Chapter 1 - Worlds Together Worlds Apart PDF

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These are notes for chapter 1. This course was taught by Professor Digeser....

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Professor Digeser History 2A Spring - 2020

CHAPTER 1: BECOMING HUMAN 

Introduction: ➔

Homo sapiens, or modern humans, originated in a small region of Africa about 200,000 years ago and migrated out of Africa less than 100,000 years ago. ‘‘We are all Africans’’. ●

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Out of Africa Thesis; thesis which contends that modern humans are descendants of recent migrants out of Africa However, there are doubters and do not agree with the thesis; they believe that as the early dispersed geographical settings, they took on diverse personality traits and distinctive physical appearances, with the result that they appear today as different races. But now it is becoming clear that all humans share a common heritage, and our differences are not genetic or crudely physical, but mainly cultural. Most of the common traits of humans evolved over many millennia and crystallized on the eve of the exodus from Africa. The differences in humankind’s cultures are less than 15,000 or 20,000 years old.

➔ Hominins preceded humans; humans came from only one stock of migrants

out of Africa. ◆ As they fanned out across the world, our ancestors adapted to environmental constraints and opportunities. ◆ They created languages, families, and clan systems, (often innovating to defend themselves against predators).

◆ One of the biggest breakthroughs was the domestication of animals and plants-- the creation of agrarian settlements. Humans began producing their own food and stopped following it. Evolution vs Modern Humans ●

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Evolution: is the process by which the different species adapt in response to their often changing environments in ways that enable them to survive and increase in number; adaptation to environmental surroundings. Transformative changes were often brought by dramatic alterations in climate and by ruptures of the earth’s crust caused by the movement of tectonic plates below the earth’s surface. The changes in the rotation of the earth around the sun caused radical climate variation.  Climate change has been dramatic and radical over time. ○

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There were times when glaciation reached all the way to the equator, while other times the climate was so warm that dinosaurs flourished in antarctica and ferns grew in the canadian arctic.

The term modern humans refers  to members of the various homo sapiens subspecies that evolved about 200,000 years ago (in relative terms to life of the universe & earliest hominins). Humans evolved in varying environments, passed through successive waves of migration, adaptation, and innovation.

Precursors to Modern Humans Creation Narratives ●

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Creation narrative  : various accounts of the creation of the universe and humankind’s place in it, conceived by virtually all peoples. Creation narratives have varied over time and across cultures. Example: only 350 years ago, english clerics claimed on the basis of biblical calculations and christian tradition that the first day of creation was Sunday, October 23, 4004 B CE.

But now we see things differently and know that the universe dates back some 13.75 years ago and hominids began to separate from apes some 6 or 7 million years ago.

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Hindus, Muslims, Christians and Jews believed in a creationist account of humanity’s origin. 

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Judaic-Christian belief in creation was based on the first book of the Old Testament, Genesis, which portrayed God creating the universe from nothingness, all the plants and animals and the first set of human beings (Adam and Eve) over a period of seven days. This story became foundational for western societies and also for the islamic world, which accepted Old and New Testaments as the word of God. Modern discoveries about humanity’s origins have also challenged other major cultural traditions, because no tradition conceived that creatures evolved into new kinds of life, that humans were related to apes, and that all of humanity originated in a remote corner of Africa. ■

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Brahmanical Vedas and the Upanishads (date to 7th or 6th century BCE) and remain fundamental to Hindu faith today, the world is millions not billions of years old. The chinese do not appear to have their own creation story. The Buddhists believe in a continuous reappearance of human and animal souls.

Evolutionary Findings and Research Methods ●

Geologists made early breakthroughs in the 18th century when their research into the layers of the earth’s surface revealed a world much older than biblical time implied ○

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Evolutionary biologists, Charles Darwin, concluded that all life had evolved over long periods from simple forms of matter. In the 20th century, astronomers, evolutionary biologists, climatologists, & archeologists have employed dating techniques to pinpoint the chronology of the universe’s creation, the evolution of all

forms of life on earth, & the decisive role that changes in climate have played in the evolution of living forms. ○

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These scholars of ancient cultures whose information comes mainly from non-literary sources such as fossils, monuments, & artifacts.

Early Hominins & Adaptation ●

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In his Descent of Man (1871), Darwin predicted that Africa was the likely birthplace of humanity. In 1924, an Australian anatomist at the Witwatersrand University Medical School, named Raymond Dart discovered a skull and bones that appeared to be human and partly ape ○ ○

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He labelled it the Southern Ape of Africa, or Australopithecus africanus Believed that the creature was an extinct race of apes intermediate between living anthropoids (apes) and man This individual had a brain capacity of approximately 1 pint or a little less than ⅓ that of a modern man Australopithecines: Hominins species that appeared 3 million years ago and unlike other animals, walked on two legs. Although not humans, they carried the genetic and biological material out of which modern humans would later emerge. Colleagues & mentors disagreed with him, so he ended his research. Robert Brown, a Scottish doctor, discovered other fossils and in 1946 published a book with Dart, T  he South African Fossil Ape-Men:The Australopithecine (this book convinced doubters). Australopithecines, over many million years in Africa, developed into more than six species. - Species: a group of animals or plants possessing one or more distinctive characteristics

◆ Lucy

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In 1974, an archeological team working at a site in present-day Ethiopia unearthed a relatively intact skeleton of a young adult female australopithecine in the valley of the Awash River ○

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Named the skeleton based on the popular Beatles song ‘Lucy in the Sky with Diamonds” Stood a little over 3 ft tall, walked upright, skull contained a brain within the ape size range, and her jaw and teeth were human-like; her arms were long, legs were short --she was probably a skilled tree climber, might not have been two-footed at all times, Skeleton was half a million years older than any other complete hominid skeleton found

◆ Adaptation ●

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The places were researchers found early hominin remains in southern and eastern africa were characterized by drastic changes in the earth’s climate, with regions going from being heavily forested and well watered to being arid and desert-like and then back again Survival required constant adaptation (the ability to alter behavior and to innovate) and finding new ways of doing things.

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In adapting, early hominins began to distinguish themselves from other mammals that were physically similar to themselves The major trait at this stage that gave early hominins a real advantage for survival was bipedalism: they became 2 footed creatures that stood upright ○

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At some point, the first hominins were able to remain upright move about, leaving their arms and hands free for various tasks; ex: carrying food over long distances They were the only primates to move consistently on two legs; were able to migrate out of hostile environments and into more hospitable locations as needed Primates: an order of mammals consisting of humans, apes, & monkeys Why did these primates, unlike gorillas & chimpanzees, leave the shelter of trees and venture out into the open grasslands, where they were vulnerable to attack? Answer is not self-evident.

Fifteen million years ago there were apes all over the world, so why did a small number of them evolve new traits in Africa? ◆ Environmental Changes

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Approximately 40 million years ago, the world endured its fourth great ice age. Had warming & cooling phases that lasted between 40,000 & 100,000 years each. ○

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Between 10 & 12 million years ago, the climate in Africa went through one such cooling & drying phase. To the east of Africa’s Rift Valley, stretching from South Africa north to the Ethiopian highlands, the cooling & drying forced the forests to contract & the savannas to spread. Here some apes came down from the trees, stood up, & learned to walk, run, & live in savanna lands -- thus becoming the precursors to humans & distinctive as a new species.

Using two feet for locomotion augmented the means for obtaining food & avoiding predators & improved the chances of these creatures to survive in constantly changing environments

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Hominins also had opposable thumbs; another trait that helped them survive ○

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Hominins also used increased powers of observation & memory; cognitive skills which they used to gather food & to hunt for meat ○

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Survived by hunting small game & gathering wild plants; also by finding safe hiding places

Early hominins lived this way for more than 4 million years

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They sought ecological niches where a diverse supply of wild grains & fruits & abundant wildlife ensured a secure, comfortable existence.

Hominins communicated through gestures, and might have established a form of spoken language that led to the establishment of rules of conduct, customs, & identities.

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These skills were also used for problem solving & much later, language too

Early hominins were highly social; they lived in bands of about 25

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Gave them great physical dexterity, enhancing their ability to explore and to alter materials found in nature--especially to create & use tools

Their survival was surprising; there were not many of them and they struggled in hostile environments surrounded by a diversity of large mammals, including predators such as lions. Over this 4 million year period, their brains more than doubled in size; their foreheads became more elongated; their jaws became less massive; & they began to look much more like modern humans

Adaptation to environmental changes also led to new skills & aptitudes-- this expanded the ability to store & analyze information With larger brains, hominins could form a mental map of their world; larger groups of hominins created communities with a shared understanding of environment 

 ◆ Diversity ● ●

Hominins were much older and much more diverse than we thought Researchers discovered bone remains of a chimpanzee-sized hominin named Orrorin tugenensis, that walked upright on two-feet ○

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They had teeth closer to modern humans but arms & hands for tree climbing which seemed more apelike

Researchers found a skeleton (named it Homo naledi) with upper body parts that resembled that of the early pre-Homo finds, while hands, palms, & wrists, the long legs & feet, are similar to those of modern humans; but brains were small so they were probably part of the australopithecine group

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Homo Habilis & the Debate over Who the First Humans Were 1 million yrs after Lucy, first examples of creatures named Homo, or true appeared; brains were much larger British paleontologists Mary & Louis Leakey made most significant findings of early humans in Africa; found a skull which they named Dear Boy ○

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Also found tools with the skull; the tools were used for butchering & hunting animals Leakeys believed that tools represented a new stage of evolution of human beings; they gave these creatures new name, H  omo habilis (skillful man)

Homo habilis, first tool making one; Homo  erectus first to be bipedal; Homo sapiens first with truly large brain Early Humans on the Move: Homo Erectus Homo erectus: species that emerged about 1.5 million years ago & had a large brain & walked truly upright; also had superior eye-hand coordination. It means standing man. ○ Lost much of its hair & developed darker skin as protection from the sun ○ Was able to survive (one of the only ones); many more failures than successes in the gradual changes that led Homo erectus to  be one of the few hominin species that would survive until the arrival of H  omo sapiens ◆ Infant Care & Family Dynamics

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One of the traits that led to the survival of Homo erectus was  the development of extended periods of caring for their young Enlarged brain → big problem: head to large to pass through female’s pelvis at birth ○

Result: offspring required to long period of protection by adults while they matured & their brain size tripled

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Maturation & brain growth required mothers to spend years breast-feeding & prepping food for children after their weaning

◆ Use of Fire ●

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Homo erectus began to make rudimentary attempts to control their environment by means of fire -- another significant marker in the development of human culture. It was also powerful, for here was a source of energy that humans could extinguish & revive at will. Because they were able to boil, steam, & fry wild plants, early humans could expand diets. ◆ Early Migrations

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Homo erectus individuals first migrated to Southwest Asia, then along the Indian Ocean shoreline, moving into South Asia & Southeast Asia and later northward (China); from East Asia to Japan, as well as from New Guinea to Australia; Europe was last place occupied in Afro-Eurasia

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