Anthropology
By
Timothy Crain
Background of Human Origins According To Evolution
There are two commonly
accepted genera, Australopithecus and Homo, in the family
Hominidae. There is, however, another genus, Ardipithecus, which has
recently been discovered as the earliest common ancestor to all hominids.
Australopithecus
- The species in this genus all fall under
two types of forms, either robust or gracile forms. These two types are known
from some fossils that were found in South and East Africa. The differences
between the robust and gracile forms are pretty much differences in their
adaptive profiles, as the differences in the face and head of these two types
indicate that each on had different diets and thus had different diets and thus
had separate niches. This helps explain the co-evolution of these two groups.
Robust Forms - These forms were found from
about 4 million years ago until they disappeared suddenly about 1 million years
ago. The adaptive profile of the robust species indicates a strong reliance on
fibrous, gritty vegetation. The extremely large teeth, robust jaws and heavy
bony architecture are all really convincing evidence for this type to be doing
some really intense chewing. This type includes species such as A. aethiopicus, A. boisei and A.
robustus. 1
Gracile Forms—These forms were found from
about 4 million years ago to about 2 million years ago. The adaptive profile of
the gracile forms includes the very big advantage of being specialized in generalism rather than in hard-to-process plant life. There are no bony crests
for heavy chewing muscles, but the presence of smaller cheek teeth the
generally ‘lighter’ appearance of the gracile species indicates that this type
had more of an opportunistic approach to carving out a niche for itself instead
of only having one where it could survive, like the robust species. The gracile
type includes such species as A. anamensis, A. africanus and A.
afarensis. 1
Ardipithecus - The only species from
this genus, A. ramidus, is found about 4.5 million years ago. This is
the earliest hominid, and has been found in deposits in the surrounding area of
Aramis, Ethiopia.
Homo
- The genus Homo first emerged about 2.5 million years ago, and precedes
H. erectus species. H. erectus is most likely the first hominid
to leave Africa. The genus Homo includes species such as H. habilis,
H. erectus, and H. sapiens . Around the time of the dispersal of H.
erectus out of Africa about 2 million years ago, the sapien human lineage
was established. The establishment of separate populations of H. erectus
in Eurasia created regional groups that reproduced with neighboring regions.
This model of gene flow argues that the variations we see in modern humans, are
the products of 2 million years of limited inter-population reproduction as
well as much intra-population reproduction. This model can be viewed as several
gene pools being established soon after the
out-of-Africa hominid dispersal.
These growing gene pools began to establish growing connecting streams, which
maintained enough genetic homogeneity, that a single, inter-breeding species
remains. We, as modern humans, are the products of this pooling model.
H. heidelbergensis - This species has been
found in places all the way from
Africa to Eastern Europe
at times from about 600,000 years ago – 200,000 years ago. This species is
unusual for it has a lot of features which are similar to
H. erectus.
H. neanderthalensis -
These species are found from
about 130,000 years ago – 30,000 years ago. They are mostly found throughout
Western Europe.
H.
sapiens - This group of hominids share the anatomically modern traits
associated with us. Their origin in the fossil record
marks the time when
modern traits first appear. The earliest modern H. sapiens have been found
in South Africa and within a few thousand years these modern features were
found throughout Eurasia.
Hominids
have an amazingly sheer diversity on
the fossil record. No other mammal has spread over a larger area, nor evolved so many new forms of
behavior within so little time.
The
origins of this variability are behavioral as well as genetic. As human
ancestors evolved, accumulating technology gave our biological variability a
big boost. But before technology could have much of an impact, our evolution
was also helped along by the human tendency to migrate and the resulting
geographic isolation of different hominid. Separated from each other, hominids
evolved different regional characteristics. 2
Genetic variability within hominid species, and the mostly
unreliable fossil reconstruction or geological dating, makes these distinctions
very controversial. They are also not very important: early humans were a
restless species evolving at a breakneck pace. As a further complication,
fossils document the coexistence of different hominid species over the last 2
million years - sometimes in adjacent or
overlapping geographic regions.
Exactly how these different species coexisted or interacted is unclear.
Evolutionist
View #1: Out-of-Africanists
H. neanderthalensis - This
group has perhaps provided the most fuel for Out-of-Africa/ multi-regionalist
debate. Their robust appearance has been argued by the out-of-Africanists to be
the hallmark of a distinct species, reproductively isolated from modern humans.
H. sapiens - It is the contention of
the Out-of-Africanists that these modern humans at 100,000 years ago spread
rapidly throughout the Old World, competing with, and ultimately leading to the
demise of, all other Old World hominids. The Out-of-Africanists argue that old
world hominid populations existing before the spread of modern human characters
were not assimilated by modern features but rather disappeared as the result of
extinction.
The key problem with the African Eve theory is the replacement of the
indigenous population in the other parts of the world by Homo sapiens
recently migrated out of Africa. 3
Evolutionist View #2: The Multi-Regionalists
H. neanderthalensis -
It is the contention of
the multi-regionalists that the Neanderthals did not die out. Instead, they
think that the influx of anatomically Modern Europeans would thus carry with
them the genes of H. neanderthalen
sis.
H. sapiens - The Multi-Regionalists
argue that the disappearance of Old World hominid populations such as H.
erectus, H. heidelbergensis were not the result of extinction. Modern human
features and most likely culture, coming out of Africa, assimilated these Old
World hominid populations.
The perspective of
Multi-Regionalists is that extending to the origin of H. erectus, there
have been populations of humans living around the old
world, and these all contributed to successive generations,
eventually
leading to modern
humans.4
Conclusion
I
think that these two groups are really close to finding out the actual truth.
The Out-of-Africanists think that life came from one person, Eve, who is found
in Genesis 5 and we later find out in Genesis 3:16 that Eve will
bear children 6. And since she and Adam were the only ones there,
all life would have to have come from her. The Multi-Regionalists are partly
right because as we migrate, over time we look a little different and have
different body shapes to accommodate for the different surroundings. But these
two groups are sadly wrong in the fact that they base their beliefs on
evolution. They have the right idea; they just put it into the wrong theory.
Bibliography
1) A
Description of Fossil Hominids and Their Origins. Craig Byron.
http://www.archaeologyinfo.com/perspectives004.htm
2) Chart
of Human Evolution. Handprint Media.
http://archaeology.about.com/gi/dynamic/offsite.htm?site=http%3A%2F%
2Fwww.handprint.com%2FLS%2FANC%2Fevol.html
3) Letters
To The Editor. Adam Chou.
http://www.americanscientist.org/template/AssetDetail/assetid/31207
4) Homo
sapiens. C. David Kreger.
http://www.archaeologyinfo.com/homosapiens.htm
5) The
Holy Bible. Genesis 2:22, 23
6) The
Holy Bible. Genesis 3:16
