Figure 1.-- A geologically driven drier climate and declining rain forest habitat forced early Homonoids (Hominins) out of the rain forrest trees and onto Savanah in search of food. This made an erect stature an advantage as opposed to the ape-like stature more adapted to movement in trees. Australopithecus species, the most immediate human ancestior appeared (about 5 million years ago). Lucy (Australopithecus afarensis, discovered by the Leakeys in Erhiopia is arguably the most famous fossil of all time lived (about 3.2 million years ago).

Geological changes take place over immense time spans. Geological changes such as the creation of mountain ranges or the tectonic movement of continents involve millions even billions of years and human history is meaured in the thousands. The same, however, is not the case for homids in general. Geological change has created the geographic features which have in turn impacted and incluenced primate/humanoid evolution and eventually history. There are some geological events that have directly affected both evolution and history. Scientists belive that the earth dates to the time that that the accretion of material began forming a core (4.55 billion years ago. Extraresterial events (meteors, comets, and even other planets) have struck earth and played an important if not fully understood role in geological development. The most important has to be collision with Theia that most believe is what created the moon and occurred very early in earth's history (about 4.51 billion years ago). The moon helped stabilize earth's climate which plyed a key role in making earth ideal for life. Life appear (about 3.5 billion years ago). The breakup of Gondwana leading to the modern cpntinnrs bgan (abouut 185 million years go). The next important event was the Chicxulub meteor strike which led to the extinction of the dinasours and the rise of the mammals (about 66 million years ago). Primates appeared probably as a response to the resources in the lower canopy (about 50-55 million yers ago). The great apes appeared (11-16 million years ago). Proto-homonids may have appeared as early (7 million years ago). These very early fosils have only recently been discovered (Sahelanthropus, Orrorin, and Ardipithecus) -- all in Africa. The principal destinguishing feature here was an erect stature. And the driving force from the beginning was gelogically driven climate change. A drier climate and declining rain forest habitat forced early Homonoids (Hominins) out of the trees and onto Savanah in search of food. This made an erect stature an advantage as opposed to the ape-like stature more adapted to movement in the trees climbing. Australopithecus species, the most immediate human ancestior appeared (about 5 million years ago). The famous Lucy (Australopithecus afarensis lived (about 3.2 million years ago). The first Homonoids appeard (about 2.5 million years ago) which might be seen as the beginning of pre-history. Our species (Homo sapiens) began to appear (about 0.2 million years ago). By this time the current geology was largely formed, but we know much more about climate events and not just the geology. We know of powerful volcanic eruptions (supervolcanoes) that injected enormous amounts of material into the atmosphere and set off sunamis. And because of the debris injected in the atmosphere, affected climate. This has caused feeezing conditions even in the tropics. And the imapact on agriculture and historical events was subtantial. In fact, volcanos may have played a key role in human development. Scientists theorize that horrific "volcanic winter" occurred 71,000 years ago, when Mount Toba in Sumatra erupted. It was followed by the coldest 1,000 years of the last Ice Age. This caused widespread famine, killing off most humanoids. Only scattered bands of humans suvived. It was this population "bottleneck" that created the rapid "differentiation" - or genetic divergence - of the surviving populations. [Ambrose] DNA work support this and suggest thast all modern humans descended from a few thousand people, presumably the survibors of Toba. More recent volcanic erruptions have been only a small fraction of the power of a supervolcano like Toba. Even so, they have impacted historical events. There are many ice ages in earth's longbgeological history. Scientis do not agree as to what causes ice ages. A mix of distance from the Sun, the position of the continents, and solar output. The last ice age happened around 20,000 years ago. And with the falling sea levels we see the pepoling of the America. Geology has continued to impact history. The devastating volcanic eruption of Santorini in the Aegean may have been responsible for the destruction of Minoan civilization (about 1600 BC although dates differ). The eruption of Krakatau (about 535 AD) may have played a role in the European Dark Ages. The eruption of Tambora in Indonesia (1815) caused atmopspheric events that were well observed in Europe. In contrast, Pinatubo (1991) was a minor event, but had a notable impact on climate.

Geology and Evolution

Geological changes take place over immense time spans. Geological changes such as the creation of mountain ranges or the tectonic movement of continents involve millions even billions of years and human history is meaured in the thousands. The same, however, is not the case for hominids in general. Geological change has created the geographic features which have in turn impacted and incluenced primate/humanoid evolution and eventually history. There are some geological events that have directly affected both evolution and history.

Earth's Geological History

Scientists believe that the earth dates to the time that that the accretion of material began forming a core (4.55 billion years ago. Extraresterial events (meteors, comets, and even other planets) have struck earth and played an important if not fully understood role in geological development. The most important has to be collision with Theia that most believe is what created the moon and occurred very early in earth's history (about 4.51 billion years ago). The moon helped stabilize earth's climate which played a key role in making earth ideal for life. Life appear (about 3.5 billion years ago). Scientists disagree as to when plate tectonics, with its subduction zones, spreading centers, earthquakes and other features began. One research team estimates (about 3.2 billion years ago).

Mammals and Primates

The breakup of Gondwana leding to the modern continents began (about 185 million years go). This was a world dominated by dinasaurs. Mammals were small unimpressive animals. The next important event was the Chicxulub meteor strike which led to the extinction of the dinasours and the rise of the mammals (about 66 million years ago). Primates appeared probably as a response to the resources in the lower canopy of the rain forrests (about 50-55 million years ago). The great apes appeared (11-16 million years ago).

Homonids

Proto-homonids may have appeared as early (7 million years ago). These very early fosils have only recently been discovered (Sahelanthropus, Orrorin, and Ardipithecus) -- all in Africa. The principal destinguishing feature here was an erect stature. And the driving force from the beginning was gelogically driven climate change. A drier climate and declining rain forest habitat forced early Homonoids (Hominins) out of the trees and onto Savanah in search of food. This made an erect stature an advantage as opposed to the ape-like stature more adapted to movement in the trees climbing. Australopithecus species, the most immediate human ancestior appeared (about 5 million years ago). The best known famous Lucy (Australopithecus afarensis lived (about 3.2 million years ago). Lucy when found by the Leakeys in Ethiopia was the earliest known Homonid. This was before the proto-homoinids were known. The first true Homonoids appeard (about 2.5 million years ago) which might be seen as the beginning of pre-history.

Modern Man (about 0.2 million BP)

Our species (Homo sapiens) began to appear (about 0.2 million years ago). Extensive fossil evidence indicates that modern humans evolved in Africa around 200,000 years ago. [cDougall et. al..] This is confirmed by DNA researchers. This means that all living people share an African ancestor that lived around this time. [Soares et al., 2009] By this time the current geology was largely formed, but we know much more about climate events and not just the geology. We know of powerful volcanic eruptions (supervolcanoes) that injected enormous amounts of material into the atmosphere and set off sunamis. And because of the debris injected in the atmosphere, affected climate. This has caused feeezing conditions even in the tropics. And the imapact on agriculture and historical events was subtantial. In fact, volcanos may have played a key role in human development.

Migration Out of Africa (about 50,000 BP)

There is no definitive date for the migration out of Africa. There is some disagreemnenht among scientists, but there is an increasing consensus based on DNA evidence that the move out of Africa occurred (about 50,000 BP). [Quintana-Murci et. al.] The migratory impulse is not surprising as earlier Homonids such as H. egaster were migrating as well. It is widely believed that these migrations were primarily the result of the search for resources, especially food. The first migration seems to have been a coastal migration ending in New Guinea and Australia. It was presumably driven by the drive to find uexploited resources along the seaside. The later and more important migration occurred into Central Asia and may have resulted from following the migrations of heard animals.

Toba (71,000 BP)

Scientists theorize that horrific "volcanic winter" occurred 71,000 years ago, when Mount Toba in Sumatra erupted. It was followed by the coldest 1,000 years of the last Ice Age. This caused widespread famine, killing off most humanoids. Only scattered bands of humans suvived. It was this population 'bottleneck' that created the rapid "differentiation" - or genetic divergence - of the surviving populations. [Ambrose] DNA work support this and suggest thast all modern humans descended from a few thousand people, presumably the survibors of Toba. More recent volcanic erruptions have been only a small fraction of the power of a supervolcano like Toba. Even so, they have impacted historical events. There are many ice ages in earth's long geological history.

Last Ice Age

Scientists do not agree as to what causes ice ages. A mix of distance from the Sun, the position of the continents, and solar output. The last ice age happened around 20,000 years ago. And with the falling sea levels we see the pepoling of the America.

Santorini (1600 BP)

Geology has continued to impact history. The devastating volcanic eruption of Santorini in the Aegean may have been responsible for the destruction of Minoan civilization (about 1600 BC although dates differ).

Krkatau (535 AD)

Tambora (1815)

Pinatubo (1991)

In contrast, Pinatubo (1991) was a minor event, but had a notable impact on climate.

Sources

Ambrose, Stanley. University of Illinois. Ambrose's theory is summarized in "Ancient 'volcanic winter' tied To rapid genetic divergence in humans", Science Daily (September 8, 1998).

McDougall, I., F.H. Brown, and J.G. Fleagle. "Stratigraphic placement and age of modern humans from Kibish, Ethiopia," Nature (2005) Vol. 433, No. 7027, pp. 733-36.

Soares, P., L. Ermini, N. Thomson, M. Mormina, T. Rito, A., Röhl, and M.B. Richards. (2009). "Correcting for purifying selection: An improved human mitochondrial molecular clock," The American Journal of Human Genetics (2009) Vol. 84, No. 6, pp. 740-59.

Quintana-Murci, L., O. Semino, H.J. Bandelt, G. Passarino, K. McElreavey, and A.S. Santachiara-Benerecetti. Genetic evidence of an early exit of Homo sapiens sapiens from Africa through eastern Africa", Nature genetics (1999) Vol. 23, No. 4, pp. 437-41.

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Created: 1:26 AM 6/29/2018
Last updated: 1:26 AM 6/29/2018