It has been shown that newlywed’s relationships with their in-laws are important to predicting marital success. But does this effect begin to wear off with time? ... Read more »
Bryant, C., Conger, R., & Meehan, J. (2001) The Influence of In-Laws on Change in Marital Success. Journal of Marriage and Family, 63(3), 614-626. DOI: 10.1111/j.1741-3737.2001.00614.x
Timmer, S., & Veroff, J. (2000) Family Ties and the Discontinuity of Divorce in Black and White Newlywed Couples. Journal of Marriage and Family, 62(2), 349-361. DOI: 10.1111/j.1741-3737.2000.00349.x
If you have a few minutes and three buckets try this experiment. Fill one bucket with ice-cold water, another bucket with room temperature water and the third bucket with hot water. Then, place one hand in the cold bucket and your other hand in the hot bucket. Give it a few minutes and then put [...]... Read more »
KENRICK, D. (1989) Influence of popular erotica on judgments of strangers and mates. Journal of Experimental Social Psychology, 25(2), 159-167. DOI: 10.1016/0022-1031(89)90010-3
In our man-made world, it can feel like everything is converging all at once. Indistinguishable glass skyscrapers sprout up in cities all over the globe, near identical car models vent carbon dioxide into the air on different continents, and people around the world see their waistbands expand as they gulp down the same McFood … Continue reading →... Read more »
Three years ago, a friend and I were eating a slice of lime. If we had had any normal sense of taste, the sour fruit would have made us squint our eyes and twist our faces. Instead, we just sucked the juice from the fruit without twitching a muscle. To mock sourness some more, we [...]
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Ayako Koizumi, Asami Tsuchiya, Ken-ichiro Nakajima, Keisuke Ito, Tohru Terada, Akiko Shimizu-Ibuka, Loïc Briand, Tomiko Asakura, Takuma Misaka, & Keiko Abe. (2011) Human sweet taste receptor mediates acid-induced sweetness of miraculin. Proceedings of the National Academy of Sciences. info:/10.1073/pnas.1016644108
One of the main thrusts of the paper by Hadjistavropoulos, Craig, Duck, Cano, Goubert, Jackson, et al., is that pain communication can serve several functions – it can be an action where a message is sent or received; it can be an interaction where the message is sent, received and interpreted; or it can be … Read more... Read more »
Hadjistavropoulos, T., Craig, K., Duck, S., Cano, A., Goubert, L., Jackson, P., Mogil, J., Rainville, P., Sullivan, M., de C. Williams, A.... (2011) A biopsychosocial formulation of pain communication. Psychological Bulletin. DOI: 10.1037/a0023876
The fish tapeworm Diphyllobothrium latum has reared its narrow scolex head around the world in freshwater fish-eating communities. This article looks at its history, culinary (mis)adventures and global travels. Included is a breathtaking video of the tapeworm in action.... Read more »
Scholz, T., Garcia, H., Kuchta, R., & Wicht, B. (2009) Update on the Human Broad Tapeworm (Genus Diphyllobothrium), Including Clinical Relevance. Clinical Microbiology Reviews, 22(1), 146-160. DOI: 10.1128/CMR.00033-08
This is the seventh contribution to my series on doctoral and master dissertations on Supply Chain Risk Management. This again is a master thesis from the MIT. An immense effort and dedication is spent on these works only to find the results hidden in the libraries. So the goal is raise interest in the research of my peers.... Read more »
Pochard, S. (2003) Managing Risks of Supply-Chain Disruptions: Dual Sourcing as a Real Option. Massachusetts Institute of Technology, Master Thesis . info:/
Van Gogh (source)
"Let's not forget that the little emotions are the great captains of our lives and we obey them without realizing it." -- Vincent Van Gogh
Humans are understandably enthralled with emotion. We see emotions as a core aspect of our daily lives and relationships with others. Our emotions can shift our behavior, lead us to reinterpret our social environment, and sometimes cause us physical discomfort. Specific emotional states--like happiness, for instance--have even become lifetime goals. Emotions, as Van Gogh suggests, are indeed the "great captains of our lives."
Given that emotions hold such a profound influence on us, one would think that (a) there would be a ton of psychological research devoted to the study of emotions, and (b) emotion research would already have generated the clear truth about the nature of emotion experience. Actually, while (a) is quite true [there is even a journal called "Emotion"], (b) is surprisingly false. The reason: Emotion researchers disagree about what an emotion is, and where emotion research should go in the future.
Read More->... Read more »
Keltner, D., & Haidt, J. (1999) Social Functions of Emotions at Four Levels of Analysis. Cognition , 13(5), 505-521. DOI: 10.1080/026999399379168
Tracy, J., & Matsumoto, D. (2008) The spontaneous expression of pride and shame: Evidence for biologically innate nonverbal displays. Proceedings of the National Academy of Sciences, 105(33), 11655-11660. DOI: 10.1073/pnas.0802686105
[Author's Note: I don't think that I have ever traveled so much in my entire life. For the past few months I have been chasing down dinosaurs - and the paleontologists who study them - across the American west, from Ekalaka, Montana to Ghost Ranch, New Mexico. All of it is for my next book, [...]... Read more »
M. Antón, A. Turner, M. J. Salesa, J. Morales. (2007) A complete skull of Chasmaporthetes lunensis (Carnivora, Hyaenidae) from the Spanish Pliocene site of La Puebla de Valverde (Teruel). Estudios Geológicos, 62(1), 375-388. info:/
Barnosky, A., Matzke, N., Tomiya, S., Wogan, G., Swartz, B., Quental, T., Marshall, C., McGuire, J., Lindsey, E., Maguire, K.... (2011) Has the Earth’s sixth mass extinction already arrived?. Nature, 471(7336), 51-57. DOI: 10.1038/nature09678
Berta, A. (1981) The Plio-Pleistocene hyaena Chasmaporthetes ossifragus from Florida. Journal of Vertebrate Paleontology, 1(3), 341-356. DOI: 10.1080/02724634.1981.10011905
Cooper, S., Holekamp, K., & Smale, L. (1999) A seasonal feast: long-term analysis of feeding behaviour in the spotted hyaena (Crocuta crocuta). African Journal of Ecology, 37(2), 149-160. DOI: 10.1046/j.1365-2028.1999.00161.x
Ferretti, M. (2007) Evolution of bone-cracking adaptations in hyaenids (Mammalia, Carnivora). Swiss Journal of Geosciences, 100(1), 41-52. DOI: 10.1007/s00015-007-1212-6
Kurten, B., & Werdelin, L. (1988) A review of the genus Chasmaporthetes Hay, 1921 (Carnivora, Hyaenidae). Journal of Vertebrate Paleontology, 8(1), 46-66. DOI: 10.1080/02724634.1988.10011683
Tseng, Z., Antón, M., & Salesa, M. (2011) The evolution of the bone-cracking model in carnivorans: cranial functional morphology of the Plio-Pleistocene cursorial hyaenid Chasmaporthetes lunensis (Mammalia: Carnivora). Paleobiology, 37(1), 140-156. DOI: 10.1666/09045.1
TURNER, A., ANTON, M., & WERDELIN, L. (2008) Taxonomy and evolutionary patterns in the fossil Hyaenidae of Europe. Geobios, 41(5), 677-687. DOI: 10.1016/j.geobios.2008.01.001
WERDELIN, L., TURNER, A., & SOLOUNIAS, N. (1994) Studies of fossil hyaenids: the genera Hyaenictis Gaudry and Chasmaporthetes Hay, with a reconsideration of the Hyaenidae of Langebaanweg, South Africa. Zoological Journal of the Linnean Society, 111(3), 197-217. DOI: 10.1111/j.1096-3642.1994.tb01483.x
My love for Portal, Portal 2, and video games in general is certainly no secret. Nor is my love for comics and other geekery.Recently I played through the Portal 2 single- and multi-player campaigns (with my Activision and Call of Duty buddy, Bryan).I love the Portals.(Screenshot from Portal 2)Of course, me being... well... me, I couldn't help but think about why I loved the game and then a bunch of weird brainy neuro stuff.Basically the end result of my over-intellectualization was that sometimes games are just fun.That's it. End of post! Hope you enjoyed it....Oh. You're still here? ::sigh::Okay,I guess I can continue on. For science. Or rather, for neuroscience.If you're unfamiliar with the Portal games, a wonderfully homicidal AI is trying to murder you in the name of advancing science. Your goal is to stay alive by surviving her tests using only a gun. But this is a special gun. It creates portals that allow you to teleport between portal A and portal B. Momentum, a function of mass and velocity, is conserved between portals. In layman's terms: speedy thing goes in, speedy thing comes out.This game has some ridiculously crazy 3D spatial reasoning puzzles and I got to thinking about how the hell I was able to shoot a portal at a wall, shoot another across the room, and know that when I went into one I would come out the other. There's a lot going on here to let the brain do this!Seriously, some of these puzzles are mind-bending. Watch this speed run:Get all that? There's a reason why scicurious gets motion sick when she tries to play the Portal games.(As an aside, it also contains one of the best end game songs ever, written by Jonathan Coulton.)In this post I'll give a brief introduction about how the human brain can even conceive of teleporting between two portals. More specifically I'll talk about visual attention and working memory. You can't really conceive of moving from portal A to portal B without first knowing where the two portals are relative to each other and to the room you're in.I want to make it clear how hard it is to study something like spatial attention and memory. These concepts are more metaphors or placeholder terms we use in neuroscience to describe observable psychological and behavioral phenomena than actual brain processes. They're kind of ill-defined and nebulous, though there's a massive literature that attempts to unite the behavioral with the neuronal.The first mind-blowing spatial attention thing to know about is hemispatial neglect. The most common form of hemispatial neglect results from damage to the right posterior parietal lobe. It manifests as the inability to conceive of or see one visual hemifield.What does that mean?Well, check this out:Literally, there is no conception of "leftness".The above examples are of two drawings from a patient with hemineglect. Notice that, when copying a drawing, the patient is missing the whole left half of the object. And when free drawing, they show a similar effect. There's a great review on this topic by Masud Husain and Chris Rorden from 2003 in Nature Reviews Neuroscience.In that paper the authors do an amazing job summarizing what we knew about neglect at the time. I'll also take this moment to emphasize yet again how much we've learned about human cognition from work done with patients with brain lesions.Visual attention is an enormously huge domain that strongly overlaps with research into visual working memory.The thing about working memory is that there's a lot of controversy in the field about well, how it works. There's a really cool researcher by the name of Paul Bays (who worked with Husain of the previously-mentioned paper) that summed up the debate very succinctly in the introduction of a 2009 paper they wrote in the Journal of Vision:The mechanisms underlying visual working memory have recently become controversial. One account proposes a small number of memory "slots", each capable of storing a single visual object with fixed precision. A contrary view holds that working memory is a shared resource, with no upper limit on the number of items stored; instead, the more items that are held in memory, the less precisely each can be recalled.This all stems from George Miller's famous paper from 1956, The magical number seven, plus or minus two: some limits on our capacity for processing information (decent Wikipedia summary here).Anyway, visual attention and working memory are extremely difficult to disentangle. You can see the strong relationship between the two concepts in brainSCANr:(In fact, I believe a big chuck of working memory research is conflated with attention... I've got a project to try and demonstrate just that).The number of experimental paradigms used to study attention and/or working memory is enormous so, although there are fairly "standard" paradigms, even slight differences between stimulus presentation, timing, task, etc. can lead to fairly big differences in results.However, the visual experiments that require a person to sit in a darkened room while some images flash at them on a computer screen has lead a number of researchers to call into question what is actually being tested in these situations. Does remembering when an X appears on a screen really encapsulate human memory? Does noticing a green square in a sea of red squares typify attention?Of course, more ethological ("real-world" scenario) experiments sacrifice control for validity... making the whole damned thing a mess.But this messiness is part of the allure... if it was easier we'd have figured it out decades ago and I'd be out of a job! :)Husain, M., & Rorden, C. (2003). Non-spatially lateralized mechanisms in hemispatial neglect Nature Reviews Neuroscience, 4 (1), 26-36 DOI: 10.1038/nrn1005... Read more »
Husain, M., & Rorden, C. (2003) Non-spatially lateralized mechanisms in hemispatial neglect. Nature Reviews Neuroscience, 4(1), 26-36. DOI: 10.1038/nrn1005
Bays, P., Catalao, R., & Husain, M. (2009) The precision of visual working memory is set by allocation of a shared resource. Journal of Vision, 9(10), 7-7. DOI: 10.1167/9.10.7
Miller GA. (1956) The magical number seven plus or minus two: some limits on our capacity for processing information. Psychological review, 63(2), 81-97. PMID: 13310704
Hippocampus in Green from 3D Brain iPad AppCardiorespiratory fitness appears to be associated with a variety of benefits in cognitive functioning. The mechanisms for this benefit are unclear. Association studies do not provide evidence for the pathways between related variables. For understanding pathways, clinical trials, longitudinal studies and multivariate approaches are more powerful approaches.Amanda Szabo and colleagues at the University of Illinois at Urbana-Champaign recently published a multivariate study looking at fitness, hippocampus and forgetting in a group of elderly adults in the journal Neuropsychology. The hippocampus is a brain region known to crucial to working memory. Changes in hippocampal volume have been linked to age-related cognitive decline and the development of Alzheimer's disease.The key elements of design in this study included:Subjects: 158 older adults with a mean age of 66.5 yearsVariables: Fitness level as measured by VO2 estimate from a graded exercise test, brain hippocampal volume from a brain 3T MRI scan, spatial working memory task, subjective rating of forgetfulness (Frequency of Forgetting Questionnaire)Statistics: Path analysis examining direct and indirect effects of fitness on hippocampal volume, working memory test performance and subject rating of forgetfulness using the comparative fit index (CFI)The authors started with a presumed pathway model for the mechanism of the relationship between fitness and forgetfulness in the following pathway:fitness levels predict hippocampal volumehippocampal volumes predicts working memory function performanceworking memory performance predicts subjective forgetfulnessFitness levels were associated with a variety of sociodemographic and medical variables at baseline including: self-reported physical activity, presence of hypertension, cardiovascular disease, body mass index, education level, gender and age. These baseline variables were evaluated and controlled in the final pathway analysis.The authors found their predicted model held up in the analysis: "cardiorespiratory fitness is associated with the frequency of forgetting indirectly through its influence on hippocampal volume and, in turn, spatial working memory".The study noted fitness level is not the sole determinant of hippocampal atrophy. Age alone is an independent contributor of hippocampal atrophy. Fitness may reduce the effects of age-related hippocampal atrophy and forgetfulness but it is unable to reverse the effect. So fitness is not a panacea but it appears to be an important factor in maintaining cognitive function in later life. Now, I just wonder if my wife can help me find my running shoes?3D Brain image of the hippocampus in green screen shot from the author's collection.Szabo, A., McAuley, E., Erickson, K., Voss, M., Prakash, R., Mailey, E., Wójcicki, T., White, S., Gothe, N., Olson, E., & Kramer, A. (2011). Cardiorespiratory fitness, hippocampal volume, and frequency of forgetting in older adults. Neuropsychology, 25 (5), 545-553 DOI: 10.1037/a0022733... Read more »
Szabo, A., McAuley, E., Erickson, K., Voss, M., Prakash, R., Mailey, E., Wójcicki, T., White, S., Gothe, N., Olson, E.... (2011) Cardiorespiratory fitness, hippocampal volume, and frequency of forgetting in older adults. Neuropsychology, 25(5), 545-553. DOI: 10.1037/a0022733
Efficacy of Treatment of Trochanteric Bursitis: A Systematic Review
Lustenberger DP, Ng VY, Thomas M. Best TM, Ellis TJ. Clin J Sport Med. 2011 Sept; Vol 21(5), 447-453.
Trochanteric bursitis presents as lateral hip pain and can be a very frustrating condition to treat. To date, there have been no systematic reviews of the literature comparing the various treatment modalities used. In this systematic review, the authors attempt to evaluate the efficacy of the various treatments for trochanteric bursitis. They conducted a literature search to identify articles on trochanteric bursitis treatment and compared the efficacy of the various treatment options. ... Read more »
Lustenberger DP, Ng VY, Best TM, & Ellis TJ. (2011) Efficacy of treatment of trochanteric bursitis: a systematic review. Clinical journal of sport medicine, 21(5), 447-53. PMID: 21814140
by Persuasion Strategies in Persuasive Litigator
By Dr. Ken Broda-Bahm - In the pivotal scene of “My Cousin Vinnie," a movie beloved by those who follow legal persuasion, the defense attorney, played by Joe Pesci, asks the judge permission to treat his now estranged girlfriend as a hostile witness. This is a request that the judge, with a knowing look, quickly grants. The scene provides an important reminder that even when a witness might formally be on your side, there could be one or more dynamics at work making your own witness "hostile" to your interests. I was recently asked by a legal team faced with...
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Hart, R., Carlson, R., & Eadie, W. (1980) Attitudes toward communication and the assessment of rhetorical sensitivity. Communication Monographs, 47(1), 1-22. DOI: 10.1080/03637758009376016
I was on the phone with my mom recently, and she told me about a recent study she saw on CTV stating that watching SpongeBob Squarepants was bad for children. I scoured the internet, and found the research article in question. While searching, I also found reference to the study in the media. The headlines [...]... Read more »
Lillard, A., & Peterson, J. (2011) The Immediate Impact of Different Types of Television on Young Children's Executive Function. PEDIATRICS. DOI: 10.1542/peds.2010-1919
While at Bari Conference (see here), the news was spreading that OPERA Collaboration, a long baseline experiment using muon neutrino beams launched by CERN by CNGS Project, detected a possible Lorentz violating effect. Initially, it started as a rumor in the comment area at Jester’s blog (see here). Then, Tommaso Dorigo provided a full account [...]... Read more »
The OPERA Collaboraton: T. Adam, N. Agafonova, A. Aleksandrov, O. Altinok, P. Alvarez Sanchez, S. Aoki, A. Ariga, T. Ariga, D. Autiero, A. Badertscher.... (2011) Measurement of the neutrino velocity with the OPERA detector in the CNGS beam. arXiv. arXiv: 1109.4897v1
Giovanni Amelino-Camelia, Giulia Gubitosi, Niccoló Loret, Flavio Mercati, Giacomo Rosati, & Paolo Lipari. (2011) OPERA-reassessing data on the energy dependence of the speed of neutrinos. arXiv. arXiv: 1109.5172v1
Giacomo Cacciapaglia, Aldo Deandrea, & Luca Panizzi. (2011) Superluminal neutrinos in long baseline experiments and SN1987a. arXiv. arXiv: 1109.4980v1
HIV has 10 genes spread throughout roughly 10 thousand nucleotides. The genes Rev and Tat (and Tev, when it’s present), completely overlap with the larger gene Env. When a gene lies within another, we say that the two genes are “nested.” How does the virus know which protein to code if the information is overlapping? The key is the “reading frame.” Remember, a gene is a string of nucleotides (A, G, C, and T), and a protein is a string of amino acids (also denoted with letters), so it really boils down to translating the string of nucleotides into one made of amino acids. It takes three nucleotides (each triplet is called a "codon") to code one amino acid. So, suppose you have a string of DNA that looks like this (the example is taken from this wonderful site):ATGCCCAAGCTGAATAGCGTAGAGGGGTTTTCATCATTTGAGGACGATGTATAAThe three nucleotides in green on the left make the five-prime end, where the translation starts, and it can start at any of the three "green" nucleotides. Now, if you begin reading from the A, you get one reading frame, if you begin from the T, you get a second frame, and, lastly, if you begin from the G you get a third one. Like this:ATG|CCC|AAG|CTG|… becomes MPKL… TGC|CCA|AGC|TGA|… becomes CPS… GCC|CAA|GCT|GAA|… becomes AQAE…As you can see, a single strand of DNA can have three possible reading frames because, depending on where you start partitioning the DNA, the triplets change, giving rise to different sequences of amino acids. At this point, you’re probably wondering why go through all this trouble. Overlapping and nested genes are not uncommon in organisms like virus and bacteria, which have very short genomes (compared to us). For these organisms, a compact genome means a speedier replication process, which is evolutionary advantageous .But how do you explain overlapping genes in more complex organisms like mammals ? Our genome is huge compared to that of a virus, and, like I’ve said many times before, it’s mostly non-coding. If there’s plenty of room for extra genes, why do we have overlapping ones?It gets even more complicated. HIV carries RNA, which is single-stranded, hence, the three reading frames. But we have two strands of DNA, hence six possible reading frames, and some overlapping gene pairs in our genome are indeed transcribed on opposite strands of DNA. These pairs are called sense-antisense gene pairs, and we really don’t know their function. One reason they exist could be that they simply are a remnant of evolution . However, recent studies have shown that these gene pairs may be associated with cancer  and diseases such as Alzheimer . In fact, a mutation in the overlapping regions “doubles” its effect in a way, since it affects both genes.Such associations should not be completely surprising and in fact, I believe they are the tip of some deeper regulatory mechanism that we have yet to understand. If we go back to our very first ancestors, bacteria, we see that these primitive organisms have evolved complex regulatory mechanisms based on sense-antisense genes. These mechanisms have been studied in particular in the context of drug resistance, where it has been shown that this type of “antagonist” transcription has a role in controlling how bacteria exchange genetic material , and, as a result facilitate the rise of drug-resistant subspecies. I should explain this phenomenon more in detail in a later post. Kumar A (2009). An overview of nested genes in eukaryotic genomes. Eukaryotic cell, 8 (9), 1321-9 PMID: 19542305  Sanna CR, Li WH, & Zhang L (2008). Overlapping genes in the human and mouse genomes. BMC genomics, 9 PMID: 18410680 Yu W, Gius D, Onyango P, Muldoon-Jacobs K, Karp J, Feinberg AP, & Cui H (2008). Epigenetic silencing of tumour suppressor gene p15 by its antisense RNA. Nature, 451 (7175), 202-6 PMID: 18185590 Guo JH, Cheng HP, Yu L, & Zhao S (2006). Natural antisense transcripts of Alzheimer's disease associated genes. DNA sequence : the journal of DNA sequencing and mapping, 17 (2), 170-3 PMID: 17076261 ... Read more »
Kumar A. (2009) An overview of nested genes in eukaryotic genomes. Eukaryotic cell, 8(9), 1321-9. PMID: 19542305
Yu W, Gius D, Onyango P, Muldoon-Jacobs K, Karp J, Feinberg AP, & Cui H. (2008) Epigenetic silencing of tumour suppressor gene p15 by its antisense RNA. Nature, 451(7175), 202-6. PMID: 18185590
Guo JH, Cheng HP, Yu L, & Zhao S. (2006) Natural antisense transcripts of Alzheimer's disease associated genes. DNA sequence : the journal of DNA sequencing and mapping, 17(2), 170-3. PMID: 17076261
Chatterjee A, Johnson CM, Shu CC, Kaznessis YN, Ramkrishna D, Dunny GM, & Hu WS. (2011) Convergent transcription confers a bistable switch in Enterococcus faecalis conjugation. Proceedings of the National Academy of Sciences of the United States of America, 108(23), 9721-6. PMID: 21606359
by Rita Handrich in The Jury Room
Last year, my then 16-year-old daughter volunteered at the SXSW Festival registration here in Austin. She came home after the first day and told me she had looked up from her computer workstation to assist the next person in line only to see a large birthmark covering 2/3 of his face and neck. She didn’t know [...]
Related posts:Beards and glasses: More ‘small stuff’ you might want to sweat
The Danger of Stereotyping: Does Gay + Black = Likable?
Maybe you better sweat the small stuff…
... Read more »
Miller, S., & Maner, J. (2011) Sick body, vigilant mind: The biological immune system activates the behavioral immune system. . Psychological Science. info:/
Our cells ask a lot of our chromosomes. Chromosomes contain all of our genetic material, but are required to compact themselves into skinny little things that can be easily divided during cell division. Throw a terrible virus into the mix, and chromosomes start to have trouble with their duties. During mitosis, duplicated chromosomes separate after receiving a signal allowing anaphase to begin. Until this signal is relayed, each pair of chromatids stays attached to one another by the cohesin protein complex. Premature chromatid separation was recently found in some types of white blood cells in HIV-infected people, and can lead to cells having an incorrect number of chromosomes. This same research group more recently showed that this HIV-induced premature chromatid separation is caused by Vpr, an HIV accessory protein. Vpr causes premature chromatid separation by disrupting the higher-order structure of DNA surrounding the centromere, the region where kinetochores allow attachment to the mitotic spindle. In the images above, the cohesin complex (pink, arrows) is found within the centromere of a control chromatid pair (left). In cells expressing the HIV accessory protein Vpr (right), the cohesin complex is absent from the centromere of a loosely-bound chromatid pair (arrowheads).Shimura, M., Toyoda, Y., Iijima, K., Kinomoto, M., Tokunaga, K., Yoda, K., Yanagida, M., Sata, T., & Ishizaka, Y. (2011). Epigenetic displacement of HP1 from heterochromatin by HIV-1 Vpr causes premature sister chromatid separation originally published in The Journal of Cell Biology, 194 (5), 721-735 DOI: 10.1083/jcb.201010118... Read more »
Shimura, M., Toyoda, Y., Iijima, K., Kinomoto, M., Tokunaga, K., Yoda, K., Yanagida, M., Sata, T., & Ishizaka, Y. (2011) Epigenetic displacement of HP1 from heterochromatin by HIV-1 Vpr causes premature sister chromatid separation. originally published in The Journal of Cell Biology, 194(5), 721-735. DOI: 10.1083/jcb.201010118
Eating less makes you live longer. Despite the jokes that it just makes it seem longer, it’s true – animal studies, including in nematodes and rats show an up to 50% increase in lifespan, and the Calorie Restriction Society believes that it can work for people too. The CALERIE study at Duke University is a two year study to assess its practicality and safety. Researchers had linked the lifespan extension to the gene SIR2, which codes for sirtuins, but a paper in Nature has cast doubt on this connection.... Read more »
Burnett, C., Valentini, S., Cabreiro, F., Goss, M., Somogyvári, M., Piper, M., Hoddinott, M., Sutphin, G., Leko, V., McElwee, J.... (2011) Absence of effects of Sir2 overexpression on lifespan in C. elegans and Drosophila. Nature, 477(7365), 482-485. DOI: 10.1038/nature10296
What do stone axes have to do with the LIA ?In his famous paper entitled “The anthropogenic greenhouseera began thousands of years ago” Ruddiman put forward a fascinating idea: “CO2 oscillations of ∼10ppm in the last 1000 years are too large to be explained by external(solar-volcanic) forcing, but they can be explained by outbreaks of bubonicplague that caused historically documented farm abandonment in western Eurasia.Forest regrowth on abandoned farms sequesteredenough carbon to account for the observed CO2 decreases. Plague-driven CO2changes were also a significant causal factor in temperature changes during theLittle Ice Age (1300–1900 AD)”. There has been a lot of controversy surroundingRuddiman’s paper.More recently, the ideathat plagues caused farmland abandonment and were followed by re-forestationhas been applied to the Amazon Basin and the LIA. Severalscholars have proposed that the depopulation caused by the diseases thatEuropeans brought to the Americas after 1492 induced a large scalere-forestation which, in turn, decreased the amount of atmospheric CO2 andcontributed to the LIA [Dull et al., 2010; Faust etal., 2006; Nevle and Bird, 2008].In order to assess the likelihood of this hypothesis we need to know i) populationsize in pre-Columbian America and ii) the kind of agriculture pre-Columbians practiced.Citing Denevan, Nevleand Bird  write that “Evidence forthe habitation and modification of American landscapes by tens of millions ofPre-Columbian agriculturalists [Denevan, 1992] exists in thewidespread distribution of anthropogenic Amazonian Dark Earth soils, raisedfields, irrigated terrace zones, roads, aqueducts, and numerous large-scaleearthworks distributed throughout Amazonia, the Andes, Central America, andparts of North America”.Many of the papersaddressing this topic cite Denevan with regards to pre-Columbian populationdensities and agriculture. So, what are Denevan’s views on the matter? I will focuson Amazonia, as it is the largest forested area in the world and most of thework on pre-Columbian population density and agriculture that is cited tosupport this hypothesis have been done in Amazonia (for example the worksof Denevan himself, Erickson and Heckenberger).How many people lived in Amazonia in 1491?The first estimate wasgiven by Betty Meggers who said that population density in pre-Columbian Amazoniawas 0.3 people Km-2. She didn’t do any distinction betweenfloodplains (varzea) and uplands (terra firme) because varzea’s fertility wasoffset by unexpected and destructive floods, which made varzea as unsuitablefor people as terra firme.Denevan then proposed amodel in which people settled on the rivers’ bluffs. They were able to takeadvantage of the varzea but avoided the danger of the floods. According to [Denevan,1992] population density was 14.6 people km-2 in the varzea and 0.2 people km-2 in the terra firmeforests. It is interesting that Denevan’s estimate for terra firme is lower thanMeggers’ estimate. This is important as terra firme represents 98% of the Amazonianrain forest.In2003, Denevan changed idea and wrote: “For varzea population densitywould be 10.4 per square kilometer […] For terra firme forests it isimpossible to estimate an average population density and a total population […]Estimating average population densities for the savannas with any confidence isimpossible.” Then, he concluded: “...consequently I now reject thehabitat-density method I used in the past to estimate a Greater Amazoniapopulation in 1492 of from 5.1 to 6.8 million. I nevertheless still believethat a total of at least 5 to 6 million is reasonable” [Denevan, 2003].The stone axesAlthoughDenevan has rejected his own estimate of 0.2 people km-2 for terrafirme, it is still important to highlight how he justified that his estimatewas smaller than Meggers’. Denevan defends that pre-Columbians did not practiceslash and burn agriculture because they did not have metal tools and cuttingthe forest with stone axes would have been too much work. Hence, they preferredto live in savannahs, where they developed raised field agriculture, or on theriver bluffs, where Amazonian Dark Earth (ADE) sites are actually found. In Denevan’s view,raised fields and ADEdeveloped in order to minimize the need of clearing the forest: pre-Columbianspreferred to build raised fields and ADE because such type of agricultural intensification required less workthan cutting the forest with stone axes. Thevery same archaeological evidence that Nevle and Bird  use to infer high rates of pre-Columbian deforestation are usedby Denevan to infer that pre-Columbians actually did not cut the forest!Thequestions I have should now be clear: 1) could have such a small population of 0.2people km-2 significantly modified the Amazon forests? 2) How didthey have such an impact if they had to cut the forest with stone axes? 3) Do raisedfield agriculture and ADE suggesthigh levels of deforestation? Or is it the other way round?I don’t want to bemisinterpreted here; I am not saying that pre-Columbian population was small ort... Read more »
Ruddiman, W. (2003) The Anthropogenic Greenhouse Era Began Thousands of Years Ago. Climatic Change, 61(3), 261-293. DOI: 10.1023/B:CLIM.0000004577.17928.fa
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