All posts by mcook5

Hamiltonian Medicine article review

In this review, the authors explore the idea of Hamiltonian Medicine (HM). The driving force behind this idea is Hamilton’s theory of inclusive fitness, which incorporates the fitness of an individual and the effects said individual has on those that carry genes identical to the individual’s via descent. The authors argue that this is a theory that is widely accepted by the thinkers and practitioners of Darwinian Medicine (“the application of evolutionary concepts and tools to understand health and the causes and treatments of disease”), but is not systematically used as it ought to be in a number of contexts. Thus, the goal of their review is to show how HM can provide insights that have been missed/overlooked in the current Darwinian Medicine mode of thought. First, they describe three domains of social relationships covered in the scope of HM: 1) interactions between cells 2) interactions between genes and 3) interactions between humans. They then go on to describe six principles of HM, which all focus on the impact that interactions within and between the three aforementioned domains can have on human health. One example is the relatedness between microbes and the effect that this can have on virulence and transmission. This type of interaction also is dependent on how their hosts, in this case humans, behave, and thus the two domains of relatedness overlap to have a compounded effect on human health. They also point out how intragenomic conflicts and resource conflicts can have profound effects not just within societies but also within individual families. And lastly, they point out new ways of thinking about diseases such as cancer and mental illness. For example, cancer cells exhibit many similarities to microbes in an HM context, which could offer new perspectives from which alternative treatments might found. As a whole, HM seems to offer a very cohesive and profound insight to understanding human health in an evolutionary context. One of the challenges, which the authors mention, is that pursuing this kind of thought and research is going to be incredibly difficult and involved, because of the complex and interdisciplinary nature of this branch of thought and practice. Thus it will take time and experimentation for HM to effectively put into practice and to become a major branch of research. But, it seems that the knowledge and understanding that could come from pursuing it would be well worth the investment – as long as adequate funding and organization go into it.

A New Take on Why Babies Cry at Night

Babies have a tendency to cry at night, much to the dismay and frustration of many a parent. There are many reasons for why this might be: the baby is hungry, cold, wet, just wants to be held, someone made a noise that woke them up. However, a recent study described in a Science News article provides another reason for why this nighttime crying occurs: it prevents the baby’s mother from getting pregnant again.

Evolutionary biologist David Haig proposes in the past, babies that cried at night had a better chance of survival. This is because the constant interruptions have multiple effects on the mother, many of which act as a kind of birth control. In addition to interrupting potential late-night liaisons and making the mother exhausted, regular nighttime breast-feeding causes hormonal changes in the mother that can delay ovulation (though this is not a foolproof contraception method). Combined, these results of nighttime crying reduce the chances of the mother getting pregnant. How does this relate to the baby’s survival? The answer is simple: if the mother is not devoting resources to another child then the baby will receive more attention and care from the mother during a very vulnerable stage in life. Thus the baby will be more likely to survive its early childhood, and  therefore be more likely to reach reproductive years during which it can pass on its genes to offspring.

While many point out that babies crying at night is caused by a number of other factors, Haig’s proposal provides a new evolutionary significance for the phenomenon. Not only can nighttime crying be seen as sibling rivalry, as the baby is trying to avoid having more siblings for as long as possible, but also shows an example of the battle between sex-linked genes. Male genes tend to cause behaviors that will result in the passing on of genes to the next generation, regardless of the cost to the mother- which explains why male babies have a tendency to cry more at night than females, because there is no guarantee that the mother’s next baby will carry the male’s genes. However, females carry certain genes that tend to make them sleep longer at night as babies, which acts more in the interests of the mother who wants to have more energy to care for her young. Additionally, Haig points out that nighttime feeding is not actually necessary for the baby in our modern day society where most babies have access to adequate nutrients, which supports the idea of nighttime crying being a clever, though unintentional, survival strategy of babies – and also means that moms don’t need to feel too bad if they skip a nighttime feeding session or two.

They Live Among Us: A look at cardiac fibroblasts

Fibroblasts are a cell type that are found throughout the human body; in your lungs, in your heart, below your skin. While there are a wide variety of fibroblasts, typically they are lumped together and regarded as a type of “biological glue” – there to hold everything together by providing components for the extracellular matrix, but not doing much else. However, a recent study at Monash University has proved that this is not entirely the case.

A Science Daily article describes the work of Dr. Milena Furtado, et. al. on cardiac fibroblasts. According to their study, cardiac fibroblasts are actually unique in their genetic makeup in a very significant way: they “remember” that they are specialized heart cells – the result of lingering transcription factors that are absent in other types of fibroblasts. These lingering transcription factors keep cardiogenic genes activated in these fibroblasts, which gives them the potential to contribute to heart development and repair.

This is very exciting, because it potentially offers a new way of treating heart disease. Evolutionarily, fibroblasts occur in a number of vertebrate species and perform very important roles in each of them. However, our understanding of how specialized the fibroblasts are or are not is fairly limited in a number of circumstances. The fact that we are just now discovering that cardiac fibroblasts have the ability to influence heart development and perhaps even more importantly the repair of heart tissue is a testament to this. But this study shows that there is potentially a lot can learn from systems like the fibroblasts, which could in turn have huge implications for the treatment of disease. In the case of heart disease, we currently have no knowledge of how to get the heart to repair itself. So if we could find a way to manipulate fibroblasts in order to get them to help with this process, it might reduce the need for heart transplants and provide a safer alternative to dealing with heart disease. Thus, while it not a guarantee of success, this study shows the importance of exploring new avenues and gaining new perspectives when studying disease.

Dieting: Going Back to Our Roots

A recent New York Times article describes a book that was released in Britain earlier this year and has started a new dieting craze in that part of the world. Titled “The Fast Diet”, this book describes a dieting plan that uses the idea of intermittent fasting: eating whatever you want (within reason) for 5 days of the week, then only eating two tiny meals a day during the other two. Co-author of the book Dr. Michael Mosley describes how, by following this regimen, he: lost 20 lbs., reduced his blood glucose and cholesterol levels, and reduced his body fat percentage. Many others have also claimed to have similar results, and this brings up the question of: why does this diet work so well?

Mosley mentions that the earliest ancestors of humans lived a feast-or-famine existence, gorging themselves when they had the chance and then going without until they were able to find another source of nourishment. The Fast Diet therefore is simply a return to our evolutionary roots, to the lifestyle that humans were adapted to prior to the introduction of agriculture. Additional support for this idea can be found in the fact that in times when the body does not have food to store, it turns its energies toward repair and recovery. If food came only periodically, then it makes sense that natural selection would favor individuals who put obtaining nutrients from food and storing them as a higher priority than performing comparatively insignificant repairs that could wait until later.

This idea of returning to our evolutionary roots is certainly an interesting idea, and Mosley and co. have demonstrated that their way has the potential to help improve human health in our modern society. However, there are also many other factors that play a role in how our diet affects our health. For instance, agriculture not only provided a more constant food supply but also changed the composition of what we eat. Our sugar and cholesterol rich diets have just as much, if not more, of a say in how much of how our diet affects us as the intervals in which we eat. So while The Fast Diet might be a step in the right direction, it should also be noted that there are many other factors that need to be accounted for in forming a healthy diet as well.

Cardiovascular Disease in an Evolutionary Context

Cardiovascular disease (CVD) is one of the leading causes of death not just in American society but globally. Millions of people die every year from various forms of heart disease, two of the more common ones being hypertension and atherosclerosis. Because it is such a major health problem in modern society, much research has been and is being done to find ways to help treat the symptoms and causes of the disease, to help find ways to prevent people from developing heart disease, and to understand the genetic and epigenetic causes behind the disease. However, what Dan Yang and Zhihua Liu discuss in their paper is the necessity of looking at CVD in an evolutionary context if we are to be able to more comprehensively understand CVD and how to treat it the most effectively.

One of the biggest factors that contributes to CVD in humans that Yang and Liu point out is that we are currently experiencing an evolutionary mismatch with our environment. That is, our diet and lifestyle in modern society is very different from what it was as recently as 10,000 years ago. We now eat more food (much of which is modified from its natural state), have a much more sedentary lifestyle, are under more/different types of social and psychological pressures, and engage in many more harmful activities (smoking, alcohol consumption, etc.). All of these are risk factors for CVD, and most are the result of our society evolving faster than natural selection can act. As a result, our genetic makeup is not suited to deal with many of these aspects of modern society, which leaves us susceptible to CVD.

Yang and Liu then discuss what this perspective means for the future of researching CVD. A lot of research is focused on the genetic (and epigenetic) causes of CVD, and manipulating genetic and epigenetic factors can have a lot of downstream effects that might not be anticipated. Therefore they urge researchers to keep in mind the evolutionary context and purpose of the genes that are being manipulated, because otherwise genetic manipulation can end in disaster.

I found this article very interesting, because CVD is of personal interest but also because it is a very complicated form of disease. We can and should do a lot of investigating into the mechanics of CVD, but if we don’t understand why it occurs (which means understanding the evolutionary context of the disease and the history and purpose of the genes that are involved in it) then we can’t treat and prevent it in the most effective manner – the obvious goal of researchers and physicians. Their optimism about evolutionary medicine becoming a mainstream science was encouraging, and hopefully we will see more of this type of research in the coming years.