In the 2013 release of the Statistics on Obesity, Physical Activity and Diet (England), the key findings were that 65 percent of men and 58 percent of women in England were Overweight (with over a 1/3 of these men and nearly ½ of the these women classed as Obese). This has increased from the figures published in 1993 of 58 and 49 percent of men and women being Overweight, respectively. Although it doesn’t make great reading, if we include the Obesity figures, it’s even more telling. Between 1993 and 2011 the percentage of the population who are classed as Obese has risen from 13 to 24 percent in men and from 16 to 26 percent in women.
This situation is reflected in other measures of our health as a nation too. I covered the state of play as of 2007 in an article which you can find here: http://
As suggested in the previous pieces in this series, it is becoming increasingly obvious that our environment is at odds with our ancestral genome. The genes that make up our genome were ‘selected’ to be able, at a minimum, to allow us survive, but also thrive in a particular set of conditions. These conditions are the precise keys that fit the locks of our amazing, but woefully under-realised genomic potential.
One of the key features of our past was physical activity, and due to our unique ability to utilise true bipedal movement, this allowed us to develop in a seemingly very remarkable way; that development being the size of our brain.
We don’t know the precise details of how our evolution actually occurred, but from the limited fossil record that we do have we are able to approximate a very good working model. So far it seems that, sometime between 7-9 million years ago our common ancestor, an ape-like species called ‘Oreo’ (Oreopiticus Bambolii) was the first of our progenitors that was making the transition to upright posture. This was a pivotal moment in our evolution. By initiating this change in our anatomy Oreo and the descendents that followed which included ‘Ardi’ (Ardipithecus Ramidus ~ 4.4 million years), ‘Lucy’ (Australopithecus Afarensis ~ 3.2 million years) and another Australopithecus Afarensis called Kadanuumuu (‘Big Man’) who co-existed at the same time as ‘Lucy’, but had a more optimal structure for bipedal gait, set the scene for our already increased brain size to become larger…much larger.
The ability to stand upright gave us two huge advantages; it freed up our hands, which allowed us to utilise them for development of technology and to communicate more effectively, especially over distance and time. This further increased our already expanding brain capacity via an interplay between our emerging intelligence and the new found ability (thanks to our liberated hands) to harness extelligence. But that in itself is a whole other story, what we need to address here especially in regards to the benefits that bipedalism provided, is energetics.
To be able to grow and maintain such a large brain requires energy, a lot of energy. Although it is less than 2% of your entire weight, your brain uses 20% of all your energy. To feed this brain power, the human form has made some amazing adaptations, and it is these adaptations that we are neglecting in current society.
Humans are not unique in all ways among the apes, like us Chimpanzees will not only gladly eat meat, but will go hunting for it; with the usual target being monkeys, but they have been known to take down larger prey such as Gazelles too. However, to provide sufficient meat, which is much more efficient means of obtaining quality nutrition, for a family of energy hungry human brains, the occasional snared monkey will not cut it. However, this is where we ran into trouble, or rather ran out of it.
Compared to other animals, humans are relatively puny, we are slower, weaker, and less agile than the many quadrupeds. That’s okay you say, humans didn’t need to be physically dominant as we had weapons such as spears and bows and arrows. Well yes we did, but we didn’t have sharp stone tipped spears until about 300-400,000 years ago, and bows and arrows a good while later. Our ancestors were hunting a long time prior to this technological leap.
So how did we do it? Well Oreo set us on a path, from which we evolved a deciding specialism that enabled us to hunt down and kill even the largest and most powerful of game; that specialism was endurance. Whereas bipedalism reduced our ability to produce powerful agile movements, when applied to endurance, it is a boon. At faster speeds over shorter distances quadrupeds have a distinct physical advantage, so it’s unlikely we could catch our prey simply by outpacing them, and even if we did, unlike a chimpanzee who has the strength to body-slam a gazelle, humans simply don’t have the physical strength to over-come most larger animals. But if we pursue them for long enough our unusual anatomy comes to the rescue.
It’s hopefully apparent that when we move we generate heat as a by-product of metabolism. In order to regulate temperature many animals pant to dissipate the heat load, however at faster speeds they cannot do this as effectively, so need to take regular breaks in order to cool down. Humans have no need for this, as we radiate heat via our exposed bare skin and via sweating, so although we can’t quite keep pace when the animals are galloping we can force them to continue moving until they overheat and become exhausted, at which time we can kill them by stabbing them with sharp pointy sticks or clubbing them with blunt, heavy instruments.
In addition to thermoregulation, bipedalism is a surprisingly efficient means of locomotion. At lower speeds our legs act as a pendulum which costs approximately a ¼ of the energy of quadrupedalism, but it’s when we pick up the pace just a touch that our ace card becomes apparent. At speeds above walking pace our legs act similar to springs. Each step forward stores elastic strain energy which is returned with remarkable efficiency upon toeing off, so much so that although we are moving at speeds approximately double that of walking, the energy cost is roughly the same. At higher speeds when we transition into sprinting once again the quadrupeds have the advantage, but for the needs of persistence hunting where humans pursue larger game in the hottest part of the day at speeds of 4-6 mph for 3-5 hours, we have the upper hand.
This is just one example of our evolutionary past in which our genome was set. The genome still to this day requires these same environmental demands in order to express itself optimally. In the next part we’ll take a look at the types of demanding activities in which we evolved to meet, but just for this introduction I wanted you to begin to appreciate that our current lifestyle although culturally stressful, has nowhere near the physical demands of our past.
How much more demanding? Well, consider the fact that our ancestors would often travel 9-15 km per day to hunt down prey in the above manner alternating between walking and running in the midday sun of the increasingly arid African/ Asian continents, that’s pretty demanding. 9-15km is roughly 12,000-20,000 steps; if you’ve got a pedometer wear it on a normal day, the average person is said to take around 5,000 steps, see how you measure up.
Remember this is just part of the basic numbers regarding the hunting behaviours of our ancestors. Add onto this rudimentary and totally incomplete analysis, our other behaviours such as foraging, shelter creation/ maintenance and other day to day survival needs, and you can see that our genome is not receiving anywhere near the stimulus it evolved upon.
Our genome is phenomenal; we see glimpses of it from the elite performances of our champion academics, athletes and artists. The majority of us though just don’t ask it the right questions, so is it any surprise that we’re getting the answers we are?
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