A brain that analyzes input but can’t affect output doesn’t help survival, as an eye seeing danger isn’t useful if the muscles don’t move the body away from it. Given that every creature is in a basic feedback loop with its environment (Figure 6.20), the brain must control this loop to survive. but last century psychology split into two camps on the issue of what controls the feedback loop:
a. Behaviorism argued that people are machines driven by outside events, so stimuli and responses entirely define the loop and what the brain does.
b. Constructivism argued that the brain controls the loop by actively constructing reality, hence it can produce more sentences than we could ever learn from stimulus-response associations (Chomsky, 2006).
They differed on what controls the basic feedback loop, as in behaviorism it was driven by input but in constructivism, it was driven by the brain (Figure 6.21). Since a circular process can be initiated by a choice at any point, logic lets both be true, so the loop can be driven by external events or by brain events. Behaviorism then just reinvents Newton’s mechanistic universe, as did Dawkin’s selfish gene (5.7.2), and Crick’s pack of neurons (6.1.1). However biological evolution requires choice, and in psychology learning requires it, so brains must control the feedback loop to learn or evolve.
The brain isn’t input-driven as computers are but both face similar problems when they update. For example, when Microsoft upgraded the DOS operating system to Windows, it just replaced it, so decades of user learning suddenly became obsolete, as copying files by complex commands like xcopy now just needed a simple mouse drag and drop. If nature worked like this, the mammal brain would have replaced the reptile brain, making it obsolete, along with hundreds of millions of years of evolutionary experience!
That nature doesn’t discard advances but builds on them led an American Institute of Mental Health physician to propose Triune theory, that our brain is a reptile brain overlaid by a mammal brain overlaid by a human brain (MacLean, 1990) (Figure 6.22). He linked the reptile brain to the hind-brain cerebellum, the mammal brain to the mid-brain limbic system, and the human brain to the neocortex of higher thought. Autism was then just the reptile brain taking over, and anxiety was the mammal brain taking charge. In this view, evolution first evolved a reptile brain to handle movement, then a mammal brain to handle emotions, and finally a neocortex for human thought, so our brain was three brains in one, each overlaying the last.
The triune brain explained autism and animals, so Temple Grandin, an authority on animal psychology who is also autistic, wrote:
“To understand why animals seem so different from normal human beings, yet so familiar at the same time, you need to know that the human brain is really three different brains, each one built on top of the previous at three different times in evolutionary history. And here’s the really interesting part: each one of those brains has its own kind of intelligence, its own sense of time and space, its own memory, and its own subjectivity. It’s almost as if we have three different identities inside our heads, not just one.” (Johnson & Grandin, 2006).
However the triune model was rejected by biologists because evolution doesn’t deposit layers like geological strata, so as one critic put it: Your brain isn’t an onion with a tiny reptile inside. Evolution didn’t build a reptile brain, then a mammal brain, then a human cortex because it isn’t a linear production line. Nor did it add new brains without precedent, as bat wings are modified forelimbs that existed before, so even reptiles have a primitive cortex that lets them care for their young and solve problems (Patton, 2008).
Triune theory also didn’t explain how warm-blooded birds evolved from reptilian dinosaurs over millions of years. Birdbrain is a term of ridicule but they aren’t dumb, as crows can bend a wire into a hook to get food their beak can’t reach (Weir et al., 2002) (Figure 6.23), while children can’t use tools like this until about eight, and even then only half succeed (Cutting et al., 2014). Birds like nutcrackers can hide 30,000 seeds over a 200 square mile area and recover them six months later, so they are more like feathered apes than reptiles. For example:
“On a university campus in Japan, crows and humans line up patiently, waiting for the traffic to halt. When the lights change, the birds hop in front of the cars and place walnuts, which they picked from the adjoining trees, on the road. After the lights turn green again, the birds fly away and vehicles drive over the nuts, cracking them open. The birds wait patiently with human pedestrians for a red light before retrieving their prize. If the cars miss the nuts, the birds sometimes hop back and put them somewhere else on the road.” (Earthfire Institute).
Birds then are smart, but while the mammal cortex is folded, their cortex is smooth because it evolved differently (Jarvis & et al., 2005). Evolution then wasn’t just building a human brain, but rather bird and mammal brains evolved from the basic reptile design by different paths, that later converged to achieve equivalent functional benefits (Lefebvre et al., 2004). Triune theory doesn’t allow this, as it proposes that the hind, mid and forebrains evolved in sequence, so an alternative that allows them to evolve simultaneously is now explored.