Organic Evolution: Evolution of the Immune System
John Frelinger
Dr. Travis
Organic Evolution
30 April 2012
Evolution of the Immune System
Animals are constantly bombarded by an immensely varied array of disease causing pathogens including bacteria, fungi, viruses and other parasites. The number of microbes living in the human body outnumber the actual human cells by a factor of 10, and for every single species of animal and plant on Earth, there are viruses that infect them. With the unrelenting threat of disease-causing pathogens all around us, and even within us, how can the constantly vulnerable organisms defend themselves? Evolution has provided an answer to this problem—the immune system. The immune system is a vastly complex orchestra of cells working together to help eliminate potentially harmful pathogens from the body. Some form of host defense is found in every multicellular organism, however there are myriad variations in the immune systems of different organisms.
Vertebrates have evolved an acquired immune response, in which a specific immune system is activated to clear an infection that is initially controlled by a non-specific (innate) immune response. This highly adaptable system is important to the survival of vertebrate species. Surprisingly, however, 90% of animals (invertebrates) do not have this kind of response. Despite lacking a seemingly critical adaptation, invertebrates continue to survive and reproduce. Why does it appear necessary for vertebrates to have an acquired response in order to survive, but the more numerous invertebrate species do not? Research indicates that there is an evolutionary lineage of the immune system that stems from the split of invertebrates and vertebrates. Innate immunity, which is found in all animals, is assumed to be at the beginning of this evolutionary tree. After the diversification of species (vertebrates branching from invertebrates), mechanisms of immunity also diverged. In this paper I will first discuss the function of the innate immune system
Dr. Travis
Organic Evolution
30 April 2012
Evolution of the Immune System
Animals are constantly bombarded by an immensely varied array of disease causing pathogens including bacteria, fungi, viruses and other parasites. The number of microbes living in the human body outnumber the actual human cells by a factor of 10, and for every single species of animal and plant on Earth, there are viruses that infect them. With the unrelenting threat of disease-causing pathogens all around us, and even within us, how can the constantly vulnerable organisms defend themselves? Evolution has provided an answer to this problem—the immune system. The immune system is a vastly complex orchestra of cells working together to help eliminate potentially harmful pathogens from the body. Some form of host defense is found in every multicellular organism, however there are myriad variations in the immune systems of different organisms.
Vertebrates have evolved an acquired immune response, in which a specific immune system is activated to clear an infection that is initially controlled by a non-specific (innate) immune response. This highly adaptable system is important to the survival of vertebrate species. Surprisingly, however, 90% of animals (invertebrates) do not have this kind of response. Despite lacking a seemingly critical adaptation, invertebrates continue to survive and reproduce. Why does it appear necessary for vertebrates to have an acquired response in order to survive, but the more numerous invertebrate species do not? Research indicates that there is an evolutionary lineage of the immune system that stems from the split of invertebrates and vertebrates. Innate immunity, which is found in all animals, is assumed to be at the beginning of this evolutionary tree. After the diversification of species (vertebrates branching from invertebrates), mechanisms of immunity also diverged. In this paper I will first discuss the function of the innate immune system
Cited: Hedrick, S. (2004). The Acquired Immune System: A Vantage from Beneath. 602. Stockdale, C., Swiderski, M., Barry D., and Richard McCulloch (2008).Antigenic Travis, John. (2009). “On the Origin of the Immune System”. Sciencemag Vol