Sunday, May 24, 2009

When most fertile, females choose the jerk

This paper, entitled "Changes in Women’s Mate Preferences Across the Ovulatory Cylce," examined how women rated men displaying certain characteristic indicators of good genes and good investment throughout their ovulatory cycle. First, a sample of women rated men based on the following traits and characteristics: “intelligence, warmth, degree of social respect, ability to be a good father, sexual faithfulness, capacity for financial success, physical attractiveness, muscularity, confrontativeness with other men, and arrogance." The men participating in the study as subjects also rated themselves based on these characteristics. Next, a different sample of women rated the attractiveness of each man as a long-term or short-term mate.

Their hypothesis questioned if mate preference varies depending upon where the woman is in her ovulatory cycle. They predicted that women would prefer good gene indicators when they are most fertile and good investment indicators in other contexts.

These indicators are important from a female perspective for a number of reasons. Females are capable of yielding a limited number of gametes in her lifetime. Gestation and lactation are also incredibly energy-consuming and required years of commitment before a woman is able to mate again to successfully rear another child. For these reasons, it is argued that women are the choosier sex.

Examples of good gene indicators are those phenotypes that correspond to good health and developmental stability. Particularly when women seek partners as short-term mates (ahem one night stands), it is predicted that she would prefer indicators of heritable fitness, or genes that will most likely yield successful offspring. Facial symmetry and masculinized physical features are examples of good gene indicators. They reflect good health and high testosterone levels, respectively. From an evolutionary standpoint, these indicators are advantageous because they will lead to fitness-enhancing characteristics passed on to the next generation.

They recognized that some traits, namely paternal investment indicators, had not been tested to empirically support the hypothesis that fluctuation in female preference does not extend to traits such as warmth, kindness, and faithfulness. They hoped to examine a wider variety of physical and behavior characteristics in men that serve as indicators of good genes and good investment.

Women’s ratings of men’s attractiveness were analyzed using a multilevel regression. The analysis described how women’s attraction to men as long-term or short-term mates related to the men’s characteristics (that both sexes were able to identify). They found that nine out of ten male traits were more preferred in the context of choosing short-term mates rather than long-term mates, including arrogance, muscularity, confrontativeness, etc.

They also analyzed women’s preferences for male characteristics as it relates to their degree of conception risk. In other words, they were looking for characteristics of men that women found attractive when they were most fertile, or at risk of producing a conceptus. They did find significant evidence that women preferred six traits of men for short-term mate interactions more when they were most fertile! These traits include confrontativeness, arrogance, muscular physical features, social respect, and physical attractiveness.

This supports the notion that women’s mate preferences predictably shift throughout their ovulatory cycle. When they are most fertile, women tend to preference indicators of good genes.

When they tested for fluctuations in female preference for long-term mates in good parental investment indicators across the ovulatory cycle, they found none. Women did not prefer parental investment mate qualities more when they were ovulating than when they were not.

These findings provide further support for the good genes hypothesis, which predicts women will prefer indicators of heritable genetic quality more when they are most fertile and assessing men as short-term mates.

Gangestad, S. W., Garver-Apgar, C. E., Simpson, J. A., and A. J. Cousins. 2007. Changes in Women’s Mate Preferences Across the Ovulatory Cylce. Journal of Personality and Social Psychology 92(1): 151-163.

Tuesday, May 12, 2009

High emotional intelligence linked with high orgasm frequency

According to a study in the Journal of Sexual Medicine, "variations in emotional intelligence--the ability to identify and manage emotions of one's self and others--are associated with orgasmic frequency during intercourse and masturbation."

In short, the study found:

Emotional intelligence was not associated with ... age and years of education, nor did we find a significant association between emotional intelligence and potential risk factors for [female orgasmic disorder] FOD such as age, body mass index, physical or sexual abuse, or menopause. We found emotional intelligence to be positively correlated with both frequency of orgasm during intercourse ... and masturbation .... Women in the lowest quartile of emotional intelligence had an approximate twofold increased risk of infrequent orgasm ... Low emotional intelligence seems to be a significant risk factor for low orgasmic frequency. Consideration of this behavioral risk factor may need to be incorporated into research into FOD and possible treatment approaches.

This is interesting, and probably a valid finding in that it appears to be statistically demonstrable that there is a correlation between measured emotional intelligence and orgasm frequency. The correlation is positive, modest (between 0.13 and 0.23 Spearman's, and confirmed with logistical regression), and statistically significant.

They also found through a study using matched pairs of twins a statistically significant difference in both emotional intelligence measured by standard tests and patterns of orgasm frequency.

A worthy consideration with which to read this article is that contributers to emotional intelligence come from both environmental and genetic variables. To assume this correlation is entirely due to genetics is presumably not entirely true.

Original Source:

Burri, A., Cherkas, L., & Spector, T. (2009). Emotional Intelligence and Its Association with Orgasmic Frequency in Women Journal of Sexual Medicine DOI: 10.1111/j.1743-6109.2009.01297.x

Sunday, May 10, 2009

Homosexual and masturbatory behavior observed in flour beetles

This behavior in the 0.13-inch-long (three-millimeter-long) Tribolium castaneum, which can be found infesting flour in most temperate areas, has been observed for decades

They found that homosexual encounters did not improve a male's sexual success with females, as measured by the number of offspring carrying his genes. There was also no connection between homosexual activity and social dominance—male beetles that had many sexual encounters with other male beetles did not earn more attention from females.

What the team did find was that males were dribbling sperm onto each other. This suggested that males might be trying to get rid of old sperm, lining up fresher sperm for their next female encounter.

The team also found that if one male leaked semen on another male and the semen-covered male later bred with a female, the female's eggs could become fertilized with the sperm of the male she had never encountered. That a male could inseminate a female without directly breeding with her came as a big surprise.

It reveals that the flour beetles' homosexual behavior yields a direct reproductive benefit, allowing males to inseminate females without expending time or energy having sex with them.
"We could not believe these results when we first saw them, so we ran the experiment over and over again to make sure it was actually happening," Lewis said.

Levan, K. E., Fedina, T. Y.; Lewis, S. M. 2009. Testing multiple hypotheses for the maintenance of male homosexual copulatory behaviour in flour beetles. Journal of Evolutionary Biology. 22(1):60-70.

Same-sex mating observed in fungal species

Cryptococcus neoformans is a major cause of fungal meningitis in predominantly immunocomprised individuals.

Recently it was discovered that C. neoformans can undergo same-sex mating under laboratory conditions, especially between α isolates. Whether same-sex mating occurs in nature and contributes to the current population structure was unknown.

In this study, natural αADα hybrids that arose by fusion between two α cells of different serotypes (A and D) were identified and characterized, providing definitive evidence that same-sex mating occurs naturally. A novel truncated allele of the mating-type-specific cell identity determinant SXI1α was also identified as a genetic factor likely involved in this process.

In addition, laboratory-constructed αADα strains exhibited hybrid vigor both in vitro and in vivo, providing a plausible explanation for their relative abundance in nature despite the fact that AD hybrids are inefficient in meiosis/sporulation and are trapped in the diploid state. These findings provide insights on the origins, genetic mechanisms, and fitness impact of unisexual hybridization in the Cryptococcus population.

This study provides the first evidence of this and sheds light on the genetic and environmental factors that play important roles in the evolution of the current population structure of this pathogenic fungus.

Lin X, Litvintseva AP, Nielsen K, Patel S, Floyd A, et al. (2007) áADá hybrids of Cryptococcus neoformans: Evidence of same-sex mating in nature and hybrid fitness. PLoS Genet 3(10): e186. doi:10.1371/journal.pgen.0030186