An environment is a natural unit consisting of all plants, animals and micro-organisms (biotic factors) in an area functioning together with all of the non-living physical (abiotic) factors of the environment.
Central to the environment concept is the idea that living organisms are continually engaged in a highly interrelated set of relationships with every other element constituting the environment in which they exist.In other words any unit that includes all of the organisms (ie: the "community") in a given area interacting with the physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles (i.e.: exchange of materials between living and nonliving parts) within the system is an environment.
The human environment concept is then grounded in the deconstruction of the human/nature dichotomy, and the emergent premise that all species are ecologically integrated with each other, as well as with the abiotic constituents of their biotope.
A greater number or variety of species or biological diversity of an environment may contribute to greater resilience of an environment, because there are more species present at a location to respond to change and thus "absorb" or reduce its effects. This reduces the effect before the environment's structure is fundamentally changed to a different state. This is not universally the case and there is no proven relationship between the species diversity of an environment and its ability to provide goods and services on a sustainable level.
The term environment can also pertain to human-made environments, such as human environments and human-influenced environments, and can describe any situation where there is relationship between living organisms and their environment. Fewer areas on the surface of the earth today exist free from human contact, although some genuine wilderness areas continue to exist without any forms of human intervention.
The environments are described initially as simple two-dimensional grids containing food arranged in some layout. The creatures in these worlds can have evolved sensors, internal states, and actions and action-triggering conditions. By allowing all three of these components to evolve, rather than prespecifying any of them, we can explore a wide range of behaviour types, including “blind” and memoryless behaviors
We are interested in the effects that the environment can have on an organism’s adaptive behavior.Also how the physical, spatial structure of the environment can foster the evolution of,and be in turn exploited by, particular adaptive behaviour generating mechanisms.
As it turns out, even without this added complexity and realism,the sorts of behaviors that can evolve to take advantage of static spatial environments are still varied and interesting.By categorizing environments and describing the sorts of behaviors that are adaptive in them, we hope to provide not only insights into natural evolved systems,but also useful guidelines for the design of artificial agents existing in various application domains.
Rather than manipulating the environment with the specific aim of evolving creatures that can navigate, or communicate, or learn, we want to explore a more general question: what will creatures evolve to do, given certain environmental regularities or structures? What behaviors will prove adaptive in various types of environments? These questions require us to do two very intertwined things: both elucidate the sorts of environment-exploiting behavioural mechanisms that creatures might employ, and describe and characterize how environments can vary in ways that lead to the evolution of different forms of adaptive behaviour. Obviously such goals are very ambitious, and perhaps still beyond but at least by beginning to formalize our thinking about these questions, we can hope to make some progress in our understanding of the complexities involved in the behavioural interactions between environments and organisms.
In a simulated 2-dimensional world across which food is distributed in some fashion, creatures attempting to find and eat that food may get along fine with no sensory systems, or without memories or internal states, or with very few motor commands; or the creatures may find it virtually essential to possess long-distance sensors, sophisticated internal world models, and finely-tuned motor sequences before they can achieve any adaptive advantage at all. What sensors, states, and actions prove adaptive depends on the environment in which the population of creatures evolves. But since it is exactly those three components (at least) which define an organism’s adaptive behaviour, in order to study the effects of the environment on adaptive behaviour we must instantiate our study in a framework which allows the evolution of all three components, something not usually attempted in evolutionary simulations. Cariani (1990) and Pattee (1989) in particular have issued the call to consider the evolution of sensors and effectors in addition to the behavioural links in between, since it is only through the former two that creatures can ground themselves in connection to the outsideworld.The exploration of the evolution allows us to see how exactly those sensors and effectors, the process that Cariani calls semanticadaptation, along with the syntactic-adaptation of evolving information-processing mechanisms, thereby yielding a more complete picture of the evolution of behaviour in general.
It is an environment that encompasses the interaction of all living species. The concept of the natural environment can be distinguished by components:
Complete ecological units that serve as natural systems without massive human intervention like all vegetation, microorganisms, soil, rock,satmosphere and natural phenomena that occur within their boundaries.
Universal natural resources and physical phenomena that lack clear-cut boundaries, such as air, water, and climate, as well as energy, radiation, electric charge, and magnetism, not originating from human activity.
The natural environment is contrasted with the built environment, which comprises the areas and components that are strongly influenced by humans. A geographical area is regarded as a natural environment.
It is difficult to find absolutely natural environments, and it is common that the naturalness varies in a continuum, from ideally 100% natural in one extreme to 0% natural in the other. More precisely, we can consider the different aspects or components of an environment, and see that their degree of naturalness is not uniform. If, for instance, we take an agricultural field, and consider the mineralogic composition and the structure of its soil, we will find that whereas the first is quite similar to that of an undisturbed forest soil, the structure is quite different.
The Earth's layered structure. (1) inner core; (2) outer core; (3) lower mantle; (4) upper mantle;
(5)lithosphere;(6)volcanic lava
Earth science generally recognizes 4 spheres, the lithosphere, the hydrosphere, the atmosphere, and thebiosphere[3] as correspondent to rocks, water, air, and life. Some scientists include, as part of the spheres of the Earth, the cryosphere (corresponding to ice) as a distinct portion of the hydrosphere, as well as the pedosphere(corresponding to soil) as an active and intermixed sphere. Earth science (also known as geoscience, the geosciences or the Earth Sciences), is an all-embracing term for the sciences related to the planet Earth. There are four major disciplines in earth sciences:
geography, geology, geophysics and geodesy.
These use physics, chemistry, biology, chronology and mathematics to build a qualitative and quantitative understanding of the principal areas or spheres of the Earth system.
LIFE:
Evidence suggest that life on Earth has existed for about 3.7 billion years. All known life forms share fundamental molecular mechanisms, and based on these observations, theories on the origin of life attempt to find a mechanism explaining the formation of a primordial single cell organism from which all life originates. There are many different hypotheses regarding the path that might have been taken from simple organic molecules via pre-cellular life to protocells and metabolism.
Although there is no universal agreement on the definition of life, scientists generally accept that the biological manifestation of life is characterized by organization, metabolism, growth, adaptation, response to stimuli and reproduction. Life may also be said to be simply the characteristic state of organisms. In biology, the science of living organisms, "life" is the condition which distinguishes active organisms from inorganic matter, including the capacity for growth, functional activity and the continual change preceding death.
A diverse array of living organisms (life forms) can be found in the biosphere on Earth, plants, animals, fungi, protists, archaea,and bacteria—are a carbon- and water-based cellularform with complex organization and heritable genetic information. Living organisms undergo metabolism, maintainhomeostasis, possess a capacity to grow, respond to stimuli, reproduce and, through natural selection, adapt to their environment in successive generations. More complex living organisms can communicate through various means.
It is the common understanding of natural environment that underlies environmentalism — a broad political, social, and philosophical movement that advocates various actions and policies in the interest of protecting what nature remains in the natural environment, or restoring or expanding the role of nature in this environment. While true wilderness is increasingly rare, wild nature (e.g., unmanaged forests, uncultivated grasslands, wildlife, wildflowers) can be found in many locations previously inhabited by humans.
Goals commonly expressed by environmental scientists include:
Reduction and clean up of pollution, with future goals of zero pollution;
Cleanly converting non-recyclable materials into energy through direct combustion or after conversion into secondary fuels;
Reducing societal consumption of non-renewable fuels;
Development of alternative, green, low-carbon or renewable energy sources;
Conservation and sustainable use of scarce resources such as water, land, and air;
Protection of representative or unique or pristine ecosystems;
Preservation of threatened and endangered species extinction;
The establishment of nature and biosphere reserves under various types of protection; and, most generally, the protection of biodiversity and ecosystems upon which all human and other life on earth depends.
Very large development projects - megaprojects - pose special instructions and risks to the natural environments. Major dams and power plants are cases in point. The challenge to the environment from such projects is growing because more and bigger megaprojects are being built, in developed and developing nations alike.
Reference :
http://www.eskimo.com/~wilson/ps/esabfgu.pdf
http://en.wikipedia.org/wiki/Natural_environment 
