Meet the Flintstones?

The Raw and the Rotten (5)

In 1960 an animated cartoon, The Flintstones, first aired on national TV. There were only three networks at that time and they all turned to annoying noisy static screens at midnight after an obligatory rendition of the National Anthem, so competition for time slots was fierce. The Flintstones not only managed to find and keep their slot for seven years, they did so for the most coveted part of the daily schedule, Prime Time. The Flintstones was the first animated series to air on Prime Time. It remained the only animated series on Prime Time until The Simpsons, which first aired in 1989.

The success of the Flintstones remains a mystery to me.  It was related to its central comedic premise, the transportation in time of then contemporary family life into the Stone Age. This vision of the stone age was certainly idiosyncratic—except to Creationists—replete with dinosaurs, in addition to standard Ice Age fauna such as mammoths and sabertooth cats. Moreover, the male protagonists, Fred Flintstone and his friend Barney Rubble, were exceptionally well groomed by caveman standards, hair cut short and faces clean-shaven. Their permanent and prominent five o’clock shadows, thick bodies and large heads sans necks were the primary indicators of their cavemanishness. That and their animal skin attire, coarsely cut, as if with a sharp stone tool. Incongruously in that respect, Fred always wore a tie. Their wives, Wilma and Betty, were even better groomed, their hairstyles recognizably fashionable to viewers, and their attire quite fetching.

Whatever liberties the creators took in creating Paleolithic conditions, their portrayal of modern family life was quite orthodox, reflecting the norms of the 1950s and early 1960s. Fred and Barney “brought home the bacon” (or dino ribs), Wilma and Betty were homemakers and especially, shoppers. The family dynamics aped the tropes of the popular sitcoms at that time; Fred Flintstone was modeled after Jackie Gleason’s character in the Honeymooners.

The comedic vision throughout relied on anachronisms resulting from a sort of time travel to the past. A currently popular school of thought also views the human condition as anachronistic but with the opposite arrow of time. From this perspective, we are Stone age Creatures abruptly hurled into the Information Age. It is alleged that “human nature” evolved in a period called the Paleolithic, spanning over three million years. And we remain adapted to these conditions. Unfortunately, about 10,000 years ago everything changed in an evolutionary eyeblink when humans started farming. This so-called Agricultural (or Neolithic) Revolution changed everything for us, so quickly, so drastically, that our “paleo selves” got left behind. There was simply not enough time for our genes to catch up with this cultural shift, psychologically and dietarily.

Think of a caveman, emerging from a Manhattan subway. You can shave him, dress him with suit and tie, but he’s still a caveman. Even if thoroughly socialized to these modern urban conditions, he will find himself inherently out of synch with the times, his biological nature at odds with the cultural conditions he must navigate. There is more than a hint of Freud here (see, in particular, his Civilization and its Discontents.)

The adaptive mismatch views are characteristic of Evolutionary Psychology, Darwinian Medicine, the Paleo Diet and most recently, Pegans (Paleo Vegans). There are several defects in this mismatch framework. Perhaps most fundamental is that there was no Agricultural Revolution, more like a seamless transition from foraging to farming over many thousands of yeaars. Moreover, humans continue to biologically evolve to the present day; if anything, the rate of human biological evolution has accelerated in response to the cultural conditions we create. This is called biocultural coevolution.

In this post I turn to the putative Paleolithic environment to which we are alleged to be matched, when “Human Nature” is claimed to have been fixed. Mismatchers seem to think that there was some generic Paleolithic environment, called the “environment of evolutionary adaptation” to which we are genetically adapted, from our behavior to diet.

I will focus on diet. As a number of archaeologists and anthropologists have emphasized, there was no such thing as a generic Paleolithic environment and no such thing as a generic Paleolithic diet. Paleolithic foods varied widely over time and space. At the outset of the Paleolithic tour ancestors ate their food raw, by the end, our food was cooked. At the outset of the Paleolithic our ancestors were confined to Africa, by the end, humans inhabited virtually every corner of the earth. Our only dietary adaptations to the wide variety of Paleolithic environments was to become dietarily flexible, uber-omnivores.

Before the Paleolithic

But before we get to the Paleolithic we need to consider the four to five-million-year period that preceded it, a formative period in human evolution.

Let’s begin at the point in time when the human lineage—called hominin—parted evolutionary ways with the chimpanzee/bonobo lineage 6-7 million years ago. Paleontologists are particularly interested to track changes in brain size (based on skulls), diet (based on jaws and teeth), the transition to upright walking (based on hips, legs and especially feet), and manual dexterity (based on wrist, hands, and fingers, especially the thumb). Archaeological evidence of tool-making has, from the outset, figured prominently in these investigations. New discoveries are frequent, many undermine previous conventional wisdom about how we came to be and when. Only the fossils are set in stone. In what follows I paint with a broad brush.

The first thing to note is that there was nothing like a linear change in any of these traits; nor were changes in these traits highly correlated. If modern humans are used as the standard, mosaicism ruled. Moreover, the hominin lineage is quite bushy and at any given evolutionary point in time, there were several of these hominin mosaics “walking” the earth. Actually, the first well characterized hominins didn’t do a whole lot of walking. But they certainly walked better than chimps. Grouped in the genus Ardipithecus, they lived from about 5.5+ million to 4+ million, years ago. Ardipithecus seem to have spent more time on the ground than chimps, taking advantage of a general drying trend that left forest more open, less dense. The first discovered is quaintly referred to as Ardi. Like all subsequent hominins Ardi was an omnivore with a more varied diet than the most omnivorous chimps. The increased omnivory is thought to reflect increased time spent on the ground and consequent exposure to novel food sources. On the plant side fruits were still important, but Ardi also ate somewhat tougher plant materials than chimps, such as tubers and hard hulled nuts. On the animal side there was also greater variety, probably including insects, snails, eggs and small vertebrates, such as turtles, birds and porcupines. Ardi’s brain though was about the same size as that of a chimp or bonobo, slightly smaller according to some.

The next group of species to appear in the hominid lineage are members of the genus Australopithecus. The first Australopith appeared about 4.4 million years ago and other species were around until about 1.5 million years ago. Australopiths were more committed to a bipedal mode of locomotion and lived in a more open environment than Ardipithecus. But they were still pretty comfortable in the trees. Though omnivorous their diets included much more plant than animal material. Of the former, fruits remained important but their thickened tooth enamel relative to Ardis indicates that Australopiths also consumed tougher plant material such as grasses, nuts and tuberous roots. Animal foods included invertebrates and small vertebrates; they may have scavenged the carcasses of larger prey.

It is doubtful that Australopiths hunted themselves. Given the abundance of large carnivores in their habitats, lion-size or larger—including a giant hyaena that no doubt figured prominently in Australopith nightmares—they were more prey than predator. Their brains were somewhat—but not dramatically--larger than those of chimps, averaging 466 cubic centimeters versus an average of 360cc for chimps. There was considerable variation but no discernable trend toward increased brain size during the three million years that Australopiths walked the earth.

Paleolithic means “old stone age”, and its onset corresponds to the first evidence of tool use around 3.3 million years ago. Obviously, it’s an anthropocentric—and technology based—demarcation of time preferred by archaeologists, not the geological term preferred by paleontologists. Even as an archaeological term, “Paleolithic” is misleading.  In the words of archaeologist John Hoffeker, “A fundamental irony of Paleolithic (or “Old Stone” Age) archaeology is that it concerns a period of human history when most artifacts probably were made from wood”. But wood decays much more rapidly than stone, so most of what can be found is made of stone, not wood. This state of affairs is called preservation bias. The upshot is that the absence of evidence is not evidence of absence. And it applies equally to inferences about past diets. Animals parts, particularly bones and teeth, persist much longer than plant material. And mammal parts persist much longer than the hard parts of birds, fish and insects. These preservation biases may well have skewed interpretations of what our ancestors ate, in particular, the emphasis on mammal meat. We will come across other diet-related preservation biases later.

The Tumultuous Pleistocene

Most of the Paleolithic period occurred during what geologists call the Pleistocene (about 2.6 million years ago to 11,700 years ago). In popular culture the Pleistocene is known as the Ice Ages. The Pleistocene was a particularly dynamic period of time climatically. Glaciers advanced and retreated in Northern Eurasia multiple times. During the advances much of Europe was under ice. Sea levels rose and fell just as dramatically. During glacial maxima sea level was up to 450 feet lower than at present. You could walk from Malaysia to Bali. Those parts of the world not directly affected by glaciation, such as interior Africa, were nonetheless impacted in huge ways. During glacial advances conditions became cooler and dryer. Forests, including rainforests, shrunk dramatically; grasslands and deserts expanded. The opposite occurred during periods of glacial retreat. It was under these dynamic conditions that all human species evolved.

A species called Homo habilis ({2.3-2.8}-1.65 MYA), was an archetypal early Pleistocene human. (Homo means human, so I will refer to all members of the genus, not just Homo sapiens, as humans.) The species name, habilis, means skillful, able or adept in Latin. Mary and Louis Leaky who first discovered this species waggishly referred to Homo habilis as “handy man”, primarily because the first fossils were found with clear evidence of stone tools, mostly rocks that were smashed with other rocks to make jagged edges on one side for cutting.

When the manufactured rock tools were discovered it was assumed they were primarily used to process meat. But it Is now widely agreed that they would be just as useful for processing tough plant material. To the extent that stone tools were used to process meat, it was mostly scavenged meat, especially as it relates to bone marrow, which is both nutritious and delicious. Much of the marrow is concentrated in the center of the limb bones.

Handy Humans couldn’t kill this kind of prey with their primitive hand axes but they could scavenge them from the carcasses of animals killed by any one of a large number of large predators roaming the premises. There were different ways they could have scavenged. One is to scare off the large predators—say, a sabre-tooth cat--soon after the kill, before the sabre-tooth is sated and ready to leave anyway. A lot would depend on the species of sabre-tooth; there were several. On the large end of the size spectrum was one species that was significantly larger than today’s African lion. Even worse, from the perspective of Handy Humans they seemed to have worked in packs. But just one of those formidable creatures should deter a group of hobbit sized Handy Humans (3’3”-3’11”; 45-80 lbs.) armed with their unimpressive weaponry. If Handy Humans were aggressively scavenging to any degree, it was from the kills of much smaller predators and hence the corpses of much smaller prey.

The second kind of scavenging is much less dangerous because non-confrontational. The downside is that the scavenger only gets the leftovers, which are often meager and putrefied. Fortunately, some of the most likely leftovers would be the marrow-laden limb bones. Sabre-tooth and other large cats cannot crack these bones. The giant hyenas, however, could. So, one reason those giant hyenas were the stuff of nightmares for Handy Humans is that they were in direct competition for the marrow. In any such competition Handy Human would have been the loser. Again, this suggests a reliance on smaller prey with which the hyenas would not bother. But there was always the occasional elephant, hippo or rhino corpse from a natural or accidental death. These could last for weeks, though in an increasingly putrefied state.

This brings us to a longstanding dispute in the anthropology community with respect to the meat component of the Pleistocene human diet. Beginning in the 1960s, The Man-the-Hunter (and Woman-the-Gatherer) narrative has shaped perceptions about human meat consumption regarding both the quantity of meat consumed and the way it was procured. Traditionally it was assumed that early humans were effective hunters of largish mammals such as antelopes and hence consumed their meat fresh. Beginning in the 1970s, though, a few notable mavericks proposed instead that meat was mostly obtained through scavenging in the early Pleistocene and that scavenged meat remained important throughout the Pleistocene, even as humans became more adept hunters. The debate continues. A relevant consideration relates to stomach acidity.

In arguing for the importance of meat obtained via hunting relative to plant foods obtained through gathering, advocates of Man-the-Hunter call attention to the fact that contemporary humans have extremely acidic stomachs. This is significant because the stomachs of herbivores have very low acidity, those of omnivores are significantly more acidic, while those of carnivores are even more acidic. Meat, it seems, requires acidic preparation for digestion. Therefore, we must derive from top carnivores of lion-like proficiency.

But the acidity of human stomachs far exceeds that of lions. The only creatures with stomachs as acidic as ours are scavengers, vultures for example. The highly acidic stomachs of vultures are thought to function as a pathogen filter, given their penchant for microbe-infested putrid flesh. The acidity of human stomachs is consistent with a significant scavenged dietary component. Moreover, early humans would be unique amongst predators if they didn’t augment their diets with scavenged remains. Lions and wolves are prolific scavengers as well as hunters. (To Be Continued)