Sunday 20 September 2015

Out Of Africa

Every human today is the descendant of a small group of modern humans who left Africa around 60,000 years ago to explore the planet. We can see the legacy of these journeys today in the diversity of races and cultures around the world.

Earth's population was one million 50,000 years ago.

Humans left Africa to enter

  • South Africa - 1,20,000 years ago
  • Europe - 60,000 years ago
  • Asia - 50,000 years ago
  • Australia - 45,000 years ago
  • Russia - 25,000 years ago
  • North America - 15,000 years ago
  • South America - 12,000 years ago                            

The last glacial period lasted from 100,000 years to 50,000 years ago. Siberia and Alaska were linked by 1,000 km of Ice. This was known as Bering Land Bridge. It is because of this bridge Homo Sapiens were able to travel from Russia to the Alaska. This was followed by a slightly warm period before the temperatures dropped again till 10,000 years ago.

Evidence has been found that Neanderthals buried their dead starting from at least 60,000 years ago.

Needle to sew cloths was invented 30,000 years ago.

23,000 - 30,000 year old needle found in China

Hunting and foraging was the only way of life up till 12,000 years ago.

By 10,000 years ago humans had spread through every continent. Later explorers from medieval Europe found their New World already Inhabited.

 Bows and arrows appeared in the late Ice age and came into widespread use about 10,000 BC. The two types of arrows included Flint arrows Mesolithic arrows.
Flint arrow heads

Shamans were the doctors, priests and medical men of that time.

Human population increased and stretched as areas that had been glacial became temperate.


Monday 14 September 2015

The Ice Age

There were four major Ice Ages in Earth's history. The earliest of these is believed to have occurred around 2.7 - 2.3 billion years ago during the Proterozonic period*.

The Big Chill - The abrupt cooling about 1.5 million years ago led to the last ice age known as Pleistocene Epoch, probably resulted from small shifts in the Earth's tilt towards the Sun.

The climate was divided into two periods :

  • Glacial Period(Cold)
  • Inter Glacial Period(Warm)
Glacial Period

The current Inter Glacial period began around 10,000 years ago.

After 5,000 years of irregular warming and cooling the world shifted from Glacial period to the current Inter Glacial period.

El NiNo Phenomenon - It is the reversal in the flow of water in the Pacific ocean that causes change in weather in every 2 to 7 years time. It is one of the most powerful factor that affects climate after seasons. It is the warm phase and its counterpart cool phase is known as La Nina Phenomenon. 

*Proterozonic Period - The period extending between 2.5 Billion years and 541 million years ago.

Thursday 10 September 2015

Our Remote Ancestors

Evolution of Humans 

  •  Homo Habilis - Between 2.8 and 1.5 Million years ago(communication through Signs andGrunts).
  • Homo Erectus -  Between 1,5 Million and 70,000  years ago.
  • Homo Heidelbergensis - Between 600 and 200 thousand years ago(First to develop Hyoid bone*).
  • Homo Neanderthalensis- Between 300,000 and 50,000 years ago(Lifespan was 30-40 years).
  • Homo Sapiens- From 150,000 onwards.

Homo Erectus

Around 8,000 BC Jericho, Palestine( the oldest continuously inhabited town) is founded.

Homonin - It is the term used for all early humans.

Paleolithic Period -   Period between 2.5 million years ago(first use of stone tools) till 10,000BC (beginning of agriculture).

Stone Tools - Homo Habilis used the simplest stone technology, which was refined by Homo Erectus into stone axes. The Neanderthals were the first to mount stones on spear heads.

Paleolithic Stone Tools

Around 24,000 years ago Neanderthals died at the hands of Homo Sapiens who were successful in adapting to every corner of the globe.

Human language may have evolved because of the need to handle complex social information around 40,000 years ago. 

Brain Development - The earliest signs of development of Broca's area, the part of brain which controls speech, occur in Homo Habilis 2 million years ago. It is located on left hemisphere of the frontal lobe in our brain.    

Evolution of Homonin Skull

*Hyoid Bone - A bone that is present in neck of humans which is necessary for co-articulation and speech.                     
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