The Fattest Ape: An evolutionary tale of human obesity

Fat-Humankind's Greatest Asset In the Evolutionary War:

One of the biggest problems of our era is the problem of obesity. Obesity, especially in our modern culture is viewed as an undesirable trait. Take the pinnacle of urban civilization in America, New York City, for example. If you look closely at your surroundings when walking down a street in NYC, you will notice the flashy social media and billboards that are constantly screaming “skinny is the new beautiful”. Furthermore, any seasoned couch potato can tell you just how annoyingly abundant those weight loss and bodybuilding programs are that crowd the television commercials. Sometimes we find ourselves wondering, why is it so hard to be skinny? Why are we so prone to weight gain? Why do I have so much fat? Why is it that I still gain weight even as I eat leaves for breakfast, lunch, and dinner?

Evolution has its answers.

Evidence has shown that modern humans and Neanderthals coexisted for a period of at least 10,000 years and that we occasionally mated with them.  However, we, the Homo sapiens, eventually beat the in this evolutionary struggle to survive.

Using remains of Neanderthals found throughout the world, scientists have been able to reconstruct renderings of Neanderthals. It is found that Neanderthals had very fit bodies that they were in great shape. In addition to their “ripped, muscular physiques,” their bodies were highly specialized for the intense active lifestyle needed to survive in the cold conditions of Ice Age Europe, putting most “modern-day bodybuilders to shame.” Their diet consisted mainly of meat, fat, and marrow and they spent the majority of their time hunting large game. Bone isotopes show that they consumed as many as 4000 calories a day of this carnivorous diet. However, as Scientific American writer Jesse Bering describes, “this massive dietary intake, and in particular an almost exclusive, physiologically pigeonholed reliance on flesh led eventually to the Neanderthals’ downfall.”

In addition, Anna Bellisari points out, the Neanderthal’s “metabolic demands finally outstripped the ability to supply adequate energy for maintenance and reproduction, despite their use of caves, rock shelters and fire for protection and warmth. Large game animals, the primary food sources, had become more difficult to find. Neanderthals were forced to move to southern Europe and western Asia, their final habitats before they completely disappeared.” In fact, there is evidence that the last remaining Neanderthals in France and Spain may have resorted to cannibalism because they became so desperate for meat.

Our ancestors, Paleolithic foragers that lived at the same time period, lived on a diet that was “probably the most nutrient-dense and healthful in all of human history […] the Paleolithic combination of lean meat, wild nuts, fruits and vegetables was lower in carbohydrates and higher in protein and micronutrients, including cancer-preventing antioxidants, than the modern industrial diet.” In addition, there is evidence showing that natural selection “operated on human phenotypes that were better able to store fat […] human fatness evolved, and it was in face a remarkable evolutionary innovation.” Compared to other primate species, humans have a greater level of body fatness and reduced levels of muscle. This can be seen by comparing a baby chimp to a human baby in which the chimp by six months could life itself with one hand, whereas the human counterpart could barely sit up and was bathing in a suit of baby fat. “Our own species easily wins the crown for being the fattest ape.”

With this said, as our ancestors and the Neanderthals competed for food and resources in the changing climate, our “adipose-pocketing ancestors” gained a “leg-up” over their muscular, fit counterparts. This ability to store fat and to eat a more variable diet allowed humans to survive during food shortages and deal with other environmental stress better. As a result, being “fat” was most likely chosen for as a beneficial trait 10,000+ years ago.

An obese person can trace their “being significantly overweight to some combination of genetic factors – over 600 genes, makers and chromosomal regions have been associated with human obesity phenotypes using the Human Genome Obesity map.”

These remarkable “fat” genes are one of the reasons we are here today. Yet, it is ironic and unfortunate that these genes no longer prove to be beneficial in our modern agricultural and sedentary lifestyles (at least in the human population not suffering from food shortages and starvation). In many cases, it has proven to become deadly, a disease of some sort.

With the population growing fatter by the minute, it is too bad that we are not succumbed to the same environmental pressures of 10,000 years earlier where being “fat” would have been an extremely valuable trait. Still, as great as it would be to be complimented about my love handles and muffin top belly, I would much rather live in our world today where I can spend my time doing much more than just hunting and gathering from dawn to dusk. So the next time you feel down about your weight, just remember, this fat is part of the reason you are here today!

By Stephanie Wu

http://blogs.scientificamerican.com/bering-in-mind/2010/11/02/the-fattest-ape-an-evolutionary-tale-of-human-obesity/

http://www.nytimes.com/2010/05/07/science/07neanderthal.html