1) Short Preliminary Project Proposals
Assignment:
Write 6-8 sentences describing your project idea, approach to studying it, and its relation to the themes or general perspective of the class. You are not tied to doing what you propose, but this exercise will help you think through possible projects to find ones that really interest you and to think through how doable and appropriate they are.
Value: 2% of class project grade
Due: Posted to class blog by Tuesday, Oct 9, 9am. Please post your preliminary proposals as comments to this blog entry.
2) Peer review of another’s proposal
Write a short, one paragraph (3-6 sentences) constructive critique on another student’s proposed project.
3) Project proposal
Write a description of your proposed project, including a summary of what you plan to research, how you plan to tackle it, and its general and personal relevance (i.e. why is it interesting or important for you?). Make these no more than 1 page, single spaced, one inch margins. But they can certainly be shorter. We don’t need an extensive list of references, so only include a few if they’ll help us better evaluate your proposal.
Due: E-mailed by Tuesday, Oct 23, 9am
28 comments:
Life History theory has dealt fundamentally with variables that are found mainly in foraging populations, and disregard modern industrial societies. Variables such as overcrowding, pollution, food storage means, as well as the importance of higher education to name a few, all have an impact on life history events. For example, the use of mechanical refrigeration has allowed for milk to be readily available which could change the growth rate and in turn the age of reproduction. I would like to look at certain variables found in a handful of the larger cities of industrialized nations (overcrowding, pollution, specialization?) and compare them to specific life history events, such as age at death, and reproduction rates. I would use a multi-regression model to control for conflicting variables and hope that this could shed some light on how the majority of the world’s population is affected by industrialized society. This type of research could also give governments more information about how their policy affects individuals.
Chen, Hsiu-Ling, et al. "Biochemistry examinations and health disorder evaluation of Taiwanese living near incinerators and with low serum PCDD/Fs levels." Science of the Total Environment 366.2/3 (Aug. 2006): 538-548. Academic Search Complete. EBSCO.
Craig, Lee A., Barry Goodwin,and Thomas Grennes. "The Effect of Mechanical Refrigeration on Nutrition in the United States." Social Science History 28.2 (Summer 2004): 325-336. Academic Search Complete. EBSCO.
Marks, John. "Biopolitics." Theory, Culture & Society 23.2/3 (Mar. 2006): 333-335. Academic Search Complete. EBSCO.
Historically,hominid social groups maintained a solitary existence within prescribed territorial ranges, with interspecific competition occurring occasionally thru chance encounters provoked by resource availability. As recently reviewed by Stiner et al. (1999) population numbers were minimal and highly dispersed throughout the Middle Paleolithic with no visible increase being recorded until the Upper Paleolithic. From this point on adoption of highly mobile subsistence strategies among growing populations served to facilitate diversified and inter
regional social contact, resulting in an explosion in material and social behaviors. Recent anatomical assessments among a wide European population from EUP, LUP & Mesolithic time periods reveal a sudden increase in stature, characterized as 'very tall' for both males and females; followed by a marked decrease in stature during the LUP and Mesolithic. For lack of a better argument the authors target increased nutrition as the ultimate cause. In keeping with recent research on the consequence of changes in body size among species, my paper seeks to explain the unexpected increase in stature this time period displays as the product of social selection, precipitated by competition, and fashioned by an adaptive strategy aimed at achieving or maintaining social dominance.
Fred’s proposal – Does the Grandmother Hypothesis add up?
Back when we were talking about human life histories, I became interested in the grandmother hypothesis. In Hill and Kaplan (1999), they said they had found in the Ache people that reproductive benefits of supporting grandchildren did not outweigh benefits of continuing to reproduce. After some discussion and reading, I heard about the “stopping early” hypothesis, which suggests that mothers may stop reproducing so they can support their pre-reproductive offspring until they reach adulthood. I had an idea of my own I’d like to test: perhaps mothers live longer because they carry genes to delay senescence after reproductive activity has stopped. These genes may allow their sons to live longer, and their sons can keep reproducing until death. If this is the case, sons of women who live longer should have longer life spans and produce more offspring. Together, these three benefits may outweigh the benefits of producing more offspring. In order to test this, I’ll need access to a life history data set with reasonable confidence in paternity. I’ll also need some help with the math involved in determining how great the fitness benefits are, although if there isn’t a correlation between mother and son lifespan than I won’t get to that part of the paper.
How are two islands of very similar proportions, average rainfall and isolation able to have two very distinct human colonization events? How does the size of an island affect the success of its colonists? What role does deforestation of native flora play? Theories abound as to not only the success of Tongans, but also the demise of Easter islanders. For my project, I hope to analyze available geographic, ecological and cultural data from a variety of Polynesian islands in hopes to explain the distribution of humans throughout the Pacific. Understanding the variables that contribute to a successful initial insular colonization will help to explain the observed assemblages throughout time and space, and may also have broad reaching effects to initial mainland colonization and demise (e.g. Chaco Canyon, Fertile Crescent).
Unifying life history models.
Empirically, life history traits covary in very predictable ways. Size, metabolic rate, and lifespan covary positively with each other, and covary negatively with fertility and mortality. Three different sets of theoretical models, all originating from UNM, claim to explain these relationships. While each one appears successful in isolation, it is not yet clear whether and to what degree they are mutually incongruent, redundant, or complementary in combination. I’d like to find out.
Models and arguments by West, Brown, Savage, and others claim that the covariation of life history traits follow from the optimization of the animal’s metabolic network given an exogenous body size. The strength of these arguments is greater for some relationships (e.g. between size and metabolic rate) than others (e.g. between size and mortality).
Optimal life history models by Charnov and by Kaplan and Robson optimize body size and mortality reduction to maximize lifetime fertility, in different ways. The two models realize the costs of mortality reduction in different ways, and Charnov optimizes growth rate, while Kaplan-Robson does not. Charnov explicitly assumes some allometric relationships between variables (e.g. ¾-power scaling of energy available for growth and reproduction) and predicts specific allometric relationships between other variables, whereas Kaplan-Robson assumes only the general sign and curvature of relationships and produce no specific predictions regarding allometric exponents at the optimum.
The conceptual distance is smaller between Charnov and West et al. (because of shared assumptions regarding energy availability and growth) and between Charnov and Kaplan-Robson (because of similar problem-structure) than between West et al. and Kaplan-Robson. So I’d like to begin by addressing the potential for unity (or disunity) across these shorter distances. I might start with Charnov and Kaplan-Robson.
A couple specific questions I’d like to handle: Can Kaplan and Robson’s main result (that increased productivity later in life will lead to an increase in optimal allocation to mortality reduction) be replicated in Charnov’s model? How would the Kaplan-Robson model respond to the endogenization of growth rate? Does Kaplan and Robson’s unique net lifetime budget constraint greatly change the problem?
A couple questions regarding the gap between Charnov and West et al.: West et al. suggests that adult mass is about the same as asymptotic mass, whereas Charnov says that it should be 30% smaller. Is this a problem? How do these different results square with the empirical growth data presented with the West et al. model?
Another possibility for the term paper: We’ve been curious whether Tsimane social networks show the kind of modular self-similarity that Marcus Hamilton suggests is characteristic of most foraging societies. I plan to do these analyses over the next month, and so might present the results in a paper for this class.
Another other possibility: We’ve started looking at how the distribution of wealth changes with the size of a population or economy. Could focus on this for a paper.
For my project, I am looking at the relationship between sexual dimorphism and monogamy. This was first mentioned during discussions of body size variance over time. The theory behind sexual dimorphism indicates that males will be significantly larger than females where sexual competition is necessary; as a result, areas that show high rates of monogamy should lead to smaller variances in height between men and women. My primary question is whether this is actually the case, but more specifically, if it is still evident now. In addition, I would like to see if rates of dimorphism very significantly in countries where nutrition is a concern to see if it changes the overall relationship. Since I cannot find an adequate measure for monogamy, I will be using divorce rates for each country, in addition to height data for each sex.
When do you become adult?
--metabolic life history theory
OGM (West et al., 2001) and Life History Model (LHM) are both mention that the lifetime and body size relationship. They concentrate on different aspect but use the same parameters, time and body size. OGM is a bottom-up model, and LHM is a top-down model. They must have joint. However, how to combine them together is still an unclear issue. Charnov et al. (2007) try to put the metabolic theory and life history theory together to estimate lifetime reproductive effort. They called the method as metabolic life history theory. In metabolic theory, OGM, we always stop as the point when the body size achieves adult body size. And LHM always start at the adult size. Let us look at the adult point. What is more common definition for adult? When do you become adult?
I’m looking into the origin and meaning of life history allometries. On one hand you have the view that such invariants are a meaningful by-product of independent optimizations—fitness maximization. On the other hand, you have Nee et al. (2005) arguing that many of these allometries are meaningless mathematical/statistical artifacts. I will work from the point of view of individual optimizing behavior—what do these allometries require of individual behavior and how do individual life-history trade-offs generate allometries across individuals and species? It may be useful to separate allometries into those generated by invariance in underlying constraints from those driven by convergence in independent maximization of life-history parameters. The ultimate goal is a better understanding of individual (implicit) fitness maximization in a stochastic environment, which might help settle some of the differences between models Paul points to. What, ultimately, are individuals maximizing?
I would like to research the similarities and differences of modern Homo sapiens and Homo Erectus. Particularly looking at the brain size and gut size differences. Using the Aiello and Wheeler "expensive tissue hypothesis", I will actually seek to argue that the larger brain is not the primary advantage Homo sapiens had over Homo erectus.Gut plasticity, I believe is what allowed modern Homo sapiens to exploit a wider range of niches and move from being mainly frugiverous, to eating more animal meat.
Diet has many major impacts on the behavior of humans. It is my suspicion that there is a correlation between proportion of starches used in the diet and the prevalence of warfare in that population. As food resources become more economically defendable we may see an increase in the prevalence of adult death due to violence. However, A correlation may exist because as the pressure to provide meat decreases, the opportunities for males to engage in raiding style warfare may predictably increase. This research will help to provide insight in to the possible causes of violence. Which could have important impacts on the life histories of the people. I will look at several small-scale societies and run multi-variate regressions to control for confounders.
In the Walker et al. (2006) paper, they mention that populations with a high disease load have an increased body size in order to increase immunity and defensive mechanisms against disease. Traditionally in anthropological research, the changes in body size have been related to latitude and changes in temperature, as a means to difuse or conserve heat. Do the global patterns of body size also correlate with the patterns of disease load, in addition to the latitudinal gradients? Is is possible to determine which, disease or temperature/latitude, is the primary causal factor in body size? This paper will address global patterns in human variation and how those patterns relate to ecological variables, specifically temperature and disease load.
I would like to examine using Agent Based Models in studying biogeography, and human biogeography specifically. The main part of my paper/project would be a literature review on what ABMs have been used to study in biogeography, and what success they have had making predictions on the key questions of biogeography. Failing finding any information on ABMs and biogeography I will try to find examples of ABMs use that could be combined with other data in a biogeographical context. I would also like to complete a small ABM or cellular atomata model program after having looked at what the current state of research is in the area. I am hoping that the literature review will be able to give me some guidance into the variables used in ABMs to study human biogeography.
Poulin notes that parasitism is among the most prolific and successful modes of life displayed by living organisms, as measured by how often it evolved and how many parasitic species are presently in existence. A community ecology approach to studying parasite prevalence has been undertaken over the last few decades with spatial analysis characteristics applied more recently, however, questions concerning the relationship between parasites and their hosts still remain. One difficulty is that species diversity may be attributed to the characteristics of the host and/or the parasite. One must consider the life history traits, patterns of dispersal and network interactions between hosts and how this may affect the colonization patterns of parasites.
Janzen noted that the MacArthur-Wilson hypothesis can be applied to other structures and geographic spaces than oceanic islands. Applying their equilibrium biogeography model to human populations (or individuals) could be a step in teasing apart parasite-host dynamics: How does the accidental introduction of parasites between human groups affect the population dynamics of the host and parasite? Does the immigration of new parasite species to a human host lead to the extinction of species already present? How does that affect both populations (humans and parasites)? These are some of the questions I hope to address in the coming weeks/ years.
General intelligence (also called g or g-factor), as measured by IQ scores, has been found to be the most consistently heritable mental trait, with a heritability of around 0.8 (Miller, 2004); this exceeds heritability of physical traits such as height (0.5). A number of researchers have found substantial biogeographic variance in g across nations and continents, with the highest median IQ scores in modern, industrialized countries with good nutrition and healthcare, and the lowest median IQs in the developing world, particularly sub-Saharan Africa. Some intelligence researchers (e.g. Kanazawa) hypothesize that g is only one kind of intelligence (a domain-specific adaptation), which evolved to help humans deal with ecological and technological novelty. Thus, according to domain-specific hypotheses, g should be lowest where conditions are most similar to the human EEA (i.e. sub-Saharan Africa), and should increase with exposure, over several generations, to modern technology (this is known as the Flinn effect, after the researcher who first identified it). Others (usu. those who view g as a domain-general adaptation) explain the geographic variation in IQ as a consequence of parasite/disease load. The higher the parasite/disease load, the more energy must be devoted to physical maintenance, reducing the energy available for growing a large, complex brain (absolute brain size has been found to correlate c. 0.4 with general intelligence, controlling for sexual dimorphism). While either of these hypotheses would explain the observed geographic variation in intelligence, it is likely that only one of them is correct, as they depend on very different constructs of intelligence (several domain-specific intelligences vs. a single domain-general intelligence). Which hypothesis is borne out by the evidence?
Caveat: Intelligence tests were created in the 20th century by technologically modern European and North American societies, and may not be very accurate at measuring intelligence in traditional hunter/gatherer and pastoralist societies. Are IQ tests so inherently culturally biased that comparisons of this kind are impossible, at least with the tests we currently employ? (I am aware of the potential for misguided, racist interpretations of this type of research, but think it is possible to steer clear of them.)
Dan,
Can you be more specific about the predictions of your hypothesis? Do you expect less or more starch in the diet to be correlated with increased violence? What does proportion of starch indicate, a better or worse diet? How do you intend to measure dependence on meat? I like your idea overall, but I want to hear more specifics.
Senorita; You have an interesting topic, and here is a suggestion for another perspective. I would think that gut plasticity is controlled by subsistence strategies. In other words, proximately, what you eat determines what you are, but ultimately, for higher organisms,how you go about obtaining food determines what you eat. For instance, it has been suggested that brain size developed in response to social complexity, so the edge one social species holds over another must (might) rest on organizational efficiency, which in turn establishes strategies for what you eat.
Deepta,
I think taht your question is a good one, in terms of how nutrition may also play a role into the amount of sexual dimorphism found within a group. You mentioned using divorce rates as a measure of monogamy; do you plan on limiting your study to areas recording divorce and consequently marriage rates? What about societies where marriage or divorce is not allowed or common? It would be interesting to include infidelity rates into your paper in terms of areas where divorce is not common or permissible, if possible, to determine if that would change the patterns at all.
Peer View for Paul’s “Unifying life history models”:
I like this ideal very much. I believe that those two models have connection. Within those two classical models, however, there are several parameters share the same name but different definitions, such as adult size. I would like to suggest that unify those parameters first. Make sure whenever we talk about adult size, it means the same thing in both models. It will be the first step to connect those two models. You question about the adult mass between West et al. (the same as asymptotic mass) and Charnov (30% smaller) should, somehow, come from the meaning difference. Will or should organisms stop growth first then reproduce?
Fred:
I like your topic as I have always been curious about the grandmother hypothesis, but I’m now more curious about your idea. It sounds a bit like the antagonistic pleiotropy hypothesis with a LHT twist. I was wondering what impact those genes would have on the daughters. Also, what are some reasons that the two might not correlate?
Dtinucci,
While I like the “out-of-box” approach to such a phenomenon, I would make sure not to entirely discount the nutrition hypothesis. There is a large body of stature research of elites vs. laypeople, famines, etc. that all point to a nutritional element. More along the lines of your proposed research, in order for there to be an increase of stature in such a short period as a result of selection, there must be a very heavy negative selection against shorter individuals. You could make an argument for the this sort of selection through a variety of vectors; however, if these processes contributed to such a rapid increase in species wide stature, processes equally as powerful must contribute to later reducing stature. Lastly, consider (but please don’t dwell on) the Osteological Paradox as a potential caveat to the whole deal.
Fred,
I’m not quite sure I understand your topic. Are you indicating that women live beyond their reproductive capabilities to ensure the reproductive success of their sons? I don’t see how the two are related. If the women are carrying the genes to delay senescence, this may not have much effect on the sons. If it is simply reproductive success you are looking at, having a grandmother around may be as useful for the women, possibly more so, than for the men. Particularly in hunter-gatherer societies, this means one more person who can assist with the care for the children and take over the gathering duties for women who may be unable to work for a time. Another point to consider is that women who are living beyond menopause are using up resources that could go to their offspring, so there is the possibility of canceling out some of the benefit. Lastly, I didn’t understand how you plan to go about testing your theory, can you give some more detail?
Wenyun,
I like the idea for your paper, I think that your question of when do humans become adult is very important to both life history and OGM. What data will you use to determine this point? You could look at average age of reproduction as one indicator. You might look at social aspects as well; when are men considered to be an adult in their society. If this age is constant across societies it might be a good indicator of the adult age. Of course you would have to look at the prevailing literature in both LHT and OGM to see what the adult age is considered to be in both of them. It would be interesting to use several methods to determine an adult age and see if they generate the same answer.
Aaron,
I think your idea is really interesting but I see why you think this issue has many caveats. First, it is very difficult to characterize the Flynn effect and the casual mechanism behind increased scores is still greatly debated (nutrition hypothesis, your mention of western tech, etc.).
I was a little confused by the description of fluid intelligence and domain specific intelligence. It might be easier to refer to them as Gf and Gc. Much of the literature now refers to them and fluid and crystallized intelligence, which is culturally specific. There is also a great deal of debate as to whether measuring fluid with tools designed in the western world are even measuring anything meaningful.
(Adrilla et al's paper show huge gaps in understanding on how the tests are used).
Finally, in terms of heritability, one must consider that if you have high heritability you might also have high variation.
It's a great idea. Good Luck!
Hi Wenyun,
Looks great.
So first, I am curious to know more about the 'metabolic life history theory' of Charnov et al. (2007). I haven't seen it yet and am very interested in what it says!
Do you feel like this 2007 paper succeeds in combining the OGM and LHM? Is there difficulties with it, either on its own or in comparison with the earlier models?
I don't think it's true that the life history models (e.g. Charnov 1993, 2001) 'start at the adult size'... unless I'm not understanding what you mean. These models try to solve for optimal growth/maintenance/reproduction behavior from conception (or weaning) on out through the rest of life. They *do* certainly assume that growth and reproduction do not overlap; that may be what you mean.
In response to your related comment on my proposal: You ask, "will or should organisms stop growth first then reproduce?" I think it is true that for determinate growers, both the OGM and LHMs simply assume that growth and reproduction do not overlap. Do you think we should consider a model in which they do overlap for determinate growers? Now, when the OGM addresses indeterminate growers, it assumes that growth and reproduction do indeed overlap. But you're thinking of doing something different, right?
What method are you thinking of using to answer the question "When do you become an adult"? Do you want to come to a consensus theoretical definition of adulthood by comparing the various models? Or do you plan to make inferences from data about what organisms actually do?
hey dan, great topic, one i've played with a little bit too. we should chat about it. what data are you thinking of?
Hey Dan and Oskar,
Here's my paper using the SCCS: polygyny.pdf. See especially section 3 of the analysis section ("Violent conflict and polygyny") and tables 12 through 16 (pages 21 through 27).
To summarize. (1) Conflict and polygyny are positively associated, in different ways depending on the subsistence type. (2) In foragers and horticulturalists, reliance on hunting looks negatively associated with conflict. (3) Greater male contribution to subsistence is negatively associated with conflict. As you'll see, these conclusions aren't too strong, and may or may not be true when you control for other variables.
and dan (another post?!),
the other resource besides the SCCS is HRAF (human relations area files). this might ultimately be better. i don't know if our library has the right subscriptions for it, but check it out.
Thanks a ton Paul,
I'll check it all out.
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