Encephalization cultural tests of the human species. Dissemination 76th
Encephalization coefficient is a parameter that corresponds to the relative weight of the brain in relation to body weight of each species. It is considered that the regulation of a large number of vital functions (breathing, motor skills, thermoregulation, blood pressure …) by the central nervous system must correspond with increased brain size and once the basic size reached, to ensure these minimal functions, any development of additional brain mass is intended to more complex cognitive tasks. This previous consideration leads us to conclude that all cognitive and behavioral activity has a histological support and therefore anatomically, on the encephalic mass associated with the neuronal interconnections between the cortex and subcortical areas (most primitive), and neo cortex development.
This blog will be used to describe the first human cultural test in this process encephalization which has led to the human species become the living being with most encephalization coefficient (7.6) of the planet, compared with 4 (dolphins) and 2.5 (chimpanzees), and consequently to develop cultures in different parts of the planet.
40 million years ago climate change called Cenozoic glaciation began. Consequence of it major changes in rainfall patterns, sea levels and distribution between desert and jungle areas occur, isolating populations and performing a positive selection on populations of primates, who had gene expression in ROBO1.
It can be considered that from there derives the separation between the orangutan lineage and lineage of ancestors of gorillas, chimpanzees and humans who stay accomplished 12 million years ago. Maintaining the selective pressure of the ice caused the late separation, 7 million years ago, between hominids, chimpanzees and bonobos.
The coefficient of human encefalización grew, acquiring new skills and behaviors, and found the first cultural evidence 1.8 billion years consisting in development of an instrument carved songs. After about 4000 generations (equivalent to 100.000 years) hominids developed a degree of encephalization that allowed them to design bifaces stones. This is the second cultural test of preparing tools dating back 1.7 million years.
It is considered that softening on weather conditions allowed the increase in human population and gene expression MCPH1 1.1 million years ago. This gene is associated with the emergence of more complex skills such as handling and use of fire, which constitute the third cultural evidence of encephalization with an age of 0.35 million years (350.000 years). Also at this time corresponds fixing the current genetic structure of the Y chromosome (which are transmitted to subsequent generations is done exclusively through the 50% of male sperm.
A worsening weather conditions occurs between 180 to 130,000 years ago (Riss glacial period) and consequently start a new positive selection on mitochondrial genetic variants that fix the current genetic structure of circular DNA of human mitochondria (whose transmission to the next generation is done exclusively through all female eggs)
In this situation the settlement ROBO1, MCPH1, of the male Y chromosome and a circular mitochondrial DNA genes, the human race went through a new selection process caused by the combination of volcanic Toba catastrophe and Wurn glacial period. The first, which occurred 73.000 years ago, that caused a volcanic winter that lasted six years, followed by the second which lasted until 10,000 years ago leading to the human species to extinction.
Probably these phenomena made a positive choice for those few people possessors of the DRD4 gene in their 2R and 7R variants related to the control of dopamine, the ability of imagination and risk-taking. After about 1500 generations from Toba catastrophe, the selected human population expanded by the planet and sequentially new cultural evidence result of new skills derived encephalization process appear: appearance of graphics (40,000 years) molding clay (29,000 years) , ceramic tiles (27,000 years) and sharp points (16.000 years)
After Wurn glaciation further evidence of the encephalization appear: appearance of molten copper ornaments (9000 years), domestication of cereals and livestock (6700 years), zoomorphic figurines (6500 years), write (6000 years) and megalithic or pyramidal constructions (5,500 years).
Consequence of this information can conclude that those cultural phenomena that have occurred simultaneously in different parts of the world are not the result of external phenomena to the evolution of the human species, all the contrary, the process of encephalization caused by human genetic endowment and selected by the ambient conditions is the origin of distant cultures among themselves having equal steps in similar times.