Hominid Evolutionary Tree
Evolution vs Creationism
Some people do not accept the theory of evolution of which human evolution is a part.
Statements included here are intended as a summary of the material required by some educational courses, not as a contribution to or endorsement of either position in the evolution vs creationism debate.
This page follows from the introduction to Human Evolution for students of some first-level courses in biology, human biology, and related subjects. These pages are also related to further information about humans compared with gorillas (humans vs gorillas) and humans as primates.
Human evolution is sometimes described using a diagram called the Hominid Evolutionary Tree. That is often shown in textbooks and online illustrated by sketches of a series of figures or skulls whose physical features change progressively from those similar to monkeys to sketches (on the same scale) of modern humans. Pictures on diagrams of the Hominid Evolutionary Tree may be very interesting and helpful to students unfamiliar with the concept of human evolution - but are usually difficult to draw, especially if also under mental and time pressure, e.g. in an exam.
The main points about the Hominid Evolutionary Tree can be summarized without beautiful artwork.
Here is an example of a simple diagram of the Hominid Evolutionary Tree:
The important things to remember about this hominid evolutionary tree are:
- The full names of the species (which appear inside the rounded rectangles),
- The positions of the named species on the hominid evolutionary tree,
- The characteristics that distinguish the named species from each other - either label the characteristics on the diagram (which would result in the overall diagram including more text than that avove) or include a table or a series of short paragraphs to provide the same information clearly.
Notes about the simple diagram of the Hominid Evolutionary Tree
- This simple Hominid Evolutionary Tree has two branches to show that members of the genus Australopithecus existed at the same time as members of the genus Homo.
- The Australopithecus branch stops at approx 500,000 million years ago whereas the Homo branch continues until the present time. This represents the extinction of the Australopithecus genus approximately 500,000 years ago compared with the continuing survial of the Homo genus.
- The timescale is not very detailed due to the amount of detail required for school-level biology courses, as well as limitations on the accuracy of accepted scientific information about precise dates in the distant past. Also, expert opinion changes over time as new information becomes available, e.g. because new fossils are being found and identified and new technologies are being developed to date both new and older samples with greater accuracy.
Table comparing key features of species in Hominid Evolutionary Tree
Genus = Branch of Hominid Evolutionary Tree
Name of Species
Summary of key features
Features of Skull
Genus = Branch of Hominid Evolutionary Tree:
Common ( 'Australophithecus' and 'Homo' )
Name of Species:
Australophithecus afarensis
Summary of key features:
- Bipedal; Walked upright / 'erect'
- Ape-like skull but canine (teeth) smaller than those of modern apes
- No evidence of production or use of tools or objects as tools
Features of Skull:
- Small cranium
- Low forehead
- Nose and mouth projects forwards (sometimes described as 'projecting face')
- Large molars (teeth)
- Deep lower jaw
- Large zygomatic arch
Genus = Branch of Hominid Evolutionary Tree:
Australophithecus
Name of Species:
Australophithecus africanus
Summary of key features:
Features of Skull:
- More distinctive chin than afarensis
- Projecting face (nose, mouth, chin)
Genus = Branch of Hominid Evolutionary Tree:
Australophithecus
Name of Species:
Australophithecus robustus
Summary of key features:
- Taller than africanus
- Solid build
- Long arms
Summary of key features:
- More distinctive forehead than africanus
Genus = Branch of Hominid Evolutionary Tree:
Australophithecus
Name of Species:
Australophithecus boisei
Summary of key features:
- Long arms
- Short neck
Features of Skull:
- Forehead more distinctive and vertical than that of robustus
- Overall shape of skull more similar to that of modern humans than any other species in the Australophithecus genus
Genus = Branch of Hominid Evolutionary Tree:
Homo
Name of Species:
Homo habilis ('Handy Man')
Summary of key features:
- Anatomy of skull (esp. smaller teeth) suggests that Homo habilis may have been the first 'humans' to produce / use tools.
Features of Skull:
- Projecting face (although slightly less pronounced than that of Australophithecus afarensis)
- Larger cranium than Australophithecus afarensis
- Smaller teeth than Australophithecus afarensis
Genus = Branch of Hominid Evolutionary Tree:
Homo
Name of Species:
Homo erectus
Summary of key features:
- Use of more advanced tools (that is devices that would have taken more planning and skill to make) e.g. axes with handles.
- Knew about fire
- Might have cooked meat
- Considerable physical endurance.
Features of Skull:
- Higher forehead
- Face almost flat (not described as 'projecting' as per Homo habilis)
- Distinctive brow ridge - that is, corresponding to the location of eyebrows on modern humans
- Larger cranium (than Homo habilis or Australophithecus), implying larger brain.
Genus = Branch of Hominid Evolutionary Tree:
Homo
Name of Species:
Homo sapiens (Neanderthal)
Summary of key features:
- Fully erect
- More muscular structure than that of modern humans
- Complex social behaviours
- Possible concept of 'afterlife' suggested by evidence of burial ceremonies
Features of Skull:
- Larger brain than modern humans - suggested explanations incl. a larger volume of brain / neural tissue being necessary to control greater bulk of muscle mass.
Genus = Branch of Hominid Evolutionary Tree:
Homo
Name of Species:
Homo sapiens (Modern)
Summary of key features:
- Developed and produced more advanced tools for a wide range of uses
- Worked in organized groups to hunt large mammals
- Made wall paintings
- Developed simple musical instruments
- Developed language - which is said to facilitate more advanced communication between individuals
Some people find it easier to remember the comparative details about the features of the skulls by actually studying real skulls, or models of these skulls, or even just detailed diagrams of them in order to observe the differences themselves. This can improve understanding as well as aid memory. If these teaching aids are not available in your school you may be able to look at some skulls e.g. of Neanderthal man, in a museum or exhibition.
According to the standard theory of human evolution (as taught in first-level biology courses) all forms of 'early humans' except for the species of Homo sapiens that evolved into 'modern humans' became extinct many 1000s years ago. Estimations of dates vary with location and as more information is revealed by archeologists. The approximate time period after which the Neanderthals seem to have ceased to exist is sometimes referred to as 'Early History'.
