Out of Africa Hypothesis & the Concept of Race

Out of Africa Hypothesis & the Concept of
Race

In recent decades, scientific breakthroughs have consistently lent
increased support to the “Out of Africa” hypothesis, which asserts that
modern humans originated in Africa, then migrated throughout the globe
from there. Support for competing theories has virtually disappeared
from scientific journals and peer-reviewed publications. Molecular
biology (genetics), archaeology, geology and dendrochronology (tree-ring
dating) all point to the likely conclusion that human populations
originated in Africa about 100-200,000 years ago, migrating outside the
African continent around 80,000 years ago.

(Continued Below)


Geologic evidence is based on “Stratigraphy”, which is the study of
sedimentary layers. For example, modern human fossils are found deeper
in sedimentary layers the closer you get to Africa. Dating methods add
further understanding to this sequential evidence. Tree ring dating and
radiocarbon dating combine to show dates of uncovered specimens
throughout the world. The oldest anatomically-modern human fossils are
found in Africa, with the oldest human fossils in other regions of the
world dating to more recent dates. Generally, the farther from Africa,
the more recent the dates of the oldest specimens in each respective
region. Radiocarbon and tree-ring dating (dendrochronology) are the most
reliable dating methods in dating specimens and artifacts.

Finally, genetic testing adds further perspective to the picture. All
modern humans show one of three genetic mutations found in African
populations, while African populations do not show later genetic
mutations exhibited in non-African populations. Genetic analysis also
provides added insight into chronology, by applying genetic mutation
rates to samples to determine how long ago a specimen lived.

The multitude of tests performed by any of these technologies
generally paint a similar picture of human history. If any of these
methodologies were unreliable, then results would appear to be random
across a broad spectrum. There are certainly anomalous test results on
occasion that would appear to undermine any one or all of these
techniques, but in any scientific study, the “statistical outliers” are
thrown out, since the preponderance of evidence generally points to the
truth.

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Illusions of Race

Studies regarding
human origins and migrations reveal the fact that all people are truly
part of the same human family, separated only by time and distance.
Genetic studies in particular show that peoples of different “nations”
or “races” are fundamentally equal. However, as they are separated by
time apart, distance or other geographical barriers, groups of people
will naturally develop along different trajectories. Even though humans
are basically similar, their individualized geographic realities, along
with the law of natural variance, dictates the development of varied
languages, cultures, religions, and even values to an extent.

As a result, people
from far-away or nearby “nations”, or members of different “races”, seem
foreign to each other. In reality, “foreigners” are simply a mirror of
ourselves if our mutual ancient ancestors had exchanged respective
migratory paths.

Even more than
cultural and language differences, humans have traditionally used skin
color as perhaps the leading factor for categorizing or differentiating
people, or even making generalizations or assumptions about people. The
fact that skin pigmentation represents just one out of about 3.5 billion
letters in the genetic code illustrates just how erroneous such
generalizations are, and how the concept of race is simply a matter of
perception.

The skin pigmentation
gene governs the amount of melanin in the skin and hair. The more
melanin, the darker the skin/hair, with lower amounts dictating lighter
skin/hair. Higher melanin amounts drastically decreases the risk of skin
cancer. As humans originated in sun-soaked Africa, liberal amounts of
melanin was advantageous for this hairless species, causing
anatomically-modern humans to evolve as a dark-skinned people.

Humans migrated out
of Africa several thousand years later, as dark-skinned people
comparable to modern sub-Saharan Africans. However, the farther north
they migrated, the less melanin they needed in order to gain protection
from the risk of skin cancer. In fact, in less sun-soaked climates,
higher melanin (i.e. darker skin pigmentation) actually inhibits the
critical production of vitamin D. In sun-rich environments such as
Central Africa, there is enough UV-A being radiated to enable the
sufficient production of vitamin D in people with elevated melanin
levels. But this is not the case in less sunny environments to the
north. Therefore, lower sun intensity means lower melanin levels are an
evolutionary advantage.

The sun was somewhat
less intense in Asia than the humans’ point of origin in Central Africa.
Therefore, over the course of several thousand years, somewhat lower
levels of melanin were produced in the skin/hair of Asiatic humans,
giving them a light brown pigmentation. The lightening effect was even
more dramatic for humans in sun-poor Europe, whose melanin was pressured
even further downward by natural selection (favoring individuals with
sufficient vitamin D levels), to the point of producing very light
colored skin, with lighter colors of hair also emerging in northern
populations.

Genetic evidence
indicates that both “white” skin pigmentation and even blue eyes first
appeared in the Caucasus region (Southern Russia) around 10,000 BC. This
is corroborated by archaeological evidence. Before 10,000 BC, cave
drawings in Europe portrayed dark-skinned humans.

To summarize, skin color is merely a
result of sunlight (UV-A) exposure of ancient ancestors over the course
of thousands of years, which is then genetically passed down, with
variations still present to this day. On average, those with darker skin
pigmentation are inherently just as likely to be intellectually,
physically and morally proficient as those with lighter skin
pigmentation, based on a virtually identical genetic code.

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Overview of Scientific Disciplines Used to
Understand Human Origins and Migrations

Geological Evidence: Stratigraphy

Stratigraphy is a branch of geology that studies the sedimentary
layers. It is governed by the Law of superposition, which states that
sedimentary layers are deposited in time sequence, with the oldest at
the bottom, and the youngest at the top. Sedimentary layers are
comprised of sedimentary rock, which is formed by minerals or organic
materials that are compacted by sediment. The sediment (ice, water,
dust, etc.) exerts considerable pressure until the mineral or organic
matter forms into rock.

A percentage of fossilized human remains and material culture
(artifacts) will be covered by sediment, and preserved in the
sedimentary layer corresponding with its age. Fossils and artifacts do
not get jumbled into other sedimentary layers. When a human dies, or a
tool is left behind, it cannot become deposited into the sedimentary
layer from the preceding time period, since it has become hardened rock,
buried beneath several feet of loose and/or hardened soil. Once
fossilized human remains or artifacts undergo the sedimentary process,
they are permanently suspended in the layer associated with their time
period, unable to change position between sedimentary layers (per Law of
Superposition).

By itself, stratigraphy is useful in establishing sequential
chronology. In other words, “order of appearance” can be established.
For instance, if a certain species is found within a certain sedimentary
layer, and another closely-related species is only found at a deeper
layer, then you know that the species found in the deeper layer lived
before the other species. In the case of the “Out of Africa” research,
you would expect to find human fossils inĀ  a deeper sedimentary
layer than you would in Asia, while finding them in a deeper layer in
West Asia than you would in Europe (the path humans took to arrive into
Europe).

Even though exact or even approximate dating cannot be concluded by
this method alone, there is substantial value in just the sequential
chronology. However, sedimentary layers can be calibrated through other
dating methods, such as radiocarbon and tree-ring dating. If fossils and
artifacts within a particular sedimentary layer generally fall within a
certain date range, then further findings within the same layer can be
assumed to fall within this same date range.

Molecular Biological Evidence: Genetic Testing/Analysis

As stated above, genetic evidence shows that all human lineages trace
back to common ancestry in Africa. Non-African peoples exhibit mutations
found in African populations, as well as a common base genetic base.
Generally speaking, the further you travel away from Africa, the less
genetically-related the indigenous people are to Africans.

Population genetics are studied through both the mitochondrial
DNA (maternal line) and Y-chromosome (paternal line). These are the only parts of
the genome that are passed down from generation to generation virtually unaltered.
In other words, they do not recombine. Each female receives her
mitochondrial DNA directly from her mother, and each male receives his
Y-chromosome unmodified directly from his father, so each type can be tracked from generation to
generation. With this information, you can test indigenous populations
to determine which other peoples they are most closely related to, which
unveils a migration pattern that begins in northeast Africa. Or, if
ancient human remains are uncovered still containing DNA, it can undergo
genetic testing to establish a genetic marker to know which peoples
inhabited which lands at certain time periods.

Y chromosome data shows
that 80% of European men share a common ancestor going back 25,000 to
40,000 years ago, meaning that humans entered Europe no more recently
than 25-40,000 years ago, based on this evidence.

Certainly, the more straight-forward part of this equation is the
analysis of how closely groups of people are related to one another.
Through the computation of genetic mutation rates, you can approximate
how long ago a certain group of people inhabited a particular region.
Mitochondrial and Y-chromosome DNA mutate only slightly from generation
to generation, slight enough to easily link close relatives, but still
enough to establish an estimated chronology. For example, if a skull
possessing DNA were uncovered, genetic scientists can measure the
difference in genetic code between the specimen and modern indigenous
peoples, and then mathematically calculate the expected mutation rate
(or the fastest and slowest feasible rates) to determine how long ago
the person lived. Also, scientists can measure the difference in the
genome sequence between two groups of people, to determine how long ago
their most recent common ancestor lived. With this information,
scientists can estimate the length of time it took for the two groups to
migrate from the region where their most recent common ancestor resided
to their current homeland.

Mutation rates can be established through
the calibration with other dating techniques. For example, if uncovered
human remains also include organic material, they can be subjected to
radiocarbon testing. If the remains are also in close proximity to a
wooden object that contains a cross-section of tree rings (cut or carved
from a tree trunk), then dendrochronology can be used for further
calibration. After the advent of writing, literary evidence can provide
yet another chronological marker. Mutation differences can be compared
against known chronological markers to determine a mutation rate.

With
this being the case, mutation rates going back to 3000 BC are
conclusively established. Most genetic scientists agree that the
mutation rate is similar even before 3000 BC, but it could vary to an
unknown degree, since there is no compelling evidence to suggest that
the mutation rate has changed within homo sapiens by more than a
negligible amount. Radiocarbon dating has been calibrated to a fairly
high degree of confidence going back to about 30,000 years ago, and to
some degree of confidence going back to 50,000 years ago. Tree-ring
dating has been calibrated going back to about 10,000 years ago. With
all of this fine tuning, dating via genetic mutation calculations has
been fairly well established, within a fairly reasonable margin of
error.

Based on established mutation rates, the most recent common female
ancestor (based on mitochondrial DNA analysis) of all humans lived in Africa
around 200,000 years ago. This would also place the initial migrations
out of Africa at about 75-100,000 years ago, and entry into Europe at
about 50,000 years ago. Erring far to the faster end of the spectrum of
potential mutation rates before 3000 BC, the most recent common female
ancestor could be placed as recently as 100,000 years ago, with the
migration out of Africa beginning about 50,000 years ago, and the
initial entrance into Europe occurring about 25,000 years ago. On the
other hand, erring on the far opposite end of the spectrum (slower
mutation rates), our most recent common female ancestor could have lived
as far back as 500,000 years ago.

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Archaeological Evidence: Radiocarbon Dating

Over the years, large numbers of ancient artifacts
and human remains have been unearthed and catalogued. The advent of
radiocarbon dating in the last half-century has introduced a fairly
reliable way of assigning an approximate date to many archaeological
finds. Radiocarbon dating is dependent upon the presence of some amount
of organic material on the artifact or specimen. This can include any
part of once-living matter, such as a tree, plant, animal or other
organism.

All living things absorb a specific amount of “C14”
(radioisotope carbon 14) while alive, based on the atmospheric content
of C14. Once deceased, the amount of C14 absorbed will decay at a
constant rate. C14 has a half-life of 5730 years (+/- 40 years), meaning
half of the remaining C14 in an organism will decay every 5730 years.
Virtually all of the C14 will decay over the course of about 60-70,000
years. In which case, radiocarbon dating could theoretically be used up
to 70,000 years after the death of the organism.

The potentially extraneous factor is estimating the
amount of C14 in the atmosphere over the past 70,000 years. Tree-ring
dating has been calibrated to about 10,000 years ago, enabling the
nearly-conclusive calibration of radiocarbon dating to 10,000 years ago.
Analyzing plant and tree samples going back even further has helped
scientists to gain an understanding of ancient carbon profile.
Radiocarbon dating can also be calibrated with other types of
radiometric methods. Most scientists agree that C14 levels have not
changed significantly in the atmosphere over the past 50,000 years, but
since there have been minor fluctuations, which are taken into account
whenever a test is performed.

However, calibration is not necessarily precise,
but it is generally within a reasonable margin of error according to
most scientists. Other potential issues can arise. For example,
specimens can be extracted unusual environments, where the organism
consumed and/or absorbed large amounts of ancient carbon. An organism
near a naturally-occurring carbonate aquifer is one such example, as
these aquifers can percolate large amounts of old carbon into nearby
environment. Or, instrumentation or user errors can taint results. When
such flawed tests are performed, the error is generally quite obvious,
since the results will usually be far off from the generally expected
time frame. However, these are rare cases, and the bulk of the
measurements will conform toward a statistical mean, showing that the
preponderance of evidence will prove largely accurate. Those that are
flawed will produce a random measurement, generally proving to be a
statistical outlier. When extreme results are thrown out (common in any
statistical/scientific study), the bulk of the data will generally
produce results that are most likely to be representative of reality.

Dendrochronology: Tree-Ring Dating

Tree ring dating has been calibrated as far back as
about 10,000 years. Samples are taken from a cross-section of
a tree trunk. With certain species of trees in certain locations,
known ring-growth patterns have been established. Multiple samples can
be taken out of a certain species within the same ecological system
(ensuring same conditions) in order to statistically establish the most
likely-to-be-correct growth pattern. Ancient chronology can be
determined by taking a living tree, and comparing its rings to
a dead tree that is hopefully much older. Each ring is very
individualistic, like a finger print. Therefore, if one of the initial
rings on the living tree (toward the middle) matches an outer ring on a
dead tree, then it can be ascertained that the two overlapped, with the
living tree sprouting to life toward the end of the dead tree’s life. As
a result, you can calibrate the chronology back even further into time,
and so on and so forth as trunks from ancient trees are discovered in
the area (even in the sedimentary layer). Through this process, dating
has been calibrated going back as far back as about 10,000 years.

Once calibrated in a certain region,
dendrochronology can be used to calibrate other dating methods applied
to specimens and artifacts found in the area, such as radiocarbon dating
and genetic mutation calculations. Stratigraphy can be used as a general
guide to make sure that the sequential chronology produced by these
other methods are correct. In other words, if one sample was found
deeper in the sedimentary layers than another, the other dating methods
should at the very least find it to be older.

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