There has been much debate concerning the origins of bipedalism. Bipedalism, or the ability to move on two legs (eLucy, 2007) was said to have emerged due to climate change in East Africa, for sexual display purpose, to reduce exposure to sunlight, the need to use weapons and tools and many more (NOVA, 2013).
There are numerous arguments associated with bipedalism as no one can be entirely sure as to what constituted to the emergence of this trait, which was first present in hominins Australopithecus Afarensis. Anthropologists claim that there is a missing link in the evolutionary lineage that makes it hard to confirm the real cause of bipedalism emergence. However, there are some models which are widely accepted by scientific world, such as the climate change model, and model which was just recently being introduced, but is supported by convincing arguments.
Next, climate change model and rugged terrain model will be discussed in the rest of this writing. The African continent nowadays is not what it was millions of years ago. By the beginning of the Miocene, which was around 22 million years ago, lush tropical forests and woodlands covered much of the landmass in tropical and subtropical Africa (Scarre, 2005).
At that time, Sahara Desert had not yet developed (Scarre, 2005).
Apes had no difficulties in finding food resources as they rely mostly on tress, from which they can obtain fruits and leaves from. However, around 7 or 8 million years ago (late Miocene), there was a dramatic cooling event in the earth’s climate, resulting in dropping of Mediterranean Sea level and thus causing the moisture-dependent forests of this continent to be reduced as their water sources dried up (eLucy, 2007).
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Introduction What is the oceans role in climate? The oceans play a vital and pivotal role in the distribution of life sustaining water throughout our planet. 86% of the evaporation that occurs on earth is over the oceans. The oceans are the planets largest reservoir of water transferring huge amounts of water around the hydrological cycle. In fact the oceans dominate the hydrological cycle, for ...
As their sources of food had now been reduced, they were forced to look for other sources of food. Bipedalism might have emerged over time as a result of spending more and more time looking for food resources on the ground (Fagan, 1998).
However, Dr. Isabelle Winder and her team might have different ideas. The proposed rugged terrain model states that hominins developed an upright gait because it helped them to scramble and climb around the rugged landscape of East and South Africa (thejournal.ie, 2013).
The rugged landscape emerged between six and two million years ago, where much tectonic activity happened. The team pointed out that the hominins would have been attracted to difficult terrain of rocky outcrops because it offered shelter and opportunities to trap prey, which is essential in survival of the species (thejournal.ie, 2013).
Not only that, Winder argues that the broke, disrupted terrain proved a motivation to improve their locomotor skills by climbing, balancing, scrambling and moving swiftly over broken ground – types of movement encouraging a more upright gait, which over time lead to bipedalism (2013).
Even though there are different theories concerning the emergence of bipedalism, both models stress out that this trait is really important as a means of survival for the hominins. With the reduction in the width of the forest, they had no choices other than to come down to the savannah landmass to look for food. This trait enables them to move efficiently from one food source to others, which is important for equitable allocation of scarce food resources. Besides, they are able to detect enemies earlier as they can see over the tall savannah grass. Having the same purpose, bipedalism which was claimed arose from rugged terrain model affords access to terrestrial food resources and protection from predators that cannot climb or scramble (Winder et. al, 2013).
Complex topography made these and cornering for prey possible due to its structure. It is also easier for the hominins to hide from their predators, ensuring the survival of the species.
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Persistent organic pollutants (POPs) are compounds with cyclic, halogenated and are organic in nature characteristics that impart stability in their structures (Ritter, Solomon, Forget, Stemeroff, and O’Leary, 1995). Because of its structural stability, POPs withstand degradation while its organic nature makes its solubility high in lipid or organic solvent but low in water and in other inorganic ...
However, the two models differ in terms of how the hominins acquired their biped form – how the body finally became adapted to walking on two feet. As opposed to previous beliefs, the road to achieving bipedalism involved “an extended and complex opening of habitats, rather than a single, abrupt transition from dense forest to open savanna” (SpaceDaily, 2002).
This transition caused an increase dependence on upper limbs for foraging from branches of small fruit trees, and left the lower limbs for support, which over time eventually led to the emergence of this trait.
This is different from what is proposed in rugged terrain model, where bipedalism is achieved by improvement in locomotor skills. This improvement is prompted by climbing, balancing, scrambling and moving swiftly over broken ground – types of movement encouraging a more upright gait (Winder, 2013).
We can see that bipedalism arose as a result of hominins trying to ensure their survival, stimulated by different form of needs – the needs to eat, to avoid from predators, etc. These two models provide insights into how bipedalism evolved from quadrupedal type of locomotion. Though the arguments are supported by numerous evidences, there are actually still a lot of things need to be explained, and they all seem to have something in common, which is to ensure the continuity of the species.
