Evolution and Our Food
Our bodies were not designed to handle as much caloric input with so little energy outflow, as we experience today.
For the first couple of million years of our species' evolution, which was 99.5% of the human species time so far, all humans sustained themselves by hunting animals and gathering plants. So, we needed to work to get everything we ate (until 100 years ago there was no snack food).
Now we take this concept and think about the human evolution timeline. But, the problem with the typical timeline-graphic is that it was made by graphic artists - so it is not to scale when time is applied.
When time is applied, this is the actual scale:
You will notice in the above that our modern era of "not needing to 'work' to eat" only represents a fraction of human time on earth. And, you will also notice that fire was not used for cooking until at the most 1.6-million years ago (used in the image above), and may have only been as recent as 300,000 years ago. Fire and cooking allowed the evolution of Homo erectus, the earliest hominid, to resemble modern humans. Cooking made vegetables and meat far easier to chew - early humans may have spent five hours a day just chewing - our jaws need not be as strong, so they became smaller.
With today's processed foods, we can eat 5 to 6 times more food per hour than our distant ancestors, and we don't need to work to get it!
So, for most of humanity's time, there has been a scarcity of calories, not an abundance. Over the past 100 years, easy food availability has far surpassed our ability to adapt. Our bodies were not designed to handle as much caloric input and with so little energy outflow.
This concept can be further explored from its source:
- The Way We Eat Now
- Craig Lambert
- Harvard Magazine
- May-June 2004
Evolution fights dieting
Evolution favours those adapted to the environment - this is critical to how we eat and the results.
Early humans would experience a period of starvation, so their bodies learned to store more food as fat - a higher fat set-point was made. Those who did not adapt to this died. And then, if this was not enough for the next famine, our bodies would store even more food as fat for the next time - an even higher fat set point was made. Once again, those who did not adapt to this died.
Today, dieting is perceived by our bodies as a period of starvation. So when we end a "diet" our bodies try to store more fat and weight gain is thus faster.
This concept can be further explored from its source: "Why dieting doesn't usually work" by Sandra Aamodt at Ted.com