Thinking Without a Brain

I could while away the hours
Conferrin’ with the flowers
Consultin’ with the rain
And my head, I’d be scratchin’
While my thoughts were busy hatchin’
If I only had a brain.

I’ve just finished reading Richard Dawkins’ The Ancestor’s Tale, and it’s had me thinking about the non-neurological component of intelligence.

Dawkins’ book is a journey backwards through our ancestors, cast as a pilgrimage to the “Canterbury” of the remotest common ancestor shared by all life on earth. It’s an interesting journey, in part because of the way it emphasizes the literal truth of the notion that all life is related. Reading the book puts you in the position of imagining what it was actually like to be a pre-human hominid, a shrew-like early mammal, a proto-vertebrate, a worm, an amoeba, a bacterium.

In the ‘later’ (that is to say, earlier) stages of that journey, you’re inhabiting a body that doesn’t have much in the way of a brain. And yet, despite their lack of big cerebral cortexes and the resulting large vocabularies that would let them do things like post rambling conceptual pieces on their weblogs, “simpler” organisms seem to have some pretty interesting abilities that are analogous to what we like to think of as the characteristically “human” manifestation of intelligence.

I also just finished reading Jeremy Narby’s Intelligence in Nature. Narby writes in his book about Martin Giurfa of the Centre of Animal Cognition Research in France, who, along with four co-authors, published The concept of ‘sameness’ and ‘difference’ in an insect. In Giurfa’s experiment, bees were trained to enter a simple Y-shaped maze that had been marked at the entrance with a particular color. Inside the maze was a branching point where the bee was required to choose between two paths. One path, which led to the food reward, was marked with the same color that had been used at the entrance to the maze, while the other was marked with a different color. Bees learned to choose the correct path, and continued to do so when a different kind of marker (black and white stripes oriented in various directions) was substituted for the colored markers. When the experimental conditions were reversed, rewarding bees for choosing the inner passage marked with a symbol that was different than the entrance symbol, the bees again learned to choose the correct path. “Thus,” write Giurfa et al., “not only can bees learn specific objects and their physical parameters, but they can also master abstract inter-relationships, such as sameness and difference.”

Narby also talks about slime molds, which in part of their life cycle resemble huge colonial assemblages of one-celled individuals who have fused their cytoplasm into a single enormous (well, by unicellular standards) cell containing thousand of nuclei. Narby visited Japanese scientist Toshiyuki Nakagaki, whose studies have shown that slime molds can “solve” a simple maze, arranging their bodies to lie along the shortest path between two food items placed in opposite corners (see Slime mould solves maze puzzle).

Plants, too, manifest something that could arguably be called intelligence. We hyperactive denizens of kingdom Animalia aren’t really wired to notice it, but on longer time scales plants adapt and respond to their environment, and research has shown that they actually respond surprisingly quickly (albeit in ways not easily visible) to outside stimuli of various kinds — all without benefit of brains, or even individual nerve cells.

Narby visits with Scottish scientist Tony Trewavas, who has been making waves in recent years by publishing studies describing what he refers to as “plant intelligence”. (See Root and branch intelligence and Aspects of plant intelligence.) For example, Trewavas talks about earlier research by CK Kelly showing that dodder, a parasitic plant that takes the form of bright orange twining tendrils (and which I happened to be checking out a couple of days ago while taking a hike in the Caprinteria salt marsh with my son), can quickly discriminate between a “good” host and a poor one, “choosing” in a matter of an hour or two how much of its resources to devote to a particular new host plant.

All of which brings me to the item I actually wanted to talk about when I started this posting: Scientists experiment with ‘trust’ hormone. It’s an article describing recent research into how the hormone oxytocin, which I’m mainly familiar with from its medical use in stimulating contractions during childbirth, can render people more trusting.

Oxytocin is secreted in brain tissue and synthesized by the hypothalamus. This small, but crucial feature located deep in the brain controls biological reactions like hunger, thirst and body temperature, as well as visceral fight-or-flight reactions associated with powerful, basic emotions like fear and anger.

For years oxytocin was considered to be a straightforward reproductive hormone found in both sexes. In both humans and animals, this chemical messenger stimulates uterine contractions in labor and induces milk production. In both women and men, oxytocin is released during sex, too.

Then, elevated concentrations of the hormone also were found in cerebrospinal fluid during and after birth, and experiments showed it was involved in the biochemistry of attachment. It’s a sensible conclusion, given that babies require years of care and the body needs to motivate mothers for the demanding task of childrearing.

In recent years, scientists have wondered whether oxytocin also is generally involved with other aspects of bonding behavior – and specifically whether it stimulates trust.

The article goes on to describe how researchers dosed experimental subjects with oxytocin, then had them play a simple investment game that revealed the level of trust they were willing to extend to a randomly assigned trading partner. Those who got the hormone were dramatically more trusting.

Researchers said they are performing a new round of experiments using brain imaging. “Now that we know that oxytocin has behavioral effects,” Fehr said, “we want to know the brain circuits behind these effects.”

I’m sure there’s more to learn about how the brain is involved in all this, but I wouldn’t be so quick to assume that it necessarily plays the most important role. Brains are a relatively recent innovation. For most of our collective history of living on the planet we haven’t had them — yet we’ve been intelligently negotiating our environment the whole time, presumably through the same sorts of complex chemical interactions that underlie the “intelligent” behavior of our distant relatives, the slime molds and dodder plants.

Okay. Done rambling for now.

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