How did Henri Bergson explain the development of instinct and intelligence?

In his work Creative Evolution, Henri Bergson explained the development of instinct and intelligence as two diverging paths stemming from a single, fundamental life force known as the élan vital (vital impulse).12

Bergson proposed that this vital impulse is continually developing and generating new forms, rather than following a deterministic or mechanistic path. Within this process, he traced two primary lines of evolution:2

• Instinct: This line of development reached its peak in the life of insects.2
• Intelligence: This line of development resulted in the emergence of humanity.2

Bergson viewed both instinct and intelligence as manifestations of the same underlying vital impulse at work throughout the world. He argued that while intelligence is highly effective for acting upon the world through analysis and the creation of static concepts, it often fails to grasp the essential reality of life—which is characterized by duration and perpetual flux. To understand this deeper reality, Bergson emphasized the role of intuition, a global and immediate form of knowledge that reaches into the heart of things by sympathy.23