Australopithecus africanus

Australopithecus africanus means ‘southern ape of Africa’. In the scientific classification system species are commonly identified by two names (binomial nomenclature). The first name is the genus and the second is the species (the first word is always capitalized, the second is not) hence; Australopithecus africanus.  The time period for Australopithecus africanus is 3.3 to 2.1 million years BCE (before the common era).

Australopithecus africanus

Mrs. Ples

I’ve always had a soft spot in my heart for Australopithecus africanus.  While studying for my degree in Anthropology at the University of Florida my main interest was in Paleoanthropology or human evolution. The examination of the human fossil remains from the Australopithecines to Homo erectus to Heidelberg man to Neanderthal to Homo sapiens has been a lifelong interest of mine and I am always happy and excited to read about new discoveries and finds like the Denisova, Homo floresiensis and Homo naledi. 

Studying Evolution

The thing about studying human evolution is that the amount of fossil evidence is really very small. Hominin skulls are the most rare and celebrated fossils in the world. There are hundreds of great early man fossil fragments that have been unearthed from different hominin species but not tens of thousands.   New finds are being discovered on an ongoing basis and as you might expect the more fossil evidence that is uncovered and studied the more the theories about human evolution evolve and change.

Presently the common accepted theory is that fully modern humans, Homo sapiens, evolved in Africa some 350,000 to 300,000 years ago. 

The study of human evolution before that is not as clear you might expect and in fact there are several different theories based on the same fossil evidence.  Different interpretations by experts looking at the same data or evidence is not unusual in any field.

One point that is generally accepted is the evolution of humans is not a straight line through time.  Many different species and branches of species have been involved and new discoveries are yet to be made.  However, there are some generally accepted milestones along the way.

The Taung Skull

 In 1924 Raymond Dart an Australian-born, South African anthropologist and paleontologist recognized the human like features of the Taung skull, which had been unearthed in South Africa by miners.  Dart named this find Australopithecus africanus. Up to this point in time the general consensus was that Asia was the birthplace of human evolution.  This opinion took decades to change but eventually the facts are what they are.

Here is a picture of Mr. Dart holding the Taung skull.  The skull is of a small Australopithecus child.

One of the reasons Anthropologists where reluctant to accept Dart’s hypothesis that Australopithecus belonged to the early man lineage centered on brain size.

At the time the current theory was that the human brain size probably evolved first.  However, the whole theory about brain size has been turned upside down and now it’s clear the body evolved along the way first and brain size grew larger later. 

The Foramen Magnum! 

So what you have with the Australopiths is a brain size about one-third the size of modern humans.  However, the skull has human like teeth. 

But with the Australopithecus find there is the distinguishing characteristic that separates the early man fossil record from other species, the "Foramen Magnum".

The what?  The foramen magnum!  We all know what that is.  It’s the hole at the base of the skull that the backbone, spinal cord and neck connect to the head through.  Oh, that foramen magnum. 

The hole at the base of the skull, the foramen magnum, being positioned there instead of higher towards the top of the skull is clear and indisputable evidence that Australopithecus walked upright.  Bipedal is the term.

Bipedalism being the first milestone of human evolution.

After 1924 further Australopithecine discoveries added to the fossil record and substantiated  Dart’s bipedal hypothesis from the analysis of this bigger and more diverse cache of skeletal remains.

With bipedal locomotion Australopithecines could walk upright and have the head sit straight on top of the backbone and neck allowing the eyes to look forward as a natural position.   Contrast that with the foramen magnum higher up towards the top of the skull which allows an animal to walk on all fours and have the head in a natural position to have the eyes looking forward. 

This next picture shows the position of the foramen magnum in three different skulls.

This next picture shows the position of the foramen magnum and how that allows for upright walking in humans instead of the all fours of the gorilla or chimpanzee.  Note the angle of the spinal cord as it enters the bottom of the skull as indicated by the arrows.

The next picture again highlights the angle of the spinal cord as it enters the human skull thru the foramen magnum.   You can clearly see line ‘e’, for the Australopithecus, indicates the spinal cord has the same angle as in the previous picture for the fully human example.

Being bipedal allows the two arms to be used for other things instead of locomotion.

Walking upright allows the arms to be used for carrying for example, which in turn also allows the hands to be developed to be more dexterous.  See the progression?  First early man became bipedal and all the advances in human evolution that followed built upon that major physiological change including brain size.

The Making and Using of Tools

There is no way to know exactly how it all played out but just think about the broad brush stroke here.  First early man evolves to walk on two legs, that frees the arms and hands for other advantageous adaptations the most significant of which is the making and using of tools.  And there you have it, another giant milestone along the path to the ipad, rock and roll, space travel and cheeseburgers; the making and using of tools.

I mean holy mackerel, there it is in a nut shell.   Early ape like creatures evolve to bipedalism (Australopithecines), that begets tools and Katie bar the door here we are reading this on a digital device.  Reading on a digital device was not exactly the next step as there are many more milestones along the path but you get the point.  The kick starter to the whole party is walking upright and the honor of the first upright walking hominins goes to the Australopiths.  Since 1924 there have been other Australopithecines discovered besides africanus and I am going to talk about them next. 

Australopithecus africanus was the first fully bipedal creature discovered that is, however distant, a direct link along the path to us.

More About Australopithecines

In a further and deeper discussion about Australopithecines I think it might be good to go over the actual scientific classification system.  Living things are divided into seven main divisions in the taxonomy system: (1) Kingdom; (2) Phylum or Division; (3) Class; (4) Order; (5) Family; (6) Genus; (7) Species.

So for the Australopithecines you’d have;

  1. Kingdom - Animalia
  2. Phylum - Chordata
  3. Class Mammalia
  4. Order - Primates
  5. Family -Hominidae
  6. Genus - Australopithecus
  7. Species - africanus

For modern humans - Homo sapiens (Latin for ‘knowing man’);

  1. Kingdom - Animalia
  2. Phylum - Chordata
  3. Class - Mammalia
  4. Order- Primates
  5. Family - Hominidae
  6. Genus - Homo
  7. Species - sapiens

The Australopith Genus Profile

The genus Australopithecus evolved in eastern Africa probably about 4 million years ago and most likely became extinct about 2 million years ago. Two million years is a long time and during that time several species of Australopithecine are thought to have existed.  To complicate the matter there are two groups the gracile and the robust.

Group A is the 'gracile australopiths' and they are:

  1. Australopithecus afarensis
  2. A. africanus
  3. A. anamensis
  4. A. bahrelghazali
  5. A. deyiremeda

And as these things go there are skeletal remains from other individuals that suggest enough differences they might get their own species designation when more information (skeletal remains) becomes available,  they are  A. garhi and A. sediba.

 Group B is the 'robust australopiths' and they are:

  1. A. robustus
  2. A. boisei
  3. A. aethiopicus

There is a debate on whether or not these robust species constitute their own genus.  If and when it’s decided they do they will get their own genus - 'Paranthropus' - and will be called:

  1. Paranthropus robustus
  2. Paranthropus boisei
  3. Paranthropus aethiopicus

The human fossil evidence is scant as I have previously said.  So really it is hard to tell how many of the species lived at the same time but most likely several different species of Australopithecine lived at the same time and might have interacted even interbred.

Australopithecine DNA in Humans?

It is well known that Homo sapiens and Homo neanderthalensis, Neanderthals, interbred.  Most modern day Europeans and Asians carry anywhere from 1 to 3% Neanderthal DNA in them. (If you would like to see how much of a Neanderthal you are there are several DNA testing websites you can utilize for that.)  You will not find any Australopithecine DNA in you however.  I just mention it because of the Neanderthal - Human connection.

The comparison of 'Lucy' an Australopithecine to a Human in the next illustration.

As previously stated the brain size of an Australopith was about one-third the size of a modern human brain, between 400 and 500 cc.  They stood about 3 feet 11 inches to 4 feet 7 inches tall (1.2 meters to 1.4 meters).  It is generally agreed upon that they exhibited a fair amount of sexual dimorphism.  By that I mean the females where noticeably smaller than the males.  In modern human populations the males are on average 15% larger than the females.  With the Australopithecus it’s hard to tell because of the small sample size but most agree the size difference was considerably more than 15%, maybe 30 to 40%.

Limited Tool Use

Tool use was limited but still there.  It is doubtful that they had hunting tools like spears and such but tools to carve meat and maybe cut grasses.  The tools were most likely made from sharp stones or bone.

It’s amazing what can be determined through expert analysis of the fossil remains unearthed after all this time but a wealth of information can be.  Scientists do microwear studies of the teeth and three dimensional comparisons and other intricate measurements of jaws and mouth areas.  Then they can compare these to living species in similar environments.  Trace elements can also be found with computers and high tech devices to help form a picture of what they ate.  They ate fruits, vegetables, nuts, etc.  But there is also strong evidence of animal consumption through trace-element studies of the strontium/calcium ratios using stable carbon isotopic analysis.  Whatever that means and however they heck they do it the studies reveal great insights.  

To me it makes sense that they would eat what they could get.  Even modern Chimpanzees will kill and eat other animals from time to time.  So I would imagine the Australopithecines ate whatever they could get their hands on.

Australopith Socialization and Culture

The more you learn about each species of hominin  the more you can’t help but trying visualize how they lived.  I am sure they existed in small or extended family units and probably had some sort of dominance structure or leader of the group.  A large part of the study of early man by anthropologists revolves around imagining how the social structure of individual groups unfolded.

Coordination and planning in time through language gave our ancestors a huge evolutionary advantage. 

We don’t know the extent of the language use by Australopithecines but the next big bump up in evolution to Homo erectus certainly had the language skills to plan and coordinate complex strategies.

The Australopithecine tribes certainly had individual characters that stood out for one reason or another.  How and why we will never know.  But studying other similar small groups of animals always produces some individuals with a more ‘colorful’ personality.

Lucy in the Sky with Diamonds

There are plenty of famous people that you can think of but I can only think of three famous Australopithecines.  The first and most famous one is ‘Lucy’.  Lucy was discovered in 1974 near the village Hadar in the Awash Valley of the Afar Triangle in Ethiopia.

It is a great find because 40 percent of the skeleton from this female Australopithecus afarensis was unearthed. The remains got the name Lucy because of the Beatles song ‘Lucy in the Sky with Diamonds’ which was playing in the background as the workers made their discovery.  She is also known as Dinkinesh, which means "you are marvelous" in the Amharic language.

And here is Lucy.

Anthropologists have been taking a closer look at the Australopithecines and it seems reasonable to assume they still were tree climbers.  After all being able to escape a predator by quickly climbing up a tree is a good survival strategy and foraging for food in the trees would have been advantageous also.  New analysis of Lucy seems to indicate she died as a result of injuries from falling (presumably) out of a tree.

Mrs. Ples

The honor of the most compete fossil skull for an Australopithecus africanus goes to Mrs. Ples.  Mrs. Ples got her name when it was wrongly identified by paleontologist Dr Robert Broom the scientist who found her.  Broom had suggested that the skull was an example of a Plesianthropus transvaalensis species. The newspaper at the time named her Mrs. Ples.

The Taung Skull

Next to Lucy the Taung Skull would be the most recognized Australopith find.  However, the Taung Skull is considered to be the most important.  It has been called "the most important anthropological fossil of the twentieth century".