Random Thoughts

[Angrboda]

You Don't Actually Have A 'Lizard Brain', Evolutionary Study Reveals

A new study has shown that the concept of the mammalian 'lizard brain' can be well and truly put to bed.

Based on a study that examined brains of bearded dragons (Pogona vitticeps), large lizards from the Australian desert, scientists have shown that mammal and reptile brains evolved separately from a common ancestor. It's another nail in the coffin of the notion of the so-called triune brain.
Skip advert

The idea of the lizard brain first emerged and rose to popularity in the 1960s and 1970s, based on comparative anatomical studies. Parts of the mammalian brain, neuroscientist Paul MacLean noticed, were very similar to parts of the reptilian brain. This led him to the conclusion that the brain had evolved in stages, after life moved to land.

First, according to MacLean's model, came the reptilian brain, defined as the basal ganglia. Then came the limbic system – the hippocampus, the amygdala, and the hypothalamus. Finally, the neocortex arose in primates.

Under the triune brain model, each of these sections is responsible for different functions; the more basal parts of the brain, for example, were supposedly more concerned with primal responses – like basic instincts for survival.

However, neuroscientists have been decrying the model for decades. The brain just doesn't work like that, in discrete sections that each play a separate part. Brain regions, anatomically distinct as they are, are highly interconnected, a web of humming neural networks. And with the advent of new techniques, we can start to better understand how brains evolved.