Tag: human evolution

It is us who dehumanized them

by clarevmerry, posted in species in the genus Homo

To summarize my thoughts on human origins and human evolution, humans started out human. They may have been primitive – in our eyes – but they were completely what they were, and not half-way-there to what they should be.

All creatures evolve, and this produces diversity within a type of thing. For all creatures become adapted to climate and their particular environment. They may evolve a way of obtaining food that is different to their close relatives. For example, a seed-eating bird may become adapted to scavenging for meat found on roads – a recent and on-going evolution.

The human creature is no different in many respects from other creatures. What is different is that human evolution occurs as a response to human culture, and human culture is a product of the human mind. For example, a canoe nomad has a way of life based on displacement in a canoe. Canoe nomads have very well-developed arms and shoulders, with a short, stocky body.

Humans show considerable diversity geographically due to adaptation to climate, but also chronologically as they were adapted to different cultures through prehistory. Prehistoric ways of life made more demands on the skeleton for survival than is experienced by humans today.

Differences in bone structure, behaviour and culture do not mean that prehistoric members of the genus Homo were not human. It is us who dehumanized them!

The half-evolved ape-man has about as much reality as a cartoon strip about the Flintstones.

  • Our body tissues and basic body plan are over 98% genetically identical to those of apes. We are part of the one ‘tree of life.’
  • The few genes – maybe between 300 and 1000 genes that are specific only to humans, have, I believe been shared by all members of the genus Homo for over 3 million years; that is to say, since the origin of the human line.
  • Human evolution, like the evolution of other creatures, has occurred through genetic switching off. This is explained in The Steps of Creation Part I. This is based on documented genetic evidence.
  • A person has a soul. No person has ever had half a soul. You either are one and have one, or don’t have one. This is what makes possible the ability to look into your own mind and know yourself.

Summary on brain size and human intelligence

by clarevmerry, posted in human intelligence

Human evolution over the past 3.6 million years involves the increase in brain size.  There is, however, no threshold brain size to being human – over and above the brain size of apes.

The reason for the increase in cranial capacity is to accomodate a brain with a larger volume of white matter.  White matter consists of the fat-based myelin sheaths of neuron axons.  Myelin sheaths insulate neuron fibres so that signals can be passed along the fibres at greater speed.  It is the myelination of neurons that requires more volume.

Our small-brained ancestors could have a high level of talent or dexterity in one or a limited number of areas.  Increased brain size allows for more pathways in the brain, so individuals have a greater repertoire of talents.  Diversity in talents is positively selected as society becomes more complex.

The actual basis to human intelligence are the brain cells in the grey matter of the cerebral cortex.  As a person learns and makes new connections, the cortex grows.  The cortex is only 3 mm thick, and as it grows it convolutes within the confines of the skull.

Thus, intelligence is dependent upon the surface area of the cerebral cortex.  This varies between individuals; it is not genetically determined but developed by learning done by the individual; the volume and the surface area of the cerebral cortex is independent of overall brain size.

The mechanisms by which skulls evolve larger size include:

  • Delayed development such that fontanelles which are holes between cranial plates stay open for a year after birth allowing for brain growth at fetal rates in the human infant for the first year of its life.
  • Thinner skull bones and fontanelles allow for a baby’s head to be moulded during childbirth.  The deformed skull returns to a normal shape a few days after birth.  In this way an infant can be born with a larger initial size of head and not die in the process of birth.
  • Later species of mankind have wider bodies and a more sedentary life style.  This can be linked to locomotion involving canoes rather than walking.  The female pelvis has evolved towards ‘child-bearing hips’ specialized for giving birth to babies with larger heads.

Sutures – the joins between cranial plates can remain open for a long time in humans, far into adult life.  Sutures close and fuse together when an individual ceases to learn things. 

A growing brain puts pressure on sutures such that they pull apart with cartilage forming in the gap.  This process causes sutures to take on a serrated, denticulate pattern.  The complication of cranial sutures is an indication of the intelligence of the individual and for how long in life they continued to learn new things.

There are examples of fossil skulls going all the way back which show imprints of convolutions and a degree of complication of sutures.  The convolutions of the cortex leave an imprint on the endocasts of skulls, while the sutures are observed on the outside of crania.

As a final confirmation of the humanness of early species of mankind, endocasts show some revealing features.  Firstly, an asymmetry of the cerebral cortex indicates that Homo primocreatus and Homo habilis were right-handed and busy making something.  Secondly, there is an increase in size of the language areas of the brain going right back to earliest species with a clear development of Broca’s Area in Homo habilis.  Broca’s Area located in the third inferior convolution controls the motor aspects of speech.

Gorillas have a cranial capacity of 500 cc.  There have been known people afflicted by microcephalic dwarfism with a cranial capacity of 500 to 700 cc who used articulate language.  Thus, there is no threshold for the use of human language in terms of brain size.

The evolution of brain size did not make us human.  Something else makes a person human.  What the evolution of brain size did was fit beings who were already human to the demands of an increasingly complex society.

Cro Magnon type skull from after the Ice Age – the Eguisheim skull – showing complicated, denticulate sutures

Childbirth the limiting factor

by clarevmerry, posted in human intelligence

Birth in humans is difficult compared to birth in most mammals.  The limiting factor is the adjustment between size of baby and its head, and size of the bony pelvic inlet and outlet – the birth canal of the mother.  In humans cephalopelvic disproportion is a frequent problem.  Death often occurs in childbirth.

From the point of view of human evolution and increases in brain size, giving birth to a baby that starts off larger with a larger head is the direction of the trend.  Thus, a major factor in human development is those ‘child-bearing hips.’

Human evolution shows an increase in pelvic size due to increase in stature.  The first human species was only a metre high.  I’m 1.7 metres tall and many women are taller than me.  As overall height and size increase, pelvic size increases, so bigger babies can be born.

My thesis concerning human evolution is that human life style has been the main factor in changes to the body.  Early human species such as Homo ignis / Homo ergaster were adapted with narrow bodies to run fast to escape predators and to hunt animals by running them down.  Later species were far more sedentary.  Species such as Homo praecursor heidelbergensis had wider bodies.  Homo centralis / Neanderthal had medium stature and a well-built, wide body.

I see several ways of adopting a more sedentary way of life even in prehistory:

  • The first way is to use a canoe for locomotion instead of walking and running.
  • The second is to hunt using traps rather than pursue the quarry animal.
  • The third is the sexual division of labour – with women remaining in and around the camp, harvesting vegetable crops, cooking and looking after young children.  Thus, the distance that women would walk would be much less than for male hunting parties.  Later on small animals were kept for food in the camp.

When women ceased to hunt, they became specialized in the gestation of  large fetuses.  A wide body is an advantage in childbirth.

An increasingly sedentary life is an on-going trend in human culture.

Therefore, human culture and ways of life have changed with human inventions and use of technology.  The evolution of increased cranial capacity was dependent upon what human culture had to offer.  This goes back to prehistory, at least 400 000 years ago, and it is a trend that continues today.

Reconstruction of the pelvis of KNM-WT 15000 belonging to Homo ignis / Homo erectus

How did the human skull evolve increasing size?

by clarevmerry, posted in human intelligence

Human evolution shows an increase in cranial capacity – the question is, how did this come about?

The answer is:

  • The development of the skull became delayed so that the fetal condition continued long after birth with fontanelles remaining open for longer.
  • The skull bones became thinner in modern humans compared to most prehistoric species and this allows for moulding during birth.
  • The female pelvis became bigger in wide-bodied populations so babies with larger heads could be born.

Compared to animals, human babies are born helpless and dependent on the parents for protection to a much higher degree.  Human babies are born with holes in their skulls that have only cartilage and membranes covering the brain, with no bone.  These holes are called fontanelles. 

Fontanelles allow for two things:  Firstly, they allow the baby’s head to be deformed during birth as it moulds during the descent down the birth canal.  Secondly, the skull grows outwards from these holes and from sutures between cranial plates.  The longer the fontanelles stay open, the more the skull can grow outwards from them.

This delayed pattern of growth – with the fetal condition being retained after birth – is the human pattern of growth.  It is called secondary altriciality.  By the time ape babies are born their fontanelles have almost closed up.  In the human baby the fontanelles remain open for the first year and the infant’s brain grows at fetal rates during this year.

The human pattern of growth is found in Homo ignis / Homo erectus.  We can infer that babies of this species were born with open fontanelles from two million years ago.  This allowed cranial capacity to increase to 800 cc or more.

My own calculations, which will appear in a book I am currently editing, show that Homo primocreatus – Primordial Man had an intermediate degree of secondary altriciality compared to apes.  There would be a small delay in development.

Homo ignis / Homo erectus had thick skull bones and well-developed browridges.  He and she lived in a world where being clubbed over the head by an enemy was a real possibility.  Survival was dependent on a reinforced skull.

Gracilization of the skull came with Homo aequalis / Homo sapiens  100 000 years ago – I think due to internal tribal peace and a new set of weapons used against enemies.

Thinner skull bones meant that the head of a baby could mould during childbirth, thus a child with a larger head survived the birth process.  It also meant a more delicate infant requiring more protection from falls.

An alternative way of having babies with larger heads was for the female bony pelvis to become more ample.  This seems to have been the way forward for Homo centralis / Neanderthal.  These were wide-bodied people with ample pelvis for childbirth.  The skulls of Neanderthals had thick bones so they must have achieved large cranial capacity by this alternative method.

In modern people all of the above traits are combined such that women give birth to infants whose skulls mould as they are born, and continue to develop at a high rate after birth.  The combination of traits has increased cranial capacity over the course of human evolution to what we consider normal today.

Top view of skull of human new born showing the fontanelles
Cranial plates and fontanelles in the human new born

The evolution of brain size

by clarevmerry, posted in human intelligence

Human evolution in the direction of Homo sapiens has essentially been couched in terms of an increase in brain size.  Measurements of prehistoric fossil skulls done by anthropologists show the cranial capacity for different prehistoric species of mankind.  The volume of the brain case was measured with no. 8 shot or with mustard seed in the 19th century.  Cranial capacity is larger than the size of the brain that would have been inside it.  For example, the average cranial capacity today is 1400 cc and the average brain weight is 1330 grams.

There was a steady increase in cranial capacity in prehistoric species.  This is a summary of the facts of physical anthropology:

  • Chimpanzee average brain size is 380 cc (cubic centimetres) [included for comparison]
  • Homo primocreatus / Australopithecus 450 to 500 cc
  • Homo habilis 700 cc
  • Homo ignis / Homo erectus / Homo ergaster 800 to 1100 cc
  • Homo ignis antecessor / Homo erectus 1100 cc
  • Homo praecursor heidelbergensis / pekinensis / afarensis / Homo heidelbergensis 1200 cc with a range of 1100 to 1400 cc
  • Homo centralis / Neanderthal range of 1250 to 1750 cc
  • Homo aequalis / Homo sapiens of 100 000 years ago 1500 cc
  • Homo aequalis fossilis Cro Magnon man  1570 cc
  • Homo aequalis / Modern Man  1400 cc

The evolutionary thesis is that as the brain evolves and increases in size, the animal evolves into a human.  The bigger the brain, the more human the creature.

There is, however, a problem with this.  The brain of Neanderthal was larger than the global average today but he was denied the status of being human.  It was said he could only grunt and not talk, no wonder that this brute went extinct when our species came along.

It was later found, with advances in genetics, that we in Europe carry a percentage of Neanderthal genes.  This either means that we are part-animal or that Neanderthal was human after all.

Christians who adopt an evolutionary perspective on creation and an evolutionary origin for humans have more of a problem than most with human evolution.  From a Christian perspective a human person is not an animal and a human person has a soul.  Some Christians have resolved the issue by dropping belief in a human soul, but for those who still believe that to be created in the image of God is to have a soul – at what point did souls enter the human being?

The narrative goes that an ape-man managed to become far enough evolved and get a big enough brain for God to consider this creature to be worthy of being given a soul.  From then on ensouled humans had moral responsibility for their actions.  Ironically they wiped out all the hominids without souls causing them to become extinct.

For me the above question is totally meaningless.  And the answer given has quite horrific implications – firstly that there could be a creature looking just like a human that had no soul and therefore was simply an animal – although you would have no way of distinguishing between the human and the animal just by looking at them.  Secondly, the highest gift of a soul becomes the justification for mass hominidcide, and this is presented as a good thing.

My alternative thesis is that:

  1. There is no threshold brain size for possession of a soul or for being a morally responsible being.
  2. If you have a soul, you are human.  The soul is whole and in every part, there are no part-souls.  Likewise there were never any hominids part-way to being human.
  3. Even with a cranial capacity only marginally above that of apes, a human life is still possible.

Therefore, all prehistoric species that have been classified as ‘hominids’ or ‘hominins’ have, in fact, been human beings adapted to various sets of circumstances that are not found today.  They have all been peoples with culture, and persons with souls.

I had already reached this conclusion when Homo floresiensis was found on the Island of Flores, Indonesia in 2004.  The skeleton found had a cranial capacity of 380 cc and a stature of one metre.  The find was classified as a dwarfed Homo erectus, but the surprise was that it was dated to only 18 000 years old. 

Homo floresiensis is confirmation that a being with a cranial capacity the same as chimpanzees, can, in fact, be human and have lived not long ago.  The human bones were found in a cave with evidence of fire, stone tools and animals that had been hunted.

Humans are human because they have a soul.  Even the most primitive humans had souls so any being looking like a human had a soul.  There was never a situation of Homo sapiens possessing a soul confronting hominids lacking a soul.  Human evolution has brought about changes to the physical body, but not to the fundamental identity of the human being.

Life style and human evolution

by clarevmerry, posted in human life style

Over the course of three million years the member species of the human line have undoubtedly changed significantly.  This is what justifies classifying them as different species.  Each species in the genus Homo has characteristics of the skeleton and cranium that are recognizable.  What is the actual basis to this human evolution?

Since the 19th century it has been assumed that apes have gradually evolved into humans because its better to be a human and reach the so-called pinnacle of evolution.  But, upon reflection, there is no reason why this should be the case – if, for example, you were put down in a tropical forest in Africa, you would have a much better chance of surviving as a chimpanzee than as a human.

If human beings were only animals and their ancestors only upright walking apes then they would have evolved in the same way as other animals.  Through evolution they would have become adapted to an ecological niche and then remained the same for millions of years, on condition that the ecological niche continued to exist.  The niche in question is deep forest in Africa over the past three million years.  Gorillas and chimpanzees inhabited this forest with the first species of mankind.  The apes are still there like before, while mankind has changed in an extraordinary way.

The reason for that change is this: the human body is adapted to environment and climate as animals are  adapted to their environment, but the change in humans is also driven by adaptation to human culture determined by invention.  The mind of man creates a human environment to which he adapts.

Each body type in the genus Homo is adapted to a human life style.  Humans interact with their environment through the interface of a level of technology.  For example, a large cat kills its prey with sharp canine teeth and claws.  Humans have flat teeth and nails – no human hunter has ever killed prey with his bare hands.

The trajectory of human evolution makes no sense without the human mind and invention.  So this is my thesis: that human evolution goes far beyond any animal evolution because mankind has been ‘sapiens’ from the beginning.  The drive itself towards an increase in brain size in the human line is because mankind used his and her brain for human thought.  The skeletal features or form of the body are the products of that thought embodied in human culture.

Shared life style and not survival in the wild is at the root of human evolution.

There is not a gradation in humanness, but there is progress.  Progress is obtained by beings who are already human and therefore desire what is new and innovative.  Progress is not the aim of an unevolved sub-human.  There has not been a gradual gradation into being human. 

There has never been a knuckle-dragging ape-man aspiring to gradually evolve into a human, while exchanging grunts for words.  This is a fiction of evolutionary theory, a construct that was a reflection of our society, and not a true reading of the evidence lying in the ground.