Sunday, April 22, 2012

Primate Nutrition

We spend a considerable amount of time either thinking about what we will eat, getting what we want to eat, and ultimately, eating. Actually, on average, Americans 15 or older spend 67 minutes a day eating (How Much Time do Americans Spend Eating?) So what about primates and their diet activities? In this blog, we will examine some common dietary considerations for primates. 

By now you know that there is great diversity among primate species, but some generalities can be made about their diets. Typically, primates consume large amounts of plants and plant remains, which may have very different levels of caloric and nutrient value. Many primates (depending on their class) do not have the ability to synthesize Vitamin C. These species add fruit to their plant-centric diet. Additionally, primates will often consume various insects, if available to them, as insects can be highly nutritious. In captivity, primates are often fed a combination of fresh fruit (mango, apple, papaya, oranges, bananas, raisins, etc), veggies (lettuce, carrots, cucumber, sweet potato, eggplant, cauliflower, broccoli, etc), and nuts, yogurt, etc. Most facilities and institutions, including almost every zoo, have turned to prepared food products known as "monkey chow". Probably, the most common monkey chow is developed by Purina, and contains a specialized formulation with added Vitamin D3, carbohydrates, and supposed great taste. Oddly enough, a recent experiment by a blogger involved consuming monkey chow for days. Check out the Monkey Chow Diaries

Questions remain about putting most/all captive primates on standardized diets of monkey chow, with or without their added multivitamins. Obviously, this is not the seasonal diet that they would have experienced in their natural habitat. Although, without natural and competitive pressures associated with food, captive primates have one less thing to worry about. Researchers spend considerable time examining links between behavior, diet, and stress, and the impact of all three on reproductive success. As the research insights become available, many primate keepers are becoming more and more sophisticated with their rationing of food, particularly as it relates to enrichment activities.


The evolution and biological iteration of the primate is one of the most fascinating aspects of the historical "timeline of life". For a non-biologist/anthropologist, primate evolution may appear quite complicated and interconnected. In this blog, I will break down this complex process into some simple milestones and explain how we arrived at the species of monkeys that currently roam our world.

The very first class of creatures to resemble a primate was the Euarchonta, an early class of mammal that appeared around 70 million years ago (mya). This half-squirrel, half-primate was tree-living with claws and forward facing eyes (located on both sides of its head). The next milestone for primate evolution occurred around 40 million years ago, during which the early proto-primates split up into two groups with distinct and emerging characteristics, the Strepsirrhini (wet-nosed) and Haplorrhini (dry-nosed) primates. The Strepsirrhini developed into lemurs and lorises, some of the smaller-bodied, rodent-like, truly tree-dwelling primates. However, the Haplorrhini as a group diverged again about 10 million years later into what we now call "New World monkeys" and "Old World monkeys".

New World and Old World monkeys spent the next 20 million or so years further evolving and defining themselves (through a process called speciation), but their key and differentiating characteristics remain the same today. New World monkeys feature a flat nose, longer prehensile tails (a functional tail used for tree-swinging), small to mid-sized bodies, and live in the tropical canopy of Central and South America. Some of these primates include the spider monkey, sakis, marmosets, and tamarins. In contrast, Old World monkeys are probably the ones you pay close attention to at your local zoo. These primates feature a downward-facing nose, mid to large-sized bodies, non-prehensile tails, anywhere from partial tree-dweller to land-dweller, and live in a range of habitats across Africa and Asia. Some of these primates include baboons, gorillas, and macaques. These primates survived quite well and developed into the human era around 7 million years ago.

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. 

Saturday, April 21, 2012

"" Blog Review

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).

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, 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!

Perspectives on Primate Testing

Most people are far from understanding the importance of primates to modern medicine and our therapeutic research and development process. Due to their very close biological relation to humans, primates remain the “ideal” scientific model for experimentation. Many, many people have varied opinions on primate medical experimentation from a scientific, ethical, financial, and spiritual perspective. In this blog, I will try to briefly touch on some of the major discussion points in the hope that we all examine about this more and refine our thinking on the matter. 

Primate medical experimentation is used for more complicated disease research that cannot be wholly accomplished with mice, rats, rabbits, pigs, etc. The primate model is a very costly, but sometimes a necessary model because it provides a unique view of how special treatments or medicines will behave in a human system. From stem cell research to tissue regeneration studies, primates are critical to industry's ability to make strides in these areas, and ultimately improve human health. However, there is often abuse, misuse, and questionable decision-making about how many primates are used and for what purpose. What is that fine line in research that necessitates using primates? What is serious enough disease state, or a promising enough treatment? HIV? Hepatitis-C? Multiple Sclerosis? And, how do we balance the use of primates against the need to progress science and discovery. 

Recent recommendations from the government call for a major reduction in primate medical experimentation. Some of these recommendation assess the burden of the high financial costs of maintaining a primate experimentation lab. Others touch on the broader ethical and spiritual complications, with consistent pressure from outside groups (PETA, Primate Freedom Project). The pressures will no doubt increase as primate behavioral research continues to show primates have incredible learning abilities (Baboon Reading Skills: Research Shows Baboons Can Learn To Spot Real Word, The Huffington Post) 

This conflict may continue to increase as the focus of the pharmaceutical industry turns to more niche drugs (for cancer, Alzheimer's, etc) that could require primate experimentation. At its core, this is an important issue for everyone to understand and begin to form an opinion on. For more related information on the topic follow this link (Laboratory chimps get a new lease on life) and stay tuned to my blog.

Stressed Out

Research continues to show that a lower social status can be bad for your health. In a recent publication Changes in Social Status Seen in Gene Regulation in Monkeys scientists are closer then ever to defining why. Most anthropologists and psychologists that focus on this area often use the famous Whitehall studies from British civil servants as a cornerstone of their argument. The research dramatically found that wealthier, busier, more stressed senior executives actually lived healthier lives than junior and entry-level employees. This study is so interesting because all civil servants in Britain have equal healthcare access. With this reality, research has moved slightly away from looking at access to care across social classes, and focusing on genetic and behavioral explanations. 


Interestingly, primates are often studied to understand the link between social status and happiness, health, quality of life, etc. For example, primates at the lower end of the social “pecking” order have a higher risk of disease than those at the head of the pack. A University of Chicago team recently segmented a group of primates from both ends of the social spectrum and analyzed their cellular activity. They identified roughly 987 genes that were expressed differently between high and low status monkeys. 


What does this mean for all of us (humans)? Can we imagine that there is an actual difference in gene expression between our CEOs, policemen, receptionists, athletes, and janitors? What does this say about how much mental control we have over our health? Can stresses of the lower class directly lead to health problems? With the recent healthcare changes in the US and Obamacare, it is hard to imagine better access to health services won’t make a difference. But, clearly pieces of this research show that perhaps the way we "feel" and internalize our place in the world is potentially more powerful. 

For further interest or to learn more, please visit the following link Stress Response: Savior to Killer or watch the full National Geographic Episode on Stress: Portrait of a Killer on Netflix!!!