Yawns are more contagious among people with closer relationships.
163
Only about 2% of the world population has green eyes.
36
Approximately 4 to 5% of the U.S. population has one or more clinically significant phobias in a given year. Specific phobias occur in people of all ages. The average age of onset for social phobia is between 15 and 20 years of age, although it can often begin in childhood.
30
Awarding people money for doing well in IQ tests causes them to score better, $10 increased people's score by an average of more than 20 IQ points. IQ tests don’t just measure intelligence - they also measure effort.
9
Intelligent men tend to be more sexually faithful.
31