Tag Archives: hominins

Hominoids, hominids and homonins – what’s the difference?

 

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Primates: (Order Primate) includes all species with prehensile (grasping digits) with opposable thumbs. They also have forward facing eyes with binocular vision, a well-developed cerebral cortex and bicuspid teeth. This includes all the new world monkeys (such as spider monkeys) and old world monkeys (macaques), as well as the Greater and Lesser apes.

Hominoids: refers to the broad term for great and lesser apes which includes gibbons, orangutans, gorillas, chimpanzees and humans. They have no tail, an upright gait and arms shorter than their legs.

Hominids: includes just the great apes, orangutans, gorillas, chimpanzees and humans

Hominins: Refers to the bipedal human species and their relatives.  such as the following:

  • Sahelanthropus tchadensis (Tournai) – mix of human and chimp features, small brain, may have been bipedal (6.5 mya)
  • Ardipithecus ramidus – Primitive teeth, probably bipedal (4.5mya)
  • Australopithecus afarensis (Lucy) – Walked upright, about 1.2m – 1.4m tall , basic stone tools (3.5mya)
  • Homo habilis (Handy man) – More advanced stone tool making and use, brain size half of modern humans (2 mya)
  • Homo ergaster – Small face and teeth, advanced tool use and may have used fire (2.5mya)
  • Homo erectus (Java man) – Modern features, but with a visible brow ridge, brain size 60-70% of modern humans (1 mya)
  • Homo heidelbergensis – Found in Europe, brain size very similar to modern humans, advanced tool use (1 mya)
  • Homo neanderthalensis – Stocky, adapted to cold, tool use, social structures, rudimentary language possible, brain size slightly larger than modern humans. (500, 000 ya)
  • Homo floresiensis (the hobbit) is known from fossils discovered in Indonesia and co-existed with Homo sapiens. (17,000 – 95,000 ya)
  • Homo sapiens (including the sub-species Denisovans) (present day)

The Australian Museum has some good information about how the definitions for these terms have changed over time, causing lots of confusion for students and scientists alike. New technologies, such as CT scans and DNA analysis, have given us new evidence to support different theories of human evolution than from fossil morphology alone.

The Science of Human Evolution (YouTube, 54.42min) is an interesting video that describes the features of various human ancestors, based on their fossil remains.

Evolution from Ape to Man (YouTube, 50.43min) is another video that describes how the search for the “missing link” in human evolution was based on flawed thinking and how scientists have changed their theories depending on the evidence that becomes available.

Human face evolution in the last 600 million years (YouTube, 1.07min) shows an animated progression of facial features from our distant ancestors to the modern human face we recognize today.

Great Human Odyssey (YouTube, 1hr 52.06min) describes how human ancestors migrated out of Africa and developed skills, technology and talent to survive in almost every environment across the globe.

Modern humans may have interbred with Neanderthals and Denisovans (YouTube, 10.54min) – an excellent segment from Catalyst on ABC with the evidence that modern humans have DNA in common with neanderthals and Denisovans indicating that modern humans may have interbred with these species.

The Science of Human Evolution

human_evolution

Video Source (YouTube, 54.42 min)

  1. What vestigial organ, a remnant from our primate ancestors, is apparent in humans?
  2. Which species does the video refer to as our “distant cousins”?
  3. Name three characteristics that we share with these monkeys.
  4. Notharctus tenebrosus is a fossil that scientists believe to be a common ancestor of humans – how old is this fossil?
  5. What feature of this fossil’s hand is important for climbing and gripping objects?
  6. How was colour vision an important evolutionary advantage in early primates?
  7. What genetic mutation occurred to allow primates to see in colour like humans?
  8. What sense diminished as humans evolved high-colour vision? What evidence is there for this?
  9. ‘Lucy’ is a 3.2 million year old fossil from Ethiopia – why is this fossil significant?
  10. What advantages does this particular characteristic give the species?
  11. What disadvantages does bipedalism have for modern humans?
  12. What characteristic of stone-age man is an indication that human ancestors had the ability for complex thought, together with highly developed hand-eye co-ordination?
  13. In what test do 3 month old monkeys out-perform human babies?
  14. What fundamental brain architecture do all vertebrates, including sharks and humans, share?

What does it mean to be human?

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Have you ever wondered what makes us different from other animals? Why Homo sapiens appear to dominate the earth, altering the landscape and using vast amounts of energy compared to other species? The story might have began around six million years ago, when the primate lineage between humans and chimpanzees branched; in other words, we didn’t evolve from chimpanzees, they are like distant cousins, with a common ancestor six million years ago. A recent non-fiction book by psychologist Thomas Suddendorf, “The Gap – The science of what separates us from other animals” distills two traits that appear to account for most of the ways in which our minds appear quite different from other animals – the ability to cast our mind back and forward, imagining different scenarios and our drive to communicate with others, linking our minds together. I have only just started it, but so far it is fascinating and easy to read.

On Monday we had another terrific Polycom session with Tony and Frazer from the Gene Technology Access Centre. The session focussed on the characteristics of seven fossil skulls – in fact, half-scale models of skulls, including:

  • Homo sapiens (human)
  • Homo habilis
  • Homo erectus
  • Homo neanderthalensis
  • Australopithecus afarensis (also known as ‘Lucy’)
  • Gorilla gorilla
  • Pan troglodytes (chimpanzee)

We looked carefully at the models and tried to order and classify them based on the following characteristics:

  • Presence or absence of pronounced canine teeth
  • Presence or absence of a sagittal crest (presence indicates exceptionally strong jaw muscles)
  • Protruding jaw
  • Brow ridges (subtle or pronounced)
  • Presence of temporal lines
  • Cranium capacity (an indication of brain size – measured in millilitres)
  • Location of the foramen magnum – where the spinal cord passes through the skull to attach to the brain (using a ratio) – this indicates if the specimen is quadrupedal or bipedal.

If we consider the Homo sapien skull to be most advanced, it appears that the brain case has increased in size and become smoother, with a more rounded forehead and the face has become flattened, with a less pronounced jaw.