Human Evolution
by Dana Visalli
Skull shapes & sizes: Chimpanzee, Australopithecus,
Homo habilis, H. erectus, H. neanderthalensis, H. sapiens
This brief rendition of the story of human evolution attempts to capture some of the highlights
of the human evolutionary journey. The most important of these evolutionary highlights in terms
of understanding the current human situation are
1) the natural self-centeredness that all living organisms have to some to degree, a prerequisite for
survival, 2) the emergence in humans of ‘symbolic
thought’ (thought is in fact always symbolic, for
example the word or thought ‘tree’ is never actually a tree) and 3) intelligence. Unfortunately the
latter two phenomena are not the same thing.
Our species, Homo sapiens, is in the mammalian order called Primates, which means ‘of the first
rank,’ or ‘numeral uno’ (there are a total of 26
mammal orders). Primates are composed of the
monkeys and the apes. Both groups are characterized by having forward-facing eyes (which gives
them stereoscopic vision and good depth perception, very handy when jumping 10 or 20 feet from
one tree to another), grasping hands (usually with
an opposable thumb), and relatively large brains
compared to other vertebrates. There are over 300
species of monkeys, and only 24 species of apes,
the latter made up of gibbons (17), orangutans (2),
chimpazees (2), gorillas (2), and humans.
The oldest primate fossils are about 60 million
years old, and the lineage is thought to be some-
what older, dating to 80 million years ago. The
human genetic line owes its inception to this
group.
Life in the trees probably initiated the characteristic larger brain and enhanced ‘cognitive abilities’ of primates--by which we mean the capacity
to solve problems by ‘visualizing’ them rather
than via autonomic genetic programming. Life in
trees is three-dimensional, and so it takes more
awareness of one’s environment than life on the
two-dimensional ground. It selected the traits that
enhanced stereo vision and grasping hands,
which are critical to our species, and probably
bumped the functioning of the forebrain up a
notch.
Why did our ancestors leave the shelter of the
trees 6 million years ago for a dangerous life on
the savannah. Surprisingly, the current answer is
climate change, which was in turn induced by
plate tectonics. 40 million years ago the subcontinent of India, which had broken away from Africa
long before, began to be pushed into Asia, giving
rise to the Himalayas. This changed atmospheric
currents and blocked moisture from falling on
eastern Africa, transforming rainforest into grassland. Our ancestors did not leave the trees so
much as the trees left them.
Dana Visalli/[email protected]/The Methow Naturalist/www.methownaturalist.com
Australopithecus, having a good day
There is very little fossil evidence for the split
of the human lineage (hominins) from those of
gorillas and chimpanzees. Chimps and hominins
split from gorillas about 8 million years ago, followed by a split from the chimp line approximately 7 million years ago.
One genus of presumed human antecedents
that has risen to prominence is Australopitecus
(translates as ‘southern ape’), to which the famous
fossil called Lucy (discovered in 1974 in Ethiopia
and dated to 3.2 million years ago) belongs, as
well as the so-called Laetoli footprints found nearby by Mary Leakey in 1978. Both finds indicated
that there was a hominin that by 3 million years
ago had the skeletal structure that allowed it to
walk completely upright. However the brain size
of the Australopithecines was just barely larger
than the brain of a chimpanzee. The paleoanthropologists like to say that hominins stood up first,
and got smart later.
Survival must have been challenging for the
likes of Australopithecus afarensis, because they had
given up the refuge of the trees but had no way to
protect themselves against the numerous predators, especially lions and other wild cats, that frequented the savanna. They were incapable of
utilizing either fire or weapons; one Australopithecus skull has been found in a cave with leopard
canine teeth puncture marks in it.
Another informational find is a red pebble in
an Australopithicene cave dated to 3 million years
ago. The little rock is known as the Makapansgat
pebble; it has natural pockmarks on it that make it
look like a human face. The rock type of the pebble is unknown in the immediate area, and must
therefore have been carried into the cave, probably by an Australopithecus who recognized the
hominid resemblance. It would take symbolic
thought to execute such an action; no dog or cat or
chimpanzee has ever brought a rock home because they thought it looked like them. It is considered to be the first sign of symbolic thought in the
history of our evolutionary line.
One of the Australopithecines evolved into the
first species in our genus just over 2 million years
ago, Homo habilis (homo means ‘man’ or ‘human’
and habilis means ‘handy’). Chimpanzees have a
brain case capacity of about 400 cm3; Australopithecines have about 500 cm3, and H. habilis checks in
at approximately 600 cm3; so the brain was growing over time. The reason is probably that the latter two creatures were able to scavenge meat.
Australopithecus would have been able to use
‘sticks and stones’ to chase predators off of kills,
and H. habilis was able to make stone tools. They
were clearly not able to fully defend themselves
though, as ample fossil evidence indicates that H.
habilis was a staple in the diet of large predator
cats.
H. habilis appears to have persisted until 1.4
million years ago, when a larger brained (1000
cm3), larger-bodied hominid, Homo erectus
(‘upright human’), becomes dominant (there is
some overlap in the presence of the two species).
It first appears in the fossil record 2 million years
ago, and seems to have migrated out of Africa as
far east as Indonesia and Vietnam by 1.5 million
years ago. A H. erectus skull found in Dmanisi,
Dmanisi Man, a H. erectus that lived on after losing his teeth
formed over time into the
Georgia dated at 1.8 milNeanderthals (Homo neanlion years had not only
derthalensis). Others of
lost its teeth while it was
the species remained in
alive, but bone had
Africa and evolved into
grown into the teeth sockHomo sapiens, which then
ets. Thought to belong to
first left Africa 70,000
an old man of 40 years,
years ago (this date is hotsuch a toothless creature
ly contested), encounterwould have no way of
ing the Neanderthals in
surviving without the
Europe upon arrival
daily support of his clan,
there 40,000 years ago,
possibly even to the
and possibly H. erectus in
point of pre-chewing
Asia.
food for him. This is takNeanderthals seem to
en as the first evidence of
Artist’s concept of Homo erectus taming fire
have existed from about 300,000 years ago to perloving care and compassion among hominids in
haps as recently as 25,000 years ago (again, dates
the fossil record.
are uncertain). While they are best known as inIt appears likely that H. erectus tamed and utihabiting Europe, which has had the most paleonlized fire as long as 1.4 million years ago. Fire
tological work, they populated a large swath of
would have made all the difference on the trail to
Eurasia extending from Britain in the west to Kamodern humans, as it made the nights safe from
zakhstan and Russia in the East.
predators, made body hair unnecessary, allowed
Two aspects of the Neanderthals stand out.
its masters to cook food and thereby both chew
One is that they had a brain slightly larger than
less and obtain far more nutrition from both animal and plant food. Both the gut and the lower
our own species, about 1400 cm3 as opposed to
jaw could recede as they did not need to work so
our own average of 1250 cm3. They clearly had
hard, making more energy available to other parts
some smarts, being as especially forebrain size is
of the body--like the brain. H. erectus also imstrongly associated with cultural learning and beproved on the tools of H. habilis, although the dehaviors that are relatively independent of genetic
gree of improvement was greater in Africa and
programming. On the other hand, their cultural
not particularly pronounced in Asia. It is not
expression and tool making abilities changed very
known to what degree H. erectus could communilittle over their almost 300,000 existence. One palecate through speech, but some workers think that
ontologist described their tool making as brilliant,
fossil evidence reflect vocal capabilities within the
but stupid, because it was well done but never
range of H. sapiens. The species persisted for over
changed. A likely reason for this is that they proba million years, with some dating the last fossils to
ably lived in isolated clans and with relatively low
be only 50,000 years old, in China.
population numbers, so there was little opportuniThe dominant story at present is that about 2
ty for extended cultural learning.
million years ago H. erectus migrated out of Africa,
Neanderthals did create a complex culture inthe first hominin to do so. Outside of Africa it redicative of bountiful symbolic thought. They were
mained H. erectus, while inside of Africa the evoluknown to build dwellings out of animal bones
tionary pressures of an increasing population of
(and presumably animal skins) and to construct
multiple Homo species led to the emergence of one
water craft. Neanderthal tools (known as Moustethat became our immediate ancestor, Homo heidelrian tools) as old as 170,000 years are found on
bergensis. This is curious German name for an Afriislands throughout the Mediterranean. There is
can species, but so it goes. Its brain was just about
some evidence that they buried their dead in a
as large as our own. 400,000 years ago some heidelsymbolic way, and even that they made beer! Rebergensis migrated out of Africa and apparently
cent artists’ renderings of Neanderthals show
turned left instead of right, straight into the Pleisthem as much more intelligent and modern hutocene Ice Ages in Europe, where it was transman-like than previously.
The first known symbolic expression or ‘art’
by Homo sapiens is found in caves on the coast in
South Africa, with quantities of ochre presumably
used for body painting dating to 165,000 years
ago have been found, and pierced shells for beads
are dated at 100,000 years.
The oldest undisputed work of figurine art is
the Venus of Hohle Fels, found in a cave in Germany and dating to 40,000 years ago. It depicts a exaggeratedly reproductive female, and no doubt
was associated with human fertility and reproduction. The earliest cave paintings are newly dated
images on the wall of a cave in Sulewesi, IndoneThe 40,000 year-old Venus of Hohle Fels
sia, also dated at 40,000 years. There is ‘open air’
Paleolithic art on rock walls in Europe dating to
Our species seems to have left Africa about
40,000 years ago, and cave painting seems to have
125,000 years ago, migrating into the Near East
been initiated there soon after.
(Syria and Palestine). There was probably competiAgriculture arose independently in three
tion with Neanderthals at this time, and this first
core areas of the world—
‘out of Africa’ population
southwest Asia, China and
of modern humans apMesoamerica. The fact that
pears to have died out rathit arose independently on
er quickly. About 70,000
different continents sugyears ago modern humans
gest there is natural trajecleft Africa by crossing
tory for humanity in that
from what is now Ethiopia
direction. By 7500 BCE one
to today’s Yemen, and
of the first known agriculthence spreading around
tural villages, Jarmo, had
the world. They reached
emerged in northern Iraq.
Australia by 46,000 years
Jarmo was a collection of
ago, Europe by 43,000
about 25 houses, the inhabyears ago, and traveled to
40,000 year-old cave art in Indonesia
itants of which depended
Alaska via the Bering Land
on a system of mixed farming and husbandry.
Bridge (now submerged under the Bering Sea)
They grew domesticated barley, emmer and peas
about 20,000 years ago (all dates are uncertain).
combined with herding sheep and goats, while
The oldest DNA evidence of human habitation in
hunting provided only about 5% of their total
the ‘lower 48’ is fossilized human coprolites
food.
(feces) found in the Paisley Caves in southcentral
Oregon. Mysteriously, there is a modern human
site now accepted in Chile called Monte Verde
that is dated to 14,800 years old.
Interestingly Homo sapiens, which first appeared in Africa about 250,000 years ago, showed
the same slow cultural development as did Neanderthals (‘brilliant but stupid’) until perhaps
50,000 years ago, when there then began something of a ‘creative explosion.’ There is some minimal evidence of ‘symbolic art’ created by modern
humans in Africa dating to 150,000 years ago, but
evidence of an expressive explosion dates to Europe starting 40,000 years ago.
A 35,000 year-old panel of horses in Chavet Cave, France
Agriculture did not evolve because it is an easier option than hunting and gathering. It requires
far more effort in clearing land, sowing, tending
and harvesting crops and in looking after domesticated animals. It does not necessarily provide
more nutritious food. The one advantage agriculture has over other forms of existence is that in
return for a greater degree of effort it can provide
more food from a smaller area of land.
The explanation for the appearance of agriculture that best fits modern knowledge is based on
increasing population pressure. The population of
the world 10,000 years ago was about four million,
rising to about five million by 7000 years ago. It
then began doubling every millennium, to reach
50 million by 1000 BCE and 200 million by 0 CE.
The upward trend has continued every since, so
that agriculture today supports a world population of over seven billion.
The adoption of agriculture was the second
most fundamental change in human history, after
the psychological journey into symbolic thought.
Hunting and gathering societies were essentially
egalitarian (except when they had abundant food,
see for example the story of Sungir in Russia, a
28,000 year old hunting society with all the mammoth meat they could eat and a very hierarchical
social structure). Sedentary communities, almost
from the beginning, resulted in increased specialization and the emergence of religious, political
and military elites with the power to direct the
rest of society. Genetic proclivities seem to harness the mind to fabricate an abstract set of beliefs
for the purpose of of unifying individuals ensured obedience to group leaders and group values. Agriculture also gave rise to the concepts of
property and ownership.
All organisms are genetically programmed to
favor themselves, their own survival and reproduction. This is evident in the names groups of
people give themselves; for example the word Inuit means ‘human beings,’ Dine (the Navajo) means
‘the people,’ Ani-Yunwiya (the Cherokee name for
themselves) means ‘the principal people.’ The
word ‘Mediterranean means ‘the center of the
Earth,’ which is where the Mediterraneans imagined themselves to be, because of biological programming.
A brief glance of U.S. history shows us that
both South Korea and Vietnam declared indepen-
dence in September of 1945, and the U.S. went to
war in both instances to prevent natives who lived
6000 miles from our shores from exercising their
own will, because we are ‘the people’ and they are
something less than that. In both instances wars
resulted that killed 3-4 million of the local population. More recently another 3 million have been
killed in Iraq by U.S. violence. But all humans are
programmed to submit to authority and the people who inhabit North America are equally subject to this pre-programmed behavior. It is
because of this that almost no one speaks out or
acts out against the institutionalized murder of
other human beings.
The plasticity of human behavior and the
specie’s unprecedented ability to learn new behaviors suggests we can to some degree choose
modes of existence that are adaptive and functional. We are more controlled by our genes than we
have realized, and so it would seem that the more
we discover about the mechanisms of genetically
controlled behavior, the more possible it will become to transcend these controls through awareness and conscious choice. We may then in the
words of A. Rosenfeld, "for the first time in our
history, work for ourselves instead of for our
genes, exercise truly free will and free choice, give
free rein to our minds and spirits, attain something close to our full humanhood.''
Let My Country Awake
Rabindranath Tagore
Where the mind is without fear
and the head is held high,
Where knowledge is free,
Where the world has not been
broken up into fragments
by narrow domestic walls,
Where words come out
from the depth of truth,
Where tireless striving
stretches its arms towards perfection,
Where the clear stream of reason
has not lost its way
into the dreary desert sand of dead habit,
Where the mind is led forward
into ever-widening thought and action,
Into that heaven of freedom
let my country awake.
Dana Visalli/[email protected]/The Methow Naturalist/www.methownaturalist.com