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A Chronology of Human Evolution
Seven well defined "missing links."
How many more does one need?

Ardipithecus ramidus (4.4 million years ago): Fossils were discovered in Ethiopia in the 1990s. Pelvis shows adaptations that combine tree-climbing and walking upright.

Australopithecus afarensis (3.9 - 2.9 million years ago): The famous "Lucy" skeleton belongs to this species of human relative. So far, fossils of this species have only been found in East Africa. Several traits in the skeleton suggest they regularly walked upright, but they also had adaptations for climbing trees.

Homo habilis (2.4 - 1.5 million years ago): This human relative had a slightly larger braincase and smaller face and  teeth than in Australopithecus or older hominin species, but retains some primitive features also. The first fossils were discovered at olduvai gourge in Tanzania.

Homo erectus (~2.0 million years - 108,000 years ago): Homo erectus had modern human like body proportions were almost indistinguishable from ours. But it had a smaller brain than a modern person combined with more primitive facial features. The first fossil was discovered in 1891 on the Indonesian island of Java. Humo erectus survived for longer than any other close human ancestor.

Homo heidelbergensis (~600,000 years - 200,000 years ago): Homo heidelbergensis is an extinct species of archaic in the genus Homo which lived in Africa, Europe and possibly Asia. Its brain was nearly as large as that of modern Humans. The first fossil was discovered near the town of Mauer, southeast of Heidelberg, Germany in 1907.

Newest Addition (September 2015)
Homo naledi (335,000 - 236,000 years ago): The newest discovery has a mix of ancient and modern lookings features. They had small modern looking teeth, human-like feet and hands but with more primitive fingers and a small braincase. The first fossils were discovered deep in a south African cave in 2013.

Homo neanderthalensis (~600,000 years - 40,000 years ago): The Neanderthals evolved in Europe and Asia whilte modern humans were evolving in Africa. They were shorter and more muscular than modern humans but had larger brains. Neanderthals are our closest extinct human relatives. Scientific evidence suggests our two species shared a common ancestor.

This Is Us
Homo sapiens (~300,000 years - present): Modern humans evolved in Africa from a predecessor species known as Homo heidelbergensis. A small group of Homo sapiens migrated out of Africa around 60,000 years ago and spread across the rest of the world, replacing the other human species they encountered (with a small amount of interbreeding).

The Steps of Human Evolution

  1. Bipedalism: Our early ancestors may have adapted to walking on two legs as an efficient way to travel long distances, possibly to find new kinds of food.
  2. Making Tools: One of the first cultural adaptations that expanded our diets. With better nourishment, we could develop bigger, more complex brains.
  3. Lack of Fur: Early humans may have developed skin without thick fur in order to keep cool on the savanna and make body parasites easier to find.
  4. Blushing: The embarrassment and uncomfortable tingling of a blush can signal remorse and elicit forgiveness from peers in a social group.
  5. Tears of Emotion: Crying shows vulnerability and increases the chances of receiving help, which, in turn, strengthens social bonds in a group.
  6. Bigger Brains: As we gathered into larger social groups, bigger brains developed along with more complex communication and problem solving.
  7. Mystery of Fire: With fire we could cook food and vary our diet, defend against predators, and socialize more - which may have refined language.
  8. Beginnings of Art: Artistic expression and the use of symbols helped lay the groundwork for extended social networks and later for civilizations.
  9. Ritual Burial: The evolution of symbolic behaviors to accompany death signaled self-awareness and thoughts about a possible afterlife.
  10. Starch Metabolism: Humans with high-starch diets, such as those heavy on rice, have evolved specific genes that help them digest these foods.
  11. Salt Retention: Some tropical populations have genes that prevent them from losing too much salt in sweat when exposed to high temperatures.
  12. Short Stature: Small bodies in pygmy peoples may result from early reproduction, a response, in turn, to tropical diseases and early death.
  13. Thrifty Genes: Some genes found in tropical islanders aid survival on limited food resources but could lead to obesity in a high-calorie environment.
  14. Thick Hair: East Asians evolved thick hair shafts 35,000 years ago, perhaps through sexual selection or as an aid in regulating heat.
  15. Digesting Seaweed: In Japan, where a coastal diet dominates, genes in human gut bacteria help the local population extract nutrition from seaweed.
  16. Fat Metabolism: Inuit populations have a generic variant that allows them to digest the fatty foods of their regional diet, like whales and seals.
  17. 12,500 Years Ago: Evolved to live at high altitudes
  18. Arsenic Tolerance: Some Argentine populations have adapted to tolerate high levels of arsenic commonly found in the groundwater where they live.
  19. Domestication: Animal and plant domestication led to permanent settlements and later on to cities and civilizations.
  20. Urban Resistance: As humans settled in to more densely packed communities, they evolved a stronger natural resistance to infectious diseases.
  21. Lactose Tolerators: Early groups that domesticated animals, like herders in Europe, the Middle East, and Africa, evolved the ability to digest milk beyond infancy.
  22. Writing: What started as a system for trade and accounting grew into full expressions of complex language as our cities and cultures expanded.
  23. 8,000 Years Ago: Adapted to a desert climate
  24. Skin Color: Light skin (peoples living far from the equator) increases absorption of ultraviolet light rays and production of vitamin D. Dark skin (peoples living close to the equator) offer UV protection.
  25. Blood Mutations: Different populations exhibit various blood mutations; in a tropical climate, sickle-shaped cells can bestow resistance to malaria.
  26. Tall Europeans: Tall stature among northern Europeans could be another sexually selected trait, reinforced by its allure for the opposite sex.

5-3-17 Ancient humans: What we know and still don’t know about them
Ancient humans: What we know and still don’t know about them
Confused by the flood of news about ancient humans? Here’s the low-down on what new discoveries are revealing about the complicated story of our ancestors. In recent weeks, we have explored the brain of a species called Homo naledi, speculated on the idea that Neanderthals might have made it to North America deep in prehistory, and found signs of Denisovan DNA in layers of dirt in a Siberian cave that don’t actually contain any fossil bones. But who were these ancient humans? And what about the other species that pop up in the news on a regular basis? Here is New Scientist’s primer to help you understand a little bit more about seven of the most important human species in our evolutionary tree. (Webmaster's comment: Excellent article detailing what we know.)

  • Homo habilis (“handy” man)
  • Homo erectus (“upright man”)
  • Homo neanderthalensis (the Neanderthal)
  • The Denisovans
  • Homo floresiensis (the “hobbit”)
  • Homo naledi (“star man”)
  • Homo sapiens (“wise man”, or “modern humans”)

5-3-16 These are the simple steps that made us human
These are the simple steps that made us human
Over the course of several million years, primates gradually transformed into humans. This video shows you the key changes along the way.

Our closest living relatives are the great apes, and there are 6 species alive today: chimpanzees, bonobos, two species of gorilla and two species of orangutan. They all branched off from the primates just like we did, but separately from the human branch. They are not our ancestors.

Also see our Deep Time Table

A Chronology of Human Evolution
Seven well defined "missing links."
How many more does one need?