Human interrelationship

Although humans currently comprise only a minuscule proportion of the total living biomass on Earth, the human effect on nature is disproportionately large. Because of the extent of human influence, the boundaries between what humans regard as nature and "made environments" is not clear cut except at the extremes. Even at the extremes, the amount of natural environment that is free of discernible human influence is presently diminishing at an increasingly rapid pace.

The development of technology by the human race has allowed the greater exploitation of natural resources and has helped to alleviate some of the risk from natural hazards. In spite of this progress, however, the fate of human civilization remains closely linked to changes in the environment. There exists a highly complex feedback loop between the use of advanced technology and changes to the environment that are only slowly becoming understood.Man-made threats to the Earth's natural environment include pollution, deforestation, and disasters such as oil spills. Humans have contributed to the extinction of many plants and animals.

Humans employ nature for both leisure and economic activities. The acquisition of natural resources for industrial use remains the primary component of the world's economic system.Some activities, such as hunting and fishing, are used for both sustenance and leisure, often by different people. Agriculture was first adopted around the 9th millennium BCE. Ranging from food production to energy, nature influences economic wealth.

Although early humans gathered uncultivated plant materials for food and employed the medicinal properties of vegetation for healing,most modern human use of plants is through agriculture. The clearance of large tracts of land for crop growth has led to a significant reduction in the amount available of forestation and wetlands, resulting in the loss of habitat for many plant and animal species as well as increased erosion.

Natural science

As the sciences concerned with humanity split up into more specialized branches, many of the key figures of this evolution expressed influential understandings about human nature.

Darwin gave a widely accepted scientific argument for what Rousseau had already argued from a different direction, that humans and other animal species have no truly fixed nature, at least in the very long term. However he also gave modern biology a new way of understanding how human nature does exist in a normal human time-frame, and how it is caused.

Sigmund Freud, the founder of psychoanalysis, famously referred to the hidden pathological character of typical human behavior. He believed that the Marxists were right to focus on what he called "the decisive influence which the economic circumstances of men have upon their intellectual, ethical and artistic attitudes." But he thought that the Marxist view of the class struggle was too shallow, assigning to recent centuries conflicts that were, rather, primordial. Behind the class struggle, according to Freud, there stands the struggle between father and son, between established clan leader and rebellious challenger. Freud also popularized his notions of the id and the desires associated with each supposed aspect of personality.

E.O. Wilson's sociobiology and closely related theory of evolutionary psychology give scientific arguments against the "tabula rasa" hypotheses of Hobbes, Locke, and Rousseau. In his book, Consilience: The Unity of Knowledge (1998), Edward O. Wilson claimed that it was time for a cooperation of all the sciences to explore human nature. He defined human nature as a collection of epigenetic rules: the genetic patterns of mental development. Cultural phenomena, rituals, etc. are products, not part of human nature. Artworks, for example are not part of human nature, but our appreciation of art is. And this art appreciation, or our fear for snakes, or incest taboo (Westermarck effect) can be studied by the methods of reductionism. Until now these phenomena were only part of psychological, sociological and anthropological studies. Wilson proposes it can be part of interdisciplinary research.

An example of this fear is discussed in the book An Instinct for Dragons,where anthropologist David E. Jones suggests a hypothesis that humans, just like other primates, have inherited instinctive reactions to snakes, large cats and birds of prey. Folklore dragons have features that are combinations of these three, which would explain why dragons with similar features occur in stories from independent cultures on all continents. Other authors have suggested that especially under the influence of drugs or in children's dreams, this instinct may give raise to fantasies and nightmares about dragons, snakes, spiders, etc., which makes these symbols popular in drug culture and in fairy tales for children. The traditional mainstream explanation to the folklore dragons does however not rely on human instinct, but on the assumption that fossils of, for example, dinosaurs gave rise to similar fantasies all over the world.

Socratic philosophy

Philosophy in classical Greece is the ultimate origin of the western conception of the nature of a thing. The philosophical study of human nature itself originated, according to Aristotle at least, with Socrates, who turned philosophy from study of the heavens to study of the human things. Socrates is said to have studied the question of how a person should best live, but he left no written works. It is clear from the works of his students Plato and Xenophon, and also what was said by Aristotle (Plato's student) about him, that Socrates was a rationalist and believed that the best life and the life most suited to human nature involved reasoning. The Socratic school was the dominant surviving influence in philosophical discussion in the Middle Ages, amongst Islamic, Christian, and Jewish philosophers.

The human soul in the works of Plato and Aristotle has a divided nature, divided in a specifically human way. One part is specifically human and rational, and divided into a part which is rational on its own, and a spirited part which can understand reason. Other parts of the soul are home to desires or passions similar to those found in animals. In both Aristotle and Plato spiritedness, thumos, is distinguished from the other passions or epithumiai. The proper function of the "rational" was to rule the other parts of the soul, helped by spiritedness. By this account, using one's reason is the best way to live, and philosophers are the highest types of humans.

Aristotle, Plato's most famous student, made some of the most famous and influential statements about human nature. In his works, apart from using a similar scheme of a divided human soul, some clear statements about human nature are made:
Man is a conjugal animal, meaning an animal which is born to couple when an adult, thus building a household (oikos) and in more successful cases, a clan or small village still run upon patriarchal lines.
Man is a political animal, meaning an animal with an innate propensity to develop more complex communities the size of a city or town, with a division of labor and law-making. This type of community is different in kind from a large family, and requires the special use of human reason.
Man is a mimetic animal. Man loves to use his imagination (and not only to make laws and run town councils). He says "we enjoy looking at accurate likenesses of things which are themselves painful to see, obscene beasts, for instance, and corpses." And the "reason why we enjoy seeing likenesses is that, as we look, we learn and infer what each is, for instance, 'that is so and so.'"

For Aristotle, reason is not only what is most special about humanity compared to other animals, but it is also what we were meant to achieve at our best. Much of Aristotle's description of human nature is still influential today, but the particular teleological idea that humans are "meant" or intended to be something, has become much less popular in modern times.

For the Socratics, human nature, and all natures, are metaphysical concepts. Aristotle developed the standard presentation of this approach with his theory of four causes. Human nature is an example of a formal cause according to Aristotle. Their teleological concept of nature is associated with humans having a divine component in their psyches, which is most properly exercised in the lifestyle of the philosopher, which is thereby also the happiest and least painful life.

Arguments for invariance

All individuals and all societies have a similar facial grammar. Everyone smiles the same, and the way we use our eyes to convey cognition or flirtatiousness is the same. Heterosexual females find male faces that are rated more masculine and aggressive, less feminine and sensitive, more attractive during ovulation, the stage of their menstrual cycle when women are most fertile.

No success has ever been scientifically demonstrated in re-assigning an individual's handedness. Although individuals may change their external behavior (picking up scissors with their right hand instead of the left, for instance), their internal inclination never changes. Even people who lose a limb, who physically do not possess the ability to pick up scissors with their left hand, will try to do so if they are "left-handed." The percentage of left-handers in all cultures at all times remains constant (because left-handedness is a recessive trait.[citation needed])

Newborn babies, far too young to have been acculturated to do so, have measurable behaviors such as being more attracted to human faces than other shapes and having a preference for their mother's voice over any other voice.

In his book Human Universals, Donald E. Brown presents his case and identifies approximately 400 specific behaviors that are essentially invariant among all humans.

Arguments for social malleability

The Duke of Wellington is said to have become indignant upon hearing someone refer to habit as "second nature." He replied, "It is ten times nature!" William James likewise referred to habit as the flywheel of society. Habits, though, are by definition acquired, and different habits will be both the effect and the cause of very different societies.

In An Essay Concerning Human Understanding, John Locke posits that the human mind is at birth a tabula rasa or blank slate, and that the individual has freedom to shape their nature. Nayef Al-Rodhan argues that such freedom is restricted by inbuilt predilections and moral sensitivities.

Different human societies have held very different moral codes. Thus, regardless of whether objective morality exists or not, humans are clearly capable of imposing a wide variety of different moral codes on themselves.

Some have argued that the role for nurture comes not from the absence of impulses in human nature but from the plethora of such impulses—so many, and so contradictory, that nurture must sort them out and put them into a hierarchy.

Some believe there is no single universal law of behavior that holds true for all human beings. There are many such laws that apply to the majority of individuals (for example, the majority of individuals try to avoid dying), but there are always exceptions (some individuals commit suicide). Most animals, including humans, have an innate self-preservation instinct (fear of injury and death). The fact that humans may override this basic instinct is seen as evidence that human nature is subordinate to the human mind, and/or various outside factors. However, this may not be entirely unique to the human mind, as certain animals are observed to willfully commit suicide.

Nature & Animals

Plants And Animals

Originally Aristotle divided all living things between plants, which generally do not move fast enough for humans to notice, and animals. In Linnaeus' system, these became the kingdoms Vegetabilia (later Plantae) and Animalia. Since then, it has become clear that the Plantae as originally defined included several unrelated groups, and the fungi and several groups of algae were removed to new kingdoms. However, these are still often considered plants in many contexts. Bacterial life is sometimes included in flora,[64][65] and some classifications use the term bacterial flora separately from plant flora.

Among the many ways of classifying plants are by regional floras, which, depending on the purpose of study, can also include fossil flora, remnants
of plant life from a previous era. People in many regions and countries take great pride in their individual arrays of characteristic flora, which can vary widely across the globe due to differences in climate and terrain.

Regional floras commonly are divided into categories such as native flora and agricultural and garden flora, the lastly mentioned of which are intentionally grown and cultivated. Some types of "native flora" actually have been introduced centuries ago by people migrating from one region or continent to another, and become an integral part of the native, or natural flora of the place to which they were introduced. This is an example of how human interaction with nature can blur the boundary of what is considered nature.

Another category of plant has historically been carved out for weeds. Though the term has fallen into disfavor among botanists as a formal way to categorize "useless" plants, the informal use of the word "weeds" to describe those plants that are deemed worthy of elimination is illustrative of the general tendency of people and societies to seek to alter or shape the course of nature. Similarly, animals are often categorized in ways such as domestic, farm animals, wild animals, pests, etc. according to their relationship to human life.

Animals as a category have several characteristics that generally set them apart from other living things. Animals are eukaryotic and usually multicellular (although see Myxozoa), which separates them from bacteria, archaea and most protists. They are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls.

With a few exceptions, most notably the sponges (Phylum Porifera), animals have bodies differentiated into separate tissues.[citation needed] These include muscles, which are able to contract and control locomotion, and a nervous system, which sends and processes signals. There is also typically an internal digestive chamber. The eukaryotic cells possessed by all animals are surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. This may be calcified to form structures like shells, bones, and spicules, a framework upon which cells can move about and be reorganized during development and maturation, and which supports the complex anatomy required for mobility.