Dietary Variation in the Paleolithic
The Raw and the Rotten (6)
The diet of Homo habilis (Handy Humans: see previous post) may well have included more animal calories than contemporary Australopiths. Aside from cutting or smashing scavenged limb bones for the marrow, the hand axes could also be used to cut remaining scraps of muscle meat from those bones. But plants were a much more reliable food source and those hand axes were probably also used to smash and tenderize the tough fibrous parts, including roots and tubers. Given their dentition—thick enamel and large molars--the diet of handy humans is thought to have been primarily plant-based.
The human diet probably shifted somewhat with the evolution of Homo erectus, which means upright human. They evolved later than handy humans but their time on earth overlapped. Upright Humans had a long run (roughly 2.2 million to at least 100,000 years ago), the longest of any human species so far. This was also the first human species to migrate out of Africa.
Their scientific name refers to the significant skeletal changes, relative to earlier humans, changes that allowed them to walk and possibly run through wide open spaces, perhaps as well as modern humans. Upright Humans had left the trees for good and ranged widely over wide open (thinly forested) spaces.
All Upright Humans were much larger than Handy Humans. One of the most complete fossils Upright Humans, called Turkana Boy (I.6 MYA), who was 8-9 years old when he died, was already 5’3”. The first Upright Humans, though, had brains the size of other early human species. there was a noticeable increase in brain size during the long span of time Upright Humans walked the earth, though brain size was highly variable throughout that time-span.
The hand axes of Handy Humans are referred to as Olduwan, after the Olduvai Gorge in Tanzania, where they were first discovered. This is also called Mode 1 technology. Olduwan hand axes were only sharpened on one side. Upright humans developed more sophisticated stone technology, called Acheulian, after Saint-Acheul the site where these tools were first discovered, near present day Amiens in northern France. The technological advancement was to sharpen both sides of the stone, which had been previously flaked off a prepared core, into an oval or pear shape. Was this Mode 2 technology, along with their larger bodies, enough for upright humans to displace the large African carnivores as top predator? Probably not. It’s not obvious that those axes, even when attached to larger bodies, would be effective in killing large animals (100+ pounds). Nor were those hand axes a match for the teeth and claws of the real predators in any contest over a carcass. Though H. erectus was the largest humans to evolve until then, they were not physically prepossessing to any large carnivore. Some argue that working in numbers, in a coordinated way, might go far by way of compensation. There is a contentious debate over how much meat they obtained from scavenging or hunting.
Upright humans eventually colonized most of the southern (warmer) parts of Eurasia, from Spain to Indonesia. Their African exodus occurred as early as 1.9 million years ago, before the changes in brain size and shape. The main anatomical ingredient behind this unprecedented range expansion was not brains but bodies, specifically, those legs (and feet), which afforded long distance movement.
By 800,000—700,000 B.P. other human species had ventured beyond Africa. One species, Homo heidelbergensis—named for the site where the first fossils were discovered---predominated in Europe. Heidelberg Humans were the first to push into colder climes including the tundra, which was much further south then. Heidelberg Humans were much burlier than Upright Humans and just as tall. They were the first humans to specialize on large mammals, some believe their prey included mammoths.
It wasn’t because of their brawn; nor their stone tools, which were still Acheulean (Mode 2). They have to have had access to something more than a hand axe. Something that could be thrusted and thrown. Like a spear. Like a WOODEN spear. But as we have seen wood artifacts degrade much more quickly than stone artifacts, so we would expect to find the stone tips but not the shafts from this period. The first wooden spears recovered to date are around 300,000 years old and they only survived that long because they were preserved in the anoxic mud—antithetical to bacterial growth—of a lakebed. If not for that highly improbable burial they would have been gobbled up by microbes long before they were discovered.
It’s impossible to date the origin of spears. A conservative estimate would be between 800,000 and 900,000 years ago. So, Heidelberg Humans would have been familiar with them. The first probably consisted of a wooden staff sharpened at one end. Eventually, though, Heidelberg Humans, and probably Upright Humans, developed more sophisticated weapons. A big step forward was to attach a sharpened wooden or stone point to the front end. These could them be replaced, when broken; The hunter could therefor preserve his favorite—time-tested—shaft.
To attach these replaceable spear points requires planning. The shaft had to be pre-prepared. First, a groove was cut in which to insert the base of the point. Both the point and the shaft groove were slathered with an adhesive substance such as tree pitch or bitumen to secure the attachment. This is called hafting. The haft could be further stabilized with organic material that could function as twine, including fibrous plant material, strips of animal hide or intestine. Hafting could also be used to attach stone points to shorter pieces of wood to make axe-like tools or chisels.
The first spears were probably thrusted into the prey, but by 300,000 years ago the Heidelberg Humans were adept at throwing them as well, not haphazardly but with impressive accuracy. The thrown spears, even more than the thrusted, would make big game hunting more efficient but safer as well. Safer, certainly than the close contact required of stone hand axes. The sophisticated weaponry of the Middle Pleistocene Heidelberg humans is often attributed to their large brains—1250 cc on average.
In Europe, Heidelberg humans were succeeded by the even brainier and brawnier Neanderthals (Homo neanderthalis), the quintessential Ice Age human in the popular imagination. A lot of the conventional wisdom re Neanderthal Humans is, it turns out, quite wrong. It was long thought that cave art, for example, was unique to Homo sapiens. Not so. Some of the oldest known cave art was created by Neanderthals. More generally, Neanderthals were not the “Caveman” rubes they have long been made out to be. Rather, they were intelligent and culturally sophisticated, probably every bit as smart as Homo Sapiens. If, in fact, it is true that they lost out to Homo Sapiens through direct competition it was not for lack of brains; There’s were actually somewhat larger than ours.
Some believe their diets may have been a factor, that Neanderthals relied more on animal flesh than previous human species and their Homo sapiens contemporaries. On this view, The Paleo Diet might be more aptly labeled the Neanderthal diet. But it has become increasingly evident that even Neanderthals ate a lot of plant material. They ate fish, clams and other seafoods as well. The fact is, the demise of the Neanderthals remains a mystery, more a matter of speculation than science. And much of the speculation amounts to a prejudiced image burnishing of Homo sapiens by Homo sapiens. Marcus Feldman favors the view that Neanderthal extinction was mostly a matter of their small population size, which was longstanding. Small populations are particularly susceptible to random extinctions, a basic tenet of Population Biology.
Which brings us to us. Homo sapiens literally means “wise man”. Of all the distinguishing characteristics you might attribute to our species, wisdom is not the first that comes to mind. Instead, I will use the term “Modern Humans”.
The current view is that Modern Humans entered the evolutionary stage around 300,000 years ago. The brain size of the first Modern Humans were as large as ours, their skull shape was different though, albeit highly variable. In general, they were more elongated in the front, lacking the flat forehead characteristic of later modern humans. The Modern Humans that existed before 200,000 BP are sometimes called “early modern humans” (EMH), those that came after, anatomically modern humans (AMH). The changes in skull shape from EMH to AMH are generally attributed, though without much evidence, to a significant brain reorganization. The fact is that Modern Human skulls have always been highly variable, largely due to random processes that are inevitably enhanced in small populations.
Like all previous hominin species, we initially evolved in Africa; and there we remained for roughly 200,000 years. Our AMH ancestors made their first foray out of Africa to the Levant-- present day southwest Turkey south to the Sinai--more than 100,000 years ago. That first African exodus failed, however. Around 75,000 years ago, Homo sapiens were replaced in Israel by Neanderthals. This was a period of particularly erratic, high amplitude climate changes. The replacement of this small Modern Human population by Neanderthals was also probably a random event.
The next wave of AMH immigrants was more successful, perhaps because of larger numbers; they reached the Levant again, but kept on going, and going, and eventually colonized every habitat and virtually every place on earth. Nonetheless, Africa remained the center of our biocultural evolution. Innovations such as fishing, boat travel, the bow and arrow, and tools made of bone, were born in Africa. It wasn’t until about 45,000 years ago that the first of the Anatomically Modern Humans reached Europe. The Neanderthals were already there, of course. The two human species were no doubt cognizant of their differences but more than a few individuals interbred. The DNA of contemporary Europeans bears a Neanderthal signature, around 2%, East Asian DNA considerably more. Paleos have seized on this Neanderthal component in our genomes as an explanation for Celiac Disease, more on which later.
While still largely confined to Africa (200K-70K BP), the AMH diet broadened considerably, what is misleadingly labeled the broad-spectrum revolution. (A transition that occurs over more than 100,000 years is hardly a revolution.) Much of this dietary expansion resulted from increased exploitation of aquatic resources. Aquatic resources have been important sources of human nutrition from the earliest days. The best studied populations of Homo erectus preferred to live near water and inevitably learned to exploit aquatic resources. The AMH diet also included abundant and diverse aquatic animals: shellfish (from clams to crabs), fish (both marine and freshwater), waterbirds (ducks, geese, herons, shorebirds etc.) and marine mammals (including seals and beached whales). Aquatic plants, especially their bulbs and corms, were also a staple.
Some of the best evidence for the broad-spectrum revolution comes from temporary coastal encampments 200K to 100K BP. as evidenced by middens consisting of the shells of clams, abalone, mussels, oysters and such. The oldest fish bones recovered, from South Africa, are dated to 164,000 BP. Fishing may have arisen much earlier, the evidence erased by rising seas. This is true of Late Pleistocene coastal encampments worldwide, another form of preservation bias that may well distort our view of human diets. The Neanderthal diet also expanded during this period.
Out of Africa
AMH were but the last humans to migrate out of Africa and disperse to far flung parts of Eurasia. A previous consensus that there was but one migration of AMH has broken down. Many now believe it occurred at least twice. In the view of Chris Stringer there were three separate exoduses: An early migration around 90,000 years ago that might have been limited to the nearby Levant; a second migration around 70,000 years ago during which AMH quickly managed to get to Australia (by 60,000K, according to some estimates) via a southern coastal route; and a third migration around 45,000-50,000 years ago, during which Europe and Northern Eurasia were eventually colonized through various inland routes.
We bear no genetic legacy from the first migration. There is ample evidence in us of our African heritage from the third migration. The genetic legacy of the second migration seems to be confined to a few populations in South and Southeast Asia, many more populations in New Guinea and most indigenous Australians.
Omnivorous Throughout and Becoming More So
It should be clear by now that there is no such thing as “the Paleolithic Diet”, but many Pleistocene diets, all highly omnivorous and with a trend toward ever increasing omnivory. The elements of these omnivorous diets no doubt varied with habitat even when humans were confined to Africa. Once Upright Humans expanded their range beyond Africa, the variety of comestibles, and hence degree of omnivory would have increased. When AMH spread throughout the world we were aided immensely by our dietary flexibility. In all range expansions out of Africa, our species-wide diet became wider and increasingly culture-specific.
Whatever the diet of early hominins, it was consumed raw. At some point, probably in the Middle Pleistocene, cooking was invented. Cooking acted as a form of predigestion, rendering both animal and plant foods easier to stomach, a way to extract any nutrients more efficiently. But fermentation is another form of predigestion, which, some new research indicates, has a much more ancient origin.