N 750 words, discuss and provide support for the evolutionary origins Essay

N 750 words, discuss and provide support for the evolutionary origins of the following organisms or disease HIV,and how or why it spread to humans - Essay Example evidence put forward by a new team of researchers suggests that the AIDS pandemic dates back to as early as 1884 and that the virus responsible for causing the disease began circulating among humans in the Sub-Saharan African regions between the years 1884 and 1924 (National Geographic, 2012). Also, studies indicate that the first instances of this disease were observed among African primates who were detected with a virus closely related to the HIV, known as SIV (Simian immunodeficiency virus). The SIVs are known to have been transferred to humans through hunting activities and the consumption of primate meat by the humans in the African region (Hahn et al., 2000). The study of molecular phylogenies indicates the various cross-species transmission of the virus to humans. The exact number of cross-species transfer of this virus is difficult to estimate, however studies have shown that the incidence of HIV among humans is likely to be caused by as many as three such transfers in case of HIV-1 whereas the sub groups M, N and O are likely to be of independent origin (Gao, 1999; Sharp, 2001). The Evolutionary Theory: In order for any virus transferred from an animal to affect the human, it is essential for it to adapt to the new host. This is a rarity, since mostly viruses transferred from animals to humans do not affect the latter. However, this theory posits that if the virus transmitted from the animals have had several opportunities to enter the human body, it is highly likely for the said virus to adapt to it and latch on to the receptors thus affecting the human cells in the process. The same has been observed in case of the SIV virus which is a virus originally found among animals but successfully adapted to the hosts thus mutating into HIV, thus converting itself into a human virus (Kirkland, 2010). The Hunter Theory: Some researchers believe that the HIV virus is a mutation of the SIV virus commonly found among primates and has been transferred to humans