Despite slang terms that imply otherwise, the human penis contains no bones. The same cannot be said for many of our closest evolutionary relatives: Chimpanzees and bonobos both have penis bones (a macaque one is pictured, left), also known as bacula.
To find out why some primates have the feature whereas others don’t, researchers traced the bone’s evolutionary history through time. The baculum first evolved between 145 million and 95 million years ago, as reported in the Proceedings of the Royal Society B. That means it was present in the most recent common ancestor of all primates and carnivores. Why some descendants, like humans, lost their bacula appears to be due to differences in mating practices: In primates, the presence of a penis[ ... ]
Early birds and night owls have radically different daily habits. But a new study suggests they both share one trait: As the clock ticks, their decisions get dicey. Neuroscientists examined the quality of moves in more than 1 million games of chess in an online database. They charted the decisions of 99 prolific players by gauging the time they took for each move and its usefulness in leading to a victory - factors that impact games like high-speed tiebreakers in the World Chess Championships.
As expected, early risers played more games in the morning, whereas night owls were active at dusk and beyond. But both sets of players took longer for each move and made better game choices early in the day and soon after they woke up. Come evening, [ ... ]
A new study that's challenging the popular idea that we should drink eight glasses of water a day for health purposes shows that a 'swallowing inhibition' is activated by the brain after excess liquid is consumed. This inhibition mechanism helps maintain tightly calibrated volumes of water in the body.
The lead scientist has pointed out that if we just do what our body demands us to, we'll probably get it right. In other words, it is the best practice to just drink according to thirst rather than an elaborate schedule.
Building on a previous study, the researchers asked participants to rate the amount of effort required to swallow water under two conditions; following exercise when they were thirsty and later after they were persuaded to drin [ ... ]
In a new study, scientists have discovered that early marijuana use may result in abnormal brain function and lower IQ. To conduct this study, four groups of teenagers were recruited:
Those with depression who were not marijuana users
Those with depression who were frequent marijuana users
Frequent marijuana users without depression
and healthy individuals who were not marijuana users
Participants were later divided into youth who started using marijuana before the age of 17 and those who began using it later or not at all.
These participants underwent psychiatric, cognitive and IQ testing as well as brain scanning. The study found no evidence that marijuana use improved depressive symptoms; there was no difference in psychiatric symptoms between [ ... ]
According to a new study on human behavior, 90% of the population can be classified into four basic personality types: Optimistic, Pessimistic, Trusting and Envious. However, the latter of the four types, Envious, is the most common, with 30% compared to 20% for each of the other groups.
If you're the type of person who doesn't mind what you achieve, just as long as it's better than everyone else, then you're considered envious. Optimists, which account for 20% of the people tested in the study, are those who believe that they and their partner will make the best choice for both of them. Pessimists were defined in the study as those who selected the option which they see as the lesser of two evils - they accounted for 20% as well. The trusti[ ... ]
At least to some scientists it is. Scientists believe that catching a yawn is a sign of empathy, since it is more likely to occur between relatives than strangers. Plus, other social primates like chimps and bonobos do it, too. A new study suggests that women (traditionally branded the more empathetic sex) might be more susceptible to copycat yawning than men. Researchers surreptitiously analyzed more than 4000 real-world yawns on planes and trains, in restaurants, and in offices. They noted when someone yawned, and then whether a nearby acquaintance or friend did the same within a 3-minute period. Men and women spontaneously yawned with about the same frequency. But when someone else yawned first, women were more likely than men to follow [ ... ]
Seeing through objects may seem like something straight out of a comic book, but researchers have found a way to make entire animals transparent - from their brains to their bones. The method lets fluorescent proteins visibly shine through bodies, lighting up entire vascular systems (above) and other structures. To produce such light shows, researchers treat euthanized rodents with several organic solvents to remove the water and lipids that made them opaque. The technique is dubbed uDISCO because it’s a variant of the original DISCO technique, which stands for 3D imaging of solvent-cleared organs. This technique allows the highest resolution images yet for a whole body, its creators report online today in Nature Methods, and it can create [ ... ]