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Cortisol, surprise-enhanced cognition, and flashbulb memories: Scaring people with a snake screen and getting a PhD for it!

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Cortisol is a hormone that has a number of important functions. It gets us out of bed in the morning, it cranks up our metabolism in preparation for intense exercise, and it also helps us memorize things and even learn. Yes, it helps us learn . Memorization in particular, and cognition in general, would be significantly impaired without cortisol. When you are surprised, particularly with something unpleasant, cortisol levels increase and enhance cognition. This is in part what an interesting study suggests; a study in which I was involved. The study was properly “sanctified” by the academic peer-review process (Kock et al., 2009; full reference and link at the end of this post). The main hypothesis tested through this study is also known as the “ flashbulb memorization ” hypothesis. Interestingly, up until this study was conducted no one seemed to have used evolution to provide a basis on which flashbulb memorization can be explained. The basic idea here is that enhanced cognition with...
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How environmental change shaped human evolution

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Anna Di Rienzo Humans originated in Africa and then dispersed all over the world to environments that differ in terms of climate, biodiversity, etc, which has brought selective pressures on different populations. At #AAASmtg in Washington DC on Saturday, Anna Di Rienzo presented her research on the how this dispersal has left signatures of adaptation to the pressures. Here are my notes from the talk. The "Out of Africa" theory has it that humans left Africa 50 Kya and then Neolithic revolution happened 14 Kya. They shifted away from foraging subsistence to horticulture. We also know that levels of human skin pigmentation changed with latitude of populations. In addition, body size and proportions changed. For example, Inuit have quite different proportions for the cold North. Metabolic traits differ across human populations also, causing disease related traits to occur such as high blood pressure, high triglycerides, or high cholesterol. A prominent example is the rising pr...
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Assessment: Fish Consumption and Incidence of Stroke Meta-Analysis

Purpose of review: Further research was necessary into relationship between fish consumption and risk of stroke because observational studies were inadequate for determining relationship. Review strategy: Meta-analysis on cohort studies relating to fish consumption and risk of stroke. Description: Researchers searched Medline and Embase databases with relative keywords (e.g. “fish) to identify 9 total relevant cohorts (note: one study counted as two) published in English language journals from 1966 to 2003. The cohort studies chosen each provided “relative risk” and “corresponding 95%” confidence interval factors for relationship of stroke with fish consumption. Duration average of each was 12.8 years with a range of 4 to 30 years. Each study had been properly adjusted for multiple covariates. Regional variance existed: of the 9 studies, 6 were from the U.S., 1 from Europe, 1 from China, and 1 from Japan creating a regional variance. Five of the studies attained data through person...
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