The reason why life gets boring when you get older

(1)Dopamine is secreted at its peak when you’re 20 years old
(2)It decreases by 5 to 10 every 10 years thereafter
(3)When dopamine is reduced
(4)I feel like time is going by fast because I’m not very impressed and I’m not interested

(1)University of Minnesota psychology professor David Rykken surveyed 4,000 twins on their happiness levels and found that identical twins often shared similar levels of happiness regardless of their living standards
(2)Professor Ricken argues that about 50 percent of human happiness is determined by genes It means that a person is born with how bright and cheerful he or she is, how worried he or she is about how much he or she feels depressed
(3)Brain scientists such as Dean Heimer, a researcher at the U.S. National Institute, believe that happiness genes are likely genes that work on the brain’s dopamine neurotransmission system
(4)Professor Daniel Nettle, a psychologist at Newcastle University in England, said, “Feeling happiness is the brain’s work, and brain activity is determined by genes.”

(1)David T. Ricken
(2)Behavioural geneticist and professor emeritus of psychology and psychiatry, University of Minnesota
(3)It’s a twin study and a lie detection study
(4)be best known for