Will we ever completely understand how our brains work? Since all our mental activity relies on our brains, this is a question about self-intelligence. If we rely only on introspection, humans are not reliable judges of themselves. Scientific understanding of our brains and their evolutions can help. First, understanding the evolution of brain and intelligence explains why our knowledge and decisions are frequently biased. Second, the same evolutionary considerations give us insights about the failures and negative consequences of self-intelligence, not only in psychiatric conditions, but also in healthy individuals. Finally, scientific understanding of human self-intelligence is necessary to maximize the benefits of artificial intelligence to our society. Daeyeol Lee studied economics at Seoul National University and received his Ph.D. in neuroscience from the University of Illinois at Urbana-Champaign. After postdoctoral training at the University of Minnesota, he held faculty positions at Wake Forest University and University of Rochester before joining the Department of Neuroscience at Yale School of Medicine in 2006. He pioneered the neuroeconomics field, and made important discoveries about the prefrontal cortex function related to reinforcement learning. His interests include behavioral economics, time perception, numerical reasoning, computational psychiatry related to addiction and impulsivity, artificial intelligence, and evolution of intelligence. He published numerous articles in leading journals, including Science, Nature, and Neuron. He is a member of the editorial board in eLife and the steering committee of Kavli Institute for Neuroscience. He is the author of Birth of Intelligence, and a co-founder of Neurogazer. This talk was given at a TEDx event using the TED conference format but independently organized by a local community. Learn more at www.ted.com/tedx