Watching steak cook gets those juices flowing, and this may have been crucial for Paleolithic humans, having kicked a diet of mostly fruit, many thousands of years earlier.
In the warmer months at home in Toronto, I cook outside nearly every day over a combination of natural charcoal embers and live fire from wood I’ve collected from neighbours and friends: a lot of maple, and sometimes fruit wood from apple, cherry and even pear, which I use to add some splendid smoky taste to larger cuts of beef steak, among other things.
Tending the fire and watching a big steak change from raw meat to mouth-watering fare is far from unpleasant and always leaves me primed to tuck into dinner. When I have company, the meat on the fire never fails to gather the whole crowd, abandoning perfectly comfortable chairs on the patio for a stump beside the fire pit. We listen to the sizzle and delight at the bouquet of aroma as wisps of smoke erupt from orange embers, sporadically christened with savoury juices. And then we are all hungry.
That seeing, smelling and even thinking about food will prompt a gustatory response is hardly a new idea. The unappetizing-sounding cephalic-phase secretions, whether the drool of Pavlov’s dogs or the pre-absorptive release of insulin, are known to be beneficial digestive primers, readying the body to deal with the upcoming attack on homeostasis, which is what a big meal amounts to. Our impending dinner elicits hormonal and digestive responses long before our first bite, giving our bodies a head start at absorbing nutrients, dealing with the trade-offs, and returning our blood to normal levels as soon as possible.
Just as smaller amounts of cephalic-phase insulin are released in healthy humans who taste sweet things as they are ingested in order to avoid a brutally high insulin response later down the digestive tract, preparatory amounts of digestive enzymes are released along with other endocrine responses in anticipation of a meaty meal to come. This helps our taste buds in our mouths, stomach and intestines ―yes, we have taste buds in our stomachs and intestines―appropriately target and further signal our digestion to respond to what’s coming for dinner.
The same must have been true for our Paleolithic ancestors, who, at least near the end of the Lower Paleolithic Era, had access to both controlled fire and hunted meat.
Of course this would work with other foods, but preparing meat in the Paleolithic Era, like it does at my backyard fire pit, almost always involved public cooking over extended time. Meat was cooked in the open, and was often guarded, announced and socialized, even celebrated (as far as I can tell). Our move from a closed-system diet of mostly gathered fruit and leaves to a larger, changing system that often involved painstakingly hunted and prepared game was a big leap for us and happened relatively quickly, and I think must have needed other environmental, contextual and social cues to help as we developed new taste sensation priorities, becoming true omni-carnivores.
It was generally a long time before a hunted animal (or sometimes vegetable, grains in particular) ended up cooked, even after a successful hunt. Our ancestors’ diet-change was complete and radical in how it was acquired, what it consisted of, and how it was prepared (that it was actually prepared instead of merely gathered). Because this change was relatively sudden, measurable along the schedule of historical climate changes, it seems possible that our gustatory response to the prospect of this “new” food (a lot more meat), benefited from extended cephalic-phase prompting. That is, our digestion was not optimally geared to this level of carnivorism, and needed help revving up.
Spear and knife found in Mesa Verde National Park, resembling the Paleolithic.
This possibility fits within the culture of extended, public meat-cooking, and indeed it is hard to imagine a significant cephalic response from raw meat, which on its own is not appetizing to most of us, and has a much weaker smell to humans.
This possibility also fits within the necessity for the culture of cooking itself. Remember that our digestive systems, unlike true carnivores, are still not optimally geared to dealing with meat: meat must be cooked to a certain extent to kill pathogens and delay putrefaction (in the Paleolithic wild, at least), two things true carnivores had already adapted to.
Finally, this possibility fits within the drive to hunt at all. Unlike chimps, whose diet shifted to sometimes hunting and eating meat, even though they remained more or less in the same environment before this shift occurred, our ancestors’ incentive to hunt larger animals came about abruptly, relatively speaking, and may have needed a push to equate larger fauna with food. That push could have been the strong association that only a lengthy exposure to cooking smells, sounds and sights can imprint on our memories.
Most other warm-blooded vertebrates, including primates, spend much more time acquiring food than we do, and more time even than our Paleolithic ancestors did. Their diets either had far fewer elements, were on the whole less nutrient dense, or were simply harder to secure. It meant that they had to acquire and eat food much more often, necessitating wildly varying digestive responses, changing as their environment changed. What was true for us was true for our fellow beasts.
Sea lions, having lost nearly all their taste buds because they have a very limited diet, have a gustatory cephalic-phase response to the movement of their prey in their mouths, and even just to the movement of their prey. Theirs is a primed, paired-down response because they are specialists. Humans are on the other end of it: generalist, cultural eaters whose diets and gustatory systems are much more closely tied to cognition.
In truth there is so much that is not known about Paleolithic humans, whose fossilized remains and primitive tools exist but are quite rare, and in varying degrees of injury. Fortunately, this leaves plenty of room for imaginative, if woefully uninformed speculation.