Senin, 26 Juli 2010
One method being used in California is to look for partial matches between DNA from a crime scene and the state’s database of DNA from convicted criminals. A partial match, while not implicating the criminal himself, would suggest that a close relative might have carried out the crime. California used the method this month to identify a person previously convicted on a weapons charge as “probably related” to a long-sought-after Los Angeles serial killer known as the Grim Sleeper. The person’s father eventually was arrested and charged with ten murders.
This is new ethical ground for us all. As a society we need to understand the costs vs. benefits of these types of searches. The benefits are obvious – another killer identified. But the costs will be freedom lost – the freedom, for example, not to be put under suspicion and investigated for a crime unless there is reason to suspect you of an offense. Suspicion of relatives based on partial DNA matches is likely to fall disproportionately on African Americans, since they already represent a disproportionate fraction of the prison population.
Because of these concerns, California wisely put some safeguards in place for familial DNA searches. Currently, such searches require that all other investigative leads have been exhausted, that the crime is murder or rape, and that the criminal is still committing crimes – i.e. is still a threat to society. Other states considering familial DNA searches should consider similar safeguards.
Jumat, 23 Juli 2010
GM cotton has become increasingly popular with farmers – so popular that approximately 50% of all cotton planted worldwide is now GM cotton. The largest users (and cotton growers) are China, India, and the United States, in that order. With so much GM cotton being planted, we could have anticipated that the cotton pests would adapt eventually. But it’s surprising how quickly it happened – bollworm-resistant cotton was only first planted in India in 2002.
Realistically, we can expect the current generation of GM crops to remain useful for several more decades. In the meantime I’m sure that researchers at Monsanto will be working on new ways to thwart the pests, just as the pests will be slowly adapting. It’s just part of the ongoing battle between species for survival.
Rabu, 21 Juli 2010
Of course, paleoanthropologists are already debating where to place A. sediba in the human family tree; direct human ancestor, or evolutionary dead end? Regardless of the outcome, the new find is significant in that it fills some gaps in our understanding of evolutionary processes leading to humans. For instance, it appears that changes in the shape of the pelvis occurred before brain enlargement, and that the legs underwent adaptive changes for upright walking before the arms took on smaller, more human-like proportions.
Minggu, 18 Juli 2010
An interesting new idea is that the “good” bacteria in certain people’s microbiomes might actually be used to treat certain diseases. Doctors have actually cured several stubborn cases of severe diarrhea caused by a particularly difficult bacterium to treat (Clostridium difficile) by transplanting human fecal matter from a healthy person into the patients’ colons! Granted, having a fecal transplant in order to cure disease sounds a bit strange. But apparently the “good” bacteria in the fecal transplant outcompete the C. difficile and wipe them out.
Someday maybe there’ll be ointments or pills containing especially “good” bacteria for treating certain antibiotic-resistant infections such as flesh-eating Staphylococcus aureus or diarrhea-causing C. difficile. Using bacteria to kill bacteria – like using fire to fight fire.
Reference: Zimmer, C., How Microbes Defend and Define Us. New York Times, July 13, 2010.
Selasa, 13 Juli 2010
For possible answers, behavioral neuroscientists are turning to a hot new field called behavioral epigenetics. Behavioral epigenetics is the study of inherited changes in behavior or gene expression that are caused by factors other than changes in DNA, i.e., that are epi- (Greek: over, above) genetics.
According to epigenetics theory, environmental factors such as the degree of nurturing (or lack of it) by one’s parents early in life can alter the chemical structure of DNA (specifically, the degree of methylation of DNA and its associated histones). This in turn affects how and when certain genes are turned on and off. In theory, such chemical alterations in DNA could last for multiple generations (i.e., be heritable) even though the nucleotide sequence of the genes themselves hasn’t changed.
So far, there’s very little evidence to suggest that epigenetic mechanisms influence human behavior, mostly because human brain tissue is not readily available for research. However, laboratory studies show that rats raised by less-nurturing mothers tend to be more prone to stress as adults and to exhibit increased methylation of certain genes. It’s worth keeping an eye on this developing field to see where it leads.
Rabu, 07 Juli 2010
Caster Semenya May Compete. “The process initiated in 2009 in the case of Caster Semenya (RSA) has been completed. The IAFF accepts the panel of medical experts that she can compete with immediate effect. Please note that the medical details of the case remain confidential and the IAAF will make no further comment on the matter.” (IAFF statement)
Remember the old “Where’s the beef?” commercials for Wendy’s chain of restaurants? One might ask, “Where’s the proof?” Out of fairness to all athletes in sports, sports governing bodies should develop understandable policies, guidelines, or criteria for gender assignment in sports. But it won’t be easy (gender IS ambiguous, sometimes), so I’m betting the IAAF won’t even attempt it.
The Wendy’s commercial ended with the remark, “(I don’t think there’s anybody back there…)” IAAF, are you listening?
Jumat, 02 Juli 2010
How might this affect the results? Take for example, perception of self. Textbooks generally describe people has having a tendency to rate their own abilities as above average and to be motivated to maintain a positive image of themselves. But this may not necessarily be true for non-WEIRD cultures, who may place more emphasis on family relationships and less on personal choice or ability.
There’s nothing inherently wrong with studying WEIRDs, of course, as long as it is understood that the conclusions may not generalize to all cultures.
Reference: Henrich, Joseph et al. The Weirdest People in the World? Behavioral and Brain Sciences 33 pp. 61-83.
This second Australopithecus afarensis partial skeleton strengthens the hypothesis that although early human ancestors were not entirely humanlike, they also did not resemble modern apes or chimpanzees.
Details were published online on June 21 in the Proceedings of the National Academy of Science, ahead of the print version.