Survival & Success of Bipedal Primates
Bipedal primates’ survival has been an ongoing challenge to best endure in their surroundings. Natural selection implies our ancestors evolved in response to their external environments, so let’s examine some general issues and illustrate how the adaptation to bipedalism eventually lead to finding a survival niche.
- Locomotion
-- Humans’ specialized form of bipedal locomotion enables us to stride with
nearly peak efficiency. The adaptation from habitual to obligate bipedalism is
advantageous in arboreal and flatland environments alike. It’s not known why our
ancestors transitioned from an arboreal way of life to the lifestyle modern
humans have today. On flat ground, the adaptation to bipedal locomotion lent an
edge in defense against predators. - Use
of Hands -- The transition to bipedalism freed the hands for uses other than
locomotion. This adaptation meant these primates to carry objects and to make
and use tools. - Defense
Against Predators -- The erect stance of bipedal primates gave a grander view of
their surroundings, giving an edge over predators. - Acquiring
Food -- As bipedal locomotion was an efficient means of traveling long
distances, the adaptation favored hunting game. Though arboreal living provided
an abundance of various fruit, nuts, seeds, and more, flatland living encouraged
adaptations beneficial to a hunting lifestyle. The transition to ground life was
not immediate. For example, bipedal primates continued to spent a considerable
amount of time in trees, taking advantage of the security and food resources of
arboreal dwelling. - Feet
-- Early hominin foot structure suggests a divergent big toe, meaning an ability
to grasp with the foot. The grasping ability allowed these hominins to navigate
movement in trees. Conversely, the divergent big toe does not provide high
stability while moving across a flat surface. Later hominins would adapt to
flatground maneuvering ability, while maintaining tree navigating skills. This
duality indicates bipedal hominins adapted to effectively maneuver arboreal and
flat terrains
Traits That Helped/Impeded Survival Success
Adaptation is a key factor in human evolution. The evolution of physical characteristics were almost always directly affected by changes in the bipedal primates’ environment.
For example, our “close” cousins, the species H. Neanderthalensis, evolved to the colder climates of its European environment by developing lighter skin pigment in order to absorb the incredibly vital vitamin D from a cold, or weaker Sun. [1] The icy temperatures also impacted the evolution of the nose, which shaped narrow nasal passages and nostrils in order to better warm (or insulate) freezing air as it was inhaled. These characteristics are also evident in the remains of modern humans (post-H. Neanderthalensis) that populated similarly
below-freezing climates. [1]
The Neanderthals, as is commonly known, died out. However, what is not known is the reason why. Some anthropologists, propose the theory that the Neanderthals did interbreed with the modern hominins that emigrated from other regions-- and that their DNA signature was eventually “weeded out” to a small fraction of contemporary (present-day human) DNA. This theory is called the Regional Continuity Model, and denies that pre-modern humans originated exclusively from Africa. The general theory also says that these pre-modern humans migrated and thus, interbred, relatively frequently to and fro different regions, which is why supporters of this theory believe there is little to no biological difference between premodern and modern humans.
[1]
There are other anthropologists who strongly disagree, and propose variations of a theory that is the former’s polar opposite! These models, referred to as Replacement Models, vary in several respects, but most retain that the Neanderthals were an entirely separate species of hominin and could NOT successfully interbreed with modern humans that DID originate from Africa. However, this theory gave way to a revised form due to information obtained from present-day technological advances in DNA research. We now know that indeed,
some present-day human populations retain Neanderthal genes! This evidence has caused the Replacement Model to restate that while some interbreeding most likely did occur, it was very little-- and the modern humans did not completely replace, but partially replaced other populations. [1]
Since we know that pre-modern humans arrived from Africa --or other regions, depending on which theory you support-- to northern, colder climates, it was inevitable that they would have to adapt to completely new environments. The lesson we learn from the Neanderthals is that for some reason they did not adapt, and failed as a species to survive the changes in the environment, be it an invading species, or a global shift of climatic climates. The Neanderthals were built for surviving in the harsh weather of Northern and Western Europe-- it may be that
they were not able to adapt to new environments.
According to artifacts uncovered by archeologists, we learn that while it is more likely the Neanderthals had inferior tools and used them less effectively than modern humans, it could just as easily be the other way around, with the two cultures sharing and learning from each other!
For example, our “close” cousins, the species H. Neanderthalensis, evolved to the colder climates of its European environment by developing lighter skin pigment in order to absorb the incredibly vital vitamin D from a cold, or weaker Sun. [1] The icy temperatures also impacted the evolution of the nose, which shaped narrow nasal passages and nostrils in order to better warm (or insulate) freezing air as it was inhaled. These characteristics are also evident in the remains of modern humans (post-H. Neanderthalensis) that populated similarly
below-freezing climates. [1]
The Neanderthals, as is commonly known, died out. However, what is not known is the reason why. Some anthropologists, propose the theory that the Neanderthals did interbreed with the modern hominins that emigrated from other regions-- and that their DNA signature was eventually “weeded out” to a small fraction of contemporary (present-day human) DNA. This theory is called the Regional Continuity Model, and denies that pre-modern humans originated exclusively from Africa. The general theory also says that these pre-modern humans migrated and thus, interbred, relatively frequently to and fro different regions, which is why supporters of this theory believe there is little to no biological difference between premodern and modern humans.
[1]
There are other anthropologists who strongly disagree, and propose variations of a theory that is the former’s polar opposite! These models, referred to as Replacement Models, vary in several respects, but most retain that the Neanderthals were an entirely separate species of hominin and could NOT successfully interbreed with modern humans that DID originate from Africa. However, this theory gave way to a revised form due to information obtained from present-day technological advances in DNA research. We now know that indeed,
some present-day human populations retain Neanderthal genes! This evidence has caused the Replacement Model to restate that while some interbreeding most likely did occur, it was very little-- and the modern humans did not completely replace, but partially replaced other populations. [1]
Since we know that pre-modern humans arrived from Africa --or other regions, depending on which theory you support-- to northern, colder climates, it was inevitable that they would have to adapt to completely new environments. The lesson we learn from the Neanderthals is that for some reason they did not adapt, and failed as a species to survive the changes in the environment, be it an invading species, or a global shift of climatic climates. The Neanderthals were built for surviving in the harsh weather of Northern and Western Europe-- it may be that
they were not able to adapt to new environments.
According to artifacts uncovered by archeologists, we learn that while it is more likely the Neanderthals had inferior tools and used them less effectively than modern humans, it could just as easily be the other way around, with the two cultures sharing and learning from each other!