Triune brain

The Triune Brain Hypothesis was a once popular, now proven false,[1][2][3][4][5] model of the evolution of the vertebrate forebrain and behavior, proposed by the American physician and neuroscientist Paul D. MacLean in the 1960s.

The triune brain hypothesis became familiar to a broad popular audience through Carl Sagan's Pulitzer Prize winning 1977 book The Dragons of Eden.

MacLean proposed that the reptilian complex was responsible for species-typical instinctual behaviours involved in aggression, dominance, territoriality, and ritual displays.

MacLean regarded its addition as the most recent step in the evolution of the mammalian brain, conferring the ability for language, abstraction, planning, and perception.

MacLean originally formulated the triune brain hypothesis in the 1960s, drawing on comparative neuroanatomical work done by Ludwig Edinger, Elizabeth C. Crosby and Charles Judson Herrick early in the twentieth century.

[12][13] The 1980s saw a rebirth of interest in comparative neuroanatomy, motivated in part by the availability of a variety of new neuroanatomical techniques for charting the circuitry of animal brains.

Subsequent findings according to human brain evolution expert Terrence Deacon, have refined the traditional neuroanatomical ideas upon which MacLean based his hypothesis.

[13][16] Finally, recent studies based on paleontological data or comparative anatomical evidence strongly suggest that the neocortex was already present in the earliest emerging mammals.

[2] Howard Bloom, in his 1995 book The Lucifer Principle, references the concept of the triune brain in his explanations of certain aspects of human behavior.

Peter A. Levine uses the triune brain concept in his book Waking the Tiger to explain his somatic experiencing approach to healing trauma.

[19] Glynda-Lee Hoffmann, in her book The Secret Dowry of Eve, Women's Role in the Development of Consciousness, references the triune theory explored by MacLean and goes one step further.