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How Evolution Left Its Footprint In Us

An ancestral perspective on health, well-being, and thriving is one that incorporates what we have learned and now know about our specie's evolution and subsequent adaptations. We at Vital Origins believe that one reason we see so much chronic dis-ease in westernized populations is due to the reality that much of our lifestyles and environments are exceptionally out of sync with our genetics and physiology. To elucidate this claim, let's take a brief journey through the long history and the adaptations that have arisen as we have grown to take the form of the modern human.  

human-faces-evolution.jpg

It is important to note that when discussing evolution that the timeframe is huge. Often things can be narrowed down to a range, but exact dating is more difficult.

There are a many things that make us uniquely human. These adaptations have developed over enormous amounts of time. It is theorized that we last shared an ancestor with the apes on the planet now somewhere between 8-5 million years ago. What this means is that we come from a creature that lived a very long time ago that evolved into the great apes, and eventually us. Not that the apes are our ancestors, but rather like our cousins. [1]

source: http://humanorigins.si.edu/human-characteristics/bodies

source: http://humanorigins.si.edu/human-characteristics/bodies

The first major adaptation that started us on our path toward humanhood was the ability to stand upright and walk on two legs, bipedalism. Coming down from the trees, standing upright, and walking on two legs took several physical adaptations that have become more refined and still exist in our bodies today. 

The shape of the hips changed with our ancestor, Ardipithecus Ramidus, developing a sideways facing pelvis, as opposed to backward facing like an ape's. This allowed us to stabilize the weight of the upper body while walking upright. [2] In the same time frame the adaptation of having an s-shaped spine with a vertical neck emerges within another species, Sahelanthropus. This adaptation positions the neck projecting vertically from the skull, allowing the head to face forward more easily when standing. An ape's spine usually projects horizontally from the base of the skull, which makes sense when traveling on all fours, mostly. [3] The next adaptation is one of my favorites, a stiff foot. Within the foot of Ardipithecus Ramidus there is evidence of a stiffening mid-foot, the beginning of an arch, as well as toes that could bend backward towards the shin, enabling them to generate a forward force with each step.[4] All of these adaptations make it more efficient to walk upright than to trudge about knuckle dragging, or swaying about on two legs like an ape. [5] A general timespan for the given adaptations is between 4.5(Ardipithecus Ramidus)-6, maybe even 7 million years ago(Sahelanthropus).[1]

source: http://anthro.palomar.edu/hominid/australo_2.htm

source: http://anthro.palomar.edu/hominid/australo_2.htm

Further refinement continued with the species of Australopithecus who live from 4.5-1 million years ago. The foot continued to stiffen and a more pronounced arch develop. In addition the australopiths now had a big toe that was inline with the rest of the foot. [6] [7] The lower extremities indicate that the femur, the thigh bone, was angled inward bringing the knee in closer to the midline of the body. [1] These adaptation led to an even greater efficiency in bipedalism than was previously the case. The hands of australopiths start to make the shift toward shorter fingers with a longer thumb. [8] This would have begun to enable the australopiths to have a firm grasp and begin to dig, as they likely did. In addition to the physical adaptations there is a noticed shift within the diets of australopiths. Australopiths have large cheek teeth that would have been good for pulverizing fibrous tubers. As such we can assume that their diets were making the shift from soft and sugary foods towards more tough foods such as nuts, seeds, and roots. [9] They would have also been eating insects, scavenging and eating meat whenever possible.

We can see that as time passed seemingly small adaptations had a huge impact and that those adaptations became more refined well developed with each iteration of our early hominid ancestors. These changes set the stage for the major shift towards what we might look at and think of as human. 

Next we see the emergence of the species Homo, which would eventually lead to us, Homo Sapiens. Early homo start to make their way onto the scene approximately 2.3 million years ago with homo habilis. You can see that there is some overlap between these different species. As new traits and adaptations manifest that enable us to survive better, those in which the traits arise win out and pass on their genetics. These seem to have primed us for a few very specific tasks. 

In homo we see a "coming together" of the results of the previous iterations. There is a full arch in the foot, like that of a modern human's.[10] Thicker bones and bigger joints evolved in support of higher impact. [11][12] The continued trend of of energy efficiency continued with longer legs reducing the caloric cost of walking (and now running!). [13] A snout transformed into a protruding nose, which helped to humidify the hot air of the African plains, keeping the lungs from drying out. [14] To Further deal with the heat the development of millions of sweat glands, unique to homo, began to cover the body allow us to greatly regulate our body temperature. [15] This in addition to developing fine hair aided us in the most needed task of regulating our body temperature. Homo has a very large gluteus maximus, which mainly functions when running, explaining why apes' glut max isn't as large. [16] Homo has grown to incorporate large semi-circular canals within the ear, and a nuchal ligament, both necessary to stabilize the head in the activity of running. [17][1] Short toes with the ability to bend backwards, a more narrow waist than previously seen, and lower shoulders are present. [18][19] All of this combined with the dominance of slow twitch muscle fiber in the legs of homo prepare us to run like no primate before.[20] 

source: spiritedthoughts.wordpress.com/2011/06/23/nature-can-take-care-of-itself/

source: spiritedthoughts.wordpress.com/2011/06/23/nature-can-take-care-of-itself/

Within the species homo we see a myriad of adaptations that have designed us to run, but why? Well, there are more uniquenesses to homo that elucidate why that likely is.

As we started to run, we simultaneously became better at being able to throw. We began to be able to throw with greater force as the shoulder grew to have greater flexion, which, when combined with the mechanics of the upper body and longer legs, lead to a great deal of force. [21] It becomes easy to see that many of the adaptations that developed and persisted were those that enabled us to run for long distances, in the heat of the day, and to be more efficient in the lethal act of throwing to procure meat. 

source: Jay Matternes-http://www.archaeology.org/news/2893-150113-oldowan-tools-communication

source: Jay Matternes-http://www.archaeology.org/news/2893-150113-oldowan-tools-communication

As meat consumption increased and we began to process our foods with the novel ability to harness fire, the nutrient density stored in the foods we would have eaten became much more bioavailable. This means we wouldn't have to spend as much energy chewing, digesting, and even procuring food, than we had done so previously. 

source: britanica.com

source: britanica.com

This abundance of nutrients and calories would have enabled us the resources to grow much larger brains. Interestingly, it is theorized that the consequences of food processing led us to develop a smaller intestinal tract, while simultaneously growing our brains. Our diets, as well as our ability to cooperate and work as part of a larger group/community, have a positive correlation to the growth of the homo brain.[22] 

The continued expansion of brain size, increasing cooperation, language, creation of culture, art, symbology, reverence, and expansion appear to be the hallmarks of the evolution of the species homo. These characteristics persist to this day. 

This has be no means been an exhaustive summary of the many components that go into our humanness. Nor was it meant to be. Rather a general brush stroke meant to highlight many of the interconnected pieces that seem to have synergistically operated towards the blossoming of our humanity. There will be many "riffings" and posts to delve further into the necessity of developing The Vital 5 Foundations of Functioning for human well-being and thriving: Nutrition, Physical Activity, Stress Management, Sleep, and Spiritual Connection.

Thanks for reading! 

Written by: Ryan Hall

 

 

 

 

References:

[1]Lieberman, D. (2014). The Story of the Human Body: Evolution, Health, and Disease (Reprint edition). Vintage.

[2]Lovejoy, C. O., Suwa, G., Spurlock, L., Asfaw, B., & White, T. D. (2009). The Pelvis and Femur of Ardipithecus ramidus: The Emergence of Upright Walking. Science, 326(5949), 71–71e6. https://doi.org/10.1126/science.1175831

[3]Zollikofer, C. P. E., Ponce de León, M. S., Lieberman, D. E., Guy, F., Pilbeam, D., Likius, A., … Brunet, M. (2005). Virtual cranial reconstruction of Sahelanthropus tchadensis. Nature, 434(7034), 755–759. https://doi.org/10.1038/nature03397

[4]Lovejoy, C. O., Latimer, B., Suwa, G., Asfaw, B., & White, T. D. (2009). Combining Prehension and Propulsion: The Foot of Ardipithecus ramidus. Science, 326(5949), 72–72e8. https://doi.org/10.1126/science.1175832

[5]Sockol, M. D., Raichlen, D. A., & Pontzer, H. (2007). Chimpanzee locomotor energetics and the origin of human bipedalism. Proceedings of the National Academy of Sciences of the United States of America, 104(30), 12265–12269. https://doi.org/10.1073/pnas.0703267104

[6]Latimer, B., & Lovejoy, C. O. (1989). The calcaneus of Australopithecus afarensis and its implications for the evolution of bipedality. American Journal of Physical Anthropology, 78(3), 369–386.

[7]Harcourt-Smith, W. E. H., & Aiello, L. C. (2004). Fossils, feet and the evolution of human bipedal locomotion. Journal of Anatomy, 204(5), 403–416. https://doi.org/10.1111/j.0021-8782.2004.00296.x

[8]Latimer, B., & Lovejoy, C. O. (1989). The calcaneus of Australopithecus afarensis and its implications for the evolution of bipedality. American Journal of Physical Anthropology, 78(3), 369–386. Tocheri, M. W., Orr, C. M., Jacofsky, M. C., & Marzke, M. W. (2008). The evolutionary history of the hominin hand since the last common ancestor of Pan and Homo. Journal of Anatomy, 212(4), 544–562. https://doi.org/10.1111/j.1469-7580.2008.00865.x

[9]Ungar, P. S., & Sponheimer, M. (2011). The Diets of Early Hominins. Science, 334(6053), 190–193. https://doi.org/10.1126/science.1207701

[10]Ker, R.F., Bennet, M.B., Bibby, S.R., Kester, R.C., and Alexander, R.McN. (1987). The spring in the arch of the human foot. Nature, 325(8), 147-149.

[11]Ruff, C. B., McHenry, H. M., & Thackeray, J. F. (1999). Cross-sectional morphology of the SK 82 and 97 proximal femora. American Journal of Physical Anthropology, 109(4), 509–521.

[12]Jungers, W. L. (1988). Relative joint size and hominoid locomotor adaptations with implications for the evolution of hominid bipedalism. Journal of Human Evolution, 17(1–2), 247–265.

[13]Steudel-Numbers, K. L. (2006). Energetics in Homo erectus and other early hominins: The consequences of increased lower-limb length. Journal of Human Evolution, 51(5), 445–453. https://doi.org/10.1016/j.jhevol.2006.05.001

[14]Franciscus, R.G., and Trinkaus, E. (1988). Nasal morphology and the emergence of Homo erectus. American Journal of Physical Anthropology, 75, 517-527.

[15]Montagna, W. (1972). The skin of nonhuman primates. American Zoologist, 12, 109-124.

[16]Lieberman, D. E., Raichlen, D. A., Pontzer, H., Bramble, D. M., & Cutright-Smith, E. (2006). The human gluteus maximus and its role in running. Journal of Experimental Biology, 209(11), 2143–2155. https://doi.org/10.1242/jeb.02255

[17]Spoor, F., Wood, B., & Zonneveld, F. (1994). Implications of early hominid labyrinthine morphology for human bipedal locomotion. Nature, 369, 645-648.

[18]Rolian, C., Lieberman, D. E., Hamill, J., Scott, J. W., & Werbel, W. (2009). Walking, running and the evolution of short toes in humans. Journal of Experimental Biology, 212(5), 713–721. https://doi.org/10.1242/jeb.019885

[19]Hinrichs, R. N., Cavanagh, P. R., & Williams, K. R. (1987). Upper extremity function in running. I: center of mass and propulsion considerations. International Journal of Sport Biomechanics, 3(3), 222–241.

[20]Dahmane, R., Djordjevič, S., Šimunič, B., & Valenčič, V. (2005). Spatial fiber type distribution in normal human muscle. Journal of Biomechanics, 38(12), 2451–2459. https://doi.org/10.1016/j.jbiomech.2004.10.020

[21]Roach, N. T., Venkadesan, M., Rainbow, M. J., & Lieberman, D. E. (2013). Elastic energy storage in the shoulder and the evolution of high-speed throwing in Homo. Nature, 498(7455), 483–486. https://doi.org/10.1038/nature12267

[22]Aiello, L. C. (1997). Brains and guts in human evolution: The Expensive Tissue Hypothesis. Brazilian Journal of Genetics, 20(1). https://doi.org/10.1590/S0100-84551997000100023