A reconstruction of 20,000 years of Earth’s temperature

Humans spread over the Americas

After migrating into the continent by traversing the Bering land bridge, people rapidly spread across both North and South America.

Migration throughout the American continent, including the dates and the routes travelled, are still subject to ongoing research and discussion. Academics currently debate whether the migration south occured via land or water, with the latter hypothesis gaining prominence more recently.

Bread-making

Charred food remains from Shubayqa 1, an archaeological site in Jordan, infer the production of bread-like products.

It is believed ancestors of domesticated crops such as wild einkorn wheat, barley and oats collected by hunter-gatherer Natufian people, were prepared over fire for consumption.

Humans settle

The switch from hunter-gatherer to agricultural societies led to a radical change from nomadism to sedentism.

While at different paces, agriculture emerged independently across 11 main regions in the world.

The first signs of crops being cultivated were in the Levant (modern-day Middle East), a region closely connected to evolution of human civilisation.

Bering bridge closed

The Bering land bridge, once a path used by the humans who first reached the Americas, was inundated by the rising sea level. It now separates Siberia from Alaska.

At its peak, the bridge was 1000 km wide in the north-south direction, larger than New Zealand's South Island (840 km).

The Climate Optimum

Paleoclimatologists believe this period to have been slightly warmer than the 20th century average, peaking at around 8000 BCE.

The warmer conditions would last many millennia.

Cats domesticated

Research suggests the domestication of cats started with a "mutually beneficial" relationship between felines and human farmers in need of pest control.

With crops and other agricultural products attracting rodents, cats started inhabitating human settlements in search of their prey.

Later societies such as the Egyptian would worship the animals — which may have contributed to how they behave today.

A pre-writing system

Evidence of an early mnemonic proto-writing system dating to this period was found in carved tortoise shells in Jiahu, China.

The system was limited to a range of symbols. This is why it differs from a true writing system that records the writer's languages fully.

Copper smelting

Copper smelting was independently invented in different parts of the globe. The first evidence of copper smelting comes from modern-day Serbia around 5500 BCE.

Because of its lower melting point, copper naturally became one of the first metals humans consistently worked, especially for weaponry.

European migrations

Via the Balkans, migrants spread from most of Europe to the Indian peninsula.

The languages they carried with them would give rise to some of the most spoken to this day, including English, Russian, German, and the modern languages rooted in Latin.

Horses tamed

The Botai, from modern-day Kazakhstan, were likely the first to domesticate horses, about a millennium before the previously accepted consensus of horse domestication, although DNA research suggests the animals were domesticated independently in Europe.

The animals were used for transport, haulage, and meat, and took a central role in Botai culture, possibly contributing to the spread of Indo-European languages through the continent.

First evidence of coal usage

Archaeologists found evidence of coal used as a source of power at a house site in the Shaanxi Province in China. dated around 3500 BCE.

It is believed the people of northern and western China were the first to consistently use coal during its Bronze Age, between 2200 and 1900 BCE, in areas where near-surface coal was easily found.

Oceanic languages

Thousands of years before te reo developed in New Zealand, the Lapita people spoke the ancestral language known as proto-oceanic that would evolve into the Māori language.

Before reaching Aotearoa, it expanded and developed throughout the Pacific, also originating other Polynesian languages such as Tahitian, Hawaiian, and Rapa Nui.

Babylonian empire

The Babylonians largely expanded their empire during the 2nd century BCE under king Hammurabi. The ruins of the capital city Babylonia are today located 90 km south of Baghdad, Iraq.

During this period, a sesame oil market for lighting fuel arose in the area now encompassing Iraq and Syria.

Chinese script

The Chinese script developed over time from the mnemonic symbols used by people in the region into a logographic system for writing. By the second century BCE, it had over 2500 characters. Modern Chinese has in excess of 7000 characters.

It is a unique system for its uninterrupted lineage, and for much of the Common Era was the most used form of script in the world. The Chinese script was highly influential to the development of writing in the East, contributing to the creation of Korean, Vietnamese, and Japanese writing.

The Iron Age

Although iron alone did not give any advantage over the bronze tools and weapons used previously, the discovery of steel, by mixing iron and carbon, represented a technological leap.

Steel not only changed warfare but also agriculture, while iron made its way into art.

Greek alphabet

Derived from the Phoenician alphabet, the Greek alphabet was the first to introduce distinct symbols to represent vowels and consonants.

About a century after it emerged, the Greek system would give birth to the Latin script, a direct ascendant of the alphabet we use in modern times.

Ancient Greece

Divided in self-governing cities, Greece became an emerging mercantile region.

The political and demographic organisation during this time of urbanisation gave rise to the "polis", a central concept of the Classical Period in Greece, some centuries later, when art, science, literature, and philosophy flourished.

To this day, the Western democracies and culture are undeniably influenced by this era.

Rome

According to legend, two brothers raised by a "she-wolf" created the city on the margins of the Tiber river in the 8th century BCE.

Archaeological evidence points to a settlement in the area dating as far back as the 10th century.

The Romans would become a power of continental proportions, deeply influencing Western culture.

Mayan and Aztec writing

Mayan and Aztec civilisations in Central America developed writing systems of different complexities. The Mayan script is the only one that has been substantially deciphered, while there's still evolving research over whether the Aztec had a complete writing system.

Both scripts were logographic, making use of symbols to represent words, augmented by syllabic signs.

Judaism

Judaism derived from a polytheistic religion practised by the Israelites of the 7th century BCE. It is believed to be one of the first religions to have established itself as monotheistic — the belief in one god.

Judaism is the first of the Abrahamic religions, the branch that also gave rise to Christianity, in the 1st century CE, and Islam, in the 7th century CE.

NZ under 1cm of ash

The Hatepe eruption was the last explosion at Lake Taupō's caldera. The sequence of events on the northeastern side of today's lake buried the entire country in at least 1cm of ash.

It was the most violent known volcanic eruption of the last 5000 years.

Christianity expansion

Under Emperor Constantine, Christianty was adopted as the official religion of the Roman Empire. Despite their increasing number within Roman territory, Christians were still persecuted for their faith before this.

As a matter of scholarly debate, the adoption of Christianity by Rome is viewed as political manoeuvering, but with everlasting consequences. In its many forms today, Christianity is the most practised religion in the world.

Rome falls

The political end of the Roman Empire marks, for historians, the end of antiquity and the start of medieval times.

This part of history is outlined by large counterurbanisation and population decline.

Cook Islands

The earliest evidence of human presence in the Southern Cook Islands has been dated to around AD 1000.

Vikings

The Viking Era was marked by raiding and colonising, reaching as far west as the Americas.

The people from Scandinavia were the first Europeans to reach the American continent, roughly half a century before the Spanish-sponsored expeditions of Columbus.

The Little "Ice Age"

From roughly 1300 to 1850, the Northern Hemisphere went through a minor cooling period that the geologist François Matthes named the Little Ice Age.

Technically, it was not an Ice Age. According to the 3rd IPCC Assessment, it is better described as independent regional climate changes. It potentially affected New Zealand, where glaciers advanced during these centuries.

Moas extinct

Less than two centuries after the first people settled in New Zealand, hunting drove the Moa bird to extinction.

Isolated from the rest of the world, New Zealand's ecosystems did not have evolutionary mecanisms to cope with newly introduced predators like humans.

Europeans reach Australia

Dutch explorer Willem Janzsoon was the first known European to have reached Australia in modern times. During his 1605-06 expedition, he set foot on northern Queensland/Northern Australia.

However, coins as old as the 10th century have been found in Northern Australia, indicating others may made it to Australia much earlier than Janzsoon.

Māori-European encounter

Abel Tasman's Dutch expedition is recognised as the first record of Aotearoa indigenous people meeting with Europeans.

After arriving at the west coast of the South Island, Tasman sailed north, also spotting the North Island before reaching Tonga and Fiji.

Cook anchors in NZ

A century after the Dutch navigator Tasman first reached New Zealand, the British ship Endeavour, helmed by James Cook, docked in Poverty Bay/Tairāwhiti.

Cook's voyage to the Southern Pacific in search of land was commissioned by the British Admiralty.

Coal-gas illumination

William Murdock, a British engineer and inventor, used coal-gas illumination in his Cornwall home.

8.2 earthquake

A violent earthquake shook the nation on January 23, 1855.

The magnitude 8.2 quake was centred in the Wairarapa and killed at least five people.

Electricity in NZ

The first commercial application of electricity in New Zealand was a hydro-powered station in 1886, suppyling electricity the Bullendale gold mine in Otago.

Two years later, the first area to officially supply electricity to the public in New Zealand was Reefton, on August 4, 1888.

The world's first coal-powered plant was built by Thomas Edison, in 1882, in New York.

Gallipoli

Kiwi soldiers fought - and died - in the failed Gallipoli campaign of World War One.

Almost 3000 New Zealand soldiers were killed in the months-long battle in Turkey.

Everest conquered

Tenzing Norgay and Edmund Hillary reached the summit of Everest on May 29 1953.

Christchurch earthquake

The February 22, 2011 Canterbury earthquake hit with a 7.1 magnitude, leaving significant destruction behind and 185 dead.

Christchurch and Lyttleton, the epicenter of the earthquake, were among the most affected areas.