Human Evolution and Anthropology

The chronological development leading to Homo sapiens and our accomplishments is approximately as follows:

Our ancestral line diverged from the apes 6 million ears ago.  There have been more than 20 species of Homo since that time.  As recently as 50,000 years ago there may have been 4 types of humans living simultaneously (Wells).  All waves of human development and migration have come out of NE Africa, primarily the volcanic Great Rift Valley in current day Ethiopia.  One of the greatest survival characteristics of Homo has been adaptability, and the numerous climate changes such as ice ages have favored Homo development. 

Our earliest ancestors were capable of upright walking (bipedalism).  Many upright walkers are found 6 million to 3 million years ago, although all also maintained good tree climbing ability.  All Homos from this era have small brain sizes; brain size did not significantly increase until 2 million years ago.  The famous skeleton Lucy is from the species Australopithecus approximately 3.2 million year ago.  The skeleton indicates that she likely was habitually bipedal, but still maintained good tree climbing ability.  The first tools do not appear until 2.5 million years ago.

Our earliest ancestors also had inefficient bipedalism and were better adapted for trees than walking. Any speech would have been very crude.  These early ancestors were only 3 to 4 feet tall - Lucy was 3’8”.  At best, they had crude oral communication and probably no speech-based cognitive function.  It is difficult to label them human.

Homo erectus

One of our ancestors, Homo erectus, has been the most successful Homo species in terms of longevity, surviving for nearly 2 million years.  By comparison, we (Homo sapiens) have only been around for 10% as long, for 200,000 years at most.  Homo erectus was also widely dispersed, having emerged from Africa and spreading throughout the old world.  Several ancillary species spun-off from Homo erectus. 

Homo erectus was tall at 6’.  They also had developed an efficient bipedalism that enabled them to run and walk for long distances with reduced energy consumption. For the first time, there was a significant increase in brain size and the appearance of a Broca speech area.   

Homo erectus was mostly hairless.  This gave us an advantage for long term running – we can cool down by sweating.  Animals can only pant.  This enabled us to hunt persistently and turn it into a marathon. We could easily stay within sight of our prey because of our height and excellent vision and run the animal to its point of exhaustion. Homo erectus also had stone tools for the final kill.  Some bushmen hunt this way today!

Homo erectus was a great hunter. But, he did not hunt alone – rather in small groups.  And the small groups had a new skill – the ability to communicate with speech.  The level of speech would have been crude by today’s standards, but as a new tool it increased our ability to obtain food. We also needed food, because the larger brain used more energy and required considerably more sustenance.

Homo erectus had lost tree-climbing skills along with the above advances. Congregation into small groups would have been required for survival at night – perhaps in caves.  They also may have harnessed fire for warmth, protection, and cooking.  If they were able to cook it would have improved health and nutrition.

It is difficult to know their level of speech-based cognitive skills. Making stone tools such as a hand ax requires some decision making.  Did they develop social skills – perhaps around a cooking fire?  Wells reports a skull of an elder Homo erectus with no teeth and evidence to indicate he had lived that way for some time.  Did another feed him – perhaps even chewing food for him? 

The Homo erectus set of attributes and skills enabled them to be very successful in Darwinian survival.  They were among the first Homos to leave Africa, probably 1.8 million years ago.  By 1 million years ago they had populated from the Caucasus to Indonesia and into Europe and China – they had successfully inhabited the old world.  They may have still been living as long as only 50,000 years ago. 

Homo erectus was a very successful animal.  But, if we were able to meet one today, we would probably not call them “human”.

Of course, the above statement requires some definition about the threshold for becoming “human”.  It is difficult to define what it means to be “human”.  It also depends upon the era.  For the purposes here, being “human” means being able to integrate speech based cognition with vision based cognition as an integral part of the mind. 

Homo erectus was still an animal living in a vision-based world and with a vision-based cognitive mind.  They likely had some communicative speech and some elementary speech-based cognition, but it was not well-integrated into their existence.  They had a well-developed sense of self and group, but probably had not yet established the speech-based correlates of ego and group-think.  Their mind and consciousness must have felt very different to them than ours does to us.

As examples, there is no evidence that Homo erectus buried their dead.  A sense of ego causes us to bury our dead because our ego can know that we will die some day.  There is also no evidence of jewelry, clothing, or body paint – all of which are also driven by ego.  Likewise there is no sign of art or any advanced culture or items such as pottery. 

The Homo erectus mind was still largely a vision-based mind. Speech, although crude, was a fantastic new tool that assisted their survival as an animal, but speech-based cognition had probably not been integrated as part of their mind.  They were a successful animal that had a strong sense of group.  Homo erectus was always limited to existence in small groups that were not very different from animal groups.  They had not yet developed a level of group think that would enable them to evolve beyond fire groups.  

Neanderthal

Neanderthal lived in Ice Age Europe from approximately 400,000 years ago. Neanderthal was an offshoot from Homo erectus, likely via Homo heidelbergensis as an intermediary.  Neanderthal were hunters who were adapted well for ice age Europe.  They had a Broca speech area in the left temporal lobe very like ours – they also had a frontal cortex.  Neanderthal brain had slightly smaller parietal and temporal lobes.  They most likely were speaking, although with reduced speech-based cognition.  There is evidence of some advanced culture such as a flute made from bone and a sewing needle.  There is also evidence of burials.

Neanderthals were mostly meat eaters and hunted large herbivores.  Over about 100,000 years and throughout Europe, there appear few changes in Neanderthal.  Many Neanderthal male skeletons have multiple fractures – probably from needing to get close to their prey since they had no projectile weapons.  Lives were tough and short; few lived beyond age of 30.  Neanderthals lasted for almost 400,000 years.  By 25,000 years ago they vanished from the fossil record. 

Neanderthals were certainly a step closer to being human from their predecessor: Homo erectus.

Of course, Homo sapiens is the most recent evolutionary development, with first fossil evidence about 200,000 years ago.  We have been evolving since that time.