Plants, People, Planet

The article plants, people, planet provides a brief overview of the relationship between plants, people, and planet Earth, and the set of articles that address this topic while the article plant-people science discusses the transformation of this topic into a formal science. The article plants for people provides a variety of lists of economically and historically important plants. The article plant-people Big History gives a long-term historical overview of the coevolutionary relationship between plants and people. The plant-people timeline provides a chronological overview of major events and transitions in the relationship between plants and people.

Introduction – Plants People Planet

How can we possibly categorize and explain the multitude of ways in which the lives of humans intersect with the lives of plants on planet Earth?

This article provides a general introduction to the major plant-people-planet themes that are discussed on this web site.

Economic botany

The difficult problem that is posed at the head of this article is often answered in a cavalier way by treating it as a simple question about plant utility. So, for example, botanic gardens and textbooks once answered this question about ‘plants and people’ in terms of ethnography and ethnobotany – the ways in which native peoples have used plants as dyes, fibres, medicines, and tools etc.  . . . including their use in ritual and art. This narrow approach has subsequently broadened out into the more general field of economic botany. Framed in this way the question can be answered succinctly by developing a simple classification of the ways that humans use plants as commodities and resources of various kinds.

For example:

We use plants for food (e.g. grains, roots, and tubers, vegetables, herbs, fruits, nuts, and pulses); drinks (fruit juice, beer, wine, spirits, tea, coffee, cocoa, cola); food and drink additives (herbs, spices, sweeteners, flavourings, and colourings); psychotropic effects (tobacco, opium, cannabis, mescalin, heroin etc.), as poisons (strychnine, hemlock); for medicines and drugs (cocaine, echinacea); fibres (cotton, hemp, flax, sisal); dyes (indigo); perfumes and aromas (rose, jasmine, pot-pourri, incense); oils (lavender, ulan, olive), fats (avocado); waxes (beeswax), resins (for varnishes, adhesives, glazes); rubber; wood (as timber for construction, tools and weapons, fuel, source of paper); as a source of structural materials; and also for ritual, ceremony, art, and decoration.

Reciprocity

The nineteenth century question addressed by museums of economic botany: ‘How have different cultures used plants in their daily lives?’ ignored the fact that, viewed in a more detached and scientific way, the consideration of the relationship between plants and people is not just about humans using plants, but about the broader consequences of the plant-people interaction.

By assuming an anthropocentric perspective we deny plants any form of agency or causal efficacy.^[8] And yet there is clearly a two-way path of causal connection between plants and people. Certainly, humans have used plants in multiple ways: they have selected and bred new varieties, redistributed them around the globe, eaten them and used them in all the ways listed above. But, in their turn, plants have (mindlessly) transformed both human bodies, and human societies.

Humans and plants share their biological agency. Both pass through a lifecycle of birth, maturation, reproduction, senescence, and death. Humans intentionally domesticated plants but, in so doing, plants  (mindlessly) domesticated humans via the coevolutionary institution of agriculture whose sedentary lifestyle created civilization – setting humans on the path to urbanization, industrialization, and globalization.

We live in a geological epoch called the Anthropocene in which the human use of fossil fuel plant energy has influenced global biogeochemical cycles. Plants, people, and the planet are locked together in a relationship that will determine the future of the community of life.

Awareness of this relationship is now expressed internationally under the banner of sustainability. While, at first glance, it might seem that plants are merely ‘useful’ to humans, on closer inspection it is evident that usefulness is better understood as total dependence.

The relationship between plants and people is a reciprocal coevolutionary relationship that has changed dramatically over time: it is this aspect of the relationship that we need to understand more clearly.

Key criteria of understanding

The relationship between plants and people is so pervasive that it can be studied from many perspectives . . . not just economic botany – but art, science, geography, ecology, individual lives, botany, human history . . .  and so on. Clearly this requires a multidisciplinary approach: but we need to focus our attention while, at the same time, addressing our main interests and concerns.

Since this relationship has been one of constant historical change, its explanation becomes more digestible when confined within clearly stated boundaries of place and time. By starting from the broadest spatiotemporal context – that of evolutionary time and planetary space – we gain a panoramic view of the subject that provides a contextual ‘stage’ for other, more fine-grained contexts and topics.

What are the key historical factors determining the nature of the plant-people relationship when considered in this way?

Our understanding of the key factors driving history changes, along with our perspective, as we zoom in and out to focus on different ranges of time and place. This is why so many subjects are involved.

A multidisciplinary approach

In a simple way, we can regard some academic disciplines (each with their own guiding principles and critical categories) as tending to occupying their own segment of historical spacetime that grades into that of other disciplines. So, for example, the study of human change as it occurs over hundreds of years to millennia we tend to regard as learned and cultural behaviour that fits most appropriately in the domain of anthropology. But over many millennia human change becomes genetic and biological, and better placed in the domain of evolutionary biology.

Clearly, the long-term study of plants and people is multidisciplinary in character, merging first with cultural history in anthropological time, but over longer terms with evolutionary biology when it reaches into deep biological time.

This is far removed from history as we usually understand it, but it is where the big picture study of plants and people must begin – by asking how plants and people have influenced one-another over the full sweep of human history – and recognizing that this long-term relationship is one of coevolution. This grounding perspective on the plant-people relationship is contextualized in the article PlantsPeoplePlanet Big History.

Coevolution & culture

Since changing the temporal focus of study changes the character of the study itself, it is important to clarify the distinction been coevolution and culture as different ways of interpreting the same human-plant connection.

Coevolution and culture represent the two major ways that have operated together in the transformation of humans, their lives, and their environment of evolutionary adaptation: the first environment was nature itself, as human bodies and minds were forged in nature itself by the slow process of genetic change that was the result of a hunter-gather mode of living and which we call biological evolution. With the advent of settled communities and a surplus of plant energy based on cultivated cereals there began the accelerating growth we associate with rapid cultural evolution and urbanization and, later, the supercharged industrialization and globalization we associate with fossil fuels.

Coevolution is slow genetically based biological change while culture supplements this with patterns of behaviour that are learned in human communities.

Coevolution

Emphasis on plant utility does not do justice to an interdependence that dates back to a time before the origin of Homo sapiens when plants produced the planetary oxygen that supported not only human existence but the entire community of life. Viewed from the perspective of the Anthropocene, this is the most important coevolutionary relationship in the history of the planet since it is the human use of fossil fuels that is now treated as an existential threat to humanity.

Humans change plants

The most obvious influence of humans on plant vegetation is by changing the genetics of wild plants and then the relative proportions of wild and cultivated plants in the world – by influencing plant distribution, species composition, and biomass over the Earth’s land surface. Human influence on plant genetics first took the form of artificial physical selection of major crops (12,000 BCE to c. 1920) before the advent of modern plant breeding techniques based on the new science of genetics (c. 1920->), then the genetic engineering that uses a more direct method of gene insertion (1970s ->).

Plants change humans

Plants influenced the biology of primate human ancestors (see plants make sense) long before human cultural evolution gathered momentum. The historical influence of plants on humans, and the planet, is most neatly summarized through the plant energy that sustains all life. Over the sweep of human history it is the availability, capture, and use of plant energy – that grounds the coevolutionary relationship, first as the food needed to sustain bodies, then as the fossil fuels needed support large communities. to sustain the growth of industries and populations.

Culture & cultural history

The theme ‘plants and people’ becomes more digestible and inclusive when we broaden our interpretation from that of the utility associated with ethnography and economic botany to encompass the wider perspective of culture and cultural history.

But what do we mean by ‘culture’?

Definition

‘Culture’ is a slippery word with many meanings. In popular understanding it can refer to distinctive ethnic traditions (Mexican food) or refined sensibilities (going to art galleries and listening to opera and classical music).

For an anthropologist ‘culture’ is a word that encompasses both the physical and abstract: it is not just about artifacts, written records, and, say, gardens – it is also about systems of knowledge, beliefs, customs, norms, and institutions as patterns of behaviour that are created, learned, and shared by a particular group of people. In anthropology ‘culture’ is value-free – people are not more or less cultured.

But ‘culture’ has other associations connoting, for example: the way that specific societies sustain themselves and adapting to their material circumstances – the land, nature, and resources; social systems and the way people organize themselves into social groups and relationships that maintain social order and organization; a ‘meaning system’ that represents human life through symbolic language and forms of representation like art, ritual, music, religion, myth, folklore, literature, philosophy etc.

– but gathering modern integrated complexity as our species multiplied exponentially, industrialized, urbanized, and globalized.

Emphasis here is on the fact that culture is learned and specific to particular groups of people: the plants-people relationship is viewed from the perspective of anthropological time.

Material & symbolic culture

Material culture comprises all those physical human-created objects that would remain if humans were to disappear. This includes all the physical objects associated with particular cultures – not just those of art, but those of daily life, trade etc. The words ‘culture’ and ‘cultivation’, derived from the Latin colo, colere – to care for, cultivate, or refine – reflect the historical plants-people connection to a social organization that is based on plants.

Material culture is often contrasted with symbolic (non-material) culture as communal concepts, symbols, signs, and behavioral traditions that are learned and transmitted between the generations of every culture.

Symbolic culture includes values, norms, attitudes, and beliefs – moral codes, myths, social constructs (e.g. myths, chess, money, citizenship, modes of government and administration, marriage, and many other things that people in our own culture consider to be ‘real’). Symbolic culture is maintained by adherence to the behaviours of collective cultural belief. Symbolic culture is an academic realm inhabited mostly by archaeologists, social anthropologists, and sociologists.

Clearly, in fact, there is a mutual interdependence of material and symbolic culture. Material objects are created within symbolic frameworks: but assessing the relative impacts of material and symbolic cultures is a complicated and contentious academic matter and may vary between societies.

As we have seen, the problem of the relationship that exists between plants and people is often viewed through the lens of culture. This is so, for example, in the book A Cultural History of Plants (2004) edited by Ghillean Prance, former Director of the Royal Botanic Gardens, Kew.

This book was followed by the publication, in 2022, of the most comprehensive six-volume scholarly treatment of the topic under, essentially, the same title.

Following the format of a prior series on the cultural history of gardens, Bloomsbury Academic begins its six-volume series on A Cultural History of Plants with a brief overall introduction to the topic by general editors Annette Giesecke (archaeologist specializing in the history, meaning, and representation of the gardens of antiquity) and David Mabberley (botanist). The volumes span the period from c. 12,000 BP to the present, individual books covering: antiquity (c. 10,000 BCE – 500 CE), post-classical era (500 – 1400), early modern era (1400 – 1650), seventeenth and eighteenth centuries (1650 – 1800), nineteenth century (1800 – 1920), and the modern era (1920 – present).

Clearly, the content depends on the authors’ understanding of ‘cultural history’, and the categories they choose to represent it. The series Preface lists a wide range of human dependencies on plants stating that the series ‘ . . . traces the global dependence of human life and civilization on plants . . .’. Advertising material claims that it is ‘. . . the definitive history of how we have cultivated, traded, classified, and altered plants and how, in turn, plants have influenced our ideas of luxury and wealth, health and well-being, art and architecture.’

Each period volume, after an introductory overview by its editor, then divides its content into the same eight topics that allow the reader ‘to explore a meaningful cross-section of humans’ uses of plants in a given period’, as viewed through the lens of these eight key ideas:

plants as staple foods
plants as luxury foods
trade and exploration
plant technology and science
plants and medicine
plants in (popular) culture
plants as natural ornaments
the representation of plants

There is a distinction that, for the purposes of the topic ‘plants and people’ requires clarification.  When we speak of the ‘cultural history of plants’ it needs to be acknowledged that: firstly, plants do not have cultural histories, only humans do and, secondly, if culture is what distinguishes one social group from another, then we need to distinguish between, on the one hand, the impact of plants on humanity as a whole and, on the other, the impact of plants on particular groups of people.

It is also informative to distinguish between material factors that help sustain individuals and economies, and symbolic factors that contribute to the same.

Key concepts

Given the assumption that we wish to understand and explain the reciprocal relationship between plants and people over the course of human history, and that our answer will depend on the criteria that most clearly express our purpose or interest, then what are the most informative historical categories that we can deploy?

This begs the important but highly contentious question of what are the most important factors influencing human existence and history. In other words, when we examine what might be called a ‘consensus’ view of human history, we are trying to find the ways in which plants might have influenced that history. We might compare this to the question ‘In what way did ocean-going ships influence the course of history?.

Energy, social organization, technology

Given the complexity of historical interaction and multifactorial causation, what are the most succinct yet informative categories to use when studying long-term human history?

Determining the key historical factors at work, As discussed in the general article on classification, to clearly identify our direction we need a clear statement of purpose, an agreed objective to which a coherent answer can be given. Once this is known it is possible to investigate the most illuminating categories of study, given our stated goals.

This topic in historiography is addressed in the article history in 10,000 words, and also addressed through the conclusions that emerge from the recent discipline of Big History. Three headings stand out. Each of these is discussed in its own article but summarized here: energy, social organization, and technology.

Energy

The historical role of plants in the process of human-plant coevolution emerges with greatest clarity when we consider plants as sources of energy (described in more detail in the article energy capture) and therefore the significance of energy availability, capture, and use – which, over the long term, relates to geography, whose meaning depends on the technology available to overcome geographic barriers.

Humans have devised ever more efficient ways of harnessing plant energy – first, as life-sustaining food (first collected, then produced), and then, in addition, as society-sustaining fossil fuels coal, oil, and gas. It is plant energy that has underpinned the growth and development of human populations, cities, technologies, and economies. It has powered the evolution of social organization that has transformed the human environment of biological evolution into an environment of cultural evolution that has created a global community.

Social organization

Social organization is our most efficient way of explaining history in its social form of ‘getting things done’ or ‘. . .‘their capacity to get things done – to shape the physical, economic, social and intellectual environment to their own ends.’ (historian Ian Morris). This is fleshed out as ‘ . . . the bundle of technological, subsistence, organizational, and cultural accomplishments through which people feed, clothe, house, and reproduce themselves, explain the world around them, resolve disputes within their communities, extend their power at the expense of other communities, and defend themselves against others’ attempts to extend power.’ Plant energy availability (which over the long term relates to geography, whose meaning depends on the degree of technological sophistication) has largely determined the kinds of social organization that are possible and, in turn, strongly influence societal values. Social organization (social complexity) has vastly increased over time, albeit erratically, gathering momentum with the Agricultural Revolution and then accelerating rapidly with the Industrial Revolution.

For better or worse, those societies that have been most efficient and effective at ‘getting things done’ – those societies that are more socially organized (best at exploiting energy capture) – have tended to persist and dominate or absorb others. Morris is not suggesting that dominant societies are necessarily better or more desirable, or that people in such societies are happier, or that such societies do not have high costs or unpredictable futures . . . he is simply pointing out what he believes is a major causal element in human history.^[7]

Technology

Technologies are the tools that ‘get things done’ more easily than if were using just our bare hands or bare brains.^[1] They are cultural creations that we use to supplement our natural biological abilities and they can be learned and transmitted to following generations for further development.

Physical tools may be as simple as a hammer, or as complicated as a computer. Mental tools can be as simple as an idea, or as complicated as language, or mathematics. All forms of collective learning that may be recorded or passed on by word of mouth are mental technologies that have the potential to change, and preferably improve, human existence.

Technological changes can rapidly transform societies so technology is a key concept associated social organization, especially economic aspects, including agriculture, medicine, mining & manufacture, transport & communication, trade & commerce, engineering & construction, computing & information technology. Historically, culturally transmitted technological knowledge has generated an exponential acceleration in social complexity that is associated with industrialization, urbanization, and globalization, and culminated in an explosion of discoveries over the last 250 years as each technological novelty built cumulatively on the discoveries of its predecessors.

The power of technology has increased as its ‘machines’ have taken advantage of increasingly concentrated and processed forms of energy: fire, wind, water, human muscle-power, muscles of domesticated animals, coal, petrol, oil, electricity, nuclear power as we head into the new era of Informatia based on renewable forms of energy.

Plant-People Big History

This PlantsPeoplePlanet web site shares many of the aspects of symbolic culture with A Cultural History of Plants. The themes of PlantsPeoplePlanet, however, are grounded in the long-term plant-people Big History that is expressed primarily in terms of a reciprocal relationship based in material culture and science rather than a one-way influence of plants on people based in symbolic culture and art – although the two are necessarily, and inextricably, intertwined.

History inevitably falls back heavily on the written and archaeological record for its materials. From this we have inherited two major biases: first, an emphasis on the civilizations that have left this record – essentially those whose social organization has enabled them to live more efficiently, and dominate or subdue others – and, second, and in spite of globalization, and for many other reasons (discussed elsewhere on this site), there has been an academic emphasis on the West that, over the next few decades, requires correction.

Many people did not, and still cannot, read and write but live meaningful, rich and fulfilling lives. Many people lived beyond the Mediterranean and Near East, Egypt, Greece, the Roman and Han Empires, Byzantium, the Industrial Revolution, international trade, and the world’s great religions.

The biases mentioned above do not necessarily reflect moral value or an inexorable path of progress, or those people most worthy of attention; but they do reflect major currents of global historical and cultural change.

First, the Neolithic Agricultural Revolution as the domestication of plants and animals. Cereal grains were a source of concentrated energy that could be accumulated and stored, thus providing settled communities with the means for populations to grow and flourish. Hierarchical societies with a division of labour developed rich symbolic cultures that included written language (including the records needed for public administration, the law, trade, science, and many other aspects of knowledge accumulation) monumental architecture, and other benefits of scale that included armies, ocean-going ships, and long-distance trade.

If we wish to understand and explain the relationship between plants and people in its entirety then we must look – not so much to the unique cultural associations that we find in art, literature, religion, myth, and folklore – but more to the universal social, economic, and environmental categories of everyday living.

The future is then considered under the internationally agreed headings for the pillars of sustainability: environment, society, and economics.

The historical role of plants in the process of human-plant coevolution becomes more transparent when we consider plants as sources of energy (described in more detail in the article energy capture). Humans have devised ever more efficient ways of harnessing energy, first as life-sustaining food, and then as society-sustaining fossil fuels. It is plant energy that has underpinned the growth of populations, cities, and economies. 

From this perspective we see the influence of plants on the biological evolution of animals in the primate-human lineage. Human evolution then passed from a phase of living in nature to one dominated by culture as the human environment of evolutionary adaptation shifted from nature itself to surroundings and circumstances that were mostly man-made. The human environment changed from natural landscapes of wild plants to cultural landscapes of cultivated plants: from food collecting to food producing. The complexity of social organization was marked by urbanization, industrialization, and globalization as plants were woven into the fabric of urban industrial and post-industrial societies.

It can be informative to view the relationship from both plant and human perspectives.

The other side of the equation – the historical influence of plants on humans – begins unconventionally by regarding plants as an energy source and how it was energy availability, technology, and use that was the key historical determinant accelerating the growth and complexification of human social organization. This influenced the social development of both mental and physical technologies – the mental tools of symbolic languages, science, religion, value systems etc., and the material technologies associated with mining, manufacture, transport, communication, and trade.

The future is then considered under the integrated sustainability pillars of environment, society, and economics. The foundational role of plants as an energy source, firstly as food for not only humans but the entire community of life then, subsequently, that special mode of cultural evolution created by industrialization based on the fossil fuels that have propelled humanity into the Anthropocene.

Long-term human history can be understood in terms of the historical acceleration in the growth and complexity of social organization (including its populations and technologies). These are the main categories we use to explain the path of human history from nomadic hunter-gatherer, to urbanization, industrialization, and globalization.

The increasing human efficiency in utilizing plant energy includes all the material and symbolic technologies developed for its capture and use – the technologies building on what went before in the process of exponential growth in human population whose demand for resources created a global economy and community of interest.

This includes fossil fuel powered art and science, agriculture, medicine, mining and manufacture, engineering and construction, transport and communication (including computing and information technology), and the many other facets of trade, commerce, governance, and administration.  Using these selection criteria, human history can be usefully divided into four distinct long-term phases: Natura, Agraria, Industria, and Informatia.

Major themes

The lives of plants and humans are so closely integrated that it is difficult to separate the two when we consider historical outcomes and their causes. The first task, then, is to understand why plants have such a lowly status in the human sphere when they are such close coevolutionary partners. 

Plant blindness

The study of history, often assumed to begin with the stories of kings and queens, now seemingly engages every conceivable perspective – cultural, economic, environmental, colonial, post-modern, feminist, and so on.

But although plants constitute the life-support system for not only humans, but the entire community of life, it is staggering that, although many skillful wordsmiths have drawn our attention to this fact through beguiling popular prose, a scholarly historical account of the relationship between plants and people is yet to be written. Is this due to the unlikely combination of botany and history and – a lack of botanical historians. Is it the sheer complexity of the topic that would make any such attempt foolhardy? Is it simply of little interest, a topic that needs to be made more sexy by emphasizing its connections to fine art and intrepid global adventurers?

Our indifference to plants is a cognitive bias sometimes called ‘plant blindness‘^[3][4] which is an expression coined by Schussler and Wandersee in 1998^[9] who were the pioneers who first examined its reasons. It is attributed in part to our greater empathy for more active and appealing animals which, like us, possess mobility and brains (zoocentrism and zoochauvinism).^[5] In a study at Exeter University^[11] that examined 326 scientific articles published between 1998 and 2020 it was concluded that, as members of the community of life, plants seem less alive, less important, and less interesting, a view attributed to our diminished experience of nature in urbanized societies. Modernization and urbanization has, overall, had a negative impact on our experience of plants.

Perhaps our total human dependence on plants, like our dependence on the oxygen we breathe (supplied by plants), is not addressed directly in history books simply because plants are taken for granted – even though they are a necessary, not contingent, component of human existence. Without them we would not exist – so why say any more? As a ‘given’ of human existence their necessity (our total dependence on them), like our total dependence on water or the air we breathe, rather than being emphasized is, instead, taken for granted and ignored.

Only when essential resources are threatened do the consequences of their absence accrue historical significance and become part of environmental, economic, and cultural history. We see this today in relation to food security, climate change, and our human sustainability on planet Earth. PlantsPlanetPeople is one response to this situation.

Major historical transitions

What do we see when we view the plant-people relationship through the lens of evolutionary time, planetary space, and predominantly material culture?

In the simplest terms, plants have been a major source of life, health, wealth, and happiness. From a long-term perspective the relationship between plants and people has been the most important biological coevolutionary relationship in terms of its overall impacts on the biosphere.

The following points draw out the major transformations that have occurred in the plant-people coevolutionary relationship.

1. The great oxygenation event

All life depends on photosynthesis so, from a biological perspective, it is the most important chemical reaction to occur on planet Earth. It is a process that uses sunlight, water, and carbon dioxide to produce energy-rich molecules, while releasing oxygen as a biochemical waste product.

About 3.5 billion years ago, during the Archean Eon, oxygen was first added to the Earth’s atmosphere by photosynthetic blue-green ‘algae’ (cyanobacteria) that lived in a variety of freshwater and marine environments. Best known of these algae are the stromatolites, layered and sediment-trapping algae that live in shallow marine habitats. They can be seen today in Western Australia.

The oxygen first produced by these bacteria was rapidly absorbed by organic compounds and by iron-rich environments to produce layers of iron oxide on the ocean floor until, about 2.3 billion years ago, excess free oxygen began to accumulate in the atmosphere during the Great Oxygenation Event.

Though cyanobacteria were the first photosynthetic organisms, they were prokaryotes (single-celled organisms without a nucleus), and more complex photosynthetic organisms like algae and other non-flowering plants (eukaryotes, as organisms whose cells have a well-defined nucleus enclosed within a membrane) evolved much later around 1.2 billion years ago.

Non-vascular plants like mosses and liverworts first moved from aquatic environments to land around 450 million years ago during the Ordovician Period. The colonization of land by animals followed about 50 million years later during the Silurian and Devonian Periods about 420-400 million years ago. Fossils indicate that these first animals on land were arthropods such as ancient arachnids and insects. The move from aquatic to terrestrial habitats by plants, followed by animals, was a crucial event in the shaping of Earth’s ecosystems to a form that would, much later, support humans.

2. From nature to culture

But humanity’s total dependence on plants is demonstrated by the crucial role played by plants in human biological and cultural evolution . . . by changing or biological and psychological makeup and constraining our historical modes of social organization. Humans lived first as Palaeolithic hunter-gatherers in wild nature with both their biological and cultural evolution strongly determined by factors in the natural environment. Then, as Neolithic farmers, it was cultural factors that increased in significance. Humanity had taken a giant step from a mode of existence dominated by nature to one constrained by culture as, superimposed on slow biological evolution there followed a period of rapid cultural evolution. In domesticating plants and animals, humans had adopted a sedentary way of life that changed their environments of both biological and cultural evolution. The result was modern civilization, and in this sense, humans were co-incidentally domesticated by plants. Humans whose bodies and minds were fashioned by adapting to natural wild environments, now live in artificial environments, a result of the greatly accelerated increase in social organization made possible by the energy of cereal grains and fossil fuels. This has created a new set of challenges, a new environment, for both biological evolution and cultural adaptation.

The Neolithic Agricultural Revolution (c. 12,500-2500 BP) took humanity out of wild nature – out of the nomadic hunter-gatherer natural environment of evolutionary adaptation – into artificial or ‘man-made’ farming settlements with cultivated food plants that were the products of human selection. Food energy obtained from wild plants and animal hunting was being replaced by that of domesticated cereals and livestock. Cereal grains were a form of energy that could be stored for year-round use. The surplus plant energy released by agriculture enabled rapid growth in population, division of labour, and an increase in social complexity that facilitated the creation of cities (including designed urban spaces like parks and gardens) and the many cultural activities we associate with civilization. Well-governed urban communities could then take advantage of the technologies of scale by, for example, assembling armies, constructing ocean-going ships, and building up manufacturing industries. A giant step had been taken on the path from nature to culture and from wild environments to cultivated environments as slow biological evolution was supplemented by rapid cultural evolution. All these changes flowed from the surplus energy made available by plant domestication as the human population multiplied from a few million people at the dawn of the post-Ice-Age Agricultural Revolution about 10,000 years ago, to 400 to 500 million in 1650 CE.

The Industrial Revolution (c. 1750-1850) then harnessed the concentrated plant energy in fossil fuels to power technology that would put the Agricultural Revolution into overdrive as the human population soared. It took 200,000 years for the human population to reach 1 billion around 1800: by 1914 the total was about 1.8 billion. The introduction of industrial agriculture was, in effect, a Second Agricultural Revolution creating another dramatic social transformation by releasing people from toil on the land to move from the country into the city: from farm to factory. In 1800 about 3% of the world population lived in cities but by 2017 this had increased to 54.9% (Index Mundi World Demographic Profile 2018). The associated increase in social complexity resulted in technologies and social systems that connected the peoples of the world as never before.

The Industrial Revolution was a period of greatly accelerated cultural evolution characterized by growth and expansion in many factors including: human population, industrialization, urbanization, globalization, democratization, social complexity and knowledge.

The human transition from environments and lifestyles determined by factors in nature, to environments and lifestyles determined by cultural factors, has created a new co-evolutionary relationship between humans and plants. To derive maximum benefit from our association with plants we have, in the course of the Agricultural and Industrial Revolutions, altered our relationship to plants in three major ways: we have devised ever more effective ways of harnessing plant energy, we have modified plant genetics, and we have drastically altered the geographic distribution and species composition of plants over the surface of the Earth.

Human cultural evolution has transformed both plants and their environments. But in so doing we have changed the environments that also shape our own biological and cultural evolution. Humans have domesticated plants but, since plants required the sedentary lifestyle that produced modern civilization humans have, in their turn, been domesticated by plants. Botanic gardens are appropriate institutions to monitor this ongoing plant-human interdependence and co-evolution.

All of human history, and that of all animals, is founded on the availability of plant energy. From this global context of Sun and plant, all else flows …

Gradually, through the first three phases of human existence (Natura, Agraria, Industria) six significant categories of economically important plants emerged: those used in everyday living (dyes, fibres, resins etc.), medicinal plants and spices, horticultural plantation crops, agricultural crops, forestry timbers, and the ornamental plants of horticulture (first clearly recognized in the agrarian cities of the Bronze Age). There is a further and more recent seventh category, the unintentionally introduced plants that have escaped from cultivation to naturalize in the wild across the world.

3. Plant domestication

The relationship between humans and plants has been a two-way reciprocal relationship as both parties have strongly influenced the evolutionary path of the other. Significantly, this mutual dependence is only total in one direction: plants can survive without humans (although some anthropogenic plants would rapidly become extinct without us), but humans could not survive without plants.

Humans have impacted the lives of plants by altering their genetic makeup and reconfiguring their distribution and species composition over the surface of the planet.

The transition across the world from nomadic hunter-gatherer to agricultural plant cultivator followed various agriculture-like and horticulture-like paths, but all led from wild plant landscapes to the cultural landscapes of cultivated plants – the fields, parks, and gardens of today.

The transition from wild plants to cultivated plants has entailed three major human influences on plant genetics – the human intrusion sometimes referred to as artificial selection: first, those variants that increase plant utility. Among the many factors at play here are – improved yield, resistance to disease, ease of harvesting, greater visual appeal; second, the use of deliberate plant breeding techniques as a means of speeding up plant selection process; thirdly, the direct manipulation of the plant genome using genetic engineering.

3. The Neolithic Revolution

The cultivation of crops during the Neolithic Revolution created the surplus wealth that facilitated the advent of cities and civilization. This was the most momentous social transition in the history of humanity, marking the transition from nature to culture. While humans domesticated plants and animals it was these plants and animals that unconsciously domesticated, or ‘cultivated’, humans.

Agriculture provided the surplus energy that allowed settled populations to grow, increase in social complexity, and develop the physical and mental technologies associated with large sedentary populations. However, the once diverse human diet was now reduced to a few staple foods, mostly cereals that could be harvested and stored for times of need.

This lack of culinary variety as a basic component of the material culture created a desire for unusual and rare foods and plants associated with symbolic culture. These were the aromatics so popular in religious ceremony, herbs and spices to enhance monotonous fare, also rare fruits and nuts, ornamental plants and the special plants needed for building, weaponry and such. These were luxuries, often obtained from distant lands. They fetched high prices among the elite few who could afford them, and while it was staple foods that sustained humanity, these luxuries forged their own path through global history.

4. The Age of Plants – 1550-1950

The eighteenth century saw the rise of Botanophilia, a passion for plants, botany and horticulture, that swept the western world. This was a period of plant ascendancy perhaps not exceeded since our blatant dependence on plants as hunter-gatherers and the first agrarians. As food sources become secure we concern ourselves with them less. Perhaps today our day-to-day ignorance of plants has never been greater. We only know the names of common vegetables and garden plants and perhaps just a few plants growing in the wild. We have little idea of where the vegetables, fruits, and nuts we buy at the Supermarket were grown since they are now sourced based on global economics. And we know even less about how they are cultivated and what they look like as mature plants. Up to the Industrial Revolution almost everyone was employed on the land, today the number of land-workers is in the region of 2%.

4. Creating a global economy

The search for spices in the fifteenth and sixteenth centuries initiated the Age of Discovery and colonial expansion that transformed the global economy and world in a major phase of globalization that included the wide dispersal of temperate and tropical crops and adventive plants across the globe. See, for example, articles related to the Silk Road and Spice Trade and related articles.

A major legacy of this era of empire and trade was the modification of diet (especially in the Western world) as food plants formerly restricted to particular regions were now dispersed world-wide. Europeans exported their farming practices associated with the cereals wheat, oats, barley, and rye, transforming the landscapes of the Neo-Europes and imports came from southern North America (cotton), South America (maize from Mexico, potatoes, chillies, pineapples, and tomatoes from the Andes, vanilla, tobacco, and cocoa from Central America, Rubber from Bolivia and Brazil), China (rice, tea, silk), South and SE Asia (bananas, sugarcane), Polynesia (coconuts), tropical Africa (coffee). Unsually Australia has contributed no major food plants to world cuisine, the macadamia nut being the only commercialised food crop. There were also the plants associated with domesticated animals and the timbers and other plants useed in the construction of the rapidly improvong ships used for transportation.

5. Powering the Industrial Revolution

The concentrated energy contained in the coal, oil, and gas that made the Industrial Revolution possible is derived from fossilized ancient plants. We may think of spices as symbolising a time when plants were highly sought-after products that provided the incentive for world trade, inspiring improvements in technology and an Age of European Discovery. Though today it is mostly oil that powers the world economy no less than seven plants feature in today’s top ten traded commodities – in order of value: crude oil, coffee, natural gas, wheat, cotton, corn, sugar (others are gold, silver, copper).

6. Drink – the source of liquid refreshment

The six most influential drinks in human history have all been plant-based: beer, wine, spirits, tea, coffee, and cola.

7. Food – energy capture/population size/social organization

Globally there are about 3000 known food plants of which about 150 have been extensively cultivated and traded. Today about 90% of the human diet consists of about 15 species. According to the United Nations Food and Agriculture Organization just twelve crops provide 75 percent of the world’s food. Three of these crops, rice, maize, wheat, and potatoes contribute over 60 percent of the protein and calories obtained by humans from plants. We now rarely eat wild food, possibly a few berries, greens, and field mushrooms. Regional agriculture evolved based largely on local cereal plants so in East Asia this was rice, in the Middle East wheat and barley, in Central and South America maize. All staple foods were domesticated in prehistoric times and the full range of cereals, vegetables, and fruits are genetically different from their wild ancestors. Our basic need for plant crops is the single most environmentally demanding aspect of our lives with, above all, its demand for land, but also water (70-95% of our water use), energy, and infrastructure.

Since the beginning of the 20^th century, some 75 percent of plant genetic diversity has been lost. Researching indigenous crops may in part address potential threats to food security and stall the increasing loss of biodiversity. Some traditional plant varieties can help improve nutrition and health, improve local economies, create resilience to climate change, revitalize agricultural biodiversity, and help preserve tradition and culture.Food security is a potential global sustainability issue so organisations like the World Vegetable Center , the Vegetable Genetic Resources System, and Slow Food International’s Ark of Taste are making a catalogue of indigenous species of fruits and vegetables around the world while Bioversity International, a research organization in Italy, is developing policy to safeguard biodiversity of trees and in agriculture to maintain sustainable global food and nutrition security.

8. Energy capture & social organization

Foragers
The close relation between mode of energy capture and social organization over the long term begins with foragers as hunter-gatherer societies in nature capturing food energy from wild animals and plants generally in mobile bands of no more than 20- 100 people, the men hunting animals and the women collecting plant foods.

Farmers
Then beginning about 12,000 BP the formation of settled agrarian farmer societies with food-energy captured from cultivated plants and domesticated animals, most people occupied with food production, storage and distribution but sufficient food available (as wealth or affluence) to permit the increase in population, division of labour, urbanization into populations of 1000s and hierarchical cultural complexity that collectively take advantage of the benefits of scale (monumental architecture, ocean-going ships, armies, communal technology) with wider networks of communication, improved technology, and accumulation of beneficial information.

Fossil fuel industrial agriculture
All these ‘growth’ factors were accelerated with the use of the concentrated energy of the sun stored in dead plants as fossil fuels combined into modern industrial agriculture. Industrial agriculture responded to the Great Acceleration of population from 2 billion in 1930 to 7 billion in 2015 with the further addition of agrochemicals and biotechnology.

9. Three agricultural revolutions & population growth
The First Agricultural Revolution was the Neolithic Revolution of settled communities living with domesticated animals and plants. This arose independently in about five major areas across the world between about 12000 BP and 4000 BP at a time when the world population possibly ranged around 1 to 10 million.

The Second Agricultural Revolution took advantage of the concentrated energy of fossil fuels, slowly introducing industrial agriculture and bringing the world population from 350 million in 1500 to about 1 billion in 1800 then, as industrialization spread out of Europe across the world, up to 2 billion in 1930.

A Third Agricultural Revolution was needed to meet the demands of the ‘Great Acceleration’ when the world population exploded from 2 billion in 1930 to 7 billion in 2015. This began as the Green Revolution of the 1950s and ‘60s which increased agricultural output by using synthetic chemicals (fertilizers, weedicides, pesticides) and increased irrigation to boost the growth of high-yielding newly-bred cereals like dwarf wheat and rice. It was a revolution that combined modern machinery, large farms, and the bioengineering of crops that needed a high input of agrochemicals and water. This lifted much of the developing world out of poverty but there was an environmental cost. The Green Revolution was built, in part, on the genetics that had matured in the 1930s and which was supplemented, after 1980, by the genetically-engineered crops made possible by the deciphering of the genetic code in the 1950s.

10. Economic utility – provision of goods and services

We use plants as food; food and drink additives; psychoactive plants; poisons; as medicines and drugs; fibres; dyes; perfumes and aromas; oils, fats, waxes; resins; rubber; wood and timber for fuel and paper; for structural materials, decoration, and ceremony.

Plants are also the keystone of Ecosystem services.

Commentary

The reciprocal relationship between humans and plants is one of co-evolution. Humans have influenced plants by altering their genetic makeup and reconfiguring the species composition and distribution of plants across the planet. Plants have impacted on humans by influencing human biological and cultural evolution. As the source of life-energy plants have changed human biology and social organization, first through the advent of agriculture, and then through their influence on social organization as the source of fossil fuels that have powered industrial society.

to the familiar . This humble beginning would then spawn the great cultivated plant traditions of agriculture, horticulture and forestry including plant domestication as the human manipulation of plant genetics. In the modern era we see the advent of biological globalization, the human disperal of plants across the planet.

human nature

Another way of looking at our relationship to plants is by distinguishing between those aspects of our relationship to plants that are universal to our human nature, that is, common to all cultures, or innate (see Plants make sense) and how these innate responses have been integrated into cultural evolution.

Oxygen was placed in the atmosphere by plants. One way of becoming aware of the true significance of plants – a way that is usually completely ignored – is to consider their impact on human nature. Our body structure, sight, digestion and other factors have been determined at least in part by our association with plants, they are part of the process of the coevolution of humans and plants that is discussed in the article Plants make sense. We speak of the domestication of plants it was agriculture that confined humans to the cities that helped define civilization and modern life: in this sense plants domesticated humans.

First published on the internet – 1 March 2019
. . . 22 September 2022 – re-edit as part of reorganization of plants-people section of web site
. . . 3 May 2023 – revision

Four Phases of Human-Plant Coevolution
Image Courtesy Rob Cross 2019