ORIGIN AND EVOLUTION OF HUMAN BEINGS.

The problem of our origin.

• Until modern times was though that human beings has appeared over this planet in the current form.
• In the XIX century, the theory of the evolution was developed by Charles Darwin. According to it, human beigns evolved from primates, a type of mammals which appeared 65 million years ago. 
• Five million years ago, primates started to evolve into two different direcctions:

1.  On the one hand appeared the pongids: chimpanzee, orangutan, gorilla.
2. On the the other, appeared the hominids, our direct ancestors.

Hominisation process.

There were three biological changes that made hominids different from the rest of the large simians:

• A biped mode of walking. The position of their hip and the extension of their pelvis allow them to took firm steps and large strides.  As a consequence, their hands were freed from the act of walking to use for other purposes.
• Developed and opossable thumbs (far more efficient that the one belonging to pongids). That made possible to easily manipulate objects and therefore, developing tools.
• As a consequence, the brain and skull size increased, increasing their intelligence. This made possible:

1. though
2. speech
3. formation of complex societies.

Human evolution and its stages.

Definition: hominisation was the long evolutive process trough which the hominids adquired their own unique features.
Chronology: this process took place in Africa between seven and 4 million yeas ago.
Causes: a climatic change that made the african climate a lot drier. As a consquence big extensions of tropical rainforest were transformed into treeless savannah, and the primates of this zones were forced to leave the trees and descend to the ground in order to look for new food sources.
We can distinguish several stages in this process:

• First, in Africa, the oldest hominids, which were very similar to the other primates, appeared:

1. Ardiphitecus, about 4,4 million years ago. It was perhaps the first hominid that can walk upright, fed on fruits and could climb trees.
2. Australophitecus, about 4, 2 million years ago. The first hominid that used tools but did not make them.

•  Later, appeared the Homo genus: hominid classified as humans due to their appearance and toolmaking skills. We can distinguish:

1. Homo Habilis, appeared 2, 4 million years ago. Considered the first human beign. First hominid who can make tools. 
2. Homo Erectus, appeared 1, 8 million yeas ago. First hominid to leave Africa, he lived in Africa, Asia and Europe (the oldest european remains appeared 800.000 years ago). First hominid to use fire.
3. Homo Neanderthalensis. Lived between 200.000 and 35.000 years ago. He lived in Europe and the Middle East during the glacial period. He took refugee in caves and was the first hominid to bury their deads.
4. Homo Sapiens, appeared in Africa 195.000 years ago. They made tools from stone an bone and created the firsts art forms. They also extended across almost all the continents.

Ardiphitecus.

Australophitecus afarensis.

Homo Habilis

Homo Erectus.

Neanderthal.

Homo Sapiens.