Wednesday, May 17, 2006

Early humans had sex with chimps

"Our early ancestors interbred with chimpanzees after the two species drew apart millions of years ago, a new paper suggests.

The provocative idea is sketched by US genome experts, who have discovered that hominids and chimps diverged far more recently, and over a much longer timescale, than anyone had thought.

During this time, the authors theorise, the two primates were rather more than kissing cousins: they had sex, swapping genes before making a final separation."

"The ... analysis revealed big surprises, with major implications for human evolution," says Professor Eric Lander, director of the Broad Institute of Harvard University and the Massachusetts Institute of Technology, and co-author of the paper in today's issue of the journal Nature.

Until now, the belief was that humans and chimpanzees shared a common ancestor but went their separate ways around 6.5-7.4 million years ago. "

Genetically, chimpanzees are 98.5% identical to humans.

Looking at DNA

"Exploiting the mountain of data that has come from the human and chimpanzee genome projects, the researchers compared the genetic codes of the two species as they are today.

They believe that the two species made their split no later than 6.3 million years ago and probably less than 5.4 million years ago. In other words, around 1 to 2 million years earlier than the Toumai estimate.

Moreover, speciation of chimp and hominid, the process by which they emerged as separate species, took an extraordinary long time: around four million years in all."

Sex chromososmes

"Previous studies suggest that sex chromosomes are among the most vulnerable of chromosomes when it comes to interbreeding. This is because co-mingling places its genes under swift selective pressure.

Thus something unusual must have happened on the way to speciation: an initial split between human and chimp, followed by interbreeding, whose results show up in progressive younger genes, and then a final separation."

From: News in Science

Wednesday, May 10, 2006

Men's fingers and faces reveal masculinity and attractiveness to women

Both our faces and our fingers have a lot to reveal about ourselves.

New research suggests that women can spot subtle signs of interest in children in a man's face, and accurately assess his level of the sex hormone testosterone.

"Women are fine tuned subconsciously to detect the qualities they are looking for in a man - just by looking at his face."

The study was carried out by researchers at the University of Chicago and the University of California, Santa Barbara

Researcher Dr Dario Maestripieri said:

"Our results also show that women value masculinity as a desirable trait for short-term relationships and interest in infants as a desirable trait for more stable long-term relationships."

Pictures of the volunteers were shown to 29 female undergraduates, who were asked to rate the men according to whether they thought they liked children, appeared masculine, physically attractive, or kind. The women were then asked to determine men's attractiveness as short-term romantic partners or as long-term partners for relationships such as marriage.

The men women chose as being most interested in children were the same men who had expressed the most interest in children in the photo test. The women also accurately rated the men with the highest testosterone levels as being the most masculine.

Dr James Roney, who also worked on the study, said: "The research suggests that men's interest in children may be a relatively underappreciated influence on men's long-term mate attractiveness."

Other research, by Dr. Roney and Dr. Maestripieri, suggests that the ratio of the lengths of the second and fourth fingers (2D:4D ratio) is also associated with men's attractiveness as well as with levels of behavioral displays during social interactions with potential mates.

"Our results confirm that male 2D:4D was significantly negatively correlated with women’s ratings of men’s physical attractiveness and levels of courtship-like behavior during a brief conversation. These findings provide novel evidence for the organizational effects of hormones on human male attractiveness and social behavior."

Link to full article.

Another news article on finding mr. Right

A study on the attractiveness of the average face