1859 English naturalist Charles Darwin proposes that intelligence is inherited in On the Origin of Species.
From 1879 Wilhelm Wundt applies scientific methods to psychology, seeking objective ways of measuring mental abilities such as intelligence.
1890 US psychologist James Cattell devises tests to measure differences in individual mental abilities.
1920s English educational psychologist Cyril Burt claims intelligence is mainly genetic.
1940s Raymond Cattell defines two types of intelligence: fluid (inborn) and crystallized (shaped by experience).
In 1859, Charles Darwin set out his theory of evolution ...