant roots through hyphal networks, trading soil nutrients for plant sugars in a mutualism stabilised by reciprocal rewards. Because our DNA depends on phosphorus, and most plants require mycorrhizal fungi to acquire it, a substantial portion of the phosphorus in human genetic material has likely passed through a fungal network. In the ocean, upwelling systems supply trace metals that constrain marine productivity, and seafood acts as a concentrated route through which marine biogeochemistry becomes human micronutrition—iodine from seaweed and fish, selenium and omega-3 fatty acids concentrated through trophic levels.

Animals also function as what ecologists call ‘mobile links’, redistributing nutrients across landscapes and ecosystems in ways that directly affect human food security. Baleen whales recycle iron into surface waters, supporting phytoplankton blooms. Seabird guano transfers between ten thousand and one hundred thousand tonnes of phosphorus to land each year, and in Greenland the guano of thirty-three million pairs of little auks fertilises soils that sustain hares, geese, foxes, reindeer and muskoxen relied upon by local human communities. Salmon returning from the sea carry marine-derived nutrients into freshwater and forests, while insect pollinators were found to be directly responsible for more than twenty percent of vitamin A, folate and vitamin E intake in vulnerable smallholder communities in Nepal.

Against this backdrop, the paper delivers a stark warning about the Anthropocene. Human activity—industrialisation, fossil-fuel combustion, synthetic fertiliser use, monoculture farming, pesticide application and the proliferation of novel entities such as plastics and PFAS—is reshuffling the life-element relationships upon which human bodies depend. Soil micronutrient deficiencies are spreading, marine fish biomass and their cycling rates have been nearly halved by fisheries, and microbial communities are being compositionally and functionally altered by antibiotics, urban infrastructure and intensified agriculture. Eighty percent of people in low-income countries now live with degraded land, unhealthy air and water stress. Six of nine planetary boundaries have been exceeded, and the technosphere—the sum of human-made material—has, as of 2020, exceeded the dry weight of all living biomass on Earth. Yet none of this, the authors insist, implies independence. It implies disruption.

The synthesis concludes with a call for what the authors term ‘stewardship of life-element mediation’: a form of biosphere stewardship that is not merely cognitive or ethical but embodied—a set of lived practices and institutions that sustain the living relations making human existence materially possible. They point to emerging domains such as microbiome health, agroecology, rewilding, marine protected areas and nature-based solutions as evidence of a growing practical knowledge base that works with living mediators of elemental flow rather than treating food, water, health and biodiversity as separate concerns. Being human, the authors argue, means being an open system threaded through with bacteria, fungi, plants, plankton, birds, whales and the chemical elements they mobilise. Life keeps us alive. Recognising this as a biogeochemical fact, rather than a metaphor, may be among the most consequential scientific reframings of our time.

Subject of Research: The biochemistry of human interdependence with life-mediated chemical element cycles in the Anthropocene biosphere

Article Title: Humans: Intertwined with life and the basic elements in the Anthropocene biosphere

Article References: Humans: Intertwined with life and the basic elements in the Anthropocene biosphere. (n.d.). https://doi.org/10.1007/s13280-026-02474-z

Image Credits: AI Generated

DOI: 10.1007/s13280-026-02474-z

Keywords: Anthropocene, biosphere, biogeochemical cycles, human microbiome, gut-brain axis, photosynthesis, water cycle, soil health, mycorrhizal fungi, phytoplankton, planetary boundaries, biosphere stewardship