Bipedalism: Advantages and Disadvantages
By now it’s common knowledge to every scientist that the form of locomotion used by Homo sapiens or humans (and some primates) is bipedalism. This form of locomotion is very rare among mammals-even among primates- and has taken millions of years to develop to the current state it’s in. “Bipedalism is an essential adaptation of the Hominin progeny that is considered the major force behind several skeletal changes shared by all the bipedal hominins,” (Hyun, 2015, p. 929). While bipedalism comes with plenty of advantages for a hominin, it can also come with some disadvantages too. This article will look at both while discussing the transition from quadrupedal to bipedalism, how it’s one of the most efficient forms of locomotion anatomically and for collecting resources, and its factors over the course of millions of years.
For starters, let’s first take a look at the origins of bipedalism. Obviously, the change didn’t happen overnight. The transition took many years and while it can be traced back to Charles Darwin’s theory of Natural Selection, there’s no direct explanation for how the transition occurred.
“Biological evolution is an example of trial and error… i.e., if a trait works, it remains… Various traits were observed during the evolutionary timeline, but only a few remained. The reason why bipedalism remained was because it was beneficial for the efficient survival of both the unit itself and its offspring,” (Hyun, 2015, p. 930).
Though one hypothesis, known as the “savannah hypothesis” (early hominids began to walk on two legs in order to adapt to the savannah landscape) was believed for years to be true, recent research has concluded otherwise.
“Until the 1990s, the oldest definitive hominins were just under 4 [million years old] in age. In 2010 we have hominins possibly as old as 7 [million years old]… The evidence seems to point to a more closed and wooded environment between 7 and 4 [million years old], with perhaps a few patches or more open woodland but little in the way of the open savannah we see coinciding with the emergence of the genus Homo sometime between 2 and 3 [million years old]…” (Harcourt-Smith, 2010, p. 336).
It is believed that there is more than one phase that lead to the arrival of bipedal hominins. The factors that cause Homo sapiens or humans to walk on two legs reside in the structure of their skeletons. Their foramen magnum is located in the bottom middle of their skulls, which reside on top of their spines. When it comes to the spine, the Homo sapiens have a curved one, which is connected to a bowl shaped iliac pelvis and a large hip joint. This way, they can support a vertical trunk (Harcourt-Smith, 2010, p. 334).
Now let’s look at some of the benefits of bipedalism. Some of the most common advantages often linked to bipedalism are carrying, seed and nut gathering, thermoregulation, long distance walking, and visual surveillance. Back when bipedal hominins had to gather fruits and nuts or other supplies for their families, to now when Homo sapiens can simply go to the grocery store and buy their food, it’s much easier to carry and gather such items since they can now use their hands to do so rather than having to use them to walk. On top of this, a Homo sapiens’ hands are free to do many other things while walking such as carry their young, use tools, drive cars (which helps with the few disadvantages of bipedalism) and work out. Speaking of working out, on the topic of thermoregulation, obligate bipedalism helps Homo sapiens both to sweat and to cool down faster. “In one hour a horse can lose about 100 grams of water per square meter of skin, and a camel can lose up to 250 g/m2. However, a human being can easily shed 500 g/m2, enough to remove 550 to 600 watts’ worth of heat,” (Smil, 2016, p. 26). This can also tie into long distance walking. Bipedal organisms have much more endurance than organisms that are quadrupedal. Quadrupeds can move faster, but bipeds can go on longer. This is also mixed with the fact that even breathing is made easier with this form of locomotion, (Smil, 2016, p. 26). As for visual surveillance, this one can practically speak for itself. Since Homo sapiens stand taller on two legs than if they would on four legs, they are given a greater depth perception so they can see upcoming threats, locations and more a lot easier.
With every new evolved trait that occurs in a species there comes not only advantages, but disadvantages as well. One of the biggest disadvantages is the fact that Homo sapiens currently move much slower than they would have if they continued to be quadrupeds. “The concept that bipedalism was resorted to under duress is an attractive one, because it is generally agreed that when [practiced] on land by any quadruped it offers no advantages as a means of locomotion. It is slower, much more unstable, more laborious, takes longer to acquire and is very ill-designed as a posture of [defense]. Running on two legs uses twice as much energy as running on four,” (Morgan, 1993, p. 198–199). This is not to mention how long it took to develop a proper bone structure to do so. However, with the evolution of technology, producing things such as cars, planes, trains and more, it is less likely that slower locomotion is considered a large issue nowadays. It’s much easier to get around and it’s less likely that Homo sapiens have to run away from wild animals or after their food when hunting, especially now that guns and other weapons have been invented.
In conclusion, the advantages of bipedalism far outweigh the disadvantages, and the disadvantages that occur from it can be easily solved with today’s technology. From the perspective of movement, bipedalism is much more efficient than moving on four legs whether that means a greater endurance, for gathering resources, thermoregulation, and more. Science is getting better as time goes on, so there may be even more answers to the concept of bipedalism in the future. Bipedalism has taken millions of years to fully evolve in Homo sapiens, or humans bone structure, but they are all the better because of it.
Work Cited
· Harcourt-Smith, W. H. (2010). The First Hominins and the Origins of Bipedalism. Evolution: Education and Outreach, 3(3), 333–340. doi:10.1007/s12052–010–0257–6
· Ko, Kwang H. (2015). Origins of Bipedalism. Brazilian Archive of Biology and Technology, 58(6), Retrieved April 05, 2018, from http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132015000600929&lng=en&tlng=en
· Morgan, E. (1993). Bipedalism. Nutrition and Health, 9(3), 193–203. doi:10.1177/026010609300900305
· Smil, V. (2016). “Running, sweating, and persistence hunting [Numbers Don’t Lie],” in IEEE Spectrum, 53(11), pp. 26–26. doi: 10.1109/MSPEC.2016.7607022