The human species, also called homo sapiens sapiens, evolved slowly over a period of approximately million years before the present, starting by separating from a common ancestor between mankind and our closest ape relatives. Modern humans, as we know them today, emerged around thousand years before present in Africa according to the Out of Africa Hypothesis from a small founding population. They spread out from East Africa around thousand years ago and eventually inhabited the known world. Inventions in the modern era?
Ever since man first noticed the regular movement of the Sun and the stars, we have wondered about the passage of time. Prehistoric people first recorded the phases of the Moon some 30, years ago, and recording time has been a way by which humanity has observed the heavens and represented the progress of civilization.
Natural Events The earliest natural events to be recognised were in the heavens, but during the course of the year there were many other events that indicated significant changes in the environment.
Seasonal winds and rains, the flooding of rivers, the flowering of trees and plants, and the breeding cycles or migration of animals and birds, all led to natural divisions of the year, and further observation and local customs led to the recognition of the seasons.
Measuring time by the Sun, the Moon and the Stars As the sun moves across the sky, shadows change in direction and length, so a simple sundial can measure the length of a day.
It was quickly noticed that the length of the day varies at different times of the year. The reasons for this difference were not discovered until after astronomers accepted the fact that the earth travels round the sun in an elliptic orbit, and that the earth's axis is tilted at about 26 degrees.
This variation from a circular orbit leads to the Equation of Time see 'Note 2' below which allows us to work out the difference between 'clock' time and 'sundial time'.
Another discovery was that sundials had to be specially made for different latitudes because the Sun's altitude in the sky decreases at higher latitudes, producing longer shadows than at lower latitudes.
Today, artists and astronomers find many ways of creating modern sundials. A sundial with roman numerals. As you look at this dial, which direction are you facing? The progress of the sun can be recorded using the four faces of this cube.
Can you discover the orientation of these faces?
Wall Sundial Prehistoric carving said to represent the Orion constellation The oldest image of a star pattern, the constellation of Orion, has been recognised on a piece of mammoth tusk some 32, years old. The constellation Orion is symbolized by a man standing with his right arm raised and a sword at his belt and can be seen throughout the world at different times of the year.
Orion was the sun god of the Egyptians and Phonecians and called the 'strong one' by the Arabs. In parts of Africa, his belt and sword are known as 'three dogs chasing three pigs' and the Borana people of East Africa based a sophisticated calendar on observations of star clusters near Orion's belt.
Orion contains some of the brightest stars in the southern part of the winter sky in the northern hemisphere and can be seen later in the southern hemisphere. The three stars of Orion's belt and the red star of his right arm can be easily recognised The earliest Egyptian Star Map is about 3, years old and shows the most unusual conjunction of the planets Venus, Mercury, Saturn and Jupiter in the constellation of Orion and the occurrence of a solar eclipse that happened in BCE.
Babylonian records of observations of heavenly events date back to 1, BCE.
The reason for adopting their arithmetic system is probably because 60 has many divisors, and their decision to adopt days as the length of the year and in a circle was based on their existing mathematics and the convenience that the sun moves through the sky relative to fixed stars at about 1degree each day.
The constellation Taurus, the bull, a symbol of strength and fertility, figures prominently in the mythology of nearly all early civilizations, from Babylon and India to northern Europe.
The Assyrian winged man-headed bull had the strength of a bull, the swiftness of a bird and human intelligence. From about BCE the Babylonians began to develop a mathematical theory of astronomy, but the equally divided constellation zodiac appears later about BCE to correspond to their year of 12 months of 30 days each.
The earliest archaeological evidence of Chinese calendars appears about 2, BCE.
They show a 12 month year with the occasional occurrence of a 13th month. However, traditional Chinese records suggest the origin of a calendar of days depending on the movements of the Sun and the Moon as early as 3, BCE.
Over such a long period of observation, Chinese astronomers became aware that their calendar was not accurate, and by the second century CE it was recognised that the calendar became unreliable every years. This problem is called Precession and was recorded by Chinese historians in the fourth and fifth centuries CE.
In the fifth century CE the scholar Zu Chongzi created the first calendar which took precession into account, and the most comprehensive calendar was the Dayan Calendar compiled in the Tang Dynasty CE well ahead of any such development in Europe.
Precession is due to the gradual movement of the Earth's rotational axis in a circle with respect to the fixed stars. This movement produces a slow 'wobble' which means that the positions of the stars complete a cycle of about 26, years.
The Earth's axis completes a circuit about once every 26, years In the Mediterranean, Hipparchus made the earliest calculations of precession in about BCE.
The problem was taken up by astronomers in the Middle East and India who recognized that precession gradually altered the length of the year.Feb 24, · Primitive Era Vs Modern Era. PRIMITIVE ERA: I think old life style was so good because everything was pure and original.
Mostly i want to focus on the things which we use to eat or drink. In early days the fruits,different crops etc were full of nutrients and energy, but now people use fertilizers and different harmful. History Of Measuring Time When you finish this page, try the History of Measuring Time Quiz.
Prehistoric man, by simple observation of the stars, changes in the seasons, day and night began to come up with very primitive methods of measuring time. History Of Measuring Time. When you finish this page, try the History of Measuring Time Quiz.. Prehistoric man, by simple observation of the stars, changes in the seasons, day and night began to come up with very primitive methods of measuring time.
Units of Measurement The second is the base unit of time, and other units like minutes, hours, etc, are derived from it The measurement of time requires the specification of units, but there are many different units of time, some of which may be more appropriate in certain circumstances than others.
The ancient Roman units of measurement were largely built on the Hellenic system, or about mm. An accepted modern value is mm.
The Roman foot was sub-divided either like the Greek pous into 16 digiti or fingers; or into 12 unciae or inches. in late times pes foot: 1 pes. Measurement From The Primitive Era To The Modern Times *Geologic time* Aleks Ch.
# 8 Date: 24/07/ Introduction The age of Earth is as vast in time as the universe is vast in space. It is not easy to really get a "feel" for 4, million years! One way to try to get a "feel" for how big it is, is to break the number down into smaller pieces that perhaps we .