Anyone who has sucked milk on their mother's breast for a long time has a good chance of becoming a clever one (see cover story in this issue "IQ - the measure of all things"). This is confirmed by a new study of more than 3, 000 Danes headed by Erik Lykke Mortensen and Kim Fleischer Michaelsen. The scientists studied women and men born between 1959 and 1961 in Copenhagen. Intelligence tests showed that subjects who were breastfed for between seven and nine months had an average intelligence quotient of 106. In contrast, the IQ of subjects who only had their mother's breast for one month was only 99.4 on average. The subjects differed mainly in the verbal form of expression. The average IQ of the world population is 100. A quarter of all people have an IQ of over 110.