Societal and Cultural Changes in Human Evolution - Literature review Example

There have been various changes in man’s evolution which have affected his current health status. Two of these major changes include the domestication of animals and the advent of urbanization and industrialization. The domestication of animals has increased human and animal contact and has consequently caused the exposure and transmission of bacteria from animals to humans. As the population of man has also increased, urbanization has become an inevitable phenomenon. Urbanization and overpopulation has made the management of human wastes a complicated process. Its unmanageability has actually exposed many people to disease vectors and various infections like typhus, malaria, small pox, diarrhea, and other similar diseases. Animal reservoirs for diseases transmitted to humans include: cattle/bovine (tuberculosis); fleas (yersinia pestis or the plague); bugs (Chagas’ diseases); mosquitoes (yellow fever). At present, conditions in society which now affect the transmission of diseases include: environmental pressure from human activities; limited water supply; mining, deforestation, and road building; and poverty and malnutrition. Among terrorists, conditions which they may consider before considering the use of biological agents may include: mass casualty effects of biological agent; possibility of self infection; presence of trained agents capable of handling and managing pathogens; and lack of controllability of infectious agents. Microbiology Societal/cultural changes in human evolution leading to transmission of diseases to humans Throughout man’s history, many changes in his socio-cultural habits have affected his current health status. In assessing his history, there are significant changes we now highlight as crucial events in relation to the transmission of diseases to humans. One of these changes is the domestication of cattle. The domestication of cattle “brought humans into close, repeated contact with infected animals, making it easy for the mycobacteria to jump species and infect humans by the aerosol route” (Barnes, 2005, p. 160). This route of transmission has served to be the most common route from animal to humans because the earliest farmers have lived in close contact and have even shared quarters with their cattle and other beasts of burden. Man’s early existence was largely as nomads as they moved from one area to another gathering food and grazing their cattle. Most nomads also collected and sometimes stored cattle dung for their fire (Barnes, 2005). In the process, they exposed themselves to dung dust and whatever bacteria and disease which may have been existent in the cattle dung. These mycobacteria from cattle were able to readily adapt to their human hosts and consequently build and develop human strains that now saw transmission from human to human through airborne transmission (Barnes, 2005). Humans were also able to transmit the disease to animals through infected sputum found in contaminated water feed for cattle. Stellman and the ILO (1998) account that over 10,000 years ago, when man’s activities shifted from food gathering and then to agriculture, this process resulted to various health problems. The most common health threats which find its roots in animal domestication are zoonotic diseases (Stellman & ILO, 1998). These zoonotic diseases were largely dependent on agricultural practices which later led to diseases such as brucellosis, tuberculosis, and rabies. Another significant change which has impacted on the transmission of diseases to humans is urbanization. The growth of the population alongside the creation of cities has intensified the transmission of diseases from human to human (Nunn, Altizer & Altizer, 2006). Uncontrolled growth in population in concentrated areas which would later become cities has made it difficult to implement effective human waste disposal systems and to deliver clean water to the populace (Armalegos, Barnes & Lin, 1996). Diseases such as cholera (contaminated water), typhus (through lice), plague bacillus (fleas) were diseases which saw fast transmission from human to human due to urbanization. Viral diseases like measles, mumps, and chicken pox were also transmitted easier and faster because of overcrowding and overpopulation in urban centers (Armalegos, Barnes & Lin, 1996). Moreover, urban development has also marked the expansion of populations into new areas; consequently, introducing new diseases to populations which have no or little resistance to such diseases. We cite the example of Western explorers charting their passage on the so-called new world territories and introducing new diseases. We note the travels and explorations of Magellan and Columbus and their crew whose diseases ravaged many natives in the New World by bringing on diseases like smallpox, measles, and later on, syphilis (McKenzie, Pinger & Kotecki, 2008). In relation to urbanization, industrialization is also one of the significant events which have brought on the transmission of diseases to humans. The process of industrialization created wastes which were not as easy to dispose and degrade; and it has also brought on pollution in the air and the waters (Armalegos, Barnes & Lin, 1996). Areas most affected by industrialization and by diseases were the poor people located in the slums. And among the poor diseases like, smallpox, typhoid, diphtheria, yellow fever, and respiratory diseases like tuberculosis, pneumonia, and bronchitis became prevalent and easily transmissible (Armalegos, Barnes & Lin, 1996). Original animal reservoirs of disease contracted by humans 1. Cattle/bovine – reservoirs for mycobacterium tuberculosis or Tuberculosis (Swabe, 1999). Scientists believe that mycobacterium bovis is the source of the mycobacterium tuberculosis in humans. Transmission has been through inhalation and through the consumption of the cattle’s infected milk (Radostits, Arundel & Gay, 1999). 2. Fleas – Yersinia pestis or plague. More particularly, the fleas of rodents. “Fleas will acquire the pathogen from an infected blood meal – the oriental rate flea is the classic vector for plague” (St. Georgiev & Fauci, 2009). Fleas carry blood from infected rodents then transmit the pathogen to humans by biting them. 3. Mosquito – Yellow fever (Hardy, 2002). The yellow fever virus moves from infected mosquitoes that transmit the disease to monkeys. It is passed on to humans who enter areas with monkeys and mosquitoes already infected with the virus (Acha & Szyfres, 2003). 4. Bugs – Chagas’ disease (protozoan). More particularly the assassin bugs or Reduviidae with subfamily Triatominae common in Central and South America. They then pass it on to domiciliary vectors like dogs, cats, squirrels, and rats. Transmission from domestic dogs to humans is then accomplished through human-animal contact (Robinson, 2005). Conditions today that contribute to the spread of human diseases 1. Environmental pressures from human activities. These conditions contribute to the transmission of diseases. For example, with the effects of urbanized activities of people in the cities and in other crowded towns, dengue which is transmitted by the aedis aegypti mosquitoes is quickly transmitted. “Rapid urbanization, the accumulation of water retaining waste products such as plastic containers and tin cans, and increased domestic water storage, for example in open drums” (Gubler, as cited by Chopra, p. 357). Moreover, because of the increased amount and ease of international and domestic travel, the transmission and the development of new strains of the disease has become easier. 2. Limited and contaminated water supply. Low water supply in many parts of the world has also contributed to the transmission of diseases. Reports from the World Health Organization reveal that about 1 billion people around the globe lack access to improved water supply and those who lack access to improved water supplies are the poorest in society (World Water Assessment Programme United Nations, 2003). Most regions affected by limited water supply are in Asia and Africa. And with limited access to improved water supply, people in this region are exposed to water-borne diseases due to contaminated water. They are also forced to deal with poor hygiene and consequently the different diseases which may be caused from unclean and unhygienic conditions (World Water Assessment Programme United Nations, 2003). 3. Mining, deforestation and road-building. Activities like deforestation and mining have created new breeding sites for vector-borne diseases. A clear example is in the case of Brazil, where, “malaria transmission has been associated with deforested environments that provide many suitable breeding sites for Anopheles darlingi…while expansion of An. darling populations in parallel with deforestation will maintain malaria as a significant health problem in Amazonia” (Aguirre, 2002, p. 199). In some part of Southeast Asia, border malaria has been largely associated with mining activities. It has also caused the subsequent spread of the disease to Thailand, Laos, Myanmar, and other countries sharing borders (Aguirre, 2002). 4. Poverty and malnutrition. Poverty in many parts of the globe is a crucial factor in the transmission of diseases. Poverty deprives people of adequate access to potable water, to medicines, to essential food and nutrients and to health care (Hassan, Scholes, 2006). As a result, many of those who are poor are also malnourished and become vulnerable to diseases and the subsequent transmission of diseases. Moreover, “for children under five years of age in the developing world, being underweight equates to about half the mortality risk of the main infectious diseases such as diarrhea, malaria, pneumonia, and measles” (Hassan & Scholes, 2006, p. 409). Factors which terrorists may use to determine which biological agents to use 1. Mass casualty effects. The very goal which terrorists seem to seek is that of gaining or attaining the most media attention. They can easily achieve this through the use of biological weapons which cause the most deaths or casualty to the public. “Terrorists may believe that such media coverage of terror events may further recognition of their cause or increase the impact of actions” (Shea & Gottron, 2005, p. 49). Even if the attention they are able to gain from the media and from the rest of the population is mostly negative publicity or attention, the eyes of the world is on them and they can attain the attention they crave from the media and from the public in general. 2. Possibility of self-infection. Highly contagious biological agents may not be chosen by some terrorists because of the risks they bring to themselves. In instances when some terrorists have expressed the desire to die for their cause, the possibility of self-infection has been discarded by terrorists (Shea & Gottron, 2005). 3. Presence of trained agents to handle incurable and highly contagious pathogens. Some terrorist organizations have now invested much of their resources on the training of agents in the use and handling of highly contagious and even incurable pathogens. Many of these terrorists recognize the fact that these pathogens can create the most damage and gain the most attention; therefore, they have accepted the inevitability of mastering and managing such pathogens (Shea & Gottron, 2005). And by “training others to act as technicians, a terrorist organization could reduce the danger to its knowledgeable scientists, distribute the techniques for developing a pathogen program among the members of the organization, and increase the rate of pathogen production” (Shea & Gottron, 2005, p. 49). 4. Lack of controllability of contagious pathogens. Some terrorists may not be willing to risk being unable to control the pathogens and being unable to control who gets infected by the pathogens. More importantly, they are often not willing to risk injuring their constituents through the uncontrollable pathogens (Shea & Gottron, 2005). Works Cited Acha, P. & Szyfres, B. (2003) Zoonoses and Communicable Diseases Common to Man and Animals: Chlamydioses Rickettsioses, and Viroses. Washington: Pan America Health Organization Aguirre, A. (2002) Conservation medicine: ecological health in practice. New York: Oxford University Press Armalegos, G. Barnes, K. & Lin, J. (1996) Disease in Human Evolution: The Re-emergence if infectious disease in the third epidemiological transition. National Museum of Natural History Bulletin for Teachers, volume 18, number 3. Retrieved 12 February 2010 from http://facstaff.unca.edu/cnicolay/cluster/disease-evol.pdf Barnes, E. (2005) Diseases and Human Evolution. USA: University of Mexico Press Chopra, K. (2006) Ecosystems and human well-being: policy responses: findings of the Conditions and Trends Working Group Volume 3. USA: Island Press St. Georgiev & Fauci, A. (2009) National Institute of Allergy and Infectious Diseases, NIH: Volume 2: Impact on global health. New York: Humana Press Hardy, S. (2002) Human microbiology. New York: Taylor & Francis Publishers Hassan, R. & Scholes, R. (2006) Ecosystems and human well-being: current state and trends: findings of the Conditions and Trends Working Group Volume 1. USA: Island Press McKenzie, J., Pinger, R. & Kotecki, J. (2008) An introduction to community health. Missouri: Jones & Bartlett Nunn, C., Altizer, S. & Altizer, S. (2006) Infectious diseases in primates: behavior, ecology and evolution. New York: Oxford University Press Radostits, O., Arundel, J. & Gay, C. (1999) Veterinary medicine: a textbook of the diseases of cattle, sheep, pigs, goats and horses. Philadelphia: Elsevier Robinson, W. (2005) Handbook of urban insects and arachnids. New York: Cambridge University Press Shea, D. & Gottron, F. (2005) Small-scale terrorist attacks using chemical and biological agents. New York: Nova Science Publishers Stellman, J. & International Labour Organization (1998) Encyclopaedia of Occupational Health and Safety: Chemical, industries and safety. Geneva: International Labour Organization Swabe, J. (1999) Animals, disease, and human society: human-animal relations and the rise of veterinary medicine. New York: Routledge Publishers World Water Assessment Programme (2003) Water for people, water for life. Barcelona: Berghann Books Read More