Photo provided by Flickr
the Savanna-IQ Interaction Hypothesis, ..
Many into their structures. also incorporate silica, and those are among the few life forms that use silicon, although it is one of . Diatoms seem to gain , and plants seem to have structural advantages, but it is thought that plants also used silica for a defensive measure, as it helps make plants unpalatable. Eating plants full of silica structures, called , is like chewing sand. This is particularly true with grasses, as phytoliths make chewing them a tooth-wrecking process, particularly for ruminants and their thorough chewing. Grazing herbivores have heavily enameled hypsodont teeth (also called high-crowned teeth) to . In North America, hypsodont herbivores proliferated while those without that heavy enamel (also called low-crowned teeth), which were browsers instead of grazers, declined. By about nine mya, North American browsers had largely vanished and grazers dominated the new grasslands. Earth kept cooling and drying, and fewer than seven mya, steppe vegetation began replacing savanna-like grasslands, and forests were decimated. This led to the greatest mass extinction in pre-human North America in the Cenozoic Era, as many species of horses, mastodonts, bears, dogs, and small predators went extinct, as well as mice, beavers, and moles. Asia and Africa were hit similarly, although not quite as hard as North America seemed to be, but South America and Australia hardly seemed affected at all. New Zealand’s surrounding seafloor changed from warm-water communities to the Southern Ocean communities that it has today.
Photo provided by Flickr
The Savanna-IQ Interaction Hypothesis …
Wrangham’s hypothesis is more robust and subtle than this essay can do justice to, but I will survey some of the findings, implications, and controversy. Raw food has various nutritional properties that are superior to cooked food, such as vitamins, but because cooked food provides more digestible calories for humans than raw food, it represented an evolutionary advantage. Meat, starches, and seeds are far more digestible when cooked, and are much easier to chew. Today, chimps in will not eat raw seeds of trees, but when a fire passes through the savanna, they search the ground below the trees and eat their cooked seeds.
Photo provided by Flickr
Those grasslands, with their attendant grazers and browsers, and their predators, appeared in the pampas of Argentina, the plains of the Ukraine, China, and Pakistan, and, of course, Africa. Africa’s savanna fauna would have looked very familiar, with elephants, antelope (including impalas, gazelles, etc.), hippos, cats, hyenas, short-necked giraffes, horses, the first modern rhinos, and the like. In Eurasia and Africa, with the land barriers removed, all the savanna biomes resembled each other. In the late Miocene, . Those grasslands grew when the ice age began.
Photo provided by Flickr
The Savanna-IQ interaction hypothesis is a …
So far in this essay, mammals have received scant attention, but the mammals’ development before the Cenozoic is important for understanding their rise to dominance. The , called , first , about 260 mya, and they had key mammalian characteristics. Their jaws and teeth were markedly different from those of other reptiles; their teeth were specialized for more thorough chewing, which extracts more energy from food, and that was likely a key aspect of success more than 100 million years later. Cynodonts also developed a secondary palate so that they could chew and breathe at the same time, which was more energy efficient. Cynodonts eventually ceased the reptilian practice of continually growing and shedding teeth, and their specialized and precisely fitted teeth rarely changed. Mammals replace their teeth a . Along with tooth changes, jawbones changed roles. Fewer and stronger bones anchored the jaw, which allowed for stronger jaw musculature and led to the mammalian (clench your teeth and you can feel your masseter muscle). Bones previously anchoring the jaw were no longer needed and . The jaw’s rearrangement led to the most auspicious proto-mammalian development: . Mammals had relatively large brains from the very beginning and it was probably initially . Mammals are the only animals with a , which eventually led to human intelligence. As dinosaurian dominance drove mammals to the margins, where they lived underground and emerged to feed at night, mammals needed improved senses to survive, and auditory and olfactory senses heightened, as did the mammalian sense of touch. Increased processing of stimuli required a larger brain, and . In humans, only livers use more energy than brains. Cynodonts also had , which suggest that they were warm-blooded. Soon after the Permian extinction, a cynodont appeared that may have ; it was another respiratory innovation that served it well in those low-oxygen times, functioning like pump gills in aquatic environments.
06/08/2017 · - Savanna-IQ Interaction Hypothesis
The genetic testing that has been performed on humanity in the past generation has shown that the founder group’s pattern of migration was to continually spread out, and once the original settlement covered the continents, people did not move much at all, at least until Europe began conquering the world (and there were some ). There is little sign of warfare in those early days of migration, and the leading hypothesis is that people moved to the next valley rather than be close enough to fight each other. Any conflict would have been easily resolved by moving farther out, where more easily killed animals lived. Also, in those virgin continents, people need not have roamed far to obtain food. Today, an !Kung woman will carry her child more than 7,000 kilometers before the child can walk for himself/herself. If an !Kung woman bears twins, it is her duty to pick which child to murder, because she cannot afford to carry two. That demonstrates the limitations of today’s hunter-gatherer lifestyle, but in those halcyonic days of invading virgin continents (which had to be the Golden Age of the Hunter-Gatherer), those kinds of practices probably waned and bands grew fast. When they they split, and the new group moved to new lands where the animals, again, never saw people before. Unlike the case with humans, there would not have been a grapevine so that animals told their neighbors about the new super-predator. The first time that those megafauna saw humans was probably their last time. It is very likely, just as with all predators for all time, and as can be seen with historical hunting events such or , that those bands soon took to killing animals, harvesting the best parts, and moving on. To them it would not have been a “blitzkrieg,” but more like kids in candy stores. After a few thousand years of grabbing meat whenever the fancy took them, or perhaps less, those halcyonic days were over as the far coasts of Australia were reached and the easy meat was gone. When that land bridge formed to Tasmania about 43 kya, people crossed and were able to , until all the megafauna was gone on Tasmania. They also may have worked their way through the food chain, in which the first kills were the true mother lode. Nobody even deigned to raise a spear at anything less than a until they were gone. Then they started killing smaller prey, which eventually did wise up and were harder to kill, so humans had to work at it again and the brief golden age was over. The as they shaped the new continent to their liking, maybe recreating the savanna conditions that they left in Africa, may have also been used to flush out animals if they began to avoid humans.