Sex Differences
gregladen | July 23, 2008The phrase "genomic imprinting" has come to refer the turning off of a gene (a particular instance of a gene on a particular chromosome duplicated across the cells in a body) so that the gene is not expressed at all, with the turning off of the gene not caused in the body in question, but rather, during the previous generation by a process happening in the soma of one of the parents. A maternally imprinted gene is passed on to junior, but will not be expressed in junior. a paternally imprinted gene is passed on to junior, but will not be expressed in junior. Typically (as far as we know) a…
gregladen | June 24, 2008Sometimes boys are worth more, sometimes girls are worth more. In an evolutionary sense. Or, more correctly, the value of a certain sex ... as an offspring ... can be measured in fitness terms. Fisher noted this and hypothesized this was the explanation for the 50-50 sex ratio we usually see. As one sex becomes more rare, it becomes more valuable, and thus parents (mothers, perhaps, usually) bias towards that sex. Then the disparity goes away and thus the differential value goes away.
Of course, the truth is that we don't actually see the 50-50 sex ratio all the time ... many species…
gregladen | June 17, 2008Check it out:
Emma McGrattan, the senior vice-president of engineering for computer-database company Ingres-and one of Silicon Valley's highest-ranking female programmers-insists that men and women write code differently. Women are more touchy-feely and considerate of those who will use the code later, she says. They'll intersperse their code-those strings of instructions that result in nifty applications and programs-with helpful comments and directions, explaining why they wrote the lines the way they did and exactly how they did it.
The code becomes a type of "roadmap" for others who might…
gregladen | May 17, 2008MIT researchers found that phalaropes depend on a surface interaction known as contact angle hysteresis to propel drops of water containing prey upward to their throats. Photo by Robert Lewis The Phalarope starts out as an interesting bird because of its "reversed" sex-role mating behavior. For at least some species of Phalarope, females dominate males, forcing them to build nests and to care for the eggs that the females place there after mating. If a female suspects that a male is caring for eggs of another female, she may destroy the eggs and force the male to copulate with her a few…
gregladen | February 12, 2008One of the most compelling argument that the story of Noah's Ark is made up is the implausibility of having animals like tigers and lions together with animals like lambs and deer on the same boat for very long. The big carnivores would eventually eat the little cute furry things. The bunnies would be the first to go. But new evidence, shown on the Miracle Pet Show disproves this objection.
So, if it is god's will, or if people just darn try hard enough, anybody and anything can get along with anything and anybody. Put that on an inspirational poster and hang it, I say!
Or is there…
gregladen | February 9, 2008Bad News: It's a Big Lizard!!
According to a report noted in Evolving in Kansas, Komodo Dragons have been hatched in Sedgwick County without fertilization by a male.
There are two of them, both males. (Isn't that interesting?) ...
I think they should name them Jesus and Brian.
gregladen | February 3, 2008There many ways of dividing up and categorizing Natural Selection. For example, there are the Natural Selection, Sexual Selection and Artificial Selection, and then there is the Modes of Selection (Stabilizing, Directional, and Disruptive) trichotomy.
We sense that these are good because they are "threes" and "three" is a magic number. Here, I'm focusing on the Mode Trichotomy, and asking that we consider that there are not three, but four modes of Natural Selection. This will cause tremors throughout the Evolutionary Theory community because Four is not a magic number, but so be it.
[…
gregladen | January 26, 2008... but it might be a sexual organ...
The Federal Communications Commission has proposed a $1.4 million fine against 52 ABC Television Network stations over a 2003 broadcast of cop drama NYPD Blue....The fine is for a scene where a boy surprises a woman as she prepares to take a shower. The scene depicted "multiple, close-up views" of the woman's "nude buttocks" according to an agency order issued late Friday.
...
The agency said the show was indecent because "it depicts sexual organs and excretory organs , specifically an adult woman's buttocks."
The agency rejected the network's argument…
gregladen | January 21, 2008Is chimpanzee food sharing an example of food for sex?
One of the most important transitions in human evolution may have been the incorporation of regular food sharing into the day to day ecology of our species or our ancestors. Although this has been recognized as potentially significant for some time, it was probably the Africanist archaeologist Glynn Isaac who impressed on the academic community the importance of the origins of food sharing as a key evolutionary moment. At that time, food sharing among apes was thought to be very rare, outside of mother-infant dyads. Further research…
gregladen | January 10, 2008 Why is there no Birth Control Pill for men?
This latest "Ask a ScienceBlogger" question will certainly engender a wide range of responses from the Scienceblogs.com team. Answers may address physiology, endocrinology, pharmacology, economics, and other areas of scientific thinking and practice. The answer I'd like to propose can be summed up in two closely linked words pilfered from the question itself:
Men. Control.
Myriad aspects of life can be understood by recognizing a single critical fact, and the layered, sometimes complex, deeply biological effects of that fact. Males, by…
gregladen | January 3, 2008Daily alcohol use by males has been shown to increase sexual arousal and decrease sexual inhibition.
In Fruit Flies.
The current (Jan 2) issue of PLoS ONE includes a paper by Lee et al exploring thye physiological side of changes in sexual behavior under the influence of alcohol, with an eye towards understanding this process in humans, using an animal model.
Alcohol has a strong causal relationship with sexual arousal and disinhibited sexual behavior in humans; however, the physiological support for this notion is largely lacking and thus a suitable animal model to address this issue is…
gregladen | December 13, 2007 173 medical staff from the emergency department of a Turkish university hospital responded to a questionnaire about domestic violence. 69.0% of the female and 84.7% of the male respondents declared that they agreed or partially agreed to at least one reason to justify physical violence.
[source]
This research is published in an open access paper on BMC Public Health. From the paper:
Violence against females is a widespread public health problem in Turkey and the lifetime prevalence of IPV ranges between 34 and 58.7%. Health care workers (HCW) sometimes have the unique opportunity and…
gregladen | December 4, 2007Go to any bar and you'll see a lot of males standing and sitting around not mating. I'll bet you would have guessed that the reason they are not mating is that no females will mate with them for one reason or another. But there is the distinct possibility that they are very inconspicuously resisting mating opportunities. It turns out that males can do this .... avoid mating without conspicuous resistance ... more easily than females. For obvious reasons.
This could be why what has become (inappropriately) known as "reversed sexual aggression" often goes unnoticed, and a recent study of the…
gregladen | December 4, 2007NEW YORK - Girls swept a prestigious high school science competition for the first time Monday, winning top prizes of $100,000 scholarships for their work on potential tuberculosis cures and bone growth in zebrafish.
It was the first time girls had ever won the grand prizes in both the team and individual divisions of the Siemens Competition in Math, Science and Technology.
...
The Siemens competition was begun in 1998 to recognize America's best math and science students. Finalists were chosen at regional competitions and flown to New York for a weekend that included bowling and a Broadway…
gregladen | December 3, 2007Sex differences in certain abilities, which have persisted for decades in various psychological tests, are now widely believed to be the result of conditioning that is in turn shaped by cultural factors. This applies to math abilities, spatial skills, and a range of other activities. Neural plasticity is key, and widely misunderstood or ignored. (Indeed, this is at the heart of the race discussion. Some people really want genes to "cause" different levels or kinds of intelligence, but are unable to explain how a few thousand genes wire up a few billion neurons ... but that is the subject…
gregladen | November 25, 2007According to a story in the last issue of Psychological Science:
... for most women, high sex drive is associated with increased sexual attraction to both men and women. For men, however, high sex drive is associated with increased sexual attraction to only one sex or the other, depending on the individual's sexual orientation. These results suggest that the correlates of sex drive and the organization of sexual orientation are different for women and men.
[This is a repost from Gregladen.com]
This is one of those studies where a perfectly good (i.e., falsifiable) hypothesis was being tested…
gregladen | November 21, 2007The male and female human brains are different. Some of the better documented differences are similar to differences seen in other mammals. They are hard to find, very small, and may or may not be of great significance. Obviously, some are very important because they probably relate to such things as the ability ... or lack thereof ... to bear offspring. But this is hardly ever considered in the parodies we see of these differences.
[Repost from Gregladen.com]
You have all seen the sometimes funny, sometimes not cartoon depictions of these differences, for example this one:
Obviously,…