Primates & HIV

One of the most stunning, controversial, medical and scientific developments of the last several decades has been the discovery and emergence of HIV, or Human Immunodeficiency Virus. In 2010, the World Health Organization (WHO) estimated that the number of people living with HIV globally was 34 million (AIDS epidemic 2010). In the same year, AIDS (the disease caused by chronic infection with HIV) was responsible for approximately 1.8 million deaths. HIV has also been a scary development in the United States, as viral transmission shifts from a focus on homosexual individuals to heterosexuals of all races and ages. Biologists, anthropologists, and other researchers often disagree on the exact point of origin of HIV, and how it emerged in the human species. These academic questions are exacerbated by the media and conspiracy theorists with a number of creative explanations, many of which have now been discredited. In this blog, I will provide an overview of what actually occurred and address two popular but misguided theories. 

Viral Structure of HIV 1

First of all, there are two forms of HIV circulating in the human species, HIV-1 (common) and HIV-2 (only found in West Africa). Based on genetic analysis, these viruses are derived from a class of viruses called SIVs, or Simian Immunodeficiency Virus (simian aka Old World monkeys). Researchers believe that based on significant genetic similarities, SIVsm (from sooty mangabey monkeys) transformed into HIV-2, and SIVcpz (from chimpanzee monkeys) transformed into HIV-1. While the viral origin is no longer in doubt, exactly why the virus jumped and how it manifests itself differently in humans than primates is still under evaluation. Researchers do know that these SIVs often do not cause deadly disease in infected primates.

This entire body of evidence is contrary to some popular, misguided theories that seek to explain HIV and its financial and social devastation on the emerging world. Jakob Segal's (German university biologist) story is well known - that HIV was engineered by the US government in the 1970s and tested on prisoners before it was released. However, this theory was disproved as genetic analysis shows the virus existed as early as 1920. Another infamous theory comes from the development of the polio virus. This theory claims that the polio virus, developed in chimpanzee tissue, was contaminated with some SIV and introduced to the Congo in Africa in the 1950s - once again, the timing is too late as HIV had already made the jump to the human species.

Theories aside, much work is yet to be done to understand the specific moment or moments of transmission to our species. Genetic analysis can only take us so far, and then cultural anthropologists and historians must step in. Human interaction with nature, including bush meat and blood rituals, are perhaps the key to understanding a critical moment in the history of human disease. 

"iloveprimates.com" Blog Review

Response to the blog: http://iloveprimates.com/2011/12/reciprocal-altruism/

Researchers continue to try to understand Reciprocal altruism/reciprocal altruism in nature. Altruism in nature is typically defined as an unselfish act that benefits another (non-kin). This concept, as it manifests itself nature seems very strange, based on the foundations of Darwinian evolution—that any trait to share or benefit another (non-kin) at one's expense is not likely to survive multiple generations. However, reciprocal altruism can be more complicated because some benefit may come back to the initiating participant, with ultimate advantages for both participants. In this blog, I will respond to a blog post that explores the question of reciprocal altruism in primates (see link above).

Snub-Nosed Monkey (Photos)

The blog post does a nice job of introducing the concept of reciprocal altruism. Indeed, the Trivers work, The Evolution of Reciprocal Altruism, suggests that the participants must have the ability to remember one another (primates have exceptional longer-term memory) and the cost of giving (time spent grooming, food shared, etc) must be outweighed by the reciprocated benefit (coalition support, food sharing, etc). The blog post provides two specific examples from vervet monkeys and male chimpanzees, and includes a short video of this type of behavior (The Video).

Interestingly, reciprocal altruism has been explored across many species including various insects, bees, birds, etc. Despite the high-level overview from iloveprimates.com, there are some additional research perspectives and context that help to frame the discussion. One such insight is that the reciprocal altruism tends to occur between "high-ranking" individuals. This is important because it means that this relationship dynamic is even less "altruistic" if primates lower down the pecking order do not have access to such opportunities. Additionally, evidence has shown that the level of reciprocity is quite equal (think banana for banana), but there can be variation for reciprocating up the ladder to a "high ranking" individual. Finally, data analysis has revealed the complexity and range of these altruistic acts, from grooming, food-sharing, and fighting coalitions. This evidence is important because it means that higher forms of altruism existed prior to the development human-like cognitive abilities. So, keep how far humans have evolved in context the next time you lend someone your metrocard or donate money to a cause!