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Science Square (Issue 92)
Mar 1, 2013

Facing Aggression

Gómez-Valdés et al. Lack of Support for the Association between Facial Shape and Aggression: A Reappraisal Based on a Worldwide Population Genetics Perspective. PLoS ONE, 2013; 8 (1)

It is a common misconception that some people are profiled to be angry or aggressive because of their physical appearances, particularly their craniofacial shapes. In addition, there have been some studies suggesting that men with certain facial traits (round-shaped faces) are more likely to develop aggressive and unethical behavior. A new study using a sample of around 5000 individuals from 94 different countries has found no correlation between facial shape and aggressive/criminal behaviors. Researchers analyzed fWHRs (facial width-to-height ratio) and 2D/3D craniofacial landmark coordinates to estimate any possible correlation between skull shape and aggressive behaviors in men. First, they utilized the famous skull collection in Hallstatt/Austria to investigate any potential correlation between skull features and life history parameters of individuals, such as their overall fitness. Second, they analyzed the male prisoners convicted of crimes like inter-personal aggression (homicide, robbery etc.) from Mexico City Federal Penitentiary to see whether there is any relation between skull shape traits and aggressive crimes. Analyses of both databases have found no significant correlation between skull shape traits either with the fitness of males or with their aggressiveness. This study has very important social and political implications in today’s societies, as we unfortunately see many ethnical, racial and even physical prejudices. This comprehensive study has undoubtedly showed once more that physical traits cannot be a reliable predictor of complex human behaviors, which are mostly shaped by external factors such as education and socio-cultural practices.

Biggest Structure in the Universe Discovered

Clowe et al. A structure in the early Universe at z ∼ 1.3 that exceeds the homogeneity scale of the R-W concordance cosmology. Monthly Notices of the Royal Astronomical Society, January 11, 2013

Throughout history, mankind has been trying to answer the questions of “how big” or “how far,” when looking into the vast expanse of the universe. As new technologies are developed, bigger discoveries and consequently bigger numbers are brought to light. An international team of astronomers recently discovered a collection of 73 quasars which form a single structure; the largest structure ever observed in the entire universe. A quasar, short for quasi-stellar object, is the luminous center of a galaxy that surrounds a super massive black hole. The distance of these newly large quasar groups to the earth is about 9 billion light years (1 light year is approximately 9.5 trillion kilometers). The size of these structures is simply mind-blowing. Even if we have a spacecraft that travels at the speed of light, it would still take about 4 billion years to cross. If we put this overwhelming size into perspective, the Milky Way—earth’s home galaxy—is only about 100,000 light-years wide and our neighbor galaxy Andromeda is only 2.5 million light-years away from the Milky Way. So these quasars are 1600 times larger than the distance from the Milky Way to Andromeda. This discovery seriously challenges the size calculations based on the widely accepted Cosmological Principle which assumes that the universe is essentially homogeneous when viewed at a sufficiently large scale. Cosmological Principle predicts that there should not be any structure in the universe larger than 1.2 billion light-years. A four billion light-years wide structure would obviously be an outlier when compared to other structures in the universe and it might contradict with the homogeneity of the universe. However, scientists think that such contradiction would not necessarily falsify the Cosmological Principle originally established by Albert Einstein. It might only change the assumptions of the theory that define at which scale the universe can sufficiently be viewed.

More Twists on Double Helix

Biffi et al. Quantitative visualization of DNA G-quadruplex structures in human cells. Nature Chemistry, 20 January 2013.

About 60 years ago, on April 25th 1953, James Watson and Francis Crick published a one-page paper where they described the “double helix” structure of the DNA, the molecule that carries genetic information from parent to offspring. This discovery not only revolutionized the biological sciences and medicine but also dramatically changed the way we perceive life, nature and most importantly ourselves. Yet, new findings on DNA structure keep surprising us. Scientists from Cambridge University discovered the first quadruple helix—a four-stranded DNA structure in human cells which they named “G-quadruplex.” These structures were previously observed in test tubes but they were never found in cells. The building blocks of DNA molecules consist of four different bases: Adenine (A), Guanine (G), Cytosine (C) and Thymine (T). G-quadruplexes (G stands for Guanine) are formed by four guanine bases that forms a square DNA helix. Researchers found that these structures are enriched in rapidly-dividing cancer cells, specifically at the ends of chromosomes called telomeres. When researchers targeted and trapped these quadruple DNA structures with synthetic molecules, they found that DNA replication slows down and cell division is blocked. Researchers suspect that these quadruple DNA structures in telomeres of cancer cells could explain why cancer cells rapidly proliferate and divide. It is still not clear whether G-quadruplexes exist in healthy cells but targeting these structures in cancerous cells with pharmacology seems to be a promising method to stop the spread of cancer.