Human Evolution & Development
By: Lauren Ashley
Evolution and Natural Selection
"The Big Bang" and Other Theories
Some people believe that the earth was created by an extraordinary random burst of energy called the “Big Bang Theory.” Gradually, the energy cooled enough to make matter such as protons and hydrogen. Stars swirled together in giant clusters and formed galaxies, and burned up stars exploded and generated so much heat that they exploded and made elements and minerals. Because of all this, the Sun was created, as well as Earth. The Earth gradually developed chemicals in water that formed the inside of membranes, thus creating one-celled living organisms. These organisms reproduced for 3 billion years and adapted to different environments.Eventually, their cells stuck together to create multi-cellular creatures. Following this theory, it is believed that humans evolved from apes. Eons later, Africa has become the most diverse and evidential continent wholly supported by this theory. Another theory is that life emerged from nutrient-rich puddles of “organic soup.”
Hominids & Modern Humans
Chimpanzees (5-9 million years ago):
Australopithecines (1-4.2 million years ago)
Australopithecines had a brain capacity of about 375-500 cc. They were the first step towards bipedalism, and were about the same height as chimpanzees. Their face and jaws stuck out, they had larger teeth than humans, and they were small-brained. They originated and lived in Africa. The notorious skeleton, “Lucy,” was an Australopithecine.
Homo Habilis (1.4-2.3 million years ago)
Homo Habilis had a brain capacity of about 510-750 cc. They are known as the “handy man” species because of the evidence of tools found with its remains. They are bipedal, had short arms, and originated and spread through Africa. They are very similar to australopithecines in many ways. The face is still primitive, but the back teeth are smaller. Because of this, many scientists believe that Homo Habilis should be assigned to either the australopithecines or Homo Erectus. They ate mostly fruit and insects, but slowly started to evolve into eating meat.
Homo Erectus (1.9-27,000 years ago)
Homo Erectus had a brain capacity of about 850-1200 cc. They had protruding jaws with large molars, no chin, thick brow ridges, and a long skull. Their skeleton is larger and taller than modern humans, implying greater strength and height. They were omnivores, as well as bipedal. They had better tools (made out of stone) than Homo Habilis, but they could not speak. They have been found in Africa, Asia, and throughout Europe.
Homo Sapiens (200,000 years ago-present)
Homo Sapiens (humans) are the most evolved of all species. The term covers a diverse group of skulls which have features of both Homo erectus and modern humans. We have large and developed brains, culture, writing, and speech. We are the only survivors of evolution and we are evolved because of our intricate and diverse culture.
Culture and Language: What Makes Us Human?
About 7-million year ago, ape-like creatures roamed the world's forests. However, they started to move out of the forests and into plains and grasslands. Since they no longer needed to use their arms to get around, natural selection worked its process and longer legs were soon favored. (long arms weren't as much needed now). Now that their hands and arms were free, they could used them for other tasks such as hunting and gathering food and building tools or weapons.
These animals were the early ancestors of humans.
The Power of Speech:
Learning started to become a big part of everyday lifestyle. There was an increased sense of curiosity among, and when one group member learned how to do a new skill or task, they would teach everyone else so they too could do it. As early humans started to become increasingly skillful, they slowly started to control the sounds made by their mouths and make them into words. The need for improved voice control led to changes in throat design. These changes made it easier for them to choke while eating or drinking, but improved voice control outweighed this disadvantage. Because of this new language, it was easier to communicate, cooperate, and create closer relationships with each other.
The Development of Culture:
Because of the new language and way of communicating, new culture arose. People began to entertain each other with stories, show more respect for others, and find their place in the world. The development of language, laws, and customs marked a huge turning point in evolution. Evolution would now be more about evolving human cultures rather than evolving human bodies.
Human Migration:
Early humans lived in family tribes that moved around following herds of wild animals. They slept in caves or made simple shelters under trees, made their clothes from animal skins, and all-purpose tools were made. They spread across Africa, Europe, and Asia in waves of migration that continued for hundreds of thousands of years. Because of this migration, modern humans all share similar abilities to our last common ancestor, but we come in a variety of shapes and colors.
Agriculture & Humanity
Farming Pros & Cons
For farmers, who increasingly relied on a single crop, an attack by locusts or a drastic change in weather could result in famine. Also, while hunter-gatherers moved from place to place following animal herd, they left their trash and germs behind, while farmers remained in one place. Not only did this result in excessive garbage but they also shared housing and diseases with their domesticated animals.This caused disease to spread like wildfire among people and animals alike. In addition to the potential for illness and bad health, farming also resulted in the development of social classes and gender inequality. However, farming is also a good thing because it is a great food source and we no longer have to depend on hunting and gathering to find food. Farming is also a huge industry in most countries around the world, grossing a huge income, which helps support farmers and their jobs.