Is autism more common in Silicon Valley?A new study from Simon Baron-Cohen and colleagues asked pretty much this question, although rather than California, they looked at Eindhoven in Holland. Eindhoven is the tech hub of the Netherlands:This region contains the Eindhoven University of Technology, as well as the High Tech Campus Eindhoven, where IT and technology companies such as Philips, ASML, IBM and ATOS Origin are based... 30% of jobs in Eindhoven are now in technology or ICT, in Haarlem and Utrecht this is, respectively, 16 and 17%The authors found that official rates of diagnosed autism amongst children enrolled in Eindhoven schools were more than twice as high as those in kids from the comparison cities of Haarlem and Utrecht. In Eindhoven, rates of any autism spectrum disorder were 2.3%, far higher than rates elsewhere (0.6-0.8%).Narrowly defined "classical autism" was also higher. However, two control disorders, dyspraxia and ADHD, were no different.A diagnosed autism prevalence of 2.3% is extremely high. Some recent studies have found similar figures when you actually go out and attempt to find undiagnosed cases and diagnose them. But for 2.3% of kids to already have a diagnosis, is remarkable.Unfortunately, there's a big problem here, which is that this study has a sample size is 3. There were lots of data from each city: in total, 369 schools took part, with over 60,000 kids. But there were only three independent cities.So while these data convincingly show that Eindhoven has higher rates of autism than the other two regions, this might just mean, say, that half of Dutch cities have local educational systems that promote diagnosis, and Eindhoven happens to be one of them.To really answer the question of whether I.T. folk have more autism, you'd need to look at Silicon Valleys around the world, to increase your sample size.I'd be surprised if there weren't a link. Autism is highly heritable and we know that the children of people with autism, or mild autistic traits, have a higher rate. I don't think it's too controversial to say that the average programmer has above-average autistic traits, and it's quite possible that a little autism is a positive advantage in IT professions.This is certainly Baron-Cohen's hypothesis, as he's long argued that people with autism have a tendency to be strong "systematizers":This striking difference in the prevalence of ASC is in line with the hyper-systemizing theory, and will require the phase two study using diagnostic assessments and screening methods, to determine the exact nature of regional differences in population prevalence. Future research should test if this higher prevalence in a high tech region is found in other cultures (e.g., in Silicon Valley, California)...Roelfsema MT, Hoekstra RA, Allison C, Wheelwright S, Brayne C, Matthews FE, & Baron-Cohen S (2011). Are Autism Spectrum Conditions More Prevalent in an Information-Technology Region? A School-Based Study of Three Regions in the Netherlands. Journal of autism and developmental disorders PMID: 21681590... Read more »
Roelfsema MT, Hoekstra RA, Allison C, Wheelwright S, Brayne C, Matthews FE, & Baron-Cohen S. (2011) Are Autism Spectrum Conditions More Prevalent in an Information-Technology Region? A School-Based Study of Three Regions in the Netherlands. Journal of autism and developmental disorders. PMID: 21681590
Pottery is the most important type of artifact for archaeology in the Southwest. This is because the agricultural societies of the prehistoric Southwest made huge numbers of pots and often decorated them in distinctive ways that differed both from place to place and over time, often within quite short periods. With the precision available from [...]... Read more »
We usually think of farmers as sturdy, Midwestern types who raise their ruddy-cheeked children on a balanced diet of eggs, potatoes, and chores. A study from researchers at Emory University, though, suggests that our farming ancestors weren't the picture of health. When humans transitioned from hunting and gathering to farming and living in cities, the authors say, they became malnourished and more prone to disease. Oh, and they were shorter.Scientists use height as a rough yardstick of a population's health and nutrition. As an individual, your potential height comes from your parents' genes. But whether you reach that potential has to do with how healthy you are as a child--are you getting the right nutrients? Fighting diseases? And the average height of a population tells scientists roughly how healthy that population is. The tallest people on Earth today live in the Netherlands.To assess the health of various prehistoric populations, the Emory researchers pooled data from several previous studies of ancient bones, then examined how people's heights changed as their populations transitioned to agriculture. Farming first appeared around 10,000 years ago in the Middle East, then spread around the globe, sometimes cropping up (ahem) independently. The populations included in this study ranged from 9,000-year-old Chinese to North Americans from within the past thousand years.In general, the authors say, populations tended to get shorter as they transitioned from hunting and gathering to agriculture. Some bones provided evidence of malnutrition, anemia, and poor dental health. Why would farming make people sick? For one thing, relying on a smaller variety of food sources could lead to malnutrition, if crucial nutrients were missing from a farmed diet. Food supply depended on the seasons, and groups had to store enough food to last through the winter. A drought or infestation meant that the whole community went hungry. And since people were living in bigger, denser communities, infectious diseases could spread more easily.The researchers acknowledge that several studies within the larger group they looked at did not find a short-farmer effect. Those studies found that height stayed the same, or even increased, when populations made the move to agriculture. The effect may have depended on the resources available in an area; maybe populations that could grow a greater variety of foods avoided a health decline. In some areas, height initially decreased but then increased over subsequent generations.If farming were really a worse survival strategy than hunting and gathering, it couldn't have persisted. Rogue groups of humans who lived outside of the community and gathered their own food would have outcompeted their city-dwelling, farmer neighbors. Instead, farming became the norm. So this lifestyle--organizing ourselves into communities, sharing resources, dividing labor, domesticating crops and animals--must have provided a net gain in our well-being. Even if it initially made us a little more sickly, it allowed our populations to grow and spread.You might interpret these findings as evidence that you should take up a "caveman diet." If so, there are plenty of books and websites out there to help you; they generally recommend starving yourself and eating a lot of nuts and meat. I'd recommend looking into local hunting laws before you start shooting your own squirrels and pigeons. (Of course, if you're on a true caveman diet, shooting is cheating.) This book even comes with a measurement conversion table, in case you're not sure how many ounces are in a skull cup.Farming may be a relatively new development in human history, but that doesn't mean we're not built for it. For example, if your ancestors came from a dairying culture such as in northern Europe or eastern Africa, you probably drink milk and eat ice cream with no problem. This isn't the caveman way. For our ancient ancestors--as it is for humans in most parts of the world today--the enzyme that breaks down the sugar in milk (lactose is the sugar, lactase is the enzyme) faded away as humans grew out of early childhood. But the tendency to hang on to lactase has evolved at least twice since we started keeping dairy animals. Drinking a domestic animal's milk must have given these populations a serious evolutionary advantage in order for the lactase-keeping trait to spread so well. So is it "unnatural" to drink milk as an adult? My genes say no, though yours might say something different. It's not the caveman way. But we're not cavemen anymore; we're farmers.Mummert, A., Esche, E., Robinson, J., & Armelagos, G. (2011). Stature and robusticity during the agricultural transition: Evidence from the bioarchaeological record Economics & Human Biology, 9 (3), 284-301 DOI: 10.1016/j.ehb.2011.03.004... Read more »
Mummert, A., Esche, E., Robinson, J., & Armelagos, G. (2011) Stature and robusticity during the agricultural transition: Evidence from the bioarchaeological record. Economics , 9(3), 284-301. DOI: 10.1016/j.ehb.2011.03.004
Our contributor in Karachi, Md. Ali Khan, has alerted me to what seems to be a fascinating book: The Tyranny of Language in Education by Zubeida Mustafa published by Ushba Books. I’d love to read the book but trying to … Continue reading →... Read more »
Han, Huamei. (2011) Social inclusion through multilingual ideologies, policies and practices: a case study of a minority church. International Journal of Bilingual Education and Bilingualism, 14(4), 383-398. info:/
Southwestern archaeology, especially in the Chaco area, is structured chronologically primarily by the Pecos Classification. This system was initially worked out at the first Pecos Conference in 1927, and it was originally interpreted as a series of stages in cultural development, with the assumption that sites with similar characteristics and material culture were roughly contemporaneous. [...]... Read more »
Potter, J. (1997) Communal Ritual and Faunal Remains: An Example from the Dolores Anasazi. Journal of Field Archaeology, 24(3), 353. DOI: 10.2307/530690
Schachner, G. (2001) Ritual Control and Transformation in Middle-Range Societies: An Example from the American Southwest. Journal of Anthropological Archaeology, 168-194. DOI: 10.1006/jaar.2001.0379
The journal Applied Geography and the journal Land Use Policy have recently published two papers, “Spatiotemporal modeling of the expansion of mechanized agriculture in the Bolivian lowland forests” and “Deforestation dynamics and policy changes in Bolivia’s post-neoliberal era” respectively, that depict a desolating panorama. The rate of deforestation under Evo Morales’ government is even higher than it was during the previous governments. Muller et al. say that “While overall dynamics remained relatively stable over time, the expansion of mechanized agriculture between 2001 and 2005 became more tolerant to excessive rainfall and less dependent on fertile soils. This mirrors the increasing penetration of mechanized agriculture into humid and less fertile Amazonian rainforests in the northern portion of the study area [Santa Cruz]. The map of deforestation probability substantiates these patterns and shows the highest propensities for future deforestation in the north”, while Redo et al. point out that: “Although neoliberal policies triggered an unprecedented level of forest clearing in Bolivia, rates have generally continued to increase and can be indirectly linked to the administration’s new agrarian reform and pro-environmental regulations”. The “pro-environmental” regulations of Morales’ government have actually increased deforestation rates!The Northern Bolivian lowlands are not only an extremely important reservoir of biodiversity and home of many indigenous communities; they also hold an impressive amount of archaeological sites, most of which have never been studied or surveyed. As deforestation for industrial soybean production is moving northward, it now starts to affect the Llanos de Moxos, where most of these archaeological sites are found. Soy producers cut down the trees using bulldozers, and, in this way, they also destroy all the archaeological sites they encounter on the way. In the eastern Llanos de Moxos, in a stripe of forest called Monte San Pablo, between the River Cocharca and the River San Pablo (Fig. 1), Bolivian Mennonites are bulldozing pre-Columbian human-made earth mounds, which hold valuable remains and information about past Amazonian cultures. The destruction of pre-Columbian archaeological sites in the Bolivian Amazon is taking place while national and local governments look another way, and regrettably, with the complicity of some of the indigenous leaders who live in the area. Figure SEQ Figure \* ARABIC 1 Shaded areas are forests. Continuous line indicates the area of pre-Columbian monumental mounds. Monte San Pablo is east of the area (dashed lines) shown in Fig.2. (Lombardo and Prümers, 2010)Figure 2. Modis Image taken a few days ago. The yellow stripes highlighted by the arrow are the portions of Monte San Pablo that have already been cleared for soybean production. The deforested area is already larger than 10.000 hectaresI have surveyed more than one hundred pre-Columbian monumental mounds and hundreds of Km of pre-Columbian canals and causeways in the area east of Trinidad, in the Beni (see map in fig.3). The monumental mounds are huge earthworks (the average mound covers 5 hectares and is 9 meters high) entirely human made, built from 400 AD to 1500 AD. They are full of pottery and burials and only very few of them have been excavated by archaeologists. The Monte San Pablo, just east of the area I surveyed, is full of monumental mounds. Those are the mounds that are being destroyed by the Mennonite bulldozers to make room for soybeans.... Read more »
Daniel Redo, Andrew C. Millington, & Derrick Hindery. (2011) Deforestation dynamics and policy changes in Bolivia’s post-neoliberal era. Land Use Policy. info:/10.1016/j.landusepol.2010.06.004
Robert Müller, Daniel Müller, Florian Schierhorn, & Gerhard Gerold. (2011) Spatiotemporal modeling of the expansion of mechanized agriculture in the Bolivian lowland forests. Applied Geography. info:/10.1016/j.apgeog.2010.11.018
Umberto Lombardo, & Heiko Prümers. (2010) Pre-Columbian human occupation patterns in the eastern plains of the Llanos de Moxos, Bolivian Amazonia. Journal of Archaeological Science. DOI: 10.1016/j.jas.2010.02.011
Everyone knows the experience: you happen upon a wreck and know you shouldn’t look but can’t help it. You know there is a chance of seeing something you don’t want to see and which may haunt you, but you look regardless. There should be a word for this and in the absence of one, I [...]... Read more »
Reser, Jared E. (2011) Conceptualizing the Autism Spectrum in Terms of Natural Selection and Behavioral Ecology: The Solitary Forager Hypothesis. Evolutionary Psychology, 9(2), 207-238. info:/
The first in a series on hormonal contraception. This post explores why human women menstruate and how that may impact their contraceptive decisions.... Read more »
Jasienska, G., & Thune, I. (2001) Research pointers: Lifestyle, hormones, and risk of breast cancer. BMJ, 322(7286), 586-587. DOI: 10.1136/bmj.322.7286.586
Strassmann, B. (1997) The Biology of Menstruation in Homo Sapiens: Total Lifetime Menses, Fecundity, and Nonsynchrony in a Natural-Fertility Population. Current Anthropology, 38(1), 123. DOI: 10.1086/204592
Vitzthum VJ, Spielvogel H, Caceres E, & Miller A. (2001) Vaginal bleeding patterns among rural highland Bolivian women: relationship to fecundity and fetal loss. Contraception, 64(5), 319-25. PMID: 11777494
Vitzthum VJ, & Ringheim K. (2005) Hormonal contraception and physiology: a research-based theory of discontinuation due to side effects. Studies in family planning, 36(1), 13-32. PMID: 15828522
Last year, I discussed the controvery over the proposed new childhood syndrome of "Temper Disregulation Disorder with Dysphoria" (TDDD). It may be included in the upcoming revision of the psychiatric bible, DSM-V.Back then, I said:TDDD has been proposed in order to reduce the number of children being diagnosed with pediatric bipolar disorder... many people agree that pediatric bipolar is being over-diagnosed.So we can all sympathize with the sentiment behind TDDD - but this is fighting fire with fire. Is the only way to stop kids getting one diagnosis, to give them another one? Should we really be creating diagnoses for more or less "strategic" purposes? Now, a bunch of psychiatrists have written to the Journal of Clinical Psychiatry to express their concerns over the proposed diagnosis. They make the same point that I did:We believe that the creation of a new, unsubstantiated diagnosis in order to prevent misapplication of a different diagnosis is misguided and a step backward for the progression of psychiatry as a rational scientific discipline.Although they go into much more detail in critiquing the evidence held up in favor of the idea of TDDD. They also point out that it is rather optimistic to think, as some people apparantly do, that if we were to diagnose kids with TDDD, as opposed to childhood bipolar, we'd save them from getting nasty bipolar medications.As they say, the risk is that drug companies would just get their drugs licensed to treat TDDD instead. Same drugs, different label. It would be fairly easy: just for starters, there are plenty of sedative drugs, such as atypical antipsychotics, which would certainly alter or mask the "symptoms" of TDDD, in the short term. Doing a clinical trial and showing that these drugs "work" would be easy. It wouldn't mean they actually worked, or that TDDD actually existed.They also point out that the public perception of child psychiatry has already been harmed by the proposal of TDDD, and would suffer further if it were to become official.Well, of course it would, and quite rightly so. That would be a sign that child psychiatry is so out of control that, literally, the only way it can stop diagnosing children, is to diagnose them with something else!The same issue of the the same journal features another paper, claiming that "pediatric bipolar disorder" has a prevalence rate of 1.8%, and that rates of diagnosis of childhood bipolar are not higher in the USA than elsewhere, contrary to popular belief based on evidence.Their data are a bunch of epidemiological studies on bipolar disorder. One of which included children up to the age of...21. The majority included kids of 17 or 18.So, er, not children at all, then.The older the "children" in the study, the more bipolar that study found. Everyone knows that bipolar disorder typically starts in late adolescence. That's the orthodoxy and it has been seen Kraepelin. It's right there at the top of the Wikipedia page. That's not pediatric bipolar, that's just normal bipolar.All the recent controversy is about bipolar in children. As in, like, 8 year olds. Yet this paper is still titled "Meta-analysis of epidemiologic studies of pediatric bipolar disorder". The senior author on this paper also signed the paper criticizing TDDD.This, then, is the state of the debate over the future of our children.P.S. I've just noticed that in the latest draft of DSM-V, TDDD has been renamed. It's now called "DMDD". What's next? DUDD? DEDD? P-DIDDY ?Axelson DA, Birmaher B, Findling RL, Fristad MA, Kowatch RA, Youngstrom EA, Arnold EL, Goldstein BI, Goldstein TR, Chang KD, Delbello MP, Ryan ND, & Diler RS (2011). Concerns regarding the inclusion of temper dysregulation disorder with dysphoria in the DSM-V The Journal of clinical psychiatry PMID: 21672494Van Meter AR, Moreira AL, & Youngstrom EA (2011). Meta-analysis of epidemiologic studies of pediatric bipolar disorder. The Journal of clinical psychiatry PMID: 21672501... Read more »
Van Meter AR, Moreira AL, & Youngstrom EA. (2011) Meta-analysis of epidemiologic studies of pediatric bipolar disorder. The Journal of clinical psychiatry. PMID: 21672501
Axelson DA, Birmaher B, Findling RL, Fristad MA, Kowatch RA, Youngstrom EA, Arnold EL, Goldstein BI, Goldstein TR, Chang KD.... (2011) Concerns regarding the inclusion of temper dysregulation disorder with dysphoria in the DSM-V. The Journal of clinical psychiatry. PMID: 21672494
I mentioned earlier that there was a new paper out on chocolate at Chaco that I needed to read. I read it today, and it’s quite interesting. One of the most interesting things about it is that it’s by a different group of researchers than the first one and uses somewhat different methods. As far [...]... Read more »
Washburn, D., Washburn, W., & Shipkova, P. (2011) The prehistoric drug trade: widespread consumption of cacao in Ancestral Pueblo and Hohokam communities in the American Southwest. Journal of Archaeological Science, 38(7), 1634-1640. DOI: 10.1016/j.jas.2011.02.029
What does it mean to be monogamous?Sexual exclusivity between two partners?
A two-party partnership, characterized by cooperation where resources are shared and children are produced?
A genetic commitment to producing offspring with a single partner?
A social system in which only two people are contracted to marriage at a time?
Or is it perhaps some combination of these four?
For some people, establishing yourself in an exclusively committed relationship where you wake up next to the same person day after day is the realization of a major social milestone. For others, it sounds like a prison sentence. Monogamy is a great socially sanctioning agent: it awards status, recognition, and offers commentary on one’s character. It’s a marker of adulthood and maturity. But as countless people—from celebrities to our neighbors—have demonstrated, it’s not for everyone.
The societal definition of monogamy tends to equate it to monogamous marriage, creating a rigid view of coupling. However, this perspective overlooks the variations that may exist in this state. You may certainly have a single spouse or mate over a lifetime with whom you share resources and appear to be socially and sexually committed, or you may have a series of sequential mates with whom you are exclusive. It’s estimated that only about 3% of mammals are monogamous—specifically meaning that they are sexually exclusive (1). Among primates specifically, about 10-15% have traditionally been categorized as monogamous. However, anthropologist Agustin Fuentes (1999) proposed revisions to the concept of primate monogamy that suggests only 3% of primate groups may be considered monogamous (2). He argues that as a social system, the term generates far too much ambiguity, and its standards are exacting. He relegates the social connotations of monogamy to pair-bonding, a term that has become widely accepted with reference to an exclusive relationship between partners. Monogamy, as defined by Fuentes is solely:A prolonged association and essentially exclusive mating relationship between one male and one female (3).As a social system, monogamy appears to place a great deal of stress on the individual. Why have we adhered so closely to social definitions of monogamy? Does the growing awareness of infidelity in the larger public indicate a potential shift in our acceptance of variations in previously defined monogamous relationships?
It’s Time to “Settle Down”
For the purposes of today’s discussion, we’ll use the social/systemic definitions of monogamy that moves it beyond just sexual exclusivity, with the understanding that there is a fair amount of fluidity in how monogamy may be defined by individuals. For example, an unmarried cohabiting couple may be monogamous, or a childless, unmarried pair who have been dating exclusively for some time may be monogamous, or you may choose to date only one person at a time—which are all examples of monogamy: a long-term partnership entered into by two adults where resources are shared to a mutual benefit, with or without the presence of children.
There are many examples in the natural world of multiple mate preferences, and examples within human society of polygamous social customs. So where did monogamy come from?
One popular theory about the evolutionary roots of monogamy traces this social arrangement back to parental care and the survival of offspring (4, 5). Human offspring remain in a dependent phase for an extended period of time, requiring parental involvement to ensure survival. There are other benefits to parental involvement: with both parties invested in the care of the offspring, the interbirth period can be shorter. That is, humans can wean their children much sooner than other primates, and can care for multiple dependents simultaneously. But parental involvement requires much from the parents themselves—they need to produce resources for their children, sometimes to the detriment of their own needs. Paternity certainty encourages male involvement in the rearing of children: In mating systems in which only one male mates with several females, as in gorillas, paternity certainty is close to 100%, but any investment the male might provide will be divided among many offspring. Socially monogamous mating systems, in contrast, serve to increase a male’s paternity certainty, even when there is some level of sexual infidelity, while concentrating his parental efforts on fewer offspring (6).Thus, adult pair bonding that results in birthing and raising children may be an exaptation—”a system that originally evolved for one reason [protection and care of offspring], but comes to serve another” [establishment of a social system] (7, 8).
For these sorts of relationship arrangements to persist beyond infant care suggests that there may be other rewards, as well— it is possible that participation in particular relationship arrangements may result in specific, pleasurable neurochemical events. Studies conducted on voles, which display a variety of life strategies and social behaviors—apparently, they’re quite complex rodents—demonstrate that pair bonding may be regulated by the release of certain neurochemicals. For example, when male voles are exposed to female voles, vasopressin, which influences behavior and cognition, is released in the region of the brain related to sexual dimorphism, allowing them to recognize potential mates (9). In female voles, it is believed that oxytocin—the widely recognized feel-good hormone—performs a similar function (10). Oxytocin has been widely linked to maternal bonds, but vole behavior suggests that one possible reason for the persistence of monogamy may be that both partners transfer the effects of oxytocin from the parent-child bond to the pair bond itself.
In human societies, monogamy has come to carry with it a certain degree of status. Dubbed the Ideology of Marriage and Family by researchers, American definitions of success have been long linked to marriage and children:With so many of life’s rewards presumably located in coupling, parenting, and nuclear family, Americans look ever more intently in those directions. Couples expect to find happiness and meaningfulness in each other and in their children. They invest their time, attention, emotions, and resources in their own marriage and family to an extent probably unprecedented in the nation’s history. Sources of joy, identity, and meaning that once loomed large in people’s lives—such as friends, community, and kin, as well as passion in the purcuit of great casuses—are now mostly asides (e.g., we’re “just” friends) or quaint bits of nostalgia (e.g., those of 1960s flower children). Even work, long a central domain for men, is now sometimes described as if it were of little significance relative to marriage and family, regardless of the place it actually has in [people’s] lives (11).“Settling down,” for whatever reason, signifies for many happiness, less loneliness, maturity, meaning, and completeness. Researchers propose that relationship status can be informative about reproductive potential—if you’ve been in a long-term committed relationship, then others view you as having reproductive potential (12). It is a commentary on your mate quality:In an environment in which unpa... Read more »
If you have ever suffered through an episode of “Ancient Aliens” on the History Channel, you might believe that every megalithic structure in the world was constructed by extraterrestrials:
Apparently inspired by the show, one credulous soul posted this question over at Answers.com: “Can scientists prove that Stonehenge was not built by ancient astronauts?” The pithy [...]... Read more »
Two articles published last month in the American Journal of Physical Anthropology are starting to greatly complicate bioarchaeologists' use and interpretation of stable oxygen isotope ratios in an attempt to understand migration and mobility in the past. Science is constantly progressing, and it can be challenging to keep up with the latest research. The real challenge for me, though, is in interpreting the isotope analyses I have done on populations from Imperial Rome - first because only one other oxygen isotope study has been done in the entire Italian peninsula, and second because the ancient Romans were quite unlike other archaeological populations in their mobility and importation of food and water. This post, then, works through some of the ideas I laid out in my dissertation and adds to them in light of recent articles on oxygen isotope analysis.
Oxygen Isotope Redux
Studying the relative amounts of stable oxygen isotopes in organic material seems to have begun with palaeoclimate studies, as oxygen isotopes are related to various climatological factors that affect the elemental composition of water. The relative amounts of oxygen isotopes of both meteoric (rain, snow) and environmental water (rivers, springs, lakes) vary by region in relation to factors such as temperature, humidity, distance from the coast, latitude, rainfall, and elevation. This means that different water sources in different areas have different ratios of stable oxygen isotopes.
Graph showing variations in oxygen and hydrogen isotopes
(credit: fig. 6 from the SAHRA website)
The mammalian body needs oxygen to survive - not just in the form of air (inspired oxygen) but also in the form of water and food. Researchers became interested in looking at the amount of oxygen trapped in mammalian tissue decades ago and began measuring the abundance of two different isotopes of oxygen: 18O and 16O. The ratio between these two measurements - written as δ18O ‰ (per mil) - results from fractionation of the two isotopes, which is caused by different metabolic processes.
Starting in the 1990s, though, bioarchaeologists began studying stable oxygen isotopes in order to investigate ancient migration. If the majority of the oxygen that a person ingested or inspired while his teeth were forming came from local water sources, the measured δ18O value from his hard tissue would be characteristic of the geographical peculiarities of that water, taking into account metabolic fractionation processes. It should be possible, then, to use δ18O numbers to identify individuals who accessed either local or nonlocal water sources and, by inference, locals and immigrants. In the early 2000s, oxygen isotope analysis became widely used in answering questions about past human mobility, including identifying immigrants and pinpointing their geographical homelands.
Problems with Finding Immigrants' Homelands
Within the past decade, though, researchers have learned much more about oxygen isotope ratios, including the metabolic processes that affect fractionation. In fact, two articles published online on May 3 by the American Journal of Physical Anthropology demonstrate just how complicated it can be to interpret oxygen isotope ratios from past human populations - a topic that I've been thinking about a lot lately as I try to publish my own oxygen data from Imperial Rome.
δ18Ow contour lines in Italy
(credit: Longinelli & Selmo 2003)
Pollard, Pellegrini, and Lee-Thorpe (in press) are the first to put into print the issues with assigning a geographical homeland to immigrants identified through oxygen isotope analysis in their paper, "Some observations on the conversion of dental enamel δ18Op values to δ18Ow to determine human mobility." In essence, those of us working with oxygen isotopes have been attempting to relate our human dental enamel oxygen measurements to measurements of oxygen from groundwater, using one or more linear regression equations. These equations helpfully give us numbers that seem to put our interpretations of homeland on solid footing. Pollard and colleagues, however, do the math and show that the magnitude of the error introduced with the regression equation(s) means our approximations of immigrants' homelands based on the oxygen isotope ratio of local groundwater are really quite poor. They suggest instead that oxygen ratios derived from human enamel be compared directly to other human enamel samples.
Sickle Cell Disease Affects Oxygen Isotopes
Reitsema and Crews (2011) throw another wrench into oxygen isotope analysis with their paper, "Oxygen isotopes as a biomarker for sickle-cell disease?" Oxygen isotope fractionation results from various metabolic processes, as I mentioned above. In humans, differing oxygen isotope ratios can result from smoking, exercise, and disease. For example, there is increased fractionation in smokers, due to the compromised ability to diffuse oxygen through the pulmonary membranes. Conversely, people who engage in routine exercise appear to have a decrease in fractionation because of the increased rate of respiration. It has also been established that oxygen isotope fractionation is lower in people suffering from anemia, as the binding of oxygen to hemoglobin is a fractioning process.
Because of these known fractionation effects, Reitsema and Crews hypothesized that the bone tissue of an organism with sickle-cell disease would have a different oxygen isotope ratio than a healthy organism. They studied bone apatite from 24 mice - 8 control and 16 transgenic mice with human ... Read more »
Bianucci, R., Mattutino, G., Lallo, R., Charlier, P., Jouin-Spriet, H., Peluso, A., Higham, T., Torre, C., & Rabino Massa, E. (2008) Immunological evidence of Plasmodium falciparum infection in an Egyptian child mummy from the Early Dynastic Period. Journal of Archaeological Science, 35(7), 1880-1885. DOI: 10.1016/j.jas.2007.11.019
Pollard AM, Pellegrini M, & Lee-Thorp JA. (2011) Technical note: Some observations on the conversion of dental enamel δ(18) o(p) values to δ(18) o(w) to determine human mobility. American journal of physical anthropology. PMID: 21541927
Prowse TL, Schwarcz HP, Garnsey P, Knyf M, Macchiarelli R, & Bondioli L. (2007) Isotopic evidence for age-related immigration to imperial Rome. American Journal of Physical Anthropology, 132(4), 510-9. PMID: 17205550
Reitsema LJ, & Crews DE. (2011) Brief communication: Oxygen isotopes as a biomarker for sickle-cell disease? Results from transgenic mice expressing human hemoglobin S genes. American journal of physical anthropology. PMID: 21541922
Recent excavations in a sewer at Herculaneum uncovered a massive deposit of, well, poop. What can feces tell us about the ancient Romans' diet, diseases, and medicine?... Read more »
S.C. Bisel. (1988) Nutrition in first-century Herculaneum. Anthropologie, 26(1), 61-66. info:/
Capasso L. (2002) Bacteria in two-millennia-old cheese, and related epizoonoses in Roman populations. The Journal of infection, 45(2), 122-7. PMID: 12217720
Capasso, L. (2007) Infectious diseases and eating habits at Herculaneum (1st century AD, southern Italy). International Journal of Osteoarchaeology, 17(4), 350-357. DOI: 10.1002/oa.906
By Greg Downey
As any fan of the adventures of Daredevil, being blind in comic books can give you superpowers. Matt Murdoch was blinded by a radioactive accident that he befell because he tried to save a blind pedestrian from the truck carrying the waste (ah, the irony…). Murdoch developed a kind of ‘radar’ sense that allowed him to prowl Hell’s Kitchen, rooting out the miscreants and lowlifes who, like the blind Man Without Fear, preferred to lurk in the dark.
Although his personal life proved that nice guys often finish, if not last, certainly with a heavy burden of angst and personal tragedy, Daredevil built upon the observation that deprivation of one sense can lead to heightened ability in others.
Although the Man without Fear may seem implausible, in fact, researchers have examined a number of deaf individuals who seem to develop extraordinarily acute echolocation, a kind of active sonar that they use by clicking to produce echoes from their surroundings. In a recent edition of PLoS ONE, Lore Thaler from the University of Western Ontario, with Stephen Arnott and Melvyn Goodale, report on brain imaging research that tries to sort out how individuals who can echolocate – who have what one blind activist calls ‘flash sonar’ – accomplish this perception neurologically. Do they use an especially acute sense of hearing, or do they develop another kind of sense, able to transform echoes into spatial perception?
What the researchers found, in short, is that blind individuals who could echolocate did not really have better ‘hearing’; on normal tests of hearing acuity, they scored the same as two sighted subjects who could not echolocate. However, when a recording had echoes, parts of the brain associated with visual perception in sighted individuals became extremely active, as the echolocators were able to extract information from the echoes that was seemingly not accessible to the control subjects who were sighted.
Although I want to review the results from the recent article, I’m actually interested more generally in several things I think we can learn from human echolocation:
Sensing is broader than perception; that is, our nervous system may react to many things that we are not consciously aware it is noting in any meaningful way. Sensation is ‘bigger than’ consciousness (and I realize I’m using those terms loosely.).
Human echolocation highlights, again, that the anthropology of the senses needs to realize that the theory of ‘five senses,’ an idea that we really get from Aristotle it seems to me (although I have no interest in digging any deeper into the intellectual history of the concept), is a bit of cultural common sense and not at all a scientific approach or reflection of verifiable psychological or phenomenological reality.
Human echolocation is a capacity of any human being, but the extraordinary skill shown by exemplary practitioners like Daniel Kish and Ben Underwood requires much more than just a human nervous system and the right training: the skill requires a community that ‘gets it’ and supports the capacity.
For me, echolocation is not simply an oddity or a quirky case for the vast human carnival. Rather, human echolocators tell us something fundamental about the brain’s extraordinary flexibility and power to squeeze perception out of a range of information streams, some of which are normally non-conscious to us. But plasticity follows very specific patterns which helps to explain why the Canadian researchers report in PLoS ONE that they found activity in certain parts of the visual cortex.
If you’re not already fascinated by echolocation, the following clips, I hope, will ignite some spark of ‘gee whiz-ism’ in even the most blasé reader.
In this first video clip, CBS covers the story of Ben Underwood, a young man who could do remarkable things with echolocation. Ben passed away in 2009 at the age of 16, when the cancer that had led to his blindness returned. I remember the first time I saw this video clip and, even though I was already aware of human echolocation, some of what this young man could accomplish simply blew me away. It’s one thing to hear about subjects’ accuracy locating a 25 cm target at 4 meters distance, another to watch a young man bean a reporter with a throw pillow across a living room. At some points, it’s simply hard to believe how acute Ben’s echolocation was, easy to wonder if the video is some kind of hoax.
The second clip is of researcher, activist, and echolocation teacher, Daniel Kish, who, in addition to having an extraordinary capacity to maneuver by echolocation, is also one of the subjects studied in the research reported in PLoS ONE. Kish was partially blind at birth, fully blind after 13 months-of-age when his eyes were removed due to retinoblastoma in both.
Because Kish is so remarkable and such an interesting advocate for encouraging the blind to live as independently as possible that I’ve included a number of links to his websites and stories about him at the end of this piece (such as a link to World Access for the Blind).
As the authors of the PLoS ONE article write, their blind subjects used echolocation constantly in daily life, to get around familiar places, to explore cities, hike outdoors, mountain bike, and even play basketball.
Senior author Mel Goodale, Canada Research Chair in Visual Neuroscience, and Director of the Centre for Brain and Mind, says, “It is clear echolocation enables blind people to do things otherwise thought to be impossible without vision and can provide blind and visually-impaired people with a high degree of independence.” (from Science Daily)
How do they do it?
One of the interesting wrinkles in the study of echolocation by the blind is that, until some path-breaking research in the 1940s, blind individuals and psychologists alike were not sure how the blind were able to get around as well as they did. Many blind people reported what psychologists came to call ‘facial vision,’ a sensation supposedly of pressure on the face that let them know that they were approaching an obstacle when waking.
Karl M. Dallenbach
Early experiments led by Karl Dallenbach (Cotzin and Dallenbach 1950; Supa et al. 1944; Worchel and Dallenbach 1947; click here for a black and white, silent video of their experiments) on ‘facial vision’ found that blind individuals could detect a board placed in their paths as they walked toward it, but that blindfolded individuals with normal sight quickly also started to detect the obstacle on repeated trials. By thirty trials, the blindfolded subjects were as accurate as the blind in walking up to an obstacle without touching it.
But the researchers also found that the channel for perception was not touch or a mysterious kind of facial ‘sight,’ but instead linked to the sound emanating from the subjects and reflecting off the target obstacles. When Dallenbach, Supa and colleagues put their subjects in socks on carpeted floors, or interfered with their hearing, ‘facial vision’ dropped off. The sound of hard-soled shoes on the floor was likely the source of their perception (see Stoffregen and Pittenger 1995 for an excellent review of early research on echolocation).
Stoffregen and Pittenger (1995: 209) point out that echolocation is a distinctive form of perception because the sense is a ‘closed-loop system,’ that is, ‘stimulus energy that is generated by the animal propagates into the environment, is structured by the environment, and returns to receptors.’ In other words, to echolocate people and other animals must produce as well as perceive sound. They are using active rather than passive sonar. By comparing the outgoing energy with the incoming reflection echolocators can perceive their environment (although there some echolocators evidently can also pull information from passively perceived echoes, that is, of sounds that they themselves do not create).
The active nature of this sense means that the perceiver can query the environment, as we see in the video clips, pushing out more sonic energy, clicking more frequently or l... Read more »
COTZIN M, & DALLENBACH KM. (1950) "Facial vision:" the role of pitch and loudness in the perception of obstacles by the blind. The American journal of psychology, 63(4), 485-515. PMID: 14790019
Kellogg, W. (1962) Sonar System of the Blind: New research measures their accuracy in detecting the texture, size, and distance of objects "by ear.". Science, 137(3528), 399-404. DOI: 10.1126/science.137.3528.399
Merabet, L., & Pascual-Leone, A. (2009) Neural reorganization following sensory loss: the opportunity of change. Nature Reviews Neuroscience, 11(1), 44-52. DOI: 10.1038/nrn2758
Rosenblum, L., Gordon, M., & Jarquin, L. (2000) Echolocating Distance by Moving and Stationary Listeners. Ecological Psychology, 12(3), 181-206. DOI: 10.1207/S15326969ECO1203_1
Schenkman, B., & Nilsson, M. (2010) Human echolocation: Blind and sighted persons’ ability to detect sounds recorded in the presence of a reflecting object. Perception, 39(4), 483-501. DOI: 10.1068/p6473
Stroffregen, T., & Pittenger, J. (1995) Human Echolocation as a Basic Form of Perception and Action. Ecological Psychology, 7(3), 181-216. DOI: 10.1207/s15326969eco0703_2
Thaler, L., Arnott, S., & Goodale, M. (2011) Neural Correlates of Natural Human Echolocation in Early and Late Blind Echolocation Experts. PLoS ONE, 6(5). DOI: 10.1371/journal.pone.0020162
WORCHEL P, & DALLENBACH KM. (1947) Facial vision; perception of obstacles by the deaf-blind. The American journal of psychology, 60(4), 502-53. PMID: 20273385
Many recent interpretations of Chaco Canyon see it as a site of pilgrimage, and this is often specifically seen as taking the form of regular region-wide ritual events involving communal feasting, construction work on the massive buildings in the canyon, trade involving various mundane and exotic items, and ritual breakage of pottery and deposition of [...]... Read more »
Wills, W. (2001) Ritual and Mound Formation during the Bonito Phase in Chaco Canyon. American Antiquity, 66(3), 433. DOI: 10.2307/2694243
Sci has to say she’d have LOVED to take the data for this study. Get to go to Spain, hang out, put some heart monitors on people and watch some fire walking…sounds like a good time. Much more glamorous than my own daily life in the lab. Can I get a little glamour around here? [...]... Read more »
Konvalinka, I., Xygalatas, D., Bulbulia, J., Schjodt, U., Jegindo, E., Wallot, S., Van Orden, G., & Roepstorff, A. (2011) Synchronized arousal between performers and related spectators in a fire-walking ritual. Proceedings of the National Academy of Sciences, 108(20), 8514-8519. DOI: 10.1073/pnas.1016955108
In July 1914 Earl Morris, the pioneering Southwestern archaeologist who would later become famous for his excavations at Aztec and other sites in the region, happened to visit one Eudoro Córdoba, who owned a farm on the Animas River a short distance upstream of the major ruins at Aztec. On his mantelpiece were various artifacts [...]... Read more »
Morris, E. (1915) The Excavation of a Ruin near Aztec, San Juan County, new Mexico. American Anthropologist, 17(4), 666-684. DOI: 10.1525/aa.1915.17.4.02a00040
The Journal of Archaeological Science has just published a new study on ADE. The study, of Birk et al. is entitled: “Faeces deposition on Amazonian Anthrosols as assessed from 5b-stanols”. I have just read it and this is my very first impression:The new data are extremely interesting. The authors look at the presence of coprostanol (a marker for faeces) in Amazonian Dark Earth (ADE). They have found a clear change in the index used to asses different sources of stanols, when comparing samples from the topmost 10 cm with samples coming from a depth of 30-40 cm. It seems that litter degradation is responsible for this change. Moreover, it also seems that the normal indexes used to assess the human origin of the stanols do not work very well in Amazonia. This paper is going to be a valuable reference to similar studies performed in Amazonia in the future. However, while Birk et al. correctly notice that one of the most debated topics about ADE is its origin, they do not do very much to assess why the faeces were there and what is their meaning from an archaeological point of view. ADE is found in two different forms, terra preta and terra mulata. Terra preta is darker, contains more organic matter, P and charcoal and also contains lots of fragments of ceramic. Terra mulata is like a light version of terra preta, it contains more nutrients and charcoal compared with “natural” soils from the surroundings, but less compared to terra preta. Moreover, in the terra mulata sites there is no pottery. Terra preta is found in small patches of about 1 hectare and terra mulata if found surrounding the terra preta sites. Terra mulata can cover as much as 200 hectares. An interpretation could be that terra preta resulted from settlements while terra mulata resulted from agriculture. If this thesis was correct, the high fertility of terra preta would be a side effect of human waste disposal and not the intentional result of land fertilization. In the case of terra mulata, if we assume it has been produced by agricultural use, fertilization must have been intentional. In this case, it would have been very important to see if there is any coprostanol in terra mulata! But the study did not look at terra mulata. Many scholars talk about ADE as synonymous of terra preta, without making a distinction with terra mulata, despite the fact that the differences between the two are key to understanding the past of Amazonia (estimating past population density, the region’s carrying capacity, the levels of social complexity achieved, pre-Columbian settlement patterns, the extent of the human impact on pre-Columbian forest etc.) Birk et al. only compared samples from 4 terra preta sites with samples from natural soils. I think they missed a great occasion. If they had also looked at 4 samples from terra mulata sites they might have been able to shed new light on the matter. Perhaps they did look at terra mulata and just decided to publish the results in a second paper…keeping us waiting GRRRR JJago Jonathan Birka, Wenceslau Geraldes Teixeirab, Eduardo Góes Neves, & Bruno Glaser (2011). Faeces deposition on Amazonian Anthrosols as assessed from 5β-stanols Journal of Archaeological Science, 38 (6), 1209-1220 : http://dx.doi.org/10.1016/j.jas.2010.12.015... Read more »
Jago Jonathan Birka, Wenceslau Geraldes Teixeirab, Eduardo Góes Nevesc, & Bruno Glaser. (2011) Faeces deposition on Amazonian Anthrosols as assessed from 5β-stanols. Journal of Archaeological Science, 38(6), 1209-1220. info:/doi.org/10.1016/j.jas.2010.12.015
On June 7th, 2011, one of the world's pioneering primatologists, Toshisada Nishida, passed away at age 70. A look back at his career and his accomplishments.... Read more »
NISHIDA, T. (1973) The ant-gathering behaviour by the use of tools among wild chimpanzees of the Mahali Mountains. Journal of Human Evolution, 2(5), 357-370. DOI: 10.1016/0047-2484(73)90016-X
Nishida, T. (1976) The Bark-Eating Habits in Primates, with Special Reference to Their Status in the Diet of Wild Chimpanzees. Folia Primatologica, 25(4), 277-287. DOI: 10.1159/000155720
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