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Locomotion and dedicated bipedal-ism

 

The original rainforest apes were already well on their way to being bipedal. Like all primates they sit upright with their heads placed at right angles to their spinal column (not in line - as in most other animals). Gorillas often walk biped-ally, supporting themselves with their long arms.

 

Having to move considerable distances across open ground to the safety of another tree would necessitate improvements in the ability to walk on two feet.

 

Savannah grass, which can be a metre high or more, would perhaps demand that the ape frequently stands up for a better look round.

 

An improved ability in bipedal locomotion would see the hallux (big toe) aligning with other toes. The opposing hallux configuration needed for gripping branches would be abandoned in lieu of a more compact and robust supportive arrangement.

 

This was only a minor modification from a skeletal point of view  - as the the foot of a gorilla is identical with that of a human. It is mainly the separated toe that creates the difference in the outward appearance of the foot. From time to time humans are born with a significantly deflected big toe and the condition is known as Hallux varus.

 

 

Sweat glands and the Cooling Effect of Evaporation

 

 

We have sweat glands on the entire surface of our bodies. Perspiration serves two purposes. One is to create a cooling effect from evaporation of moisture from our body surfaces. The other purpose is to release a disinfecting brine to kill pathogens such as bacteria colonising the skin layers and surfaces.

 

Sweat glands are likely to be modified sebaceous glands which normally secrete oils for conditioning and waterproofing fur or feathers.

 

Perspiration, although essential for cooling in an equatorial climate, is expensive on water and sodium chloride resources held by the body and in these high ambient temperatures considerable water intake would be essential. Their common dietary intake would provide very little moisture replacement. For this reason, these apes would need to maintain a proximity to water resources such as a river, spring or lake in order to secure an intake of a least two litres per day of drinking water. There are vast areas of East and Southern Africa without constant water supplies where pioneering apes would find it difficult to survive and this may strengthen the notion that the vicinities around the great lakes were perhaps the first areas of habitation.

 

Losing a great percentage of the hair covering to provide a more effective surface for evaporation, however, would have its disadvantages. The ‘naked’ ape skin would become more vulnerable to damage from thorns and sharp rocks etc. To counter this, an increase in skin sensitivity will have been selected for.

 

 

Secure Nesting

 

 

Pioneering savannah apes, like their rainforest ancestors, will have built crude nests in trees each night to rest safe from predators. These could have been the lower branches of suitable Acacia species or perhaps younger baobab trees. In many areas of East Africa there are thickets of thorn bushes and it is common to find natural ‘dens’ amongst these bushes. It is possible that these apes could have exploited these enclosed areas and once inside them - sealed the entrance area with additional thorn branches. Once a useful discovery like this is made, the procedure would be repeated and copied by other groups. In time the concept would develop into a purpose-built thorn enclosure (boma). Bomas are still built by nomadic tribes in parts of Africa and India, today, although they are now much larger to include livestock.

 

Again, motor skills would be practiced in building more and more elaborate nest enclosures. General knowledge would also accumulate regarding optimum branch length and crude intertwining techniques etc.

 

Slightly more intelligent apes would build better and safer enclosures than the others and so their chances of survival would be greater. In this way genes for intelligence would survive to be passed onto future generations.

 

 

 

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