OK – if Darwin really had lessons for today’s college graduates, he’d probably have a lot to say. In coming up with the most thorough, thoughtful, and data-filled work ever completed on questions regarding the nature of life, Darwin did, in fact, come up with a set of ideas that bear on every single aspect of what it means to be human (or cat, or dog, or robin, or goldfish, or moth, or field mouse). Other intellectual approaches that try to address broad ranges of phenomena using some set of principles tend to come up relatively short.

Consider how a Darwinian approach can benefit the area of applied psychology:

Imagine, for a moment, a mental health client who’s a young adult male complaining of social problems, general frustration, and anxiety in social contexts.

A traditionally trained mental health counseling approach might, for instance, pertain to how a client’s frustrations, recent confrontational history, and social problems need to be understood in a specific family context. The client’s familial relationship history would likely be recorded and analyzed with an eye toward helping this client. Taking the cultural norms of that family into account is broad and such an approach has the capacity to help a lot of people with diverse situations. However, I must say that, devoid of evolutionary principles, this theory is a bit narrow.

Evolutionary mental health counseling would go a step farther – perhaps a great leap further. Evolutionary mental health counseling focuses on how some behavioral problem would have functioned under ancestral conditions – with a goal of possibly seeing if said behavioral problem would have had the effect of increasing reproductive success under ancestral conditions.

Such an analysis differs from the prior in that it is rooted in Darwinism. Thus, it thinks about problems in terms of Darwinian questions, to help understand (a) why the behavioral pattern evolved under ancestral conditions, (b) what factors in the situation encourage such behavior – and, perhaps, (c) what factors mobilize actions in a way that they would increase reproductive success.

An EP counselor, looking at this situation, sees things very differently from a traditionally trained counselor. The client is a single man of reproductive age – and is, at 20-some years, a prime candidate for young male syndrome (Daly & Wilson, 1983) – a time in the life of every man when he’s willing to take particularly high risks to unconsciously gain access to mates. Confrontational, risky behavior is typical from individuals in this demographic – and its ultimate goal is to try to attract mates – just as efforts among adult male caribou during mating season are designed to defeat competitors and gain access to females. The counselor works, thus, to help the client develop non-dangerous skills that are attractive to others and that help build social connections.

These two explanations for the client’s frustration and aggressive outbursts are not particularly incongruous. To some extent, they explain the behavior at different levels, with the non-EP version focusing on proximate causes (such as the immediate familial context) and the EP version focusing on distal, ultimate causes, such as how the pattern may bear on reproductive success.

Given the unmatched power of Evolutionary Theory as a tool in unlocking the mysteries of the world, it makes exquisite sense to apply evolutionary theory to academic fields with stated goals of helping others (Keller & Nesse, 2006). To the extent that the goal (helping others) is important and valued and that the evolutionary explanation opens new insights into how to move toward the goal – including implications of specific actions that can be taken, the evolutionary approach has merit.

Thus, Darwin’s lesson to the graduates is this: Don’t be afraid to apply a new way of thinking to an old problem – even if people in the field are saying “oh no, that’s not needed – really – no – really – I mean it!” In a chapter on the power of evolution, Wilson (2007) talks about “teaching the experts” – essentially arguing that students with a strong background in EvoS have cognitive skills used to make important contributions in all kinds of fields – simply because evolution often provides a new and profoundly useful way of thinking about problems. When Daly and Wilson (1988) decided to examine differential filicide rates as a function of status as a step versus biological parent, the data sorted themselves out – nearly diving like lemmings into the appropriate and predicted statistical cells. Evolutionary theory was brought in to address this issue – and the light was turned on in the room as a result.

Graduate, you’ve learned many new skills during your time in college. You’ve learned different perspectives – and you’ve learned that these perspectives don’t always go well with one another (e.g., Geher & Gambacorta, 2010). That’s fine – and I’m glad you saw that in your education. But each perspective you learned about gave you a toolbox. A unique set of ways of thinking about some set of phenomena.

Using evolutionary psychology to understand counseling psychology makes so much sense to me as I’m in a department with a strong counseling program and I’m personally very focused on EP. So I’ve recently become intrigued by applied evolutionary psychology and am currently doing a bunch of scholarship to progress the work of this field.

But I’m not that special. You can do the same. Learn about the principles of evolutionary theory. For instance, think how these ideas may help us understanding democracy – understanding how people vote and for whom they vote. Understand what kind of issues people take on. Understand what kinds of things lead to moral outrage – and why? And what is the function of moral outrage? And how common is it? And what triggers it? And what function does this behavioral pattern serve – either for individuals or, perhaps, for the broader group? This is, of course, just a sample of questions that follow from thinking like an evolutionist. Once you learn to think like an evolutionist, the number of questions to ask is endless!

I’m focusing on how evolutionary principles can help us yield new insights into different areas of inquiry – but you can progress along a different path – other intellectual paths surely have merit. How can social constructionism help explain the pieces of your world? How can hypothesis testing, learned in boring-old-stats class, help you understand the behavior of people at a small bar on a Saturday night?

How can learning about the history of the social sciences help you predict what your future might look like 10 years from now?

Thus, this post isn’t really about how Darwinism can help you better understand the world (not fully, anyway) – it’s, rather, about how the many wonderful (and even less-than-wonderful) sets of ideas you’ve been exposed to during your tenure as a student can help you understand the world beyond how you might imagine.

Darwin’s lessons to the graduates are, thus, in my mind, considerably beyond the lessons of evolution. Here is a sample of Darwin’s lessons:
1. Keep an open mind – Darwin did – and he changed the world forever as a result.
2. Collect data – don’t accept premises that have no substance behind them.
3. Realize that all the sciences and humanities are strongly interconnected.
4. A set of ideas originally designed to explain X, may well provide an exceptional explanation of Y and Z.
5. If you like intellectual approach Q, and see its predictive merit, don’t be afraid to apply Q in new domains – you may stumble upon something that no one ever dreamed of.
6. Finally, a specific implication of Darwinism for college graduates is this: Hear that robin singing in the morning? Smell the white blossoms on the natural rose bushes near the woods? See the turkey vultures soaring high – in communicative harmony with one another? Note this: The same forces accounting for these examples account for everything you see when you look in a mirror. You are part of this magnificent natural world. This insight is, for my money, what makes Darwinism a truly spiritual approach to the world. “There is grandeur in this view of life” (Darwin, 1859).

Congratulations graduates. Along with my professorial brethren, I wish you the very best in your future. Make us proud. And remember, your success is our success.

And for more information about the exciting new field of “Applied Evolutionary Psychology,” check out the Applied Evolutionary Psychology Society (AEPS – yes, from APES to AEPS)!

References:

Darwin, C (1859). On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (1st ed.). London: John Murray.

Geher, G., & Gambacorta, D. (2010). Evolution is not relevant to sex differences in humans because I want it that way! Evidence for the politicization of human evolutionary psychology. EvoS Journal: The Journal of the Evolutionary Studies Consortium, 2, 32-47.

Keller, M. C., & Nesse, R. M. (2006). The evolutionary significance of depressive symptoms:
Different life events lead to different depressive symptom patterns. Journal of Personality and Social Psychology, 91, 316-330.

Wilson, D. S. (2007). Evolution for Everyone. New York: Delacorte Press.

Wilson M, Daly M (1993) Lethal confrontational violence among young men. Pp. 84-106 in NJ Bell & RW Bell, eds., Adolescent risk taking. Newbury Park CA: Sage Press.

Wilson M, Daly M (1998) Sexual rivalry and sexual conflict: recurring themes in fatal conflicts. Theoretical Criminology. 2: 291-310.

Making Sense of Biology

Nothing in Biology Makes Sense Except in the Light of Evolution, Theodosius Dobzhansky (1973). The American Biology Teacher, 35(3), 125-129.

Nature Red in Tooth and Claw…

This line comes from the poem: In Memoriam A.H.H. by the English poet Alfred, Lord Tennyson.  It was completed in 1849 and it is a requiem for the poet’s Cambridge friend Arthur Henry Hallam, who died suddenly of a cerebral hemorrhage in Vienna in 1833. I use this line in all of my introductory lectures about natural selection.  It drives home the salient point that all individuals, and by extension species, operate in self-interest.  This expression is a six word refutation of natural theology; and at the same time an excellent illustration of the problems entailed in the naturalist fallacy.

Natural Theology held that the beneficence of the creator could be seen in the acts of creation.  This thinking goes back at least to Sir Thomas Aquinas (1225/7 – 1274), who wrote in the fifth argument of his Summa Theologie that the existence of God is proved by the order and harmony of the world that there must be an intelligent being in charge.  This view was further developed by John Ray’s The Wisdom of God Manifested in the Works of Creation (1691) which relies on argument from design utilizing somewhat sound natural history.  Over a century later, Natural Theology would develop its highest form in William Paley’s Natural Theology (1803) and Bridgewater Treatises (1832 – 1840.)  These works influenced all of Darwin and all his contemporary scholars.  Indeed the structure of on the Origin of Species was designed to counter much of the thinking of natural theology. Natural Theology failed because it cannot explain adaptation. Certainly, somewhat obvious adaptations seem readily explained by “an intelligent being.”  Fish, Ichthyosaurs, Dolphins all have torpedo shapes.  This shape is hydrodynamic, so there is no challenge to Natural Theology here.  However, why create an organism whose chief adaptation, intelligence is made possible by a large head (which makes its infant more difficult to pass through the mother’s birth canal?)  Real intelligent design would have altered the infant head growth program to make birth easy, and accelerated its growth after to birth to make learning easier. Numerous other examples abound in nature of suboptimal designs, for example why not design humans with eyes in the back of their heads?  Or why design so many microbial life forms that easily infect and often kill these same humans? Attempting to unravel adaptation and organismal diversity using this paradigm quickly became unmanageable.

Closely aligned to Natural Theology is that naturalist fallacy which proceeds from the notion that “all things natural are good.”  As a corollary to this thinking, those who operate under the naturalist fallacy assume that humans would be better off if we simply left nature alone.  Certainly, if we use the current example of the oil spill going on in the Gulf of Mexico, the naturists might have a point.  British Petroleum should have understood that offshore drilling at that depth was fraught with danger.  Thus this particular accident and the damage it is producing could have been avoided if we simply did not “mess with mother nature.”  However, this line of reasoning is fallacious.  It is an example of hasty generalization and selective memory.  How about all the other oil platforms around the world that are operating without major accidents?  And even if major accidents are inevitable when drilling for oil at these depths, what is are the benefits that result from this enterprise and do they outweigh the costs?  Indeed, don’t get me wrong here, what I am not saying is that oil drilling or ongoing fossil fuel use is okay, what I am saying is that the naturalist fallacy is not the way to critique or reject this practice.

Case in point, a colleague of mine who I respect a great deal, suggested that humans should treat other animals utilizing the same ethical and moral principles that we apply to other people.  Certainly the organization People for the Ethical Treatment of Animals (PETA) would agree with that notion.  Yet I argue that this sort of thinking flows from the naturalist fallacy, as well as anthropomorphism.  Charles Darwin remarked in The Origin of Species that if any species could be found, whose behavior solely benefited another species, than his theory of natural selection would be false.  Indeed Darwin was absolutely correct.  The vast majority of animal species are parasites and many are predatory.  Biological communities do show species associations were both species benefit (ants and acacia trees, lichens are algae and fungi, mutualism, +, +); however no species associations have ever been found which show a pattern of a species devoting its energy to the well-being of a second with no benefit coming in return.

Generally, all individuals attempt to maximize their fitness, resulting in their species increasing its abundance and geographical distribution.  This often has the impact of decreasing its competitors.  This may occur intentionally or unintentionally.  Consider the case of our hominid relatives.  Modern humans are descended from a lineage that occupied the world with other intelligent hominids.  For example, 200,000 years ago the world included the  Australopithecines, as well as H. neanderthalensis, H. erectus, and possibly a dwarf human species, Homo floresiensis, found in Java, Indonesia.  Archeological evidence exists that suggests that modern humans entered Europe around 55,000 ybp.  At that time, their skeletal dimensions suggested that they had tropical physical features, including the possibility that they retained their original dark skin.  That evidence also suggests that H. neanderthalensis had temperate/arctic physical features and the MC1R (red hair, light pigmentation gene) has been isolated from Neanderthal DNA.  Artifacts associated with both species suggest that H. sapiens was more culturally advanced.  New DNA analysis suggests that between 1 – 4% of the DNA of modern Europeans may have originated in Neanderthals¹.  This means that there had to have been some interaction between these species.  We cannot infer that the interaction was aggressive or warlike; however shortly after modern humans arrive in Europe the Neanderthals went extinct.  The hypotheses revolve around the competitive exclusion principle of ecology (Gause 1932.)  That is, two species which are very close in resource utilization cannot coexist in the same environment.  The human/Neanderthal interactions could have included direct warfare, competition for scarce resources, disease, or just chance.  Given the ice age conditions of Europe at that time, it is hard to image that there wasn’t some competition; especially since both species would have been hunter gatherers.  One model suggests that the modern human capacity for trade to augment scare resources might have given our species an edge in the competition with the Neanderthals². 

One can ask would it have been possible for modern humans and Neanderthals to have treated each other in an ethical manner. Possibly, especially when one considers that they might have been able to communicate via sign language or gestures (we do not know if Neanderthals had speech.) The FOXP2 gene is shared in both humans and Neanderthals; however the anatomy which allowed full speech did not appear until about 50,000 ybp and is never found in Neanderthal fossils³. The idea that humans might as a whole treat other species in an ethical fashion is undermined by our own history of unethical and immoral treatment of each other.  Indeed, it is argued that the domestication of animals was a key event in the creation of patriarchal societies in our species.  Certainly we do have a consistent history of ethical/moral behavior towards human outsiders; indeed such actions have been the exception and not the rule.

What has been the history of the interaction of humans with non-human species?  This is no different from the interactions of any other species in the web of life (e.g. eat or be eaten.)  For example, many large bodied predatory mammals were direct dangers to our ancestors (leopards, lions, hyenas, bears, wolves, etc.) For over 95% of our existence, these species dined on many unfortunate humans. In turn, our ancestors dined on smaller or less dangerous mammals (although one has to wonder about the sanity of the Pleistocene humans who hunted the great Mastodons!!) With the domestication of animals and the development of stable agriculture our reliance on hunting declined.  Also as our technological abilities grew (smelting of metal, development of projectile weapons) our ability to defend ourselves against large predatory mammals increased.  Ancient societies began to breed animals for food.  In modern industrial society, humans now breed animals for food on a massive scale.  For example, in 2008 the United States beef industry produced 26.56 billion pounds of beef, resulting from the slaughter of 34.4 million head of cattle! Most of this beef is consumed in the United States, that same year only 7.1% of the production was exported.  The average American pet receives more animal protein per day than that available to the vast majority of the world’s people! American pets are so well fed, that 25 – 40% of dogs and cats are obese. Thus for most of the world, as the comedian Chris Rock once exclaimed: “Don’t eat no red meat…no, don’t eat no green meat!”  Vegetarianism is a luxury that most of the world’s poor and hungry people cannot afford. Case in point, it is hypothesized that the HIV virus may have entered the human population through the practice of butchering “bushmeat” in central Africa.  Bushmeat is derived from various monkey species captured, butchered, and sold for consumption. Ironically, bush meat is considered a delicacy by some, and one recent examination of bush meat smuggled in the US has found it contaminated with a HIV-like virus.

Is carnivory a moral choice?

For the vast majority of organisms this is not a question.  As Dr. Allan Grant stated in the film Jurassic Park, “the other kind, do what they do.”  He was referring to the behavior of Tyrannosaurus rex, which evolved as a stealth/sit and wait predator and wasn’t making moral choices when it attempted to eat Lex and Tim.  Throughout the history of life, such predators had no other means of survival.  Humans evolved as omnivores.  It is hard to reconstruct Paleolithic diets; however we suspect that our ancestors ate whatever they could find including animals, edible plants, especially fruits and nuts. This fact is important in understanding how modern pseudoscientific diet fads are contributing to disease⁷.  Carnivory is not a moral choice for other animals because they do not have the mental capacity to make moral choices. In the words of another movie character, Matt Hooper: “Sharks swim, eat, and make baby sharks.  That’s all they do!” Humans on the other hand can decide that they do not wish to eat other animals.  Vegetarian diets are possible, although to remain healthy they require planning, since there are some essential amino acids that are hard to get from plants. However, is choosing to be a vegetarian or vegan a moral choice?

Moral reasoning involves making decisions about what we ought to do.  What we ought to do depends upon one’s values.  Philosophers claim that moral values are those that are worthwhile for their own sake.  Our ability to make moral value judgments results from the way our brain evolved and thus were ultimately produced by the selective pressures that made human social life and structure possible.  These selection pressures are classically thought of as kin-selection (altruism favoring closely related individuals) and reciprocal altruism (altruism that occurred between unrelated allies that benefited both parties.)  While our moral reasoning capacity evolved via genetically based selection, our moral norms evolve via cultural evolution⁸.  For example, some cultures have no problem eating dogs and cats (a practice abhorrent to Americans.)  Yet, our consumption of beef cattle is abhorrent to many Hindus.  Some Alaska Native tribes still hunt whales for cultural and food purposes.  Japan, Norway, and Iceland maintain high volume whaling industries for food consumption.  In 2005, Japan was taking 440 minke whales a year from Antarctic waters⁹.  If whale consumption is not abhorrent enough, some cultures have practiced cannibalism.  Mostly this practice had shamanist significance, although it is thought that our cousin species the Neanderthals might have eaten their old and sick for survival purposes. With all this said, when does the consumption of other species become a moral choice?

As shocking as this may sound, one species eating another is not a moral issue.  One can even argue that people eating other people is not a moral issue (so long as the human bodies involved were not murdered.)  In extreme survival situations, this has often occurred.  For example, the story which inspired Herman Melvin’s Moby Dick, is based on a real case. In 1820, an American whaling ship (the Essex, captained by George Pollard out of Nantucket, MA) was sank by a sperm whale in the Pacific Ocean.  The survivors were stranded on Henderson Island with inadequate food and water.  Eventually some took to their boats in an attempt to be rescued.  With only four men left in Captain Pollard’s boat (Coffin, Ramsdell, Ray, Pollard) they decided to draw lots to see which of them would be sacrificed to allow the others to live.  Charles Ramsdell shot his friend Owen Coffin, and the remaining three lived off his body.  After Ray died, Pollard and Ramsdell gnawed the bones of the two skeletons until picked up by Nantucket ship Dauphin 95 days after the sinking of the Essex⁹.

Might the day after arrive where carnivory might become a moral issue for humans?  Possibly, should we ever develop the technology to fully supply the proteins required for human life without the consumption of animal tissue.  One can even argue that there are moral (if not scientific) issues concerning how food production is currently achieved.  For example, is it morally wrong to feed grain to cattle so that they can be slaughtered to feed the wealthy?  I would argue yes, especially if more people can be fed with the grain you gave the cattle.  Cows are capable of converting cellulose to protein, so they don’t need to be fed grain.  There are range lands that are only suitable for growing cows, sheep, or goats.  These animals can produce protein for human populations that are protein limited.  It is inefficient to feed grain to livestock.  There are other moral concerns in food production; including how mass housing of cattle requires the use of antibiotics to maintain cattle yield. The increased yield comes at the cost of producing more antibiotic resistant bacteria, which endanger human life.  The immoral part of this process results from the profit motive associated with this means of producing meat.  These are acceptable moral reasons for criticizing the industry, but they do not amount to a moral argument for vegetarianism.

References

1. Green, R., Krause, J, Briggs, A.W….Paabo, S., A Draft Sequence of the Neandertal genome, Science 328: 710-722, 2010.

2. Horan, R.D, Bulte, E, Shogren, J.F, How trade saved humanity from biological exclusion: an economic theory of Neanderthal

Extinction, Journal of Economic Behavior & Organization, 58(1): 1-19, 2005. 

3. Lieberman, P, The Evolution of Human Speech: Its Anatomical and Neural Bases, Current Anthropology  48 (1): 39-66, 2007.

4. http://www.ers.usda.gov/news/bsecoverage.htm

5. Laflamme, D.P, Understanding and Managing Obesity in Dogs and Cats, Veterinary Clinics of North America: Small Animal Practice 36(6): 1283- 1295, 2006.

6. Stonington, J., Bushmeat Presents Latest Food Scare: Researchers Find Strains of a Virus Related to HIV in Illegal Imports of Primate Flesh, a Delicacy to Some Africans, Wall Street Journal, April 14, 2010:

http://online.wsj.com/article/SB10001424052702304604204575182463352698780.html

7. Lindeberg, S, Food and Western Disease: Health and Nutrition from an Evolutionary Perspective, (West Sussex, UK: Wiley Blackwell), 2010.

8. Ayala, F.J, The biological roots of morality, Biology and Philosophy, 2(3): 235-252, 1987.

9. Gales, N.J, Kasuya, T, Clapham, P.J, and Brownell, Jr, R.L, Japan’s whaling plan under scrutiny, Nature 435, 883-884, 2005.

10. Philbrick, N, In the Heart of the Sea: The Tragedy of the Whaleship Essex, (New York, NY: Penguin Publishers), 2001.

It seems a pregnant women is a magnet for unsolicited advice – most often tips for parenting, but even tips regarding how she should give birth. In my own experience, these tips came only from males or childless females, but I’ve not done the research to see whether my anecdotal evidence holds water. In this post, I will explore whether these birthing tips are more likely fact or fiction.

The first tip I encountered at a conference during my first trimester. I was informed that I absolutely MUST give birth in water. Our ancestors did it, and it offers a smooth transition for the baby from the amniotic fluid filled womb to our waterless world. Being no novice to childbirth, I was immediately repelled by the idea, in no small part because women in childbirth frequently lose control of their voluntary organs (to put it lightly). There is variation in how women deliver babies in traditional cultures, such as who is allowed to be present (from no one to female relatives or midwives, typically) to how removed the mother must make herself from the rest of the group, some having to find an isolated hiding spot among the trees (Hrdy, 2009). Despite the variation, in the traditional cultures studied, women give birth on land (e.g. dirt outside, dirt floor in a home) most often while in a squatting or kneeling position. But as to the location of these mythical places where women give birth in water, my searches have been fruitless. And for at least two good reasons – how could that possibly be hygienic in most “traditional” places, lacking chlorine and filtration?, and the faulty assumption this approach implies, that naturally flowing water is as warm and cozy as the amniotic fluid from which the baby emerges.

The second birthing question I received was whether I was going to eat the placenta. I experienced a second eww factor here, but my well-meaning friend was only trying to explain that some women eat the placenta because we’ve been designed to do so to provide us with extra calories after giving birth. When you actually look into this practice, however, it begins to attain mythic proportions as well. In no traditional societies do women regularly engage in the practice of eating the placenta after giving birth (Hrdy, 2009). In fact humans, as well as our great ape relatives, engage in this practice so little that we actually stand out from many other mammalian species. As Hrdy puts it, the people practicing placenta ingestion are New Age women who believe it to be tradition.

The third question is such a personal, but common one for a pregnant woman: epidural or no epidural? My response was pretty unwavering – I was going “natural” with this one. And truly, in cultures without medicinal anesthetics, women do have to give birth without any painkillers. It’s no stroll through the park, but it is doable. However, as I just learned from the book Mothers and Others, the practice of licking the amniotic fluid off of newborns and eating the placenta that many mammals engage in (e.g. dogs, cats) actually serves as a natural anesthetic!

Had I known of the natural anesthetic properties of afterbirth, would I have changed my response to number 2? Not likely. Had water birthing and placenta eating been common practice in traditional societies, that still doesn’t make them best practices (also a valid argument for getting an epidural!) – the infant mortality rate in the U.S. has dropped drastically in no small part due to modern medicinal practices, especially the adoption of sterility. Giving birth is such a personal experience. I am happy to live in a country where I get to make my own choices for how to give birth, and leave the decisions of other expecting mothers to their own discretion.

[Do you have any outlandish labor advice stories to share? Add a comment!]

**Please check back in April for a post about the meetings of the Feminist Evolutionary Psychology Society (FEPS; http://fepsociety.org) and the NorthEastern Evolutionary Psychology Society (NEEPS; http://neepsociety.com).**

References:

Hrdy, S. B. (2009). Mothers and others: The evolutionary origins of mutual understanding. Cambridge, MA: Harvard University

As happens with modern behaviors, the presumed ancestral human diet has been lifted up as a utopian ideal by which to live. The Paleo Diet (also Evolution Diet, NeanderThin) offers a way to return to our roots and reduce the risk of many current diet-related plagues – diabetes, high blood-pressure, and heart disease, to name a few. Proponents of these ancestral diets recommend removing from one’s diet foods only made possible with an agriculturalist practice – processed foods, wheat and other grains, etc. Instead, they recommend people eat fruits, nuts, and meat. Is this ancestral diet right for modern humans?

While many primates are frugivores, relying mainly on fruit for food, and other mammals are herbivores, carnivores, or omnivores, humans are most accurately diversivores – we not only eat a wide variety of foods, but we do so by design. Our digestive needs are such that we require meats to make some essential amino acids that our bodies cannot create; fruits and vegetables to provide us with necessary vitamins and minerals, etc. (Martin & Pilbeam, 1994). The agricultural diet, in its purest form, is not so far from these needs – this diet includes meat sources from cows, pigs, chicken, and a variety of other commonly slaughtered animals; grains; fruits and vegetables. Part of problem with agricultural eats is that modern foods mimic foods we were designed to eat but that were previously rare to come by. For example, with calories hard to find, we have evolved the craving for sugary and fatty foods so that we will bulk up on them when we do come across them. However, with sugars and fats far too common in agricultural societies, we end up with health problems.

Evolution is reputed for being a slow process – human ancestors didn’t just walk upright overnight. However, many lines of research now provide us with examples of much quicker heritable changes, such as that for lactose tolerance. People who come from places where cows have been domesticated for many hundreds of years possess the enzyme to digest lactose more often than those from places where cow domestication is more recent. That is why people from the Mediterranean can chow down on cheeses and yogurts, while friends from Asia may have to indulge less frequently. Agriculture as a common human practice is at least 11 thousand years old. Our bodies have kept up with lactose for 5-6,000 years, surely other changes have occurred since the advent of domestic corn and oats. We cannot view modern humans as stagnant – though evolution may move too slowly for us to notice in a few generations, our bodies (including minds) are changing as does our environment.

Finally, looking to our more traditional-living relatives, you aren’t going to see much obesity because the lifestyle won’t allow it. When is the last time you made a 20 mile hunting trip on foot? Undertook the back-breaking work of gathering roots and collecting water? Chances are never, as is true for most modern Americans. If many of us want physical exercise, we have to find it in a gym or a track. Sitting at a desk all day is a poor replication for our ancestral lifestyle. If you want to eat like our ancestors, you might also consider the demanding physical lifestyles in which they embarked. The calories in the actual foods aren’t going to vary that much, it’s the amount of calories we consume v. expend. We can’t all expect to join the Michael Phelps meal plan (~10,000 calories a day) without swimming laps like it’s a full time job.

Let me be honest – if you set before me a plate of organic fruits and veggies, or highly processed Twinkies and Ho-Hos, the choice will not be difficult – I will gorge on the mangoes. But if you want my advice on the Caveman’s diet, I’d say – walk the walk, or embrace moderate consumption of domesticated goodies. The problem isn’t agriculture, it is processed food and over-consumption, coupled with an unnatural amount of physical movement.

Further Reading:

Audette, R., Gilchrist, T., Audette, R. V., Eades, M. R. (2000). NeanderThin: Eat like a caveman to achieve a lean, strong, healthy body. St. Martin’s Paperbacks.

Cordain, L. (2002). The Paleo Diet: Lose weight and get healthy by eating the food you were designed to eat. Wiley.

Martin, R. D., & Pilbeam, D. R. (1994). The Cambridge encyclopedia of human evolution. Cambridge, UK: Cambridge University Press.

Morse, J. (2008). The Evolution Diet: What and how we were designed to eat (second edition). Code Publishing.

Simoons, F. J. (1969). Primary adult lactose intolerance and the milking habit: A problem in biological and cultural interrelations. Digestive Diseases and Sciences, 14(12), 8190836.

Making Sense of Biology: Evolutionary Medicine and the TNT phenotype

Nothing in Biology Makes Sense Except in the Light of Evolution, Theodosius Dobzhansky. (1973). The American Biology Teacher, 35(3), 125-129.

Black in America 2 aired on CNN in late July of 2009.  It featured a compelling story concerning Triple Negative Breast Cancer and the fact that African American women are twice as likely to suffer from this particularly aggressive form of the disease¹.  According to the American Cancer Society, 192,370 new cases of invasive breast cancer will be diagnosed among women in the United States in 2009. Triple negative breast cancer (TNT phenotype) represents approximately 15 percent of breast cancer cases in the United States.  Lund et al. 2009 reports that the prevalence of TNT may range between 10 – 30% of invasive breast cancers; again stressing that African American women are twice as likely to suffer from this disease².  The CNN segment focused on Dr. Lisa Newman, a surgeon and director of the Breast Care Center at the University of Michigan.  Dr. Newman has embarked on a project to collect genetic samples from Ghanaian women to test the hypothesis that African ancestry may be playing a role in predisposing women to this particular form of the disease.  The notion that African American ancestry is the culprit in this disparity raises specters of “racial medicine.”  That is the idea that races of humans exist, and that they can be differentiated by genetic predispositions to particular diseases.  An evolutionary perspective on cancer can resolve this confusion and at the same time offer fruitful avenues for further research on health disparity.

TNT phenotype of breast cancer

Cancer is defined as approximately one hundred complex diseases that behave differently depending upon the cell types in which they originate.  Cancer cells show higher than normal rates of mutation, chromosomal abnormalities, and genomic instability.  For this reason, even within cancers of a particular tissue (e.g. breast) there are several distinct molecular subtypes with distinct etiologies³.  These include the luminal subtypes which typically express hormone receptor-related genes, and two hormone receptor subtypes—the human epidermal growth factor receptor 2 (HER2) positive/oestrogen negative (ER) negative subtype, and basal-like subtype⁴.  Triple negative breast cancer is a basal-like phenotype that lacks expression of estrogen receptor (ER-negative), progesterone receptor (PR-negative) and lacks HER2 overexpression.  Other relevant features of the TNT phenotype include:

It is of interest in that this phenotype is particularly aggressive, is highly likely to reoccur, and is resistant to the current HER-2 targeted therapies such as trastuzumab, and hormone therapies such as tamoxifen and aromatase inhibiters. This phenotype has been associated with mutations that occur in the BRCA1 locus (chromosome 17q21-q24). One mutation of interest (rs79916) has a G to T polymorphism has been associated with increased risk of developing breast cancer but not necessarily the TNT phenotype⁶.  F_ST for this locus worldwide is 0.150 based on 37 populations, with the G variant of higher frequency in Sub-Saharan Africans and the T variant in higher frequency outside of Africa. The G variant has been associated with the higher risk of breast cancer in persons of European descent attending Australian family clinics.  Other risk factors that have been associated with elevated risk of developing breast cancer with the TNT phenotype are younger age and African American ancestry.  It is yet to be determined what is it about African American ancestry that contributes the risk factor.  Implicitly Dr. Newman’s collecting of genetic samples from Ghana assumes that there may be genetic factors associated with population history.  However, there is no reason to believe that and I shall explain why that is true below.

Evolutionary Explanation of Cancer

Cancers show a clear age-specific pattern.  Yet not all biomedical scientists understand why. For example, Klug et al. write in their popular genetics textbook that:

“The phenomenon of age-related cancer is another indication that cancer develops from the accumulation of several mutagenic events in a single cell.  The incidence of most cancers rises exponentially with age.  If a single mutation were sufficient to convert a normal cell to a malignant one, then cancer incidence would appear independent of age⁷.”

This analysis fails to take into account the fitness related impacts of disease.  If the accumulation of mutations in somatic cells were enough to explain cancer prevalence than why do we see such disparate life spans and cancer prevalence amongst Metazoans (e.g. Birds, Reptiles, and Mammals?)  The giant tortoise can live more than 100 years while the changeable lizard lives less than 4; in mammals the maximum life span for humans is greater than 110 years, but the mouse lives between 4 – 5 years.  Cancer is a common disease that occurs in mice as they age and some endogenous mouse mammary tumor like viral sequences have been found in human breast cancers⁸.  Thus, organisms have the same cellular structure and many molecular mechanisms in common show widely different life spans.  Therefore the explanation that cancer mortality increases with age as a result of increases frequency of somatic mutation cannot be sufficient. 

The evolutionary theory of aging is premised on that notion that natural selection cannot act against genetic (or epigenetic) phenomena that occur after organisms cannot contribute to the future gene pool.  Thus, what is of real interest is the relationship between the inflection point at which the exponential increase in mortality begins and its position relative to the graph of an organism’s reproductive fitness.  For example, Darwinian fitness of US women derived from 1996 census data is zero by age 50.   At the same time, the age-specific mortality plot of American men and women for several complex causes in the same time period (cancer, cerebrovascular disease, and accidents) changes slope from close to zero before 50 and increases rapidly afterward. 

 These results are consistent with the evolutionary theory of aging, which results from the declining force of natural selection (NS) with age.  In other words this states that NS is uncompromising in its action against alleles that negatively impact fitness early in life (during the reproductive period); while it has no power against genes whose negative impacts occur once net-reproductive output is zero.  The evolutionary theory of aging was first outlined theoretically by Peter Medawar, George C. Williams, and William D. Hamilton.  It experimental validation was conducted by Brian Charlesworth, Michael Rose, Leo Luckinbill, me and a host of others⁹.

The evolutionary theory of aging demonstrates that selection acts in the following way to mold the genetic architecture of all metazoans organism relative to their age-specific fitness:

Thus alleles that negatively impact early-life fitness are governed by the mutation/selection balance mechanism and will be extremely rare.  They are observed at the frequency of their mutation (barring modern medical intervention.) Progeria is a disease that mimics aging and progeriacs almost never reproduce.  Its frequency is around 1 in 22 million.  Mutation accumulation refers to genes that have no impact on early life fitness, but do have negative impact on late-life fitness.  Alzheimer’s disease is an example, and its frequency is determined by chance population events.  Antagonistic pleiotropy refers to genes that have a positive impact on early life fitness, but a negative impact on late life fitness.  Due to their positive impact, natural selection increases their frequency, despite the fact that they have negative late-life effects.  These alleles are therefore widespread. The genetic loci that are involved in the formation of cancer all have essential functions in early life, thus any genetic variants that impede their function will be rare.  New research suggests that hereditary cancers are actually very rare. Thus the process that is responsible for creating cancer in individuals is actually epigenetic, that is factors that influence the expression of genes in a heritable way but do not alter the nucleotide sequence.  Examples of this are DNA methylation and histone modification.  The evolutionary theory of aging will act in the same way with regard to epigenetic factors, any occurring at early life would be strongly selected against, those that are neutral in early life may accumulate, and those that are beneficial should spread.

Life History Trade-offs and Survival

The field of life history evolution exams how evolutionary mechanisms shape survival and reproductive patterns of organisms.  A consistent theme in life history evolution is the existence of trade-offs.  Some central tradeoffs observed in life history are shown below:

Experimental work concerning the evolutionary theory of aging in invertebrate organisms (Drosophila) demonstrated that there were trade-offs in life history features that resulted from selection for delayed reproduction.  It was further demonstrated that these differences in life history resulted from genetic variation. These experiments showed that there was a genetically based trade-off between early fecundity and late-life survival.  One could utilize results like this to argue for genetic variation in human populations that impact life history trade-offs.  If such genetic differences existed they could be relevant to specific disease systems operating within the evolutionary mechanisms of aging.  J.P. Rushton utilized just such as argument to claim that intelligence differences between blacks, whites, and yellows were genetically based and resulted from life history differences.  I debunked these claims in Graves 2002¹⁰.

However not all life history tradeoffs result from genetic differences in organisms.  For example, caloric restriction can produce life history trade-offs such as depressed early reproduction and prolonged survival in variety of organisms including primates¹¹.  The Colman et al. 2009 report is particularly important to this argument because it caloric restriction (without malnutrition) which is an environmental intervention, delays the onset of complex diseases (including cancer) in a primate.  With this idea in mind we can utilize evolutionary perspectives and re-examine the TNT disparity between African American and European American women to address whether it is reasonable to be looking for causality in the disparity within supposed genetic differences that might exist between these groups.

Drilling into the TNT phenotype

Recent work on the prevalence of the TNT phenotype shows that it is related to a number of life history attributes and behaviors that are not shared equivalently by African- and European American women. For example, life history variables that are associated with a greater risk of basal-like breast cancers include: lower age at menarche, increased risk for parity, younger age at first full-term pregnancy, lower duration of breast feeding, lower number of children breast-fed, decreased number of months of breast-feeding, multiple-live births and not breast feeding, and use of lactation medication.  In addition, body mass index and elevated waist to hip ratio was associated with greater risk of basal-like breast cancer in pre- and post-menopausal women.   Other variables that are associated with greater risk of basal-like breast cancers include diet, duration of smoking, and poverty¹².  Both the Lund et al. 2009 (Atlanta GA study) and Millikan et al. 2008 (Carolina Breast Cancer Study) found self-identified race (African American) as a statistically significant risk factor for TNT phenotype with many of these variables controlled between populations.  However this result in and of itself does not indicate that the important causal factor in self-identified African American race is genetic difference.  Indeed, given the large number of environmental variables that are associated with this phenotype and the large number of environmental variables that differ between African American and European American women there is no reason to believe that genetic variation uncovered in Ghana will have any use in redressing the health disparity.

Environmental versus Genetic Interventions

Even if some underlying genetic factor were contributing to the African-/European- American difference in TNT prevalence it is clear that many environmental and behavioral interventions could help reduce this disparity.  For example, the differences between African and European-American women in age of first full term pregnancy cries out for intervention. The table below shows the ratio of European American to African American births by age in 2004. 

 Source: US Bureau of the Census 2004

This table shows very clearly that African American women are having many more children at younger age than European American women. This life-history feature, especially the teen-age pregnancies is detrimental to the social and economic well-being of the African community as well as possibly predisposing African American women to TNT breast tumor phenotype at later age. Indeed the fact that more African American women are having children at younger age may be associated with less breast feeding by those women.  This may occur simply because many of these women are unmarried and therefore must work or attend school as part of caring for their children.  From the standpoint of evolutionary mechanism the greater prevalence of the TNT phenotype in African American women results from them experiencing a novel environment.  It is likely that our female ancestors were more likely to breast feed their children and maintained much lower BWI and WHR due to greater activity and less fatty diets.  Again, these social issues may be responsible for later epigenetic events which predispose these women to the TNT phenotype.  Ironically, even if genes are examined in Ghanaian women, the fact that they do share the same environment with African American women means that it will difficult if not impossible to correlate genetic differences with epigenetic mechanisms in the US.

Finally, it is important to evaluate that usefulness of genetic or intrinsic mechanisms of disease versus environmental/behavioral ones.  Genetic/intrinsic approaches suggest that an individual’s illness is the result of something that is wrong with them.  This is the thinking that resides behind all of the discussion of “racial medicine.” The racial medicine paradigm continues to find inferior genes in persons of African descent.  This notion is absurd at face value, since there is much greater genetic variation in sub-Saharan Africans than in all the rest of the world’s population combined¹³.  How can it be that all the inferior alleles should be found in Africans?  Indeed, recent studies shown that there are more deleterious alleles in European populations compared to Africans.  This begs the question why do European-derived populations in the US enjoy greater health if their genes are so bad? 

Another feature of the genetic/intrinsic mechanism paradigm is its association with and utility for the biomedical/pharmaceutical complex.  If it is really something intrinsically wrong with African American women that predisposes them to the TNT phenotype, than the obligation is there to find a drug or other medical intervention that cures them.  If true, this does not present and ethical or moral dilemma.  Drug companies should make products that help us cure disease.  However if we consider the notion that social and environmental causes play more important role than genetic differences than the dominance of research by the intrinsic/genetic paradigm is more problematic.  Here the expenditure of dollars in biomedical research and pharmacological developments may actually be causing harm.  That is, if we spent the same amount of money on social interventions, such as education, preventive care, or job creation for the unemployed, might we not narrow the health disparity gap sooner? My reading of the entire health disparity conundrum (TNT phenotype and many others) suggests that we have legitimate reasons to question the moral and ethical standing of the intrinsic/genetic program and its actions. 

References

   1.             CNN Black in America 2, http://www.cnn.com/SPECIALS/2009/black.in.america/.

   2.             Lund, MJ et al., Race and triple negative threats to breast cancer survival: a population based study in Atlanta, GA, Breast Cancer Research and Treatment 113: 357-370, 2009.

   3.             Troester, M.A. and Swift-Scanlan, T, Challenges in studying the etiology of breast cancer subtypes, Breast Cancer Research, 11:104, 2009; http://breast-cancer-research.com/content/11/3/104

   4.             Irvin, W. and Carey, L, What is triple-negative breast cancer? European Journal of Cancer 44: 2799-2805, 2008.

   5.             Definitions: c-kit is a cytokine receptor, p53 is a tumor suppressor gene involved in cell cycle checkpoints and apoptosis, TP53 is gene coding tumor protein 53, cyclins are involved in cell cycle control and checkpoints, p16 is a tumor suppressor protein, EFGR is epidermal growth factor receptor, cytokeratins are proteins of keratin-containing intermediate filaments found in the intracytoplasmic cytoskeleton of epithelial tissue, ab crystallin is a heat shock protein, and Rb is a tumor suppressor gene involved in cell-cycle check points.

   6.             Honrado, E, Benı´tez, J and Palacios, J, The molecular pathology of hereditary breast cancer: genetic testing and therapeutic implications, Modern Pathology 18, 1305–1320, 2005.

   7.             Klug, W.S, Cummings, M.R, Spencer, C.A, and Palladino, M.A, Concepts of Genetics 9^th Edition, (San Francisco, CA: Benjamin Cummings), 2009.

   8.             Wang, Y, Pelisson, I, Melana, S.M, Go1,V, Holland, J.F, and -T. Pogo, G.T, MMTV-like env gene sequences in human breast cancer, Arch Virol. 146: 171–180, 2001.

   9.             Hamilton, W.D, The moulding of senescence by natural selection.  J. Theor. Biol. 12:12‑45, 1966; Rose, M.R., The Evolutionary Biology of Aging, (New York, NY: Oxford University Press), 1994; Graves, J.L., General Theories of Aging Unification and Synthesis, in Principles of Neural Aging, Dani, Hori, and Walter, eds., Elsevier, 1997; M.R. Rose, H. Passananti, & Margarida Matos, eds., Methuselah Flies, (New York, NY: World Scientific Publishing),2004.

10. Graves, J.L., What a tangled web he weaves: Race, reproductive strategies, and Rushton’s life history theory, Anthropological Theory, Sage Publishers, vol. 2(2): 131-154, 2002.

11. Graves, J.L., The costs of reproduction and dietary restriction in mammals, Growth, Development, and Aging 57(4):233-249, 1993 and Colman, R, Caloric restriction delays disease onset and mortality in Rhesus monkeys, Science 325: 201-204, 2009.

12. Lund, MJ et al., Race and triple negative threats to breast cancer survival: a population based study in Atlanta, GA, Breast Cancer Research and Treatment113: 357-370, 2009 and Millikan, R.C. et al, Epidemiology of basal-like breast cancer, Breast Cancer Research and Treatment 109: 123-139, 2008.

13. Lohmueller K, Indap A, et al. Proportionally more deleterious genetic variation in European than in African populations. Nature 2008; 451: 994-98, 2008.

“The great tragedy of Science – the slaying of a beautiful hypothesis by an ugly fact.“

Thomas H. Huxley (1825 – 1895)

English biologist; supporter of Darwin;
father of Aldous & Julian Huxley.

Missed Opportunities

In the lead up to this, the 200th anniversary year of Darwin’s birth, I’ve attended my fair share of evolutionary research seminars. Surprisingly, few presented alternative hypotheses, or better yet, multiple alternative hypotheses. In fact, rarely was a specific evolutionary hypothesis enunciated. And when one was, the speaker usually failed to point out what critical experiment or observation could falsify it. Admittedly, these talks were directed toward a general, non-specialist audience. But many of those in attendance were students and this “omission” seemed like a missed didactic opportunity. Moreover, Evolutionary Theory is championed (all too often in courthouses in the United States) as a true science (as opposed to Creation “science”) because its hypotheses are falsifiable. So where are all these falsifiable hypotheses????

My undergraduate Invertebrate Zoology professor, Demerest Davenport emphasized (i.e. drummed it into our skulls) that adaptive questions can be addressed using “Strong Inference”. He had us all read the 1964 SCIENCE article of that name, by John R Platt1. At the time I was not especially impressed because it sounded like what we had been taught in General Biology and General Chemistry and had already accepted as standard operating procedure. In his recent blog, Massimo Pigliucci2 suggests that the main point of Platt’s article was to explain why the “soft sciences” (including the evolutionary sciences) were less successful than the new (at the time) “hard sciences” like molecular biology and modern physics. I am not sure I agree with Pigliucci’s hard- vs soft-science dichotomy (perhaps that is a discussion for a later blog). In any case, as a young scientist, my take home message was that “Strong Inference” could be applied to all kinds of questions and that it should have been applied more often than it had. Perhaps, that is still so today.

Strong Inference

“In its separate element, strong inference is just the simple and old-fashioned method of inductive inference that goes back to Francis Bacon. The steps are familiar to every college student and are practiced, off and on, by every scientist. The difference comes in their systematic application. Strong inference consists of applying the following steps to every problem in science, formally and explicitly and regularly:

1) Devising alternative hypotheses;

2) Devising a crucial experiment (or several of them), with alternative possible outcomes, each of which will, as nearly as possible, exclude one or more of the hypotheses;

3) Carrying out the experiment so as to get a clean result;

1′) Recycling the procedure, making sub-hypotheses or sequential hypotheses to refine the possibilities that remain; and so on.”1

The advantage of testing a main hypothesis against multiple, alternative hypotheses is that it protects the scientist against what T.C. Chamberlin called over “affection for his intellectual child”:

A Beautiful Hypothesis

Dr Stephen Colbert (Hon DFA) has pointed out, sometimes you have to think with your gut. And evolutionary theory can generate some great gut-worthy hypotheses that simply “feel” right. Here is an example: You all know “Why” the giraffe has a long neck? As long ago as Lamarck, the explanation has been “to get to the top of the acacia tree to reach the tender, most nutritious leaves’” Darwin and Lamarck may have differed in their notion of “How” the giraffe acquired its long neck but they would have agreed that it was advantageous in competing for food. We’ll call this the Interspecific Foraging Competition Hypothesis (IFCH). Soon after Darwin and Wallace proposed Natural Selection theory, the IFCH had become the accepted explanation for the giraffe’s long neck.

Now you have to admit that the IFCH is a beautiful hypothesis. It just feels right (sensu “Truthiness”). It just makes sense. It fits (with Darwinian natural selection).

Why ruin it by testing it?

An Ugly Fact

Why? Because there might be a better explanation. One obvious test of IFCH is to determine how giraffes actually USE their neck? In 1996, Robert Simmons and Lue Scheepers decided to do just that, and in their review of the literature, Simmons and Scheepers found that giraffes don’t use their neck in a way consistent with the IFCH — they tend to spend most of their time foraging at about shoulder height even when food is scarce and competition high. Now you could attempt to “save” the beautiful hypothesis by special pleading, or by suggesting that all of the many studies cited by Simmons and Scheepers “missed” something. Of course, then you would be reduced to simply refuting ugly facts. However, if there were plausible alternative hypotheses, then those could be explored and perhaps we can reject the IFCH without feeling empty-handed. The irony of the story of the giraffe’s long neck is that Darwin had developed another theory (Sexual Selection Theory) that could have been used to generate plausible alternative hypotheses to IFCH (although he didn’t know it at the time, he came close when he recognized that male giraffes use their long necks to swing their heavy skulls and stubby horns as weapons). But the rest of Simmons and Scheepers story will have to wait until next time.

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In the next few months, I plan to discuss other missed opportunities and other ugly facts. I invite you to comment and perhaps suggest your own ugly facts, and/or alternative (beautiful) hypotheses. One difficulty is developing multiple, plausible, alternative hypotheses and this could be a place to air your ideas and perhaps get feedback. Science really is a collaborative effort.

– Tom Nolen, New Paltz, NY

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Citations (Read these before posting comments –start by Googling the authors)

1. Platt, JR (1964). Strong Inference: Certain systematic methods of scientific thinking may produce much more rapid progress than others. SCIENCE 146(3642), pp: 347-353.
2. Pigliucci, M (2009). Strong Inference And The Distinction Between Soft And Hard Science. http://www.scientificblogging.com/rationally_speaking/strong_inference_and_distinction_between_soft_and_hard_science cited on the web, May 31, 2009.
3. Chamberlin, TC, cited in Platt (1964) above.
4. Simmons, R and Scheepers, L (1996). Winning by a neck. Sexual selection in the evolution of giraffe. American Naturalist. 148(5), pp: 771-786.