3rd Academic International Conference on
Social Sciences and Humanities & 3rd
Academic International Conference on MultiDisciplinary
Studies and Education
31-AW21-5248
THREE LEAPS IN HUMAN EVOLUTION
OKTAY KAYNAK
ABSTRACT
Bipedalism:
As a result of the rift and plateau formation in East Africa 6-7 mya, a primate made an adaptive
response to this development. And this primate hunted and gathered food in shallow waters on
two legs. This shallow water made a selective pressure on that primate to walk bipedally.
Mental Overturning:
When about 2 mya the body erection reached a certain angle, the embryo made an adaptive
response to this vertical body. The embryo turned upside down. This is the mental overturning
that started the growth of the cranium as well as the brain.
Mental Threshold:
After chasing its enemy, the chimp throws a stick and stones. It does not say to itself: ''This
stick and stones have served me effectively; I’d better keep them for another occasion''.
However, there will be a time when such a thought will occur with the development of the
brain capacity (500-550 cc).
Key Words: human evolution, mental overturning, mental threshold, anthropology
INTRODUCTION
Initially, the science of anthropology intuitively linked the bipedalism of the human species to
its intellectual capacity. As the fossils and bones of the australopithecine started to be
discovered, subsequent work and research continued to support the initial intuitive assumption.
The mechanism of evolution for all species can be explained as small changes in the
environment and habitat creating selective pressures on the organism and the organism giving
an adaptive response to these events. As these changes accumulate over a long period of time,
speciation occurs. This is how science explains the process of evolution; however, such an
explanation regarding the evolution of human beings has not, until now, been satisfactory.
This is because of the following reasons: Human beings are different when compared
to other species on earth but the same process of evolution has been assumed to apply to both
human and all the other species. Human lineage separated from a common ancestor about 6
mya, and the mechanisms of natural selection resulted in forming the modern human.
Human beings are very special and very different. These are the only living being on
earth that engages in self-investigation. Then, one can ask whether the evolution processes
regarding human beings is only specific to this species; my answer to this question is “yes”.
This human species had to experience three consecutive and important leaps before becoming
the modern human.
1- The Leap of Bipedalism
Being bipedal and growth of brain are two fundamental facts in human evolution. For many
years, researchers have put forward various theses on how these two changes in human
evolution have taken place. Theoretical discussions aimed to find answers to the basic
questions that have a highly significant influence in the development of a science. The subject of this article is to explain the reasons for becoming bipedal and the growth of the brain in
human evolution. I will comment, from an ecological viewpoint, bipedal development of
human beings, and I will explain the growth of the human brain from a completely new
perspective and through a hypothesis based on embryonic development. My aim is to clear the
way to apply this new perspective to the discussions in the world of palaeoanthropology on
these subjects.
Water has existed in the Rift Valley since the rift was formed in Africa 8-10 mya, and
this has been proved by the existence of dried lake bottom sediments and the abundance of
fresh water lakes in the region. Huge carbonated lakes, such as the Lakes Victoria and Lake
Turcana called “Green Sea” by the local population, are found throughout the Rift Valley. The
main reason of this formation is the tectonic separation zones that resulted in the rift depression.
These tectonic separation zones caused the formation of many volcanoes, underground water
came up to the earth’s surface, and lava and volcanic ash fell on the existing equatorial forests.
These changes resulted in forest fires. These forest fires have to be associated with the nonexistence
of equatorial forests to the east of the Rift Wall. Volcanic movements of important
dimensions, flood of hot and cold underground waters, great earthquakes and forest fires
changed the environment ecologically and food availability. In these circumstances, it is
interesting that our predecessor, the arboreal primate, survived perhaps in a very specific and
small area. To survive, food, shelter, defence against predators, and reproduction is necessary;
otherwise, life cannot be maintained and the species will disappear. Our predecessor primate
continued an arboreal life for a time in a small area that was not affected by fire and tried to
solve the problem of food by eating fruit, leaves, branches, and the bark of trees. Although
there had been fires in the forest and volcanic ash had rained down on the soil, there was water
in the rift that had been created in the tectonic activity. These primates fed on aquatic plant
products and by walking in the water in upright position, they were able to breathe by keeping
their heads above the surface of water. Most probably, the primates at that time met with
various aquatic plants, crustaceans, and fish. Long-tailed macaques living today along the
Ketanbe River to the north of Sumatra Province of Borneo Island of Indonesia take fish from
the river with their hands and this is evidence of primates solving their feeding problem by
fishing. This has been observed and documented by The Nature Conservancy and The Great
Ape Trust (Stewart et al. 2008).
For 4-5 my, primates lived in a semiarboreal–semiaquatic way but that does not mean
that they were amphibious. These primates would have spent the nights on semi-blasted tree
trunks, a small piece of raised land or in trees, and in the daytime, they would have walked
erect on two legs in shallow waters foraging or hunting for aquatic sources of food. This aquatic
period in the evolution process of human beings is advocated particularly by Sir Alister Hardy
(Hardy, 1960). Marine zoologist Hardy finds similarities between human, whales and dolphins
in nakedness and existence of subcutaneous fat tissues. Aquatic mammals such as sea cow
(Sirenia) and eared seal (Otariidae) resembles human beings due to various characteristics; for
example, these mammals are hairless and their subcutaneous fat tissues are attached to their
dermis. This is the same for human beings but for land animals, the subcutaneous fat tissues
are attached to the muscular tissue. Nevertheless, Hardy’s comparison is not accepted because
there is no clear knowledge about primate aquatic life. Furthermore, descriptions of the aquatic
life of primates are incorrect because they are likened to the life forms of penguins and
dolphins. If primates had solved the feeding problem through swimming or diving as dolphins
or penguins, they would have had a web formation between their foot fingers. Hardy alleges
that the head of a primate is hairy and body is naked because their head is kept above the surface
of the water when swimming. However, I suggest that our predecessor primate solved feeding
problem by walking in the shallow water, rather than swimming and diving. In my opinion, the head of a primate is hairy because the head is held above the surface of water, and the body is
hairless due to the body being in the water when hunting or foraging.
The evidence supporting my suggestion is:
1. The Rift Valley is full of both lake sediment and lake-bottom sediment.
2. Australopithecus afarensis suffered from rheumatoid arthritis.
3. The argument that the Australopithecus afarensis family of 13 members suffocated in
water.
4. The human body is hairless and head is hairy due to keeping it above the surface.
Darwin stresses in his The Origin of Species that the thesis put forward by a researcher
named Mr. Belt that human lost their hair in order to remove parasites is wrong because,
Darwin continues, many four-footed living beings in tropical countries did not react to
the same factor as others did. On the other hand, says Darwin, if we suppose that we
lost our hair in order to adjust our body temperature to the conditions of a tropical
region, we cannot explain our hairy head in spite of its permanent openness to the sun,
and this a paradox (Darwin, 1996). Keeping body in water and head above the surface
of the water due to the necessity of breathing can explain the hairless body and hairy
head.
5. Most of the Australopithecine fossils have been found at the site of an old dried lake or
on riversides together with fossils of shallow and deep-water beings such as
hippopotamus and diatoms. Additionally, the presence of fossils of remnants of
equatorial forests in the sediment of the same age shows that our predecessor primate
lived in equatorial forests. All living beings have ways of keeping their body
temperature between certain levels generally through hair and subcutaneous fat tissues.
It is widely known that when certain animals such as dolphins and whales moved from
the land to the sea, they replaced the hair they had lost with subcutaneous fat tissues in
order to balance their body temperature (Mayr, 1998). The subcutaneous fat tissue of
human beings are the consequence of life spent in water for 4-5 my.
6. Laetoli footprints found in Tanzania are the footprints of two Australopithecus walking
erect side by side on the ash layer spewed out by a volcano which had cooled and been
softened by rain water (Johanson and Edey, 1990). In my opinion, the lava had to be
fresh and cool for the formation of these footprints, and this can be happen when there
is water. My argument that these footprints are on a volcanic material that had fallen on
the lake recently has to be taken into account.
The hypothesis of erecting in water mentioned above can be tested as follows: Let us assume
a lake with sufficient dimensions for a chimp colony to easily live in and a sufficient depth to
force the chimp family to adopt an erect position, namely 70-120 cm. The lake has to be in a
tropical area like the Rift Valley; thus, chimps can easily live there in the winter. Floating trays
on the surface of the lake carry fruits, such as bananas, which are chimps’ favourites. The fruits
are placed at appropriate points that can be easily seen by the chimps. This design will force
the chimps to stand erect on their hind feet and walk towards their favourite fruit. Later, frogs,
crabs and fish are put in the lake and after determining their favourite fish, a meeting between
chimps and fish will be organised. If this experiment continues for four or five generations, we
will observe that the chimps will become erect in order to feed on aquatic products; thus, they
will survive and reproduce. Additionally, we will observe that the chimps solve their feeding
problem by keeping their body in the water and their heads above the surface of the water and the beginning of hairlessness on their bodies (Kaynak, 2007, 2008, 2010, 2013a, 2015, 2017).
Today, a discussion continues on whether the origin of a new species is mutational or due to
recombinational changes in the genetic inheritance or environmental changes. The mechanism
of natural selection is explained below. When the conditions change in the living space of a
species that prevent it from surviving, the variations in the genetic inheritance of the same
species that provide adaptation to the new conditions are selected. In other words, newborn
individuals which carry the positive mutational or recombinational genetic changes that make
the adaptation of the species possible to the new conditions are selected. If a newborn child
(variety) of the species in question carrying these inheritable genetic changes do not exist, the
population cannot adapt itself to new conditions and consequently disappear. The adaptation
of a certain species to the new conditions needs two factors. First, the existence of mutational
or recombinational inheritable genetic changes according to the new conditions is necessary
for the survival of the species. Second, the natural selection mechanism must operate in way
that it selects the appropriate individuals. A species suited to the new conditions appears in
such a mechanism. The differentiation and separation of human genetic arrays date back 6-6.5
my. It is not easy to calculate how many million years for the human bones to change in order
to permanently adopt an upright position. The upper body was forced to become hominid after
the lower body became hominid in 4-5 my. This occurred because only a double carrier
skeleton system as in modern humans can allow the living being to survive. For the axis of
gravity of the carrier skeleton to be in the soles of the feet, the body has to take an upright
posture, the rib has to become cylindrical, and the head must be placed over the body like
human beings of today.
2- The Leap of Mental Overturning
Unfortunately, the upright position and the angle of vertebra femur cannot be discerned in
Australopithecus fossils because this angle is destroyed during the fossilization process;
however, we have been erect on two feet for 4-5 my. At this point, the question arise; although
the primate are walking on two feet for 4-5 my, why the brain of the primate did not grow?
This question is asked because the pelvis structure on Australopithecus fossils has been ignored
and yet, the pelvis of Australopithecus is somewhere within in the range of evolution between
the pelvis of a primate and a contemporary human being. All the Australopithecus’s bones,
from the toe to the ilium bone of the pelvis, resemble the contemporary human being except
for the angle of the vertebra pressing on the pelvis and ilium bone of pelvis. The
Australopithecus’s upper body, vertebra structure, skull and the shape of jaw are like a primate.
In other words, the process of resemblance started with the toe and ended with the jaw and
skull. Scientists have taken this resemblance into consideration and intuitively found a relation
between upright position and an intelligent living being. Everything started with adapting to an
erect position and this started with the toe.
The position of the embryo in the uterus changed at a certain phase of the gradual
process of the body becoming erect. The Australopithecus embryo turned its head towards the
mother’s diaphragm and its body came close to the birth canal after turning a 180° somersault
in the uterus. Without this somersault, which I call mental overturning, Australopithecus would
have kept its head turned towards the birth canal. After this mental overturning, each
prospective mother Australopithecus started to give birth to offspring which had a skull that
was larger than mother’s. This increasing size of the Australopithecus’s skull has also been
seen in the fossils while other changes cannot be observed. Due to the gradual process of the
erection of the body, the rib narrowing and becoming cylindrical cannot be discerned (Kaynak,
2007, 2012b, 2013c, 2015 2017). Different skulls of Australopithecus led some to conclude
that there are different species of the Australopithecus. However, these are not different
species; rather, they are Australopithecus generated through body erection and rib narrowing.
The most important result of mental overturning is that offspring started to be born with their face towards one of the legs of the mother (Trevathan, 2011). Yet, after the completion of the
body erection, offspring started to be born with the face towards the back of the mother which
is a characteristic of contemporary human beings (Rosenberg and Trevathan, 2001). This is
peculiar to human beings since all the other mammals are born facing the abdomen of the
mother. The reason for this important difference is mental overturning. This weakness that
starts with birth forces the offspring to adopt a semi-terrestrial life. The offspring primates cling
to the hair of their mothers just after birth. The origin of the human babies grasping whatever
is held out to them is a reflex that has to be connected with the infant of the primate that clings
to the hair of mother. The offspring of a primate clings to the mother for survival because it is
born in a nest in a tree. In anthropoid fossils, skull volumes of 400 to 800 cc have been found.
The increase in the skull volume starts to correspond to the body erection angle. After the body
erection process begins, the skull volume continues to change till the angle of vertebra femur
reaches 180°. One has to pay attention to the fact that the skull volume determines the quantity
of brain tissue (Kaynak, 2014).
The development of the erect position freed the hands of primates to produce tools and
consequently, primates were regarded as intelligent beings. A coordination exists between the
front and rear extremities of contemporary chimps. Their hands are free and they can use their
hands; however, they are not intelligent living beings. According to another thesis, chimps are
intelligent living beings because they became social after being erect on two feet. They can
face each other and have developed speech (Mayr, 1998). Yet, Darwin stressed that some other
living beings can be face to face and had various organs which allow them to produce speech
but they cannot speak. For Darwin, the skill has to be developed in order to produce speech
(Darwin, 1996, 2002).
The human embryonic skull develops and takes its shape and form in conformity with
internal and external vectoral forces that affect the skull. These forces can be explained as:
1- External forces: gravity, pressure of the uterus and amniotic sac, pressure of abdomen
muscles of the mother, pressure of diaphragm and other internal organs of the mother.
2- Internal forces: gravity, resistance of the intra cranial fluids, and brain tissues coming into
existence.
Today, science suggests that the human embryo skull develops, takes its shape and form
in conformity with these vectoral, internal and external forces. The existence and development
process of a human embryo skull is not similar to the release of a coil spring (Blechschmidt,
2003, 2004). My opinion is that the impetus and direction of these vectoral forces changed as
the body gradually became erect. Consequently, the volume of the Australopithecus’s skull
corresponds to different phases of body assuming the perpendicular angle during the process
of becoming erect (Kaynak 1983, 2007, 2010, 2012a, 2013b, 2017). The increase of the skull
volume continued until the body took the fully-upright position. Some changes occur on the
shape of the skull of the child taken out during birth by forceps or by vacuum technique. In an
experiment, one side of the cervical muscles and / or chewing muscles or both cervical muscles
and chewing muscles of newborn rats and rabbits were removed. It was observed that while
the non-operated half of the skull of these animals developed normally and specific to the
species, in the part of the next skull from which the cervical and chewing muscles were cut out,
the metacarpus did not develop; in other words, this part of the skull developed in a different
form.
The adult human body is 70% water, and more than 90% of the embryo in the uterus is
water. The bones can be warped, and they stretch but they do not break. When a pressure
exerted in one direction from any angle on the skull of an embryo of four or five months, it is
expected that the skull would be deformed in conformity with the direction of the pressure.
Since deformations are not observed on the skull in the uterus, it is understood that the embryo is packaged and bundled by the uterus. A very young human baby cannot keep hold her head;
however, due to the design of the uterus, the embryo can keep its head exactly over the body.
At seven months, the foetus turns upside down in preparation for birth, and in this position, the
body is kept over the head. It is this mechanism that causes the human skull to become round,
the jaw to become small, the arch of the eyebrows to straighten, and the skull volume to
increase. Unlike other animals, the human baby is born without synostosis having soft spots
called fonticulus between the skull bones. This that means human bone and tissue development
cannot respond to the human embryo skull development, and the growth of the skull process is
faster than tissue formation. Since the rib cage has been transformed from a conical to a
cylindrical shape, the abdominal region has narrowed and the human uterus cannot enlarge;
consequently, the process of birth begins with uterine contractions. In other words, the foetus
is born without completing its development. This is only observed in the human uterus and
human embryo.
We can conclude, as a result all of these, that the human uterus is unique among
mammals and produces a distinct living being because of its own uniqueness. The
Australopithecus has a great jaw, protuberant eyebrow arch together with a small skull. It is
not possible for both a large skull and a great jaw with a protuberant eyebrow arch to exist in
the Australopithecus. I, at this point, come to the conclusion that the gradually diminishing jaw
and straightening eyebrow arch were replaced with great skull. This development was created
by the uterus in the female human, which gradually adapt herself to being erect. Here there are
questions to be raised: Does the jaw diminish and does the skull grow simultaneously or in
parallel with each other? Could the skull grow and could the jaw keep its size? No, the skull
would have not be able to grow when the jaw continues to be of a large size because this change
is generated by the uterus, and the human uterus should not be overstretched but should allow
the embryo to assume its natural shape. The human uterus pushes the embryo backward by
pushing the incisors seen at the extreme point of the primate skull. The nose and chin area come
into existence as a result of this pushing backward. This front mandibular projection makes no
vital contribution to the human species. These are the results of the design of the uterus. The
process of evolution process does not develop body organs which it does not use in natural
circumstances. Evolution, at the most, keeps caducous organs that are left by the predecessor
of a certain species. This front mandibular projection does not exist in any primate. It comes
into being through uterus’s push on the incisors so that the embryo moves backwards.
All the ideas I have put forward here can be tested by the following experiment: We
can implant a chimp embryo into a human uterus. We can support the development of this
embryo in the human uterus through medicines and medical techniques. One of these
techniques is to take the cells which specialized for forming the placenta that are lined up in
single file on the human zygote of 4-5 days and to remove the cells producing the placenta out
of the chimp zygote. The cells that will generate the chimp are taken and put into the cells that
will produce the placenta taken from the human. When this mixed zygote is implanted into
human uterus, the transplant rejection is prevented for this placenta will be a human placenta.
When the birth is realized in these conditions, the newborn’s body will be hairy, and the hands
and feet will be like those of a chimp but the head will be rounded and the volume of the head
will be greater. Among other things, the nose and front mandibular projection will be extended
and the jaw will become smaller. The pressure made by human uterus from the front will
transform the jaw from a U to V shape. The result is that the living species we have acquired
is Australopithecus. Both the uterus and the embryo within it have evolved over 4-5 my. More
and more growth of the skull’s volume has to be expected. For the available uterus has taken
its final shape. We will not acquire a skull in an amazing greatness but it will be bigger than
chimp’s skull (350 cc) in all conditions (Kaynak, 1983, 2007, 2015, 2017).
Additionally, the chimp’s embryo will complete its development in the human uterus
with the head above the body for seven months and turning upside down, the body above the
head in the last two months, as it is the case with a human baby. The chimp will be born with
its face not turned to the mother’s abdomen but similar to a human newborn, with its face
towards mother’s back. Most probably, it will be born without synostosis, but with fonticulus
as in a human new-born baby (Kaynak, 2015, 2017).
3- The Leap of Mental Threshold
The present day chimp, with its 350 cc brain, can tear down a tree branch and attack its enemies
with it. It can also pick up a stone and throw it at its enemy. When the predator cheetah
approaches the capuchin monkeys of the Brazilian forests, they climb the cliffs and roll down
an avalanche of rocks and stones, forcing the cheetah to retreat. These monkeys can also make
use of stones in a sophisticated manner in order to break coconuts. Chimps can also make use
of a stone for cracking fruit seeds. In a way, both primates use the stone as a tool as well as a
weapon. Chimps make use of thin twigs for hunting termites and collecting honey from
beehives. If a chimp with its 350 cc brain can do such things, one should wonder what its
capabilities would be if it had a 500 cc brain.
After chasing its enemy, the chimp throws a stick at it but does not say to itself: “This
stick has served me effectively; I’d better keep it for another occasion”. If the chimp had a
brain of 500 cc, would it say, “I’d better keep this stick and even improve it”? The chimp may
not think so with a brain of 500 cc, not even with a 550 cc or 600 cc brain but there will be a
time and a brain capacity that such a thought will occur.
This is the critical point, which I have labelled as the mental threshold. Once this mental
threshold was crossed, the hominid that held a stone in one hand and a stick in the other had
the courage to intrude into the hunting zone of any animal including the worst predator.
When it reached the capacity to influence his prey as well as his predator from a distance
with the help of sticks and stones, the hominid departed from the rift in order to colonize the
world. After crossing this mental threshold, the hominid became cognizant of his nakedness,
became self-aware, and came to understand that sticks and stones could be used as weapons.
The human mind is the result of the incredible adaptive response given by the embryo to the
vertical body posture (Kaynak, 2015, 2017).
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