That solves extinction from environmental degradation.

3. Ecological degradation in food production and the need for new sustainable paradigms in agriculture From the neolithic period, different human groups have developed agriculture, devising processes for the obtention of seeds, sowing, plantation maintenance, harvest and exchange and commercialization of food. In many cases these activities have altered the dynamic balance of ecosystems, and in the Anthropocene, the agriculture is recognized as a primary driver of global change and as the main contributor to environmental risks (Foley et al., 2011). The degradation of ecosystems (their structure, dynamic and evolution) for food production can be explained in two ways: • By the appropriation processes of natural resources and environmental services, where any intervention generates negative impacts on environment; • By disposing residues to the environment. According to González de Molina and Toledo (2014) these emanations should be analyzed by both the quality as well as the quantity of the materials of the residues, meaning if they are recyclable or not by nature or if they surpass or not the natural recycling capacity. Nevertheless, when the appropriation of nature is done disregarding the productive vocation of the ecosystems, its capacity to renovate itself and its existence is threatened. This in turn generates certain changes that end up affecting society (Toledo, 2008). For example, a reduction on crops productivity or the use of agrochemicals to attenuate the loss of soil fertility. In these cases the farmer spends a great amount of time recovering the ecosystem, generating additional negative pay offs causing the producer to overexploit its labor to balance the relation. It could be considered that nature generates penalizations to wrong decisions made by the producer, accumulating in time and space, which could lead to a collapse of the material base and even the disappearance of populations, states or civilizations, requiring sustainable interventions over the ecosystems (González de Molina and Toledo, 2014). Nonetheless, processes such as the circulation, transformation and specially consumption increase the pressure over nature. According to González de Molina and Toledo (2014) in human history the volumes of materials-products that circulate as well as the distances covered before they are consumed, have increased. Going from the non-merchant and non-monetary trade, to the trade mediated by money, private property and markets. The latter results in a vast network of trades that is intimately linked to the transformations where the old relation, direct and almost immediate between appropriation and consumption gets blurred (González de Molina and Toledo, 2014). These authors argue that at a global level and at the beginning of the XXI century, consumption constitutes a powerful factor that demands incentive and even subordinates the other metabolic processes. Examples around the world could explain the important role of consumption. For example, a global increase in the levels of meat consumption, is recognized as one of the greatest threats to tropical ecosystems and biodiversity (Machovina and Feeley, 2014). Livestock production accounts for up to 75% of all agricultural lands (Foley et al., 2011), so that a rise in the consumption of meat products increases the demand for animal feed and consequently changes the land uses with the associated negative environmental impact on ecosystems and biodiversity. Also, it is known that agri-food systems in which higher calories are consumed by humans stem from animal products that have a higher total calorie throughput (Mayer et al., 2015). Likewise, another interesting example is related to commerce between northern and southern countries. After the XX century, the consumption in northern countries and the international commerce with southern countries has been a factor that has promoted the expansion of agricultural border and has contributed to intensifying the exploitation of the soil in southern countries. This represented an increase in volumes of foods and produced agricultural raw materials, as well as in increased productivity by having higher yields per hectare (Pérez, 2006); with associated environmental costs and natural heritage exhaustion. According to Pérez (2006) the increases on productivity are very important in economic terms, but these have associated environmental implications a: i) The ecological footprint caused by the intensive introduction of energetic inputs based on non-renewable resources produce energetically deficient agriculture that is of low ecological sustainable value; and, ii) absolute increments on the use of other natural resources such as water, since the dynamic on the use of the soil has a relation of correspondence in the dynamic of the use of hydric resources for agricultural activity. The strong pressure over nature by conventional agriculture, and also the permanent demand of food by the increasing human population, implies the necessity of new paradigms for an agricultural production in the frame of productive tendency of ecosystems. In relation to this Leff proposes: The environmental crisis takes us to rethink reality, to understand its tracks of complexity and the linking of the complexity of the being and of the thinking process, of reason and passion, of sensitivity and intelligibility, so that from there, open new roads of knowledge and new existential senses for the reconstruction of the world and the reappropriation of nature (Leff, 2006). In this new perspective, the modern world crisis must be considered, especially in the rural sector, as a consequence of the transgression of the biophysical limits of the planet for food production. For Toledo et al. (2009), the way to approach the crisis is through the improvement of the reduced ways in which traditional models as well as the modern ones articulate each other and with nature. Thus, bringing about the concept of sustainable development, which allows perceiving an alternate modernity that is really the adoption of a new method of appropriation of nature. In this sense, sustainable agriculture can be understood as the management and use of agroecosystems in a way that the biological diversity, productivity, regeneration capacity, vitality and functioning capacity are maintained. So that important biological, economic and social functions at a local, national and international level can be met (today and in the future) without damaging other ecosystems (Lewandowski et al., 1999). Sustainability can be reached through agricultural practices based on the adequate and profound knowledge of ecological processes in production units and their context. Therefore, agreeing with Gliessman a greater comprehension and evaluation of the current productive processes is required to focus agricultural production toward social and economic changes that promote sustainability (Gliessman, 1998).