Mr. Dolphin or Ms. Dolphin????

Ever tried to sex a dolphin? Me neither! But it seems like it is a difficult task for obvious reasons. A team of researchers decided to compare visible features (!) sizes, and scars! For those of you who get the wrong idea (admit it) I am talking about fins.

Via Nature News

"Rowe and Dawson found that male fins had significantly more scars than female fins, probably as a result of fighting. Male fins had a median of 15% scar tissue, whereas in females this was just 3.9%. Conversely, female fins tended to have a greater number of patchy skin lesions than male fins, with a median of 12.1% coverage compared with males' 6.8%.

The two then used a statistical analysis of scarring, number of fin nicks and fin size to correctly predict the sex of 93% of the 43 dolphins in the group. This laser-sighted technique could potentially be applied to other, less-studied populations of dolphin or even to other species, the scientists say."

Sweaty T-Shirts and Immunity

A corny question to ask a prospective mate might be: So...what is your zodiac sign? A better question could be: So, what's in your HLA? A few studies suggest that people tend to choose their mates based on MHC dissimilarity. A paper by Chaix et al. published in PLOS Genetics demonstrates that European American couples are really dissimilar when MHC loci are compared....way more different than what is expected by pure randomness. Although this selection could be a semi-counscious choice as stated by the following:

"In a less direct way, other studies have focused on odor preferences: in “sweaty T-shirts experiments”, in which females were asked to smell T-shirts worn by different males, it was shown that females significantly prefer the odor of T-shirts worn by MHC-dissimilar males, although such preference was not found among females taking the contraceptive pill. However, in another sweaty T-shirts experiment, in which males where chosen from a different ethnicity from the females and females were not aware of the nature of the smell (contrary to the two previous studies), females significantly preferred the odor of males having a small number of HLA alleles matching their paternal inherited alleles than the odor of males having fewer matches."

The authors also mention that this selection could be totally up to the egg to "choose" the right sperm cell....

Languages and genomes

While looking through Technorati I stumbled on this blog post..."Litterature - Can languages be understood by treating them like genomes?". That caught my attention because a few years ago, while teaching population genetics at Carleton University in Ottawa I told my students about this tribe on Vancouver Island: The Nuu-Chah-Nulth. I have great respect for the first nations and I wanted my students to learn from an anthropological point of view, not just through a stretch of nucleotides. While doing my research for my course I found a few articles including this one: Gene flow across linguistic boundaries in native North American populations.

Using statistical methods and mtDNA analysis, the authors found that language can in fact be replaced (or modified) faster than mutations can occur because language can be transmitted in a vertical fashion (just like DNA) as well as horizontally between unrelated people. Because first nations have been subjected to tremendous pressures through the centuries it is plausible to think that at times DNA might have evolved at different speeds when compared to language evolution depending on the tribe.


A few highlights:

• The Navajo and Apache, who reside in the Southwest, have high nucleotide diversities, in the range of nucleotide diversities in populations classified as Amerind speaking.
• Several sites were polymorphic only in populations classified as Amerind-speaking, but none occurred in all populations attributed to Amerind.
• With respect to Greenberg’s three language families, the average nucleotide diversity within populations is low in Eskimo-Aleut populations and high in Amerind populations. However, nucleotide diversity varies considerably among the populations classified as Na-Dene-speaking.
• The Alaskan Athabascan and Haida populations, who reside in the North, have low
  nucleotide diversities, in the range of nucleotide diversities in the Eskimo-Aleut-speaking populations.

When reading through the blog, I slowly realize that the author is a believer of intelligent design** and that, like all ID proponents, he decides to include some no-so-objective-god-related-stuff in his blog. Here's what he states while trying to explain why languages can not be understood the same way a DNA sequence can:

"The problem is that languages are fully teleological, whereas the tools of molecular phylogeny do not acknowledge teleology in genomes."

In other words...God created the languages...so do not even try to study them with objective techniques!

**Silly me...the title of the Blog site is: Literature - A discussion of ID-relating reading