Timeline: Human Migration and Notable Events

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This timeline represents my understanding of our origins. It’s purpose is to bring some sense of perspective to the very long and complicated history of humanity on Earth. This timeline is intended to help me with the big picture. In this timeline I bring together various scientific disciplines including plate tectonics, evolution, anthropology, and genetics as well as significant scientific, religious, and mythical dates. I’ll update it as I learn new things and as new things are discovered. I hope you enjoy it and that it helps you too!

3.8 Billion BCE3.8 to 4.5 Billion BCE

LUCA – Last Universal Common Ancestor

LUCA, the last universal common ancestor, is the most recent population of organisms from which all current life on Earth descended from. Although no LUCA fossil has yet been found, geneticists can study LUCA by studying it’s descendants, that is, all life on Earth.


3.42 Billion BCE3.42 to 3.7 Billion BCE

Oldest Known Fossil-Microorganisms

micro organisms cells background

The earliest known life on Earth are fossilized microorganisms found in hydrothermal vent precipitates. Currently dated to about 3.42 billion BCE.

2 Billion BCE

Internal Organelles Evolve


Eukaryotic cells are cells with internal organs, organelles and the DNA is in the nucleus. The predecessor prokaryote cells do not have a nucleus, but do have DNA. All cells in all animals, plants, and insects are eukaryotic, but all animals, plants, and insects host millions of critters based on both eukaryotic and prokaryote cells.

1.5 Billion BCE

Animals, Plants, and Fungi Split

Eukaryote cells evolve into three separate lineages, the ancestors of modern plants, fungi and animals. Later animals evolve into the animal kingdom which includes mammals, birds, reptiles, amphibians, fish, insects, crustaceans, arachnids, echiniderms, worms, mollusks, and sponges.

600 Million BCE

First Multicellular Animals

green and black abstract painting

Organisms that consist of more than one cell took several billion years to evolve from unicellular organisms. All species of animals, land plants and most fungi are multicellular, as well as many algae. A few organisms are partially both such as slime molds and social amoebae.

540 Million BCE

First True Animals – Comb Jellyfish

Jellyfish moving through water

Through genetic analyses, scientists now believe the Comb Jellyfish is the earliest known true animal to evolve on Earth. Prior to this genetic analyses, simple sponges were thought to have evolved first.

525 Million BCE

First Vertebrates

First Vertebrates

The earliest known vertebrates originated about 525 million BCE during the Cambrian explosion. 

470 Million BCE

First Land Plants

yellow and red flowers on gray rock

The first land plants appeared during the Ordovician period. Life was diversifying rapidly during the Ordovician period.

414 Million BCE

Oldest Known Air Breather

Oldest Known Air Breather

The millipede pneumodesmus newmani is the oldest known air breathing animal. 

Circa 260 Million BCE

Plate Tectonics

Plate Tectonics

By dating rocks and fossils scientists can document the movement of the continents over time. 

To confirm and refine this science, geologists study rocks, paleontologists study fossils, and anthropologists study human societies, cultures, and relics. The location and dating of rocks, fossils, and relics allow us to understand the distant past.

  • Cynognathus, circa 242 million BCE
  • Lystrosaurus, circa 250 million BCE
  • Glossopteris, circa 275 million BCE
  • Mesosaurus, circa 285 million BCE
250 Million BCE to 1 CE

Pangaea Super Continent Breakup

Pangaea Super Continent Breakup

Animation of the break-up of the supercontinent Pangaea and the subsequent drift of its constituents, from the Early Triassic to recent (250 Million BCE to 1 CE). The super continent Pangaea existed from about 335 to 175 Million BCE.


140 Million BCE

South America Splits from Africa

Over millions of years, the modern-day South America and Africa  separated during the breakup of the supercontinent Pangaea.

66 Million BCECretaceous End -- Tertiary Start

Purgatorius — Earliest known proto-primate.

© N. Tamura (CC BY-SA)

Purgatorius is an extinct species believed to be the earliest primate or a proto-primate, a primatomorph precursor to the Plesiadapiformes. It lived in Eastern Montana about 66 million years ago during the very last years of the Cretaceous period. Although statistically unlikely, this little creature could be a direct ancestor of humans. It lived through the K-T extinction event and the extinction of dinosaurs.

56 Million BCE

Opening of the North Atlantic Ocean

North America splits from Europe. Over millions of years, the modern-day Europe (Eurasian plate) and North America (North American Plate) separated during the final breakup of Pangaea in the early Cenozoic Era. This split is a later part of that breakup and created the North Atlantic Ocean.

7 Million BCE5 to 25 Million BCE

Split from Chimpanzee

A Silvery Gibbon in Australia
280,000 Generations Ago

Humans and Chimpanzees had a common ancestor about 7 million BCE. Humans did not evolve from Chimpanzees, but both are the current evolution of a common ancestor. That common ancestor has yet to be identified and is sometimes referred to as the Chimpanzee–Human Last Common Ancestor (CHLCA). That common ancestor lived sometime between 5 and 25 million BCE with 7 million BCE being a common “best guess”. The living species that evolved from this common ancestor are gathered together in the Hominini family — the scientific taxonomic tribe. The only living species on Earth that are part of the Hominini family today are humans and two types of Chimpanzees: common and bonobo. All the other species that evolved from our common ancestor are now extinct. 

6.5 Million BCE

Walking Upright: Sahelanthropus tchadensis

Walking Upright: Sahelanthropus tchadensis

Sahelanthropus tchadensis has two human anatomical traits: small canine teeth, and walking upright on two legs. We believe it walked on two legs because the large opening where the spinal cord exits out of the cranium from the brain is located further forward (on the underside of the cranium) than in apes or any other primate except humans.

The female human evolution.

2.7 Million BCE2.7 Million to 2 Million BCE

Early Stone Tools

Early Stone Tools

The earliest known stone tools date back to at least 2.6 million years ago. These basic stone tools were made and used by early humans–hominids. Did they also use wood tools? Sure, or at least very likely, but we have yet to find any preserved back as far as stone tools which hold up to the test of time much better than wood. 

The stone tools include hammerstones, stone cores, and sharp stone flakes. By about 1.76 million years ago, early humans began to make Acheulean handaxes and other large cutting tools.

2.3 Million BCE2.3 to 1.65 Million BCE

First Earth Explorer: Homo Habilis

First Earth Explorer: Homo Habilis
92,000 Generations Ago

Homo Habilis lived about 2.3 to 1.65 million BCE. They had larger brains than predecessors and used stone tools as well as used and controlled fire. They were likely the first hominids to explore most of the Earth. We know these hominids evolved into at least 20 known species of which only Homo Sapiens survive today.

Some of our extinct distant cousins but NOT* our ancestors:

  • Homo antecessor: 1.2 million to 800,000 BCE (Spain; maybe England and France)
  • Homo erectus**: 2 million to 108,000 BCE (Eurasia)
  • Homo floresiensis: 60,000 to 50,000 BCE (Indonesian island of Flores)
  • Homo luzonensis: 67,000 to 50,000 BCE (Philippines)
  • Homo naledi: 335,000 to 236,000 BCE (Africa, along side our direct ancestors)

Our distant cousins exhibited some human traits including cave dwelling, controlled fire, team hunting, and butchering of prey with tools. The surviving tools found are made of stone and bone but it is very likely they used other less durable types of materials like wood, vines, feathers, sticks, etc. For example, the hand axe dates back to before 2 million BCE. All this evidence indicates these human traits likely evolved before 2 million BCE.

*No valid evidence, and not currently thought to be an ancestor. 
**There is a debatable hypothesis that homo erectus explored the world, returned to Africa, and those that returned evolved into homo ergaster and are our direct line ancestors.

1.76 Million BCE

Hand Axe

Hand Axe
70,400 Generations Ago

By about 1.76 million BCE, early humans began to create hand axes. They would strike really large flakes, then continue to shape them around the edges. The hand axe pictured dates to circa 1.1 million BCE. It was found at Isampur, India.


1.52 Million BCE1.53 to 1.51 Million BCE

Oldest Modern Human-like Footprints

Oldest Modern Human-like Footprints
60,800 Generations Ago

Oldest undisputed evidence of hominins walking upright efficiently, probably Homo erectus. Our style of upright walking is energetic and efficient. We use a long stride with a spring-like mechanism in the arch of our foot. These footprints found in Kenya are dated to 1.52 million BCE. They show evidence of a well-developed arch and a long stride ending in a propulsive toe-off of modern people.

800,000 BCE800,000 to 200,000 BCE

Rapid Brain Growth

blue and green peacock feather

Rapid brain growth in our human ancestors started about 800,000 BCE. Now, by rapid brain growth we mean about 600,000 years! Larger complex brains helped early humans to survive. They interacted with each other and their surroundings in new and different ways.

790,000 BCE

Fire-Altered Stone Tools

31,600 Generations Ago

Burned flint tools dated to circa 790,000 BCE were discovered at Gesher Benot Ya’aquov, Israel.


700,000 BCE700,000 BCE to 200,000 BCE

First Speakers: Homo Heidelbergensis

First Speakers: Homo Heidelbergensis
28,000 Generations Ago

Homo Heidelbergensis lived from about 600,000 to 200,000 BCE. Several species evolved from this common ancestor and the last known species identified as Heidelbergensis species became extinct about 28,000 BCE. Homo heidelbergensis lived in Africa, Europe, and possibly Asia. They had some of our human characteristics including large brains, small teeth, bipedality, and used tools.

Could Heidelbergensis speak? We believe they had the physical ability to speak (a Hyoid bone), and a complex lifestyle that would require at least simple conversations. For more information, explore archaeological research into the Hyoid bone which is unique to humans today and is required to duplicate our speech.

  Male Female
Avg. Height 5’9″ 5’2″
Avg. Weight 136 lbs 112 lbs
400,000 BCE400,000 BCE to 40,000 BCE

Split from Neanderthals 400,000 BCE

Neanderthal Skeleton
16,000 Generations Ago

Humans and Neanderthals had a common ancestor about 400,000 BCE. Humans did not evolve from Neanderthals, but both are the current evolution of a common ancestor. The two species interbred so if your definition of species is the traditional “individuals capable of exchanging genes”, interbreeding, then Neanderthals are not a separate species from modern humans. Through DNA testing we can identify DNA that came from interbreeding with Neanderthals. Neanderthals became extinct about 40,000 BCE. They built shelters, wore clothes, used tools, and spoke. We know that about .03% to 4% of the genes in modern humans is from Neanderthals. It is highest in East Asians, intermediate in Europeans, and lower in Southeast Asians. 

The common ancestor is tentatively identified as Homo Heidelbergensis which lived from about 600,000 to 200,000 BCE. The 400,000 BCE is the current best guess, but there is growing evidence the split could have come as far back as 500,000 BCE.

350,000 BCE400,000 to 300,000 BCE

Oldest Surviving Spear

Oldest Surviving Spear
14,000 Generations Ago

Long spears made hunting large animals more safe. The oldest wooden spears found so far were found in Germany and dates to circa 400,000 BCE. In fact, they are currently the oldest known wooden artifacts. The find included 3 wooden spears, stone tools, and the butchered remains of more than 10 horses.

These spears have the same qualities as modern tournament javelins and can be thrown over 200 feet. The workmanlike qualities of the heavily worked wood were similar to modern javelins where the heaviest thickest part of the spear, the center of gravity, is in the front third.

315,000 BCE

First Homo Sapiens but “not us”

12,600 Generations Ago

The first humans evolved in Africa about 315,000 BCE. These first humans had most of the traits we identify as human including looking and thinking much as we do. They used brain power, innovation, and teamwork. They spoke and controlled fire. Their lives were complex. Over the next 250,000 years they evolved into us. By about 150,000 BCE our current capabilities were mostly evolved. Today’s humans have essentially the same DNA as humans from circa 60,000 BCE.


275,000 BCE

Adam: Haplogroup A

Haplogroup A, screenshot from 23andme.com
11,000 Generations Ago

All humans today share a single grandpa, circa 275,000 BCE. We know this because all humans alive today share our ancestor’s haplogroup A genes — from our Y chromosome. He was one of many thousands of men living in eastern Africa. Many paternal lines survived for many generations but ultimately over time all the other male lineages died out. Adam’s descendants met our Eve about 100,000 years later–about 4,000 generations later.

175,000 BCE200,000 to 150,000 BCE

Eve: Haplogroup L

Haplogroup L, 23andme.com screenshot.
7,000 Generations Ago

All humans today share a single grandma, circa 175,000 BCE. We know this because all humans alive today share our ancestor’s haplogroup L genes — from our X chromosome. She was one of many thousands of women living in eastern Africa. Many maternal lines survived for many generations but ultimately over time all the other female lineages died out.

150,000 BCE200,000 to 150,000 BCE

Modern Human Looks and Brains

lover couple of caucasian male and female lay down at the beach relaxing
6,000 Generations Ago

By circa 150,000 BCE, the size of our brain and it’s capabilities matured. Think about this. A human born today and a human born in 150,000 BCE had roughly the same mental and physical capacities. This includes all of our traits including our need for attention and power, our ingenuity, our gullibility to believe things, and our intolerance of the unknown and different. If a human from this time landed in a modern morgue, the doctor performing yet another autopsy would most likely think it was a modern human.

How many times since 150,000 BCE did humans create new religions and Gods? How many times did they discover or invent things that were then lost for thousands of years? Human knowledge builds on previous knowledge, but only if it can be passed down, and survive the test of time. It’s reasonable to believe that various forms of writing and labels were developed and lost countless times. Many interesting advances developed, and lost. No doubt, the stubborn belief in myth or dogma has led directly to the suppression of various human advances countless times. Many times through the use of war and genocide.

Let’s look at just one modern human example. We know the Greeks several thousand years ago knew the Earth was a globe. Over time, the information, the advance, was lost because of the belief in myth and a desire to control others.


120,000 BCE130,000 to 100,000 BCE

Many Early Out of Africa Migrations

The “out of Africa” migration took place in many waves of which two are widely recognized: 130,000 to 100,000 BCE, and the Southern Dispersal around 70,000 to 50,000 BCE. Through genetic DNA testing we know that none of the genetic differences prior to circa 70,000 BCE exist in today’s humans.

76,000 BCE

Earliest Known Prepared Burial, “Mtoto”

Circa 76,000 BCE someone, perhaps the child’s parents, carefully prepared a human child aged about three years old for burial. They dug a circular pit at the entrance to a cave (likely their cave), placed the child in the hole on his or her right side with knees drawn toward the chest.

After proper analysis of the surrounding soil and the decomposition that has taken place in the pit over the years, the archaeologists believe the child, now nicknamed Mtoto, was intentionally buried shortly after death.

70,000 BCE70,000 to 40,000 BCE

Oldest Known Bracelet

Oldest Known Bracelet

It was discovered inside the Denisova Cave beside ancient human remains. The Denisova Cave is a cave located in Siberia, Russia. Other cave finds include woolly mammoth and woolly rhino bones. Scientists say there is evidence that the bracelet’s maker used a drill. This is the earliest known example of advanced drilling in the world.

Head of the museum Irina Salnikova said: ‘The skills of its creator were perfect. Initially we thought that it was made by Neanderthals or modern humans, but it turned out that the master was Denisovan.” This has led to speculation that these earliest humans, Denisovans, were more technologically advanced than previously thought. If true, it might be that the Denisovans were more skilled than Homo sapiens and Neanderthals of the time.

Like Neanderthal DNA, Denisovan DNA exists in modern humans. Non-African East Asians and Europeans have about 2% Neanderthal DNA. Modern Melanesians derived about 5% of their DNA from Denisovans.


60,000 BCE71,000 BCE to 51,000 BCE

“The” Human DNA

Spiral strands of DNA on the dark background
2,400 Generations Ago

A human baby born today, and a human baby born in 60,000 BCE have nearly indistinguishable DNA. There are differences but essentially humans are the same now as they were then. The popular website 23andme.com focuses on 23 changes in DNA that signify your ancestors recent migration. 23andMe.com, ancestry.com, and many others identify differences for their customers. Finally, the medical community is currently in an intense wave of identifying genetic differences that lead to medical problems with the idea of early diagnosis, prevention, and through the use of mRNA correction.

Through mtDNA sequencing, we currently believe the most recent common ancestor of all the Eurasian, American, Australian, Papua New Guinean, and African lineages dates to between 73,000 and 57,000 years ago.

55,000 BCE70,000 to 55,000 BCE

Successful Out of Africa Migration

Successful Out of Africa Migration

Through minor DNA changes, we know which early humans have descendants alive today. This successful “out of Africa” migration, the Southern Dispersal, took place around 70,000 to 50,000 BCE. Our ancestors proceeded to colonize all the continents and larger islands, arriving in…

38,000 BCE38,000 to 33,000 BCE

Bone Flute

Bone Flute
1,600 Generations Ago

The oldest undisputed musical instrument is the Hohle Fels Flute discovered in the Hohle Fels cave in Germany’s Swabian Alb in 2008. The flute is made from a vulture’s wing bone perforated with five finger holes.

38,000 BCE38,000 to 33,000 BCE

Venus of Hohle Fels

Ramessos, CC BY-SA 3.0 , via Wikimedia Commons

The Venus of Hohle Fels is a 2.4″ figurine made of wooly mammoth ivory that was unearthed in 2008 in Hohle Fels, a cave near Schelklingen, Germany. It was pieced together from six pieces found in a cluster, about 10 feet below ground, and about 60 feet from the cave entrance. The left arm and shoulder are still missing. In place of a head, a carved ring protrudes indicating the sculpture was likely worn as a pendant. Using radiocarbon dating, the figurine is dated to between 38,000 and 33,000 BCE.

28,000 BCE28,000 to 21,000 BCE

Advanced Sewing Needles

Advanced Sewing Needles
1,200 Generations Ago

Humans used bone and ivory needles like these about 28,000 BCE to sew warm, closely fitted garments. These bone needles are from Xiaogushan, Liaoning Province, China, and are dated to about 28,000 to 21,000 BCE.

9,700 BCEStart of "our" Holocene geological epoch

Neolithic Revolution

Trevethy Quoit a Portal Dolmen in Cornwall
468 Generations Ago

The Neolithic Revolution is the earliest known Agricultural Revolution. It is very likely that humans practiced forms of agriculture earlier. How much earlier? Well, without evidence, we are guessing. For convenience, anthropologists label humans as hunter-gatherers prior to the Neolithic Revolution. The fact is that the current theory states that agriculture started magically all around the world circa 9,700 BCE. I think it is much more likely this is simply the earliest farming we have yet to discover and will likely push this date back further and further over time.

The Neolithic revolution is the belief in a wide-scale transition of many human cultures during the Neolithic period from a lifestyle of hunting and gathering to one of agriculture and settlement, making an increasingly large population possible. These settled communities permitted humans to observe and experiment with plants, learning how they grew and developed. This new knowledge led to the domestication of plants. A stable lifestyle led to more leisure time and more time to think about things which led to what we would call civilization today. Only the most sturdy of structures from this time period survived the test of time.

9000 BCE

Jericho Founded

St Geaorge Monastery Desert
360 Generations Ago

How old is Jericho? Jericho has been continuously inhabited since at least the 90th century BCE. That makes it at least 50 centuries older than 4000 BCE which is about the time the Bible indicates God created the Earth.

7,100 BCE7,100 to 5,700 BCE

City of Catalhoyuk

The city of Çatalhöyük was a very large Neolithic city in the southern Anatolia peninsula in modern day Turkey. The population of 5,000 to 10,000 lived in mudbrick buildings. Some of the larger buildings have ornate murals. A painting of the village, with the twin mountain peaks in the background is frequently cited as the world’s oldest map, and the first landscape painting.

No sidewalks nor streets were used between the dwellings. The clustered honeycomb-like maze of dwellings were accessed by holes in the ceiling and by doors on the side of houses. The doors were accessed by ladders and stairs. The rooftops were effectively streets. I can imagine on good whether days the rooftop of the massive honeycomb building was similar to a Roman forum some 5,000 years in the future–a place to meet, socialize, and perform business.



6500 BCE6500 through 1900 BCE

Sumer Civilization

From 6500 to 4000 BCE, the Sumer civilization increased in social polarization. For example, central houses in the settlements became bigger. This early Sumer culture is characterized by large unwalled villages with multi-roomed rectangular mud-brick houses. The village featured public buildings including temples and centralized government. They had fine quality greenish colored pottery decorated with geometric designs in brown or black paint. Their known tools that survived the test of time included sickles made of hard fired clay, stone, and metal and the use of ploughs. Villages included craftspeople, potters, weavers and metalworkers, but the bulk of the population were farm workers.

The known Sumerian city-states written history goes back to before 2700 BCE, and starting about 2300 BCE the records are fairly complete.

6,000 BCE

Oldest Known Flute in China

Oldest Known Flute in China

The Jiahu gudi is the oldest known musical instrument from China. This 8,000 year old flute dates back to circa 6,000 BCE. Gudi literally means “bone flute”.

4,004 BCESunday, October 23, 4004 BCE

4004 BCE, The Bible’s Earth Creation Date

240 Generations Ago

Interpreting the date God created the Earth by reading and interpreting the Bible is very difficult. You can put dates on events, time between events, etc. then convert it to the modern Julian calendar. One popular interpretation is Sunday, October 23, 4004 BCE. Generating this date, and similar, rely on the Ussher chronology technique. The Ussher chronology technique comes from the 17th-century Archbishop James Ussher. Ussher created a chronology of the history of the world formulated from a literal reading of the Old Testament. Updates and various interpretations along the same lines are frequently lumped under Ussher chronology.

3500 BCE

Man Made Glass

blue green and red heart shaped stone

The earliest known man made glass dates back to circa 3500 BCE and to Egypt and Eastern Mesopotamia. Discovery of glassblowing around 1st century BC was a major breakthrough in glass making.

3180 BCE3180 to 2500 BCE

Skara Brae Scottish Village

Skara Brae Scottish Village

Skara Brae is a stone-built Neolithic settlement, located on the Bay of Skaill on the west coast of the largest island of Scotland. It consists of ten houses made of flagstones within earthen dams that provided support for the walls; the houses included stone hearths, beds, and cupboards. A primitive sewer system, with “toilets” and drains in each house which carried waste to the ocean using water to flush waste into a drain.

2300 BCEFounded 2300 to 1500 BCE to current

Major Religion: Hinduism

Hinduism was founded sometime before 1500 BCE, but does not have a founder so the exact date is difficult to specify. Like most ancient religions, it is a synthesis of various traditions. Hinduism today is generally centered around the Vedas, ancient sacred texts.

1755 BCE

Code of Hammurabi

A set of about 300 legal laws written in stone from ancient Near East that withstood the test of time. Hammurabi, the sixth king of the First Dynasty of Babylonian, wrote it in the Old Babylonion dialect of Akkadian. The text itself was copied and studied by Mesopotamian scribes for over a millennium.

For example:

“If a man should blind the eye of another man, they shall blind his eye.”

1,700 BCE1700 to 1100 BCE

Rigveda Samhita, Veda Book 1 of 4

Rigveda Samhita, Veda Book 1 of 4
148 Generations Ago

The Rigveda, Sanskrit for “praise knowledge”, is a collection of sacred texts of Hinduism. The sounds and texts of Rigveda have been orally transmitted since circa 2000 BCE. It discusses cosmology, praises deities, and covers philosophical questions including…

  • 1.164.34: “What is the ultimate limit of the earth?”, “What is the center of the universe?”, “What is the semen of the cosmic horse?”, “What is the ultimate source of human speech?”;
  • 1.164.34: “Who gave blood, soul, spirit to the earth?”, “How could the unstructured universe give origin to this structured world?”;
  • 1.164.5: “Where does the sun hide in the night?”, “Where do gods live?”;
  • 1.164.6: “What, where is the unborn support for the born universe?”;
  • 1.164.20 is a parable of the Body and the Soul.

The other three books of the Veda were written centuries later:

  • Yajurveda, circa 1000 BCE
  • Samaveda, circa 1000 BCE
  • Atharvaveda, circa 700 BCE


1344 BCEcirca 1340 to 1320 BCE

Oldest Known Monotheistic Religion: Atenism

Oldest Known Monotheistic Religion: Atenism

In the ninth year of the reign of Akhenaten, he declared the traditional supreme God Aten to be the only God of Egypt with himself as the sole communicator to Aten, kind of like an early Pope. This early attempt at monotheism failed after about 20 years and Egypt returned to their traditional polytheistic religion.

About the image: Akhenaton and Nefertiti seated, holding 3 of their daughters, under the rays of the sun god Aten giving Ankh-symbols to them (Picture provided by ArchaiOptix).

65 CE

Earliest Known Magnification

crystal lens ball in a woman’s hand, with a refracted view of a misty country lane

The earliest known magnification dates back to the first century. These simple early magnification devices consisted of using natural crystals or a glass globe filled with water. It is reasonable to assume the use of natural crystals for magnification was around for many thousands of years. One possible specimen is the Nimrud lens dating back to 750 BCE.

Although man-made glass was in common use about 3500 BCE, eye glasses would have to wait about 4,500 years later. Eye glasses were invented in the 13th century. A few centuries earlier, a reading glass was in common use. A piece of glass you set on a page of text to magnify the letters well enough to read easily.

These early devices provided a max of about 2x, or perhaps 3x, magnification. The microworld of cells and large bacteria would have to wait for the invention of good quality microscopes about 1630. The nanoworld of smaller bacteria, viruses, proteins, and molecules would have to wait for the invention of the electron microscope in 1931.

1590 to 1640 CE

Microscope Invented = Microworld Discovered!

Various bacteria cells in microscope. Streptococcus pneumonia, p

With the invention of the microscope, humanity became aware of the microworld which is defined as 1 to 1000 microns. A micron is equal to one thousands of a millimeter. A cell is about 10 microns wide. Paper is about 100 microns thick. The unaided human eye can see items as small as 50 microns, or about half the width of a piece of paper.

Scientists use three scales when talking about the biological world: the milliworld, microworld, and the nanoworld. The milliworld contains all visible items down to 1 millimeter and includes very small things such as ants, fleas, and grains of sand.

By 1640, the microscope was perfected to the point that allowed the introduction of the microworld to humanity. The microworld contains items with a diameter from 1 millimeter to 1 micrometer, or 1 micron. The microworld contains things like single celled organisms as well as the largest bacteria. By 1640, humanity started it’s introduction to trillions of organisms living everywhere including nearly everything you touch, in the ground, inside plants, and even inside humans. Humans host over 10,000 species of organisms in, on, and through the human body — known as the human microbiome. Every human no matter how clean you think you are is playing host to 10-100 trillion organisms. This fact gradually changed how every human on Earth views life.

The nanoworld which includes smaller bacteria as well as viruses, proteins, and molecules would have to wait for the invention of the electron microscope in 1931. 

Note: The micron and micrometer are the same size, but you use microns (μ) when measuring thickness, and micrometers (μm) when measuring the distance between things. So you can say a cell is 10 microns wide, or you can say the diameter of a cell is 10 micrometers. The term nanomicron, which would be equal to a nanometer, is not currently in regular use.

1905 CE

Radiometric Dating

Iodine 131(I-131)Radioactive isotopes used for hyperthyroidism treatment are stored in Lead boxes
5 Generations Ago

In 1905, radiometric dating was discovered. It is a method used to date rocks and other objects based on the known decay rate of radioactive isotopes. This technique is used to date rocks. Paleontologists regularly order discoveries in chronological order and estimate their age. Knowing the age of rocks allows paleontologists to assign known values to rocks and fossils to firm up the known historical calendar.


Electron Microscope = Nanoworld Discovered!

pathogen virus background

Starting in 1931 with the invention of the electron microscope, the nanoworld became visible to us. The nanoworld contains items as small in diameter as 1 micrometer (1 micron) to a diameter 1,000 times smaller, a diameter of 1 nanometer. The nanoworld includes the smallest single celled organisms, the smallest bacteria as well as viruses, proteins, and molecules.

Note: The virus was discovered in 1892 through scientific experiments and first seen in the 1930s.

1946 CE

Radiocarbon Dating

We all need a little CAFFEINE

In 1946, Willard Libby created the method for dating organic materials by measuring their content of carbon-14, a newly discovered radioactive isotope of carbon. This dating technique provides objective age estimates within a few decades for carbon-based objects that originated from living organisms.

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