Affichage des articles dont le libellé est Nourriture. Afficher tous les articles
Affichage des articles dont le libellé est Nourriture. Afficher tous les articles
Agriculture
La propagation de l'agriculture du Moyen-Orient vers l'Europe entre 9600 et 3800 avant notre ère.
La théorie du "stoned ape" de Terence McKenna
There seems to have been a profound difference in cognitive abilities between early Homo sapiens and our immediate predecessor, Homo erectus. Sure, erectus stood upright — a big, um, step forward — but with the emergence of Homo sapiens, we see traces of art, pictography, and tool usage, and we believe humankind made its first forays into language.
In the early 1990s, psychedelic advocate and ethnobotanist Terence McKenna published his book Food of the Gods in which he surmised that Homo sapiens‘ cognitive leap forward was due to their discovery of magic mushrooms. The scientific community never took McKenna’s theory very seriously, considering it mostly trippy speculation — these days, his ideas have largely been relegated to the spacier corners of Reddit. Now, however, the idea has acquired a new advocate, psilocybin mycologist Paul Stamets, who’s suggesting McKenna was right all along.
The stoned ape
In McKenna’s Stoned Ape hypothesis,” he posited that as humans began to migrate to new areas, at some point they came upon psychedelic mushrooms growing in cow droppings, as is their wont, and then ate them. After ingesting them, and more specifically the psilocybin they contained, their brains kicked into overdrive, acquiring new information-processing capabilities, and a mind-blowing expansion of our imaginations in the bargain. Many modern users of psychedelics claim the world never looks the same again after such an experience. As McKenna put it, “Homo sapiens ate our way to a higher consciousness,” and, “It was at this time that religious ritual, calendar making, and natural magic came into their own.”
The return of the stoned ape
Regarding this theory, Stamets presented “Psilocybin Mushrooms and the Mycology of Consciousness” at Psychedelic Science 2017. In his talk he sought to rehabilitate McKenna’s hypothesis as a totally plausible answer to a longstanding evolutionary riddle. “What is really important for you to understand,” he said, “is that there was a sudden doubling of the human brain 200,000 years ago. From an evolutionary point of view, that’s an extraordinary expansion. And there is no explanation for this sudden increase in the human brain.”
Why not mushrooms? Stamets portrayed a group of early humans making their way through the savannah and happening across “the largest psilocybin mushroom in the world growing bodaciously out of dung of the animals.” It needn’t have been unusually large to have its effect, of course. In any event, he invited the crowd to suspend their disbelief and admit that McKenna’s idea constitutes a “very, very plausible hypothesis for the sudden evolution of Homo sapiens from our primate relatives,” even if it’s an unprovable one.
The audience’s response was reportedly enthusiastic, though it’s fair to note that these were people attending a conference on psychedelic science, and thus pre-disposed toward such chemicals’ importance.
Just tripping?
Certainly, there’s general agreement on the mystery Stamets cited, if not so much on timing details. And consciousness, the “hard problem” even in its modern form, is an area rife with unanswered questions. What is consciousness, anyway? Is it a simple enough thing that it could have a single root cause as McKenna and Stamets say? Many experts suspect our brains gained new capabilities as the result of early community ties and the requirements of social interaction, but when?
Anthropologist Ian Tattersall tells Inverse that the where seems obvious enough: Africa, “For it is in this continent that we find the first glimmerings of ‘modern behaviors’. . . But the moment of transformation still eludes us and may well do so almost indefinitely.”
There are other researchers who’ve studied early humanity’s use of drug plants but who are skeptical of the stoned ape notiion. Elisa Guerra-Doce, an expert in the field, considers the idea too simplistic, potentially a reduction of a complex evolutionary process into a single “aha” — or maybe “oh, wow” — moment. She’s also troubled by there being little evidence of such a pivotal moment, or of drug use at all, so early in the archeological record.
Amanda Feilding of the psychedelic think tank Beckley Foundation says, however, that the stoned ape theory is at the very least a valid reminder that humans have always been drawn to and fascinated by mind-altering substances: “The imagery that comes with the psychedelic experience is a theme that runs through ancient art, so I’m sure that psychedelic experience and other techniques, like dancing and music, were used by our early ancestors to enhance consciousness, which then facilitated spirituality, art, and medicine.”
Just how early our love affair with hallucinogenic states began may have something to say about the plausibility of McKenna’s hypothesis, but, alas, we don’t know when that would have been. And, as the saying about the 1960s goes, even if any of these people were still around to ask, anyone who was really there wouldn’t be able to remember.
Comment la fin des dinosaures a directement conduit à l'émergence de la vigne
Il y a 66 millions d’années, volcanisme et astéroïde entraînaient la disparition des dinosaures. Au même moment apparaissaient les premières espèces de Vitacées, ancêtres de la vigne actuelle. Une étude révèle qu’il ne s’agirait pas là d’un hasard de l’évolution, mais qu’il y aurait bien un lien entre cette extinction de masse et l’apparition de ces plantes.
(...) Une nouvelle étude publiée dans Nature plants révèle en effet que la crise biologique ayant entraîné la disparition des dinosaures il y a 66 millions d'années aurait facilité le développement de certaines plantes, et notamment la vigne. Cette hypothèse résulte de la découverte, dans les Andes colombiennes, de la seconde plus ancienne espèce de Vitacée au monde.
Les Vitacées représentent une famille de plantes, souvent des lianes, à laquelle appartiennent les vignes domestiques (Vitis vinifera). L'analyse des grains fossilisés a montré qu'ils dataient de 60 millions d'années, soit peu de temps après l’extinction des dinosaures. Les plus anciens fossiles de cette famille de plantes ont quant à eux été retrouvés en Inde, et datent justement de 66 millions d'années. Coïncidence ? Ou la catastrophe environnementale marquant la fin du Crétacé aurait-elle joué un rôle dans l'essor de ces plantes ?
(...) Les plantes, elles aussi, ont été affectées par cette évolution de l'environnement. De nombreuses espèces ont disparu, libérant ainsi certaines niches écologiques. Mais la disparition des dinosaures pourrait tout de même avoir joué un rôle. Il est certain en effet que les dinosaures, du temps de leur présence, ont impacté les écosystèmes forestiers. Les grands herbivores, pouvant peser plusieurs dizaines de tonnes, auraient notamment permis de maintenir des forêts plutôt ouvertes. À la suite de leur extinction, ces forêts tropicales seraient devenues plus denses et compactes, entraînant le développement de plantes grimpantes et de lianes, comme les Vitacées.
En parallèle, le développement accéléré des oiseaux et des mammifères aurait favorisé leur extension géographique, ces animaux se nourrissant des fruits et permettant une vaste et rapide dispersion des graines.
Nous sommes carnivores
Une nouvelle découverte semble indiquer que nos ancêtres n'étaient pas des mangeurs de viande occasionnels, mais bien de véritables carnivores. Cela vient renforcer l'hypothèse selon laquelle notre diète aurait joué un rôle majeur dans l'évolution de notre cerveau.Extrait de la nouvelle:
Fragments of a 1.5-million-year-old skull from a child recently found in Tanzania suggest early hominids weren't just occasional carnivores but regular meat eaters, researchers say.
The finding helps build the case that meat-eating helped the human lineage evolve large brains, scientists added.
(...) Now shards of a child's skull found in Olduvai Gorge in Tanzania suggest the infant suffered from a form of malnutrition seen in meat-poor diets. This hints that meat-eating was normally a regular part of the human diet at the time. [10 Things That Make Humans Special]
The skull fragment is thought to belong to a child somewhat younger than 2. It remains unclear what hominin it belonged to — likely candidates include extinct human species such as Homo habilis or Homo erectus, or perhaps the "Nutcracker Man" Paranthropus boisei.
The kind of bone lesions the researchers saw in this fossil are known as porotic hyperostosis, which typically results from a lack of vitamins B9 and B12 in the diet. This kind of nutritional deficiency is most common at weaning, when children switch to solid foods. The researchers suggested this particular infant died because of lack of meat, which is rich in B-vitamins. Alternatively, if the child still depended on the mother for milk, it may have been the mother who lacked meat.
780,000-Year-Old Baked Carp Is Earliest Evidence Of Humans Cooking With Fire
Archaeologists in Israel have discovered evidence of what may be the first-ever baked fish supper. After analyzing the remains of an enormous extinct carp, the study authors concluded that the animal was carefully cooked at a low-to-moderate heat 780,000 years ago, pushing back the earliest use of fire to prepare food by over 600,000 years.
Les humains hypercarnivores
While many modern humans opt for a vegetarian or vegan diet, new research suggests that our ancestors obtained the majority of their nutrition from meat, and only diversified their food intake to include more plants at the very end of the Stone Age. Published in the American Journal of Physical Anthropology, the new study indicates that humans were apex predators for around 2 million years, with numerous species within the Homo lineage engaging in “hypercarnivory”.
Determining the trophic level – or position within the food web – of ancient humans is tricky, as we can’t directly observe the feeding behaviors of our early ancestors. Most attempts to do so have therefore focused on present-day hunter-gatherer groups, assuming that the practices of such cultures reflect those of primitive humans.
However, the authors of this latest study explain that such comparisons are highly problematic, as changes to the ecological landscape will inevitably have forced humans to alter their hunting and gathering preferences over time. For instance, the loss of megafauna like mammoths and other large animals produced a major shift in human diets.
The researchers therefore attempted to reconstruct the diet of ancient humans and determine the trophic level of our ancestors throughout the Pleistocene, which began 2.5 million years ago and ended around the time of the agricultural revolution, some 11,000 years ago. Taking a multidisciplinary approach, the team examined over 400 scientific studies covering areas such as genetics, metabolism, morphology, archaeology, and paleontology in order to determine whether early humans were specialized carnivores or more general omnivores.
Their investigation yielded 25 sources of evidence that strongly suggest that our predecessors were hypercarnivores. For instance, stomach acidity is a hallmark of carnivorous animals, as this ensures that any pathogens lurking in meat are killed. The fact that modern humans’ stomachs are more acidic than most carnivores’ points to the fact that our ancestors were well adapted to consume the meat of large animals they hunted, which would have fed a community for days or even weeks and would therefore have been full of bacteria.
This is backed up by the fact that several archaic hominids were morphologically adapted to hunt megafauna. Homo erectus, for instance, was equipped with shoulders that were ideal for throwing spears but unsuitable for tree climbing, suggesting that the species probably ate more meat than plants.
Human ancestors
How the diet of ancient humans changed as our brains evolved. Image credit: Dr Miki Ben Dor
Furthermore, genes that facilitate the digestion of plant acids and starch did not become widely expressed within the human genome until late in the Pleistocene. According to the study authors, this indicates a lack of evolutionary pressure to switch to a plant-based diet while the hunting was good. Yet as animal sources become scarcer, humans that consumed more vegetation enjoyed higher survival rates.
According to the researchers, this late switch to a more omnivorous diet provided the spark for the advent of agriculture, leading to a change in the types of stone tools used by ancient humans. Looking through the archaeological records, they found that tools associated with processing plants only appear around 40,000 years ago and increase in frequency around the time of the agricultural revolution. Prior to this, most tools were designed for hunting, with the same types of artifacts found across all areas inhabited by humans.
"Archaeological evidence does not overlook the fact that stone-age humans also consumed plants," explained study author Miki Ben-Dor in a statement. "But according to the findings of this study plants only became a major component of the human diet toward the end of the era."
"Early humans gained energy budget by increasing rate of energy acquisition, not energy-saving adaptation"
A team of researchers affiliated with multiple institutions in the U.S., the Institute for Advanced Study in Toulouse, France and the Max Planck Institute for Evolutionary Anthropology in Germany has found evidence that suggests early humans gained an energy budget by increasing their rate of energy acquisition, not by taking advantage of adaptive strategies. In their paper published in the journal Science, they describe their study of energy expenditure versus energy intake in early humans.
In this new effort, the researchers noted that humans long ago diverged in significant ways from the other great apes. They wondered how this happened and decided to look at energy intake and expenditure. People and other animals have to put in a certain amount of work (expenditure) to receive an energy intake. Climbing a tree to fetch a banana is a simple example. The amount of energy required to climb a tree far outweighs the potential benefit of eating a single banana. But if a single person is able to throw down multiple bananas, then the overall energy intake may surpass the effort of climbing a tree a single time. To learn more about how energy intake and expenditure might have led to modern human characteristics, the researchers studied two groups of modern people—hunter gatherers in Tanzania and forager-horticulturalists in a Bolivian rain forest.
In looking at both groups, they found that both spent more energy on subsistence but also achieved energy efficiencies compared to modern great apes. This was despite the fact that bipedalism and the use of tools are known to decrease the amount of energy expended to obtain food. The result was the acquisition of more food at a much higher rate than the great apes. The researchers suggest this indicates that humans are not cost economizers but are instead creatures that operate in high throughput ways that lead to large payoffs. They suggest that diverging from the great apes in such a way led to the production of so much food that early humans had much more time to do other things, such as socialize. They further suggest that such socializing, combined with the organizational activities involved in obtaining food led to the development of larger brains and from there, other uniquely human attributes.
"An ancient piece of chewing gum offers surprising insights into the human genome"
Five thousand and seven hundred years ago, “Lola” — a blue-eyed woman with dark skin and hair — was chewing on a piece of pitch derived from heating birch bark. Then, this woman spit her chewing gum out into the mud on an island in Denmark that we call Syltholm today, where it was unearthed by archaeologists thousands of years later. A genetic analysis of the chewing gum has provided us with a wealth of information on this nearly six-thousand-year-old Violet Beauregarde.
This represents the first time that the human genome has been extracted from material such as this. “It is amazing to have gotten a complete ancient human genome from anything other than bone,” said lead researcher Hannes Schroeder in a statement.
“What is more,” he added, “we also retrieved DNA from oral microbes and several important human pathogens, which makes this a very valuable source of ancient DNA, especially for time periods where we have no human remains.”
In the pitch, researchers identified the DNA of the Epstein-Barr virus, which infects about 90 percent of adults. They also found DNA belonging to hazelnuts and mallards, which were likely the most recent meal that Lola had eaten before spitting out her chewing gum.
INSIGHTS INTO ANCIENT PEOPLES
The birch pitch was found on the island of Lolland (the inspiration for Lola’s name) at a site called Syltholm. “Syltholm is completely unique,” said Theis Jensen, who worked on the study for his PhD. “Almost everything is sealed in mud, which means that the preservation of organic remains is absolutely phenomenal.
“It is the biggest Stone Age site in Denmark and the archaeological finds suggest that the people who occupied the site were heavily exploiting wild resources well into the Neolithic, which is the period when farming and domesticated animals were first introduced into southern Scandinavia.”
Since Lola’s genome doesn’t show any of the markers associated with the agricultural populations that had begun to appear in this region around her time, she provides evidence for a growing idea that hunter-gatherers persisted alongside agricultural communities in northern Europe longer than previously thought.
Her genome supports additional theories on northern European peoples. For example, her dark skin bolsters the idea that northern populations only recently acquired their light-skinned adaptation to the low sunlight in the winter months. She was also lactose intolerant, which researchers believe was the norm for most humans prior to the agricultural revolution. Most mammals lose their tolerance for lactose once they’ve weaned off of their mother’s milk, but once humans began keeping cows, goats, and other dairy animals, their tolerance for lactose persisted into adulthood. As a descendent of hunter-gatherers, Lola wouldn’t have needed this adaptation.
These findings are encouraging for researchers focusing on ancient peoples from this part of the world. Before this study, ancient genomes were really only ever recovered from human remains, but now, scientists have another tool in their kit. Birch pitch is commonly found in archaeological sites, often with tooth imprints.
Ancient peoples used and chewed on birch pitch for a variety of reasons. It was commonly heated up to make it pliable, enabling it to be molded as an adhesive or hafting agent before it settled. Chewing the pitch may have kept it pliable as it cooled down. It also contains a natural antiseptic, and so chewing birch pitch may have been a folk medicine for dental issues. And, considering that we chew gum today for no other reason than to pass the time, it may be that ancient peoples chewed pitch for fun.
Whatever their reasons, chewed and discarded pieces of birch pitch offer us the mind-boggling option of learning what someone several thousands of years ago ate for lunch, or what the color of their hair was, their health, where their ancestors came from, and more. It’s an unlikely treasure trove of information to be found in a mere piece of gum.
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