A Method of Dying
"Death comes to all, but great achievements build a monument which shall endure until the sun grows cold." _Emerson
The brain is an expensive organ. It consumes 20-25% of the adult, and 70-75% of the infant (newborn), energy stores; 2/3rds of this organ is composed of fats. Your brain uses these fats from your diet to build it's cell membranes. Myelin, the protective tissue that sheaths neurons, is 30% protein and 70% fat. Myelin is essential to our nervous system, as it accelerates nerve impulses and neuron communication. This efficiency allows for the brain and nervous system to streamline.
Mammals have a distinction, in that, we do not lay eggs and expel a tremendous amount of energy in supplying the external embryo with nutrients. Instead, the placenta provides such calories and reserves internally, with 70% of its energy destined for brain growth. While pregnant, the fatty acids derived from diet are supplied to the fetus, and continue to fuel its external development through breast milk. Yet the brain grows most rapidly in the womb. Any deficiency in the required amount of fat intake diminishes the placenta, which leads to low birth weight, and most importantly, a smaller brain size at birth - endangering or dooming development and cognition. Thus, fat is the key building block to brain growth and cognitive ability.
The human female is the foundation and driver of the vast majority of our evolution. Aside from birthing our entire species, pregnancy and lactation - her dietary needs are what propelled our subsistence and social strategies.
"During the time a mother is breastfeeding, complex hormonal adjustments in her system forestall menses in all but a few cases. Within a month or two after separating her toddler from her breast, just as night follows day, the mother begins to menstruate again. But a new factor will cause her to loose more blood than she did prior to her pregnancy. Once a woman has had her first child, the increased size and more robust vascularity of her uterus will cause a small but significant increase in menstrual loss of iron. Each subsequent pregnancy will be followed by a slightly heavier menstrual flow, and this trend will continue for the rest of the woman's reproductive life.
By one avenue or another, a woman is always losing iron. Over a lifetime, the average woman loses the equivalent of approximately fifteen gallons of iron-rich blood due to menses, pregnancy, delivery, birth trauma, etc...."
_Leonard Shlain, Sex, Time and Power
Hemoglobin is an iron-rich protein which makes our blood red. The iron in hemoglobin seeks out and "grabs" oxygen, releasing it where needed, making it the most efficient carrier of oxygen to every organ in the human body. Hemoglobin plays the key role in neuron function. Blood loss of any kind results in a loss of hemoglobin, thus iron to carry oxygen through the circulatory system. The result is inertia, anemia and a weakened immune defense. "This sets up a vicious cycle to break. The more anemic a woman is, the more blood she loses, making her more anemic and causing increasing iron loss."(L. Shlain, 2003)
On average, a human female loses up to 40 quarts of blood during her lifetime of menses. Every four weeks, a woman sheds her uterine lining with several (4-8) milliliters of blood loss; Nature's way of ensuring an optimized environment for fetal development. In utero, the only source for iron for the fetus is the mother's stores. The mother must keep up the oxygen supply to her developing fetus in the womb, without neglecting her very own oxygen requirements. In the last months of development, the fetal brain consumes 3/4th's of the energy delivered by the umbilical. Laying out all of the blood vessels of the human female's placenta would stretch thirty miles (L. Shlain, 2003). The Daily Energy Expenditure (DEE) for a woman of reproductive age is, thus, slightly higher than the adult male - despite larger male body size.
Anthropologists have noticed that menses, and the amount of associated blood loss, has increased throughout the history of our species. In my view, this has strong correlation with brain development.
There are 400 miles of capillaries within the human brain. The health of that vascular system and the blood it contains is vital to brain performance, vital to higher intelligence.
Some 3,700 years ago, Hammurabi, ancient law-giver and the king of Babylon, had delivered his famous code - "an eye for an eye." Civilization was quite underway. And half a world away, on Wrangel Island, off the cost of Siberia, the last woolly mammoth fell into extinction.
In the last post, we discussed the clades and refugia of our human ancestors. Consider as well, that these refugia were home to other fauna/flora than ourselves. That, in our migration, tracking and hunting of large game, equally at the mercy of climate change, is what led us Out-of-Africa and into these New World refugia. At the outset, some 1.9mya, at the time of Homo erectus' first migration, there were 12 species of proboscids (elephants) that roamed the planet. Today, there exists only 3 (African savanna, African forest, and Asian). And those 3 genetically diverged at the beginning of the time when Homo erectus left Africa.
During these Pleistocene times, between glacials and interglacials, stadials (lower temperatures during interglacials) and interstadials (slightly warmer during glacials), the average temperature could change by as much as 41°-50°F, within a few decades time. During glacial maxima (heavy ice ages), the temperature could be up to 69.8°F colder in comparison to today. "Only during these times did the northern hemisphere conform to the movie image of the Pleistocene with extensive glaciers covering large parts of Eurasia and North America...sea levels being 393ft lower, exposing more land mass. The British Isles were connected to Europe and the North Sea being a large area of dry land. ...It was during these times that elephants (extinct species) and hippopotamus were living as far north as the British Isles." (Hofreiter & Stewart, 2009) At 700kya in East Anglia, England, Homo heidelbergensis had tracked these proboscids and pachyderms to the western edge of Europe.
The increase in brain size undoubtedly forced a necessary shift in diet - making larger, fatter game attractive and necessary. For Australopiths like Lucy, from whom our genus Homo evolved, the intake of plant foods was not enough to feed a growing brain. The very acquisition of plant foods was so time consuming, it left little space for anything else. In observance of baboons, "devoting almost all of their daylight hours to painstakingly seeking out small, nutritious food items...adult male baboons may pick up as many as 3,000 individual food items in a single day." (Milton, 1987) They lacked the capacity to adapt both in subsistence and against the pressures of climate change. So, with Homo erectus, none of the physical traits that accompany a high amount of plant food consumption are found in their skeletal remains. Their teeth and jaws are smaller than their predecessors, indicating a shift to a diet that includes, not only meat, but cooking. The loss of jaw muscle in the mandible, also relates to the cranium where those large jaw muscles are attached. When those muscles decrease in size, it releases cranial pressure, allowing for a larger brain. We can say cooking as so did their intestinal tracts shrink. Cooking implies less metabolic demand on the intestines to digest high fiber plant matter - which takes longer to extract nutrients, hence a large digestive tract. Reduced occlusion (crowdedness in the teeth) indicates a shearing of food, which implies a reduction in hardness. This lessened metabolic demand also provided more energy reserves to a growing brain. The thinner rib cage, housing a much smaller large intestine, would allow for longer limb growth and agility. In weight, the human gut is 60% of that which would be expected in a primate of similar size - even more obvious when we simply look at the robust torso of gorillas.
The McHenry quotient is ratio expressing the post-canine dentition area in relation to body mass:
"The need to consume animal fat is the result of the physiological ceiling on the consumption of protein and plant foods. The obligatory nature of animal fat consumption turned the large prey preference of Homo erectus into a large prey dependence." (Ben-Dor, Gopher, et al, 2011)
At the same time, let's dispel a myth. It was believed that Neanderthal's had an all meat diet. If so, the species would have died out due to "protein poisoning." So, as evolution, introgression and migration goes - they would have, first, inherited the subsistence patterns of their immediate predecessors (Homo heidelbergensis who inherited theirs from Erectus). Second, they would have either adopted from other groups new patterns of subsistence, or, lastly, created their own for survival when migrating to new refugia with a differing ecosystem, a habitat of different flora/fauna. For, too much meat is too much protein. The conversion of protein to energy requires liver enzymes to dispose of nitrogen, an ingredient of amino acids which compose the protein molecule. Consumption of proteins by humans is thus limited by the capacity of the liver to produce such enzymes, and of the kidney to dispose of urea - the nitrogen containing by-product from metabolism of proteins by the liver.
"By comparing modern human, Neanderthal and Denisovan genomes, the researchers identified more than 31,000 genetic changes that distinguish modern humans from Neanderthals and Denisovans. These changes may be linked with the survival and success of modern humans - a number have to do with brain development. If one speculates that we modern humans carry some genetic changes that enabled us to develop technology to the degree that we did and settle in nearly all habitable areas on the planet, then these must be among those changes." _Kay Prufer, Max Planck Institute, 2013
If iron molecules are in the presence of other animal proteins, the cells lining the stomach wall allow for more rapid diffusion of iron into the blood stream, thus more oxygen and more energy to metabolize. "Meat protein digestion is costlier compared to fat and that a larger percentage of protein escapes digestion, while fat digestion is nearly complete." (Ben-Dor, Gopher, et al, 2011) So, rather naturally, our hominin ancestors could certainly detect that consumption of fatty meat metabolizes energy more rapidly.
Upon the second wave of human migration out-of-Africa (<1.6mya), along the back of Acheulean hand axes, comes the hunting of larger game. At Acheulean sites throughout Asia, Africa and Europe - there are elephants. Acheulean hand axes found at Homo erectus sites are much larger, in strong correlation with the large amount of elephant and hippo bones.
Given the physiological energy needs of female members of the group, a forced and at times rapid evolution during the vicissitudes and vacillations of the glacial Pleistocene, and an abundance of large bodied ice-age animals - the adoption of elephants as their primary prey seems more like an inevitability than a choice, once examined.
Yet, elephants, mastodons, and mammoths do not run away, relying on their size to intimidate any such bold prey. They are easy to find - being conspicuous, not camouflaged and typically using the same migratory paths and water holes, making them easy to trap and/or ambush.
Still, the capturing of such a large beast would perhaps force the cooperation and aggregation of several small groups. This social cooperation very soon, leads to the establishment of hunting camps. And it's at these hunting camps that we can detect a shift in the hunting and subsistence strategies of our ancestors. Incentivized social cooperation and sharing is what led to the initial fraying of in-group/out-group rigidity. "We can all eat from this; bring your hunters...," or "Your tools can help us...," or "We tracked them here, you know this land best, lets work something out," laid the foundations of a more rapid socialization and technological development. But, we must consider this to be true only in areas with varying human populations. DNA evidence suggests a significant amount of in-breeding in these refugia.
At Gesher Benot Yaaqov, an Erectus camp-site in Isreal, ~780kya, these camps became specialized - with a particular setting dedicated to the extraction of...elephant brains from skulls, another for the extraction of marrow from the bone. There were places set aside for different kinds of butchering, defleshing, cutting and plant food processing. Some three-quarters of a million years ago, we see the embryonic foundation of sedentarism (residing in one place, not migratory). Though these sites were seasonal, and they remained migratory, derived from the need to track and stay in vital proximity to their food sources. But since Gesher Benot Yaaqov was occupied for more than 50k years by Erectus, surely a return to familiarity begins to establish ideas of home. And since the area surrounding The Pit of Bones in Spain was occupied for nearly 400k years - by Heidelbergensis, perhaps Denisovan and then Neanderthal - we can see this habit taking shape far earlier than is commonly believed with the onset of agriculture, I would argue, between 30k-11kya. Familiarity with previously utilized hunting grounds (migratory paths also reused by prey animals), and returning to established hunting camps led to the adoption of a home-based hunting strategy; it further freed up energy for brain development, hence, the specialized camps.
The preference for such a large animal, like mastodons, mammoths, and elephants, is it's fat constituency. Despite climate change, all hunting is thus seasonal. A long dry season, as seen in Africa, the Near East, parts of Asia during the Pleistocene, and even today, means prey animals would be much leaner. During a dry season, vegetation is also minimal, further exacerbating a prey animals' need for fat, and this trickles down through the carbon cycle (food chain). Meaning you'd have to hunt more of them to gain the normal amount of required nutrition to stay alive.
Seasonality is a cycle that can stress - and we, today, in the northern hemisphere especially, pack on ~14 extra pounds during the holiday season (historically harvests would have come in-between the vernal equinox and the winter solstice - now celebrated as holidays with feasts, subconsciously packing on winter pounds to endure the season). This would induce subsistence stress if earlier humans simply picked off animals of all shapes, ages and sizes of a prey species. These populations would have difficulty maintaining reproductive age animals and reproducing themselves. However, we begin to notice a deduced preference for prime-age animals with Homo erectus. Native Americans were observed to have had a particular knack for picking out the animal, that to you and I would seem normal, but from experience, they knew to have superior fat content - simply by the way the skin and fur moved across the muscle, the sheen of the coat and its curves. As such, an early hominid hunter, dependent on his prey and an expert at tracking migratory animals, would certainly have employed this same trait. Seeking out prime-age animals helped supplement the negative, at times dire, effects of seasonality.
Erectus, Heidelbergensis, Denisovan, Neanderthal, etc. were literally focusing on their own survival, not dominance. We introduce a contextual danger when we view them through the lens of modern humanity's global dominance - in spite of their intelligences. They were not apex predators. The dependence on large prey animals like proboscids and pachyderms (which includes hippopotami, and rhinos), also brought about its inherent dangers. Being evolved from scavengers fed into its hunting strategy, which when employed, attracted other large-bodied scavengers to follow even them. For example, grazing animals migrate, prey animals follow them (hominins and other carnivores), and scavengers track them all. As there were clades of humans in refugia, there were clades of giant and cave hyenas, etc. "Their migrations conspicuously match up with major events in hominin history." (Hofreiter, Stewart, 2009).
At Dragon Bone Hill, in Zhoukoudian, China, from ~700ky, the site was occupied intermittently
by a den of giant hyenas first, then later by Homo erectus, hyenas again, then Homo sapiens. The Erectus bones are mainly skulls that show signs of being eaten by giant hyenas. There are zero post-cranial remains (arms, legs, ribs, etc.). The hyenas were crushing at these bones to get at the fat-rich marrow and either passing them through digestion or scattering them in the process. The craniums were bitten into to get at the fat-rich brain matter. Then Erectus took over the site again. So, not only is fat preferred by carnivores (they tend to go for the guts first, and also eat the brains and marrow), but Erectus was a competing member of a carnivore community - filled with giants like hyenas, cave bears and lions. If we did not inherit our courage from them, then someone kindly identify where.
But, the real danger was dependence itself, a dependence on prime-age animals. Again, as climate change forces both evolution and adjustment in us, it pressures other animals. The Levant, where these hunting camps first appear, is a major conduit out of-, and into-, Africa. It also experiences a prolonged dry-season. So, the hunting of prime-age animals could have pressured large prey animals like other species of elephants into extinction; the thinking being the ability to reproduce a population and sustain reproductive age animals. The elephant was particularly sensitive - if a mere 4% of reproducing adults are hunted, the population as a whole is in real danger of dying out. (Pigs, by contrast, can suffer a 50% hit) Couple that with their fearlessness based on their size, and their predictability in terms of migration and water holes. Additionally, they move in large herds, and as a result, are hunted in such. And - our very real dependence on the dietary fat they provided a group of humans. They were not hunted to extinction by hunting the entire population. The prime-age adults suffered too much predation by early humans, against climate change.
And then, abruptly, the disappearance of elephants from the archaeological record is clearly evidenced during the transition from the Acheulean tool industry, ~500kya, into new and evolving industries like the Acheulean-Yabrudian industry in the Levant. This industry evolved from the need to hunt faster, smaller game. And more of it to supplement what was missing from larger prey.
Recall, this is around the same time, at the Pit of Bones, that Heidelbergensis began to evolve into Neanderthals - due to climate change. And elsewhere in Africa, Heidelbergensis begins to diverge into Homo sapiens. Yet, these Neanderthals had a greater caloric cost than modern humans. Our critical temperature (internal heat production maintained without clothing) is 28.2°C, while their more stocky bodies were maintained at 27°C - hardly adapted to the cold. Thus, they had to hunt more meat - just at the time when elephants en masse begins to fall out of the hominid diet. Neanderthals moved from pachyderms, to smaller game like giant deer, bison and wild horse - over time. What aided their dietary requirements against their subsistence strategy is their group size, typically no more than 14 individuals. They not only ate plants, but cooked them. "Plant microfibers and remains can be recovered from dental calculus (mineralized dental plaque that forms on teeth) and on stone tool remains," says Alison Brooks of the Smithsonian and George Washington University. They ate 50 different types of leaves, roots, water lilies, stems and starch grains like barley - and typically boiled them in water, as indicated by micro-remains.
By deduction, we can assume that since modern human hunter-gatherers residing in deserts, like the Kalahari Bushmen, eat over 82 varieties of plants in these desolate areas...and that Neanderthals ate over 50 varieties, that Heidelbergensis and previously Erectus did as well.
So, from the skeleton, we can piece together a behavioral study. And from DNA, we can logically deduct a social history. We can literally begin to distinctively classify our ancestors by not just their morphology or DNA, but by their energy requirements, what they hunted and ate:
With a hungry brain, fat intake become obligatory.Today, there is 66% fat in the Masai (Kenya) diet, between 48-70% of fat intake in the Inuit (Eskimo) diet. The average American consumes 45% of fat in their diet, which is further supplemented by fats from fish, legumes, and oils. Despite the warnings, there are no negative health effects. The only negative is calorie intake vs calorie expenditure - we are too sedentary compared to our more mobile ancestors from which we inherited these requirements - and the amount of synthetic chemicals ingredients in our food items (50 new chemicals in the human body since 1900). There is a lifestyle mismatch, and our bodies cannot evolve fast enough to keep up with our technologies. Yet, still, this shapes our evolution all the while.
As far as refugia, DNA evidence suggests that though we can detect species as being morphologically different, and geographically separated - its genetic diversity may indicate something else entirely. The genetic history of the Heidelbergensis/Neanderthals which occupied Atapuerca, Spain yielded DNA which also denotes a Denisovan ancestry. Up until now, we believed Denisovans went no further west that Siberia. It becomes obvious that admixture took place more often than simple "refugia" would allow. As previously mentioned, I believe these exchanges took place during interglacials and interstadials. As we are ultimately animals, further examples supporting this admixture evidence comes from clades of cave bears. One ancient clade resided in Siberia and the Caucasus Mountains, and the other resided in the Atlai Mountains near Mongolia, China, Russia and Kazakhstan and Western Europe. Despite geographic distance - they were genetically relative. Simply put, those bears in refugia in between, died out.
"These population extinctions can be seen as a continuum with the extinction of a species simply being the ultimate result of a succession of population extinctions." (Hofreiter & Stewart, 2013)
From refugia to refugia, clades of elephants died out. Clade upon clade of Pleistocene prey and predators followed them into the refuge of time - from the cave bear to the hyena. The dependent humans were faced with a dire challenge. And, in refugia after refugia, some populations went extinct. This is how we see Denisovan DNA in Western Europe and Neanderthal DNA in North Africa, where there is no evidence of their physical existence.
We shift according to dietary needs propelled by the energy requirements of an evolving brain, and evolve based on what the climate/biological interface allows. The human female, not only shaped our intelligence, shaped our social dynamics, but informed male hunting strategy.
Extinction is an inevitability. We, as Homo techne, need only to decide if this Earth is the final refugia.
During these Pleistocene times, between glacials and interglacials, stadials (lower temperatures during interglacials) and interstadials (slightly warmer during glacials), the average temperature could change by as much as 41°-50°F, within a few decades time. During glacial maxima (heavy ice ages), the temperature could be up to 69.8°F colder in comparison to today. "Only during these times did the northern hemisphere conform to the movie image of the Pleistocene with extensive glaciers covering large parts of Eurasia and North America...sea levels being 393ft lower, exposing more land mass. The British Isles were connected to Europe and the North Sea being a large area of dry land. ...It was during these times that elephants (extinct species) and hippopotamus were living as far north as the British Isles." (Hofreiter & Stewart, 2009) At 700kya in East Anglia, England, Homo heidelbergensis had tracked these proboscids and pachyderms to the western edge of Europe.
The increase in brain size undoubtedly forced a necessary shift in diet - making larger, fatter game attractive and necessary. For Australopiths like Lucy, from whom our genus Homo evolved, the intake of plant foods was not enough to feed a growing brain. The very acquisition of plant foods was so time consuming, it left little space for anything else. In observance of baboons, "devoting almost all of their daylight hours to painstakingly seeking out small, nutritious food items...adult male baboons may pick up as many as 3,000 individual food items in a single day." (Milton, 1987) They lacked the capacity to adapt both in subsistence and against the pressures of climate change. So, with Homo erectus, none of the physical traits that accompany a high amount of plant food consumption are found in their skeletal remains. Their teeth and jaws are smaller than their predecessors, indicating a shift to a diet that includes, not only meat, but cooking. The loss of jaw muscle in the mandible, also relates to the cranium where those large jaw muscles are attached. When those muscles decrease in size, it releases cranial pressure, allowing for a larger brain. We can say cooking as so did their intestinal tracts shrink. Cooking implies less metabolic demand on the intestines to digest high fiber plant matter - which takes longer to extract nutrients, hence a large digestive tract. Reduced occlusion (crowdedness in the teeth) indicates a shearing of food, which implies a reduction in hardness. This lessened metabolic demand also provided more energy reserves to a growing brain. The thinner rib cage, housing a much smaller large intestine, would allow for longer limb growth and agility. In weight, the human gut is 60% of that which would be expected in a primate of similar size - even more obvious when we simply look at the robust torso of gorillas.
The McHenry quotient is ratio expressing the post-canine dentition area in relation to body mass:
- Homo habilis (1.9)
- Homo erectus (1.0)
- Neanderthal (0.7)
- Homo sapiens (0.9)
These differences can first be seen dramatically between Homo habilis (the first tool-maker) and Homo erectus (the first Out-of Africa, and to carry their tools with them). Nearly half of a reduction in masticating teeth size compared to gut is hard evidence for the use of fire and cooking.
"The need to consume animal fat is the result of the physiological ceiling on the consumption of protein and plant foods. The obligatory nature of animal fat consumption turned the large prey preference of Homo erectus into a large prey dependence." (Ben-Dor, Gopher, et al, 2011)
At the same time, let's dispel a myth. It was believed that Neanderthal's had an all meat diet. If so, the species would have died out due to "protein poisoning." So, as evolution, introgression and migration goes - they would have, first, inherited the subsistence patterns of their immediate predecessors (Homo heidelbergensis who inherited theirs from Erectus). Second, they would have either adopted from other groups new patterns of subsistence, or, lastly, created their own for survival when migrating to new refugia with a differing ecosystem, a habitat of different flora/fauna. For, too much meat is too much protein. The conversion of protein to energy requires liver enzymes to dispose of nitrogen, an ingredient of amino acids which compose the protein molecule. Consumption of proteins by humans is thus limited by the capacity of the liver to produce such enzymes, and of the kidney to dispose of urea - the nitrogen containing by-product from metabolism of proteins by the liver.
"By comparing modern human, Neanderthal and Denisovan genomes, the researchers identified more than 31,000 genetic changes that distinguish modern humans from Neanderthals and Denisovans. These changes may be linked with the survival and success of modern humans - a number have to do with brain development. If one speculates that we modern humans carry some genetic changes that enabled us to develop technology to the degree that we did and settle in nearly all habitable areas on the planet, then these must be among those changes." _Kay Prufer, Max Planck Institute, 2013
If iron molecules are in the presence of other animal proteins, the cells lining the stomach wall allow for more rapid diffusion of iron into the blood stream, thus more oxygen and more energy to metabolize. "Meat protein digestion is costlier compared to fat and that a larger percentage of protein escapes digestion, while fat digestion is nearly complete." (Ben-Dor, Gopher, et al, 2011) So, rather naturally, our hominin ancestors could certainly detect that consumption of fatty meat metabolizes energy more rapidly.
Upon the second wave of human migration out-of-Africa (<1.6mya), along the back of Acheulean hand axes, comes the hunting of larger game. At Acheulean sites throughout Asia, Africa and Europe - there are elephants. Acheulean hand axes found at Homo erectus sites are much larger, in strong correlation with the large amount of elephant and hippo bones.
Given the physiological energy needs of female members of the group, a forced and at times rapid evolution during the vicissitudes and vacillations of the glacial Pleistocene, and an abundance of large bodied ice-age animals - the adoption of elephants as their primary prey seems more like an inevitability than a choice, once examined.
Yet, elephants, mastodons, and mammoths do not run away, relying on their size to intimidate any such bold prey. They are easy to find - being conspicuous, not camouflaged and typically using the same migratory paths and water holes, making them easy to trap and/or ambush.
Still, the capturing of such a large beast would perhaps force the cooperation and aggregation of several small groups. This social cooperation very soon, leads to the establishment of hunting camps. And it's at these hunting camps that we can detect a shift in the hunting and subsistence strategies of our ancestors. Incentivized social cooperation and sharing is what led to the initial fraying of in-group/out-group rigidity. "We can all eat from this; bring your hunters...," or "Your tools can help us...," or "We tracked them here, you know this land best, lets work something out," laid the foundations of a more rapid socialization and technological development. But, we must consider this to be true only in areas with varying human populations. DNA evidence suggests a significant amount of in-breeding in these refugia.
At Gesher Benot Yaaqov, an Erectus camp-site in Isreal, ~780kya, these camps became specialized - with a particular setting dedicated to the extraction of...elephant brains from skulls, another for the extraction of marrow from the bone. There were places set aside for different kinds of butchering, defleshing, cutting and plant food processing. Some three-quarters of a million years ago, we see the embryonic foundation of sedentarism (residing in one place, not migratory). Though these sites were seasonal, and they remained migratory, derived from the need to track and stay in vital proximity to their food sources. But since Gesher Benot Yaaqov was occupied for more than 50k years by Erectus, surely a return to familiarity begins to establish ideas of home. And since the area surrounding The Pit of Bones in Spain was occupied for nearly 400k years - by Heidelbergensis, perhaps Denisovan and then Neanderthal - we can see this habit taking shape far earlier than is commonly believed with the onset of agriculture, I would argue, between 30k-11kya. Familiarity with previously utilized hunting grounds (migratory paths also reused by prey animals), and returning to established hunting camps led to the adoption of a home-based hunting strategy; it further freed up energy for brain development, hence, the specialized camps.
The preference for such a large animal, like mastodons, mammoths, and elephants, is it's fat constituency. Despite climate change, all hunting is thus seasonal. A long dry season, as seen in Africa, the Near East, parts of Asia during the Pleistocene, and even today, means prey animals would be much leaner. During a dry season, vegetation is also minimal, further exacerbating a prey animals' need for fat, and this trickles down through the carbon cycle (food chain). Meaning you'd have to hunt more of them to gain the normal amount of required nutrition to stay alive.
Seasonality is a cycle that can stress - and we, today, in the northern hemisphere especially, pack on ~14 extra pounds during the holiday season (historically harvests would have come in-between the vernal equinox and the winter solstice - now celebrated as holidays with feasts, subconsciously packing on winter pounds to endure the season). This would induce subsistence stress if earlier humans simply picked off animals of all shapes, ages and sizes of a prey species. These populations would have difficulty maintaining reproductive age animals and reproducing themselves. However, we begin to notice a deduced preference for prime-age animals with Homo erectus. Native Americans were observed to have had a particular knack for picking out the animal, that to you and I would seem normal, but from experience, they knew to have superior fat content - simply by the way the skin and fur moved across the muscle, the sheen of the coat and its curves. As such, an early hominid hunter, dependent on his prey and an expert at tracking migratory animals, would certainly have employed this same trait. Seeking out prime-age animals helped supplement the negative, at times dire, effects of seasonality.
Erectus, Heidelbergensis, Denisovan, Neanderthal, etc. were literally focusing on their own survival, not dominance. We introduce a contextual danger when we view them through the lens of modern humanity's global dominance - in spite of their intelligences. They were not apex predators. The dependence on large prey animals like proboscids and pachyderms (which includes hippopotami, and rhinos), also brought about its inherent dangers. Being evolved from scavengers fed into its hunting strategy, which when employed, attracted other large-bodied scavengers to follow even them. For example, grazing animals migrate, prey animals follow them (hominins and other carnivores), and scavengers track them all. As there were clades of humans in refugia, there were clades of giant and cave hyenas, etc. "Their migrations conspicuously match up with major events in hominin history." (Hofreiter, Stewart, 2009).
At Dragon Bone Hill, in Zhoukoudian, China, from ~700ky, the site was occupied intermittently
by a den of giant hyenas first, then later by Homo erectus, hyenas again, then Homo sapiens. The Erectus bones are mainly skulls that show signs of being eaten by giant hyenas. There are zero post-cranial remains (arms, legs, ribs, etc.). The hyenas were crushing at these bones to get at the fat-rich marrow and either passing them through digestion or scattering them in the process. The craniums were bitten into to get at the fat-rich brain matter. Then Erectus took over the site again. So, not only is fat preferred by carnivores (they tend to go for the guts first, and also eat the brains and marrow), but Erectus was a competing member of a carnivore community - filled with giants like hyenas, cave bears and lions. If we did not inherit our courage from them, then someone kindly identify where.
But, the real danger was dependence itself, a dependence on prime-age animals. Again, as climate change forces both evolution and adjustment in us, it pressures other animals. The Levant, where these hunting camps first appear, is a major conduit out of-, and into-, Africa. It also experiences a prolonged dry-season. So, the hunting of prime-age animals could have pressured large prey animals like other species of elephants into extinction; the thinking being the ability to reproduce a population and sustain reproductive age animals. The elephant was particularly sensitive - if a mere 4% of reproducing adults are hunted, the population as a whole is in real danger of dying out. (Pigs, by contrast, can suffer a 50% hit) Couple that with their fearlessness based on their size, and their predictability in terms of migration and water holes. Additionally, they move in large herds, and as a result, are hunted in such. And - our very real dependence on the dietary fat they provided a group of humans. They were not hunted to extinction by hunting the entire population. The prime-age adults suffered too much predation by early humans, against climate change.
And then, abruptly, the disappearance of elephants from the archaeological record is clearly evidenced during the transition from the Acheulean tool industry, ~500kya, into new and evolving industries like the Acheulean-Yabrudian industry in the Levant. This industry evolved from the need to hunt faster, smaller game. And more of it to supplement what was missing from larger prey.
Recall, this is around the same time, at the Pit of Bones, that Heidelbergensis began to evolve into Neanderthals - due to climate change. And elsewhere in Africa, Heidelbergensis begins to diverge into Homo sapiens. Yet, these Neanderthals had a greater caloric cost than modern humans. Our critical temperature (internal heat production maintained without clothing) is 28.2°C, while their more stocky bodies were maintained at 27°C - hardly adapted to the cold. Thus, they had to hunt more meat - just at the time when elephants en masse begins to fall out of the hominid diet. Neanderthals moved from pachyderms, to smaller game like giant deer, bison and wild horse - over time. What aided their dietary requirements against their subsistence strategy is their group size, typically no more than 14 individuals. They not only ate plants, but cooked them. "Plant microfibers and remains can be recovered from dental calculus (mineralized dental plaque that forms on teeth) and on stone tool remains," says Alison Brooks of the Smithsonian and George Washington University. They ate 50 different types of leaves, roots, water lilies, stems and starch grains like barley - and typically boiled them in water, as indicated by micro-remains.
By deduction, we can assume that since modern human hunter-gatherers residing in deserts, like the Kalahari Bushmen, eat over 82 varieties of plants in these desolate areas...and that Neanderthals ate over 50 varieties, that Heidelbergensis and previously Erectus did as well.
So, from the skeleton, we can piece together a behavioral study. And from DNA, we can logically deduct a social history. We can literally begin to distinctively classify our ancestors by not just their morphology or DNA, but by their energy requirements, what they hunted and ate:
Body Size:
- Group A (Elephants > 2200lbs)
- Group B (Hippos, Rhinos, etc. <or= 2000lbs)
- Group C (Giant deer, red deer, bear and bovines, etc. 175 - 500lbs)
Energy Gained from Food Items:
- Seeds and Nuts (3,520 - 6,508 kj/hr)
- Roots and Tubers (1,882 - 6,120 kj/hr)
- Large Game (60,000 - 63,398 kj/hr)
Unfortunately, we do not have DNA samples from Homo erectus to show us how closely related they were to Heidelbergensis, Denisovans, Sapiens or Neanderthals. But, the 2% of our modern genome, and the upwards of 6% of Denisovan genome that remains unassignable to any known human genome, may yet be Erectus finally speaking through history with the aid of technology. Having survived for nearly 2 million years - from scavenger, to hunter, to hunting big game, to eventually adopting small game hunting techniques from either Neanderthals or modern Humans before their ultimate demise - we not only see a resultant morphological shift, but a truly learning and adaptive human being.
With a hungry brain, fat intake become obligatory.Today, there is 66% fat in the Masai (Kenya) diet, between 48-70% of fat intake in the Inuit (Eskimo) diet. The average American consumes 45% of fat in their diet, which is further supplemented by fats from fish, legumes, and oils. Despite the warnings, there are no negative health effects. The only negative is calorie intake vs calorie expenditure - we are too sedentary compared to our more mobile ancestors from which we inherited these requirements - and the amount of synthetic chemicals ingredients in our food items (50 new chemicals in the human body since 1900). There is a lifestyle mismatch, and our bodies cannot evolve fast enough to keep up with our technologies. Yet, still, this shapes our evolution all the while.
As far as refugia, DNA evidence suggests that though we can detect species as being morphologically different, and geographically separated - its genetic diversity may indicate something else entirely. The genetic history of the Heidelbergensis/Neanderthals which occupied Atapuerca, Spain yielded DNA which also denotes a Denisovan ancestry. Up until now, we believed Denisovans went no further west that Siberia. It becomes obvious that admixture took place more often than simple "refugia" would allow. As previously mentioned, I believe these exchanges took place during interglacials and interstadials. As we are ultimately animals, further examples supporting this admixture evidence comes from clades of cave bears. One ancient clade resided in Siberia and the Caucasus Mountains, and the other resided in the Atlai Mountains near Mongolia, China, Russia and Kazakhstan and Western Europe. Despite geographic distance - they were genetically relative. Simply put, those bears in refugia in between, died out.
"These population extinctions can be seen as a continuum with the extinction of a species simply being the ultimate result of a succession of population extinctions." (Hofreiter & Stewart, 2013)
From refugia to refugia, clades of elephants died out. Clade upon clade of Pleistocene prey and predators followed them into the refuge of time - from the cave bear to the hyena. The dependent humans were faced with a dire challenge. And, in refugia after refugia, some populations went extinct. This is how we see Denisovan DNA in Western Europe and Neanderthal DNA in North Africa, where there is no evidence of their physical existence.
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| Neanderthalensis |
Extinction is an inevitability. We, as Homo techne, need only to decide if this Earth is the final refugia.
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