Brains. What are they good for? Why do we—and loads of other animals—have them? What is the point of evolving increased neural complexity? Brains obviously confer advantages, or they would not survive the gauntlet of evolution. They must also exact a cost, or every creature would boast a headpiece of enormous potential. If every living being had a giant brain—or even a modest one—the ecological web of life would surely fail, so that brains are a niche evolutionary strategy possessed by a small minority of species, enabled only by the presence and support of the whole.

Early brains—and I’m thinking worms, here—facilitated regulation of bodily functions, and humans preserve those essential features in the brain stem. Reptiles developed the capability for more complex calculations, assessing a number of simultaneous inputs to guide decisions of fight or flight, for instance. Selection (evolution) saw to it that these calculations were, on average, functionally “correct,” becoming more nuanced over time. We, too, preserve these well-honed instincts deep in our brain structure. As animals evolved (e.g., mammals, but not exclusively so), they developed a cerebral cortex and limbic system to navigate social arrangements and better adapt to varying conditions. This is where emotions originate. Some mammals then doubled-down on this nifty cerebrum thingy to develop a neo-cortex with all sorts of cool lobes (like the frontal one) capable of forming ever-more sophisticated mental models of the wider world—allowing flexible adaptation informed by years of development and model-building during a long process of individual maturation. Among other things, culture arises from this cerebral capability (culture being socially-learned behaviors that are not stamped in genetically, as practiced by many social animal species).

In short, brains serve to form mental models of the world that help us flexibly adapt and survive. Our models are not constrained to be correct, as long as they are useful in some functional, adaptive, average sense. I’ve taken to using the term “meat-brains” to help drive the point that brains are just organs—however sophisticated—and to poke at our cultural worship of brains, to the point of being dismissive of any life not boasting comparable cognitive capacity. But having a large brain is not everything, and in fact has demonstrated itself to be one of our greatest liabilities—by conceiving and enacting modes of living not ecologically contextualized and vetted to, you know, actually work in the long term—to the tune of initiating a sixth mass extinction. Like any evolutionary adaptation, it can be taken too far.

Incidentally, I wrote this and last week’s post roughly in parallel a few weeks back, and did not carefully coordinate their order of appearance: they might have been arranged either way. Some themes are common to both, but they might be thought of as siblings that belong together.

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