History of Our Earth - Anniversary Special Post

The history of Earth concerns the development of the planet Earth from its formation to the present day. The age of Earth is approximately one-third of the age of the universe. Earth formed around 4.54 billion years ago. Volcanic outgassing probably created the primordial atmosphere and then the ocean; but the atmosphere contained almost no oxygen and so would have been toxic to most modern life including humans.

Volcanism

Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism. A "giant impact" collision with a planet-sized body is thought to have been responsible for forming the Moon. Over time, the Earth cooled, causing the formation of a solid crust, and allowing liquid water to exist on the surface.


Life of our Earth is divided into 4 ages or eons(units are in Million Years Ago) . 

• Hadean(4,540-4,000 MYA) : The Earth is formed out of debris around the solar protoplanetary disk. There is no life. Temperatures are extremely hot, with frequent volcanic activity and hellish environments. The atmosphere is nebular. Possible early oceans or bodies of liquid water. The moon is formed around this time, probably due to a protoplanet's collision into Earth. 
• Archean(4,000-2,500 MYA) : Prokaryote life, the first form of life, emerges at the very beginning of this eon, in a proccess known as abiogenesis. The continents of Ur and Vaalbara may have been formed around this time. The atmosphere is composed of volcanic and greenhouse gases. 

• Proterozoic(2,500-541 MYA) : Eukaryotes, a more complex form of life, emerge, including some forms of multicellular organisms. Bacteria began producing oxygen, shaping the third and current of Earth's atmospheres. Plants, lately animals and possibly earlier forms of fungi form around this time. The early and late phases of this eon may have undergone "Snowball Earth" periods, in which all of the planet suffered below-zero temperatures. The early continents of Rodinia and Pannotia, may have formed around this time, in that order.

• Phanerozoic(541 - present) : Complex life, including vertebrates, began to dominate the Earth's ocean in a procedures known as the Cambrian explosion. Gradually, life expanded to land and all familiar forms of plants, animals and fungi began appearing, including annelids, insects and reptiles. Several mass extinctions occur, among which birds, the descendants of dinosaurs, and more recently mammals emerge. The rise and evolution of the human species occur at the very recent phases of this eon.

The Last eon, the Phanerozoic, is represented by its three component eras: the Palaeozoic; the Mesozoic, which spanned the rise, reign, and climactic extinction of the huge dinosaurs; and the Cenozoic, which presented the subsequent development of dominant mammals on Earth. 

The Paleozoic ("old life") era was the first and longest era of the Phanerozoic eon, lasting from 542 to 251 MYA. During the Paleozoic, many modern groups of life came into existence. Life colonized the land, first plants, then animals. Two major extinctions occurred. The continents formed at the break-up of Pannotia and Rodinia at the end of the Proterozoic slowly moved together again, forming the supercontinent Pangaea in the late Paleozoic.

The Mesozoic ("middle life") era lasted from 251 Ma to 66 Ma. It is subdivided into the Triassic, Jurassic, and Cretaceous periods. The era began with the Permian–Triassic extinction event, the most severe extinction event in the fossil record; 95% of the species on Earth died out. It ended with the Cretaceous–Paleogene extinction event that wiped out the dinosaurs.

Dinosaurs were the dominant terrestrial vertebrates throughout most of the Mesozoic

The Cenozoic ("new life") era began at 66 MYA, and is subdivided into the Paleogene, Neogene, and Quaternary periods. Mammals, birds, amphibians, crocodilians, turtles and lepidosaurs were able to survive the Cretaceous–Paleogene extinction event that killed off the non-avian dinosaurs and many other forms of life, and this is the era during which they diversified into their modern forms.

Human History In Brief completes One Year

Cleopatra

As a daughter of Ptolemy XII of Egypt, Cleopatra VII belonged to the Ptolemaic Dynasty, set up by the first Ptolemy, one of the generals of Alexander the Great. The Romans supported the Ptolemaic monarchs in return for financial favors.

Cleopatra

When Cleopatra's father, Ptolemy XII Auletes, died in 51 BC, Cleopatra, as the eldest surviving daughter, ascended the throne with a younger brother. According to the tradition, the king and queen were brother and sister as well as husband and wife, so she was expected to marry her brother Ptolemy XIII. 

Cleopatra

Her brother, wanting to keep power to himself, exiled Cleopatra. In 48 BC, when the Roman political and military leader Julius Caesar led a military campaign to Egypt, Cleopatra feared for her life and fell in love with him. He defeated an Egyptian army led by one Cleopatra's sisters, Arsinoe IV. In the same campaign, Ptolemy XIII drowned - pulled into Nile by weight of his body armour made of gold. After his death, Cleopatra began to rule Egypt with her youngest brother Ptolemy XIV.

Arsinoe IV

Cleopatra gave birth to Caesarion, which may have been biological son of Caesar. After Caesar's assassination in 44 BC, she organized assassination of Ptolemy XIV, replacing him with her son Ptolemy XV(Caesarion). For next three years, Cleopatra was careful to avoid power struggle that broke out in Rome after Caesar's death.


By 42 BC, Mark Antony and Octavian(future emperor Augustus) were in control of Rome. Antont and Cleopatra meets at Tarsus,Turkey and become lovers. In 40 BC, she bears twins, Alexander Helios  and Cleopatra Selene, fathered by Mark Antony. When Antony's wife, Fulvia, died in 40 BC, he married Octavian's sister Octevia, sealing a peace deal with him. In 37 BC, Antony visited Egypt and being in love with Cleopatra, married her while still been married to Octavian's sister.


In 37 BC, seated on golden thrones, Mark Antony and Cleopatra, proclaimed themselves as living gods - she Isis and he Dionysus/Osiris and their children as rulers of the land, currently dominated by Rome. After this, Octavian had no difficulty in persuading the Roman senate to declare a war against Cleopatra.

The Death of Cleopatra by Juan Luna 1881

After her defeat by the Romans at Battle of Actium, fought off the coast of Greece, she fled to Egypt followed by Antony. Antony was besieged at Alexandria and was killed. Cleopatra learning about his fate killed herself to avoid being taken prisoner of war supposedly by a snake bite. Octavian honoured her last wish to be buried near Mark Antony. Her eldest son Caesarion was executed but lives of rest of her children were spared.

Cleopatra and Isis

This limestone stele shows Cleopatra(left) breast feeding her son while making an offering to the goddess Isis. She later claimed to be reincarnation of Isis. Daughter of the Earth and Sky, and sister-wife of god Osiris, Isis was the principle goddess of Ancient Egypt. (The Realm of Osiris)

Goddess Isis

Greek And Roman Egypt

Ancient Egypt's later history is one of fascinating change and diversity. Absorbed into the empire of the Macedonian, Alexander The Great, Egypt joined the Hellenistic(Greek) world under the Ptolemies before become a province first to Rome then to Byzantine Empire.


After the New Kingdom, The Assyrians were ousted, and native Egyptian pharaohs presided over a renaissance of their culture - the Saite era(c. 664 - 525 BC). Achaemenid Persians dominated in the years 525 - 400 BC, Egyptians then ruled until 343 BC, when the Persians returned to defeat Nectanebo II the last Egyptian pharaoh.


In 332 BC, Alexander seized Egypt from Darius III when he conquered the Persian Empire. When Alexander died, the control of Egypt passed to his general, Ptolemy Lagus, who had been his governor there. By 304 BC, Ptolemy was king of Egypt, and his descendant would rule for 300 years.

Macedo-Ptolemaic soldiers of the Ptolemaic kingdom, 100 BC

Ptolemy I Soter moved Egypt's capital from Memphis to Alexandria - the new port city founded by Alexander - where it was to remain for 900 years. It's North coast location opened Egypt to the trade and cultures of the Mediterranean.  With its library of legendary fame, it became the world's center for Greek learning.

Ptolemy I Soter

If the Ptolemies's cooperative policy was a shrewd political strategy, it paid off, because their rule brought stability to Egypt. Reforms were made to land ownership, and methods of agriculture improved. They also began to replace the Egyptian barter system with an early form of monetary banking, created royal monopolies on certain goods.

Ptolemy II Philadelphus

In 3rd century BC, during Ptolemaic times, a great light house was completed on Pharos island in the harbor of Egypt's cosmopolitan capital, Alexandria. This towering structure, destroyed by an earthquake during the medieval period - was one of the Seven wonders of Ancient world.

 Ptolemy III

By the middle of the 1st century BC, the Ptolemaic dynasty was weakened by leadership rivalries. Independence was completely lost in 30 BC, when Cleopatra VII, the last Ptolemaic ruler, allied herself with the losing side in the power struggles in the Roman Republic. Octavian, the victorious Roman leader, incorporated Egypt as his own personal domain.


The Romans probably retained much of Ptolemaic system of administration, but they slowly introduced many of their own practises in agriculture and everyday life.  As Rome's power faded from 4th century CE, Egypt came under the influence of the Eastern Christian Roman Empire based in Constantinople. By 6th century BC, Egypt was strictly christian .

Coin issued by Khosrow II

Alexandria lost it's status as the pre-eminent city of Eastern Christianity to Constantinople. The Arabs' arrival in 642 CE dramatically changed Egypt again. Persian king Khosrow II, wrestled control of Egypt from Byzantine Emperor, Heraclius, and ruled briefly(616 - 628 CE) before Byzantium won control back, between 629-641 BC.
   

Egypt then passed to Arabs, Caliph Uamr ibn al-'As found an encampment near Memphis that would later become Cairo, and introduced Islam, which dominates today.

India's First Empire

From their northeast heartland, the Mauryans came to dominate India's massive subcontinent with what became it's first real empire. This empire reached it's greatest extent and enjoy it's greatest cultural flowering under the rule of Ashoka, who also played a major part in the spread of Buddhist religion.


The Vedic Period(c.1500 - 500 BC) is named after the Vedas - ancient Indo - Aryan texts that were produced during this time and that are central to the Hindu faith. Many local dynasties came into being, and by 8th century BC, India was divided unto many small, competing kingdoms.


Around the 8th century BC large urban states known as mahajanpadas started to take shape in northern India. The northeastern Magadha area came to dominate the various warring regional powers. Its strategic position in the Ganges valley aided trade and linked it with flourishing ports in the Ganges river delta.


In the 5th century BC, just a few states, including Magadha dominated India. By the 4th century, after countless wars, Magadha had emerged as the most powerful. Ruled by prosperous  Nanda Dynasty, it set up complex irrigation projects and efficient administration system, built a strong army, and established a royal center at the city of Pataliputra(modern Patna).

Great Stupa of Sanchi

Four magnificent gateways lead to the Great Stupa at Sanchi, Madhya Pradesh. Dating from the 1st century BC, these torans are decorated with intricate carvings that is one of the greatest artistic achievement of ancient Indian art. They show scenes from the life of Buddha and feature motifs such as Ashoka's famous four lions.


Around 321 BC, the Nanda dynasty was toppled by Chandragupta Maurya, founder of Mauryan Dynasty and what would become the great Mauryan Empire(321 - 185 BC). The empire of the first Mauryan king embraced much of the Indian subcontinent and part of Afghanistan. Lands into which Chandragupta expanded included the parts of the Macedonian Empire  won by Alexander The Great by his successors the Seleucid.

Statue of Chandragupta Maurya

Emperor Chandragupta presented 500 elephants to Seleucus I Nicator in 305 BC, in return for giving up his claims to Indian lands. Seleucus used the elephants in battles fought between Alexander's "successors", notably in the defeat of Antigonus at Ipsus in 301 BC. His highly efficient centralized system of administration owed much to his minister, Chanakya ,who produced one of the greatest treatises on politics, administration, and economics ever written - Arthashashtra. 


Chandragupta died around 297 BC, as a covert to Jainism he spent his final days in ascetic repentance for a terrible famine that struck his people. The second emperor was his son Bindusara(c.297 - 265) BC. He consolidated  empire won by Chandragupta, so that only southern tip of India and Kalinga in the East remained unconquered.


Bindusara's son Ashoka(c.265 - 232 BC)  was the last major ruler of Mauryan dynasty and one of the great figures of ancient history. It was Ashoka who brought the empire to its greatest extent, gaining the Kalinga region after a particularly bloody battle.

A relief representing Emperor Ashoka 

As Ashoka's empire prospered, he promoted arts and sciences and instigated a vast building programme. It included a great many stupas, build to house supposed relics of Buddha. At some point in his reign Ashoka converted to Buddhism, he sent missionaries to spread the word far and wide throughout Asia, including Sri Lanka, in so doing played a major role in spreading of Buddhism.

Lord Buddha

The peace and prosperity of Ashoka's reign did not continue long after his death, Subsequent rulers lost territories and prestige, and there were squabbles over succession. The last Mauryan emperor, Brihadratha, was assassinated c.185 BC by his chief aide, Pusyamitra, founder of Sunga dynasty which ruled India till c.73 BC.

State Emblem of India 

Ashoka made this four-lion motif his symbol of Imperial authority and it is now used as India's official emblem. The four Asiatic lions standing back to back symbolize power, courage, confidence and pride. At the bottom is relief of an elephant(East), bull(West), horse(South) and a lion(North) and a wheel called dharma chakra.  

Indian mathematics advanced greatly under the Mauryans and the Guptas. By 4th century BC, scholars were developing the ideas of using combinations of units of different sizes. By the first century CE, they had devised a decimal like system using the symbols and redefined the concept of zero as a "placeholder" to add or multiply numbers. The concept spread from India to Islamic world and finally to the west, where it underlies the modern number system.

Around 320 CE, the region of Magadha gave birth to another great dynasty and empire, the Guptas, who dominated Northern India until c.540 CE. The Gupta dynasty's real empire builder were its two emperors: Chandra Gupta I(c.320 - 330  CE) and his son, Samudra Gupta(c.330 - 380 CE). 

Coins issued by Samudra Gupta

Great artistic achievements of well-administrated, prosperous Gupta Empire(c.320 - c.540 CE) include the Ajanta caves in western India. Some of these shows episodes from the life of Buddha. 

Ajanta Cave paintings

The Gupta era is often seen as the "classical" period of Indian culture. especially of Hindu and Buddhist art. The Guptas had a strong Hindu leaning, but Jainism and Buddhism also flourished. Buddhist monks created wonderful sculpted friezes at the Udayagiri caves. 

Udayagiri caves

Under the Guptan ruler, Kumara Gupta(c.415 - 455), cracks began to appear in the Empire as it faced incursions by Hephthalite nomads(White Huns) from the North. By the 6th century CE, they had pulled back to their original heartland, taking India back to patch works of small kingdoms.