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Health, psychology & science stories

 

Evolutionary Diet and Fitness (Interviews with De Vany & Cordain)

28 June 2000


Published in New Scientist


We’re a dynamic species: to be human is to move . Exactly how we’re supposed to move - how diversely, intensely and frequently - became the subject of hundreds of exercise prescriptions through the twentieth century: one often contradicting the other.


The Paleolithic Diet & Exercise Symposium is a cross-disciplinary forum which, since 1997, has been trying to trace this urge of ours to get up and do something to its evolutionary origins.


A leading Symposium contributor is Loren Cordain, Professor of Health and Exercise Science at Colorado State University.


Cordain points out that our ancestors ate meat for at least 2.5 million years. From this, and more direct evidence such as hunting tools and robust skeletons, we can infer a highly physical lifestyle.


Across the Palaeolithic - which began 2.6 million years ago - prey animals were large, fleet-footed or both. For men, this would have meant lots of walking or jogging (to where herds were), dramatic sprints, jumps and turns, perhaps violent struggles, and long walks home carrying kill.


Women may have incurred plentiful, but perhaps less acute, activity - for instance long walks to water or food, digging out tubers, and carrying children.


Aerobic or strength pathways would have been further employed in skinning, tool-making and presumably dancing. (Our palaeolithic ‘surrogates’ - modern hunter-gatherers - commonly dance several nights a week.)


Given that the Paleolithic ended an evolutionary eye-blink ago - in about 8,000 BC - what light does all this cast on the level of activity modern humans might be designed for?


In a couple of agenda-setting papers on this subject, Cordain and his colleagues S Boyd Eaton, S Boyd Eaton III and Robert Gotshall write that Homo erectus, who began hunting under the hot African sun 1.7 million years ago, must have evolved ‘cardiovascular, metabolic and thñermoregulatory systems capable of sustaining high-level aerobic exertion’.


In modern hunter-gatherers, erectus has not only genetic but cultural descendants. A dietary study of 229 such societies by Cordain and others revealed that 73 percent obtained over half their calories from animals.


This suggests that the hunter’s high-energy lifestyle has remained a human constant.


Tribal males who still hunt for a living have daily ranges of 15 kilometres (the !Kung Bushmen) or even 19 kilometres (the Ache in Paraguay). Hunter-gatherer men, say Cordain and colleagues, ‘commonly hunt from one to four nonconsecutive days a week...and women routinely gather every two or three days.’


Not for nothing is this lifestyle known as the ‘palaeolithic rhythm’: something very like it was probably lived out by our ancestors who emerged from the last Ice Age of the Paleolithic, more than 10,000 years ago.


The vast majority of the human genome is still adapted to that ancient, high-exertion, often carbohydrate-scarce environment.


‘Paleo-scientists’ point out that illness and mortality increased significantly wherever the Agricultural Revolution appeared in the pre-historic world.


Moreover, the modern illnesses of hypertension, NIDDM and coronary artery disease are rare to non-existent in recent hunter-gatherer societies. All are associated with low exercise levels, and also hyperinsulinaemia. ‘Syndrome X’ - as these three illnesses are collectively known - pose what some see as the number one health risk to Westernised populations.


If these are the problems, Art De Vany reckons he has some solutions.


A former professional athlete, De Vany is Professor of Economics and Mathematical Behavioral Sciences at the University of California. He’s combined his interest in Chaos Theory and complex systems with ‘the Darwinian approach that has been so successful in the new fields of evolutionary psychology and medicine’ - and applied it all to physical fitness.


De Vany views the human body as ‘non-linear and dynamic’. To mimic its evolutionary patterning, he believes, exercise should mix order and chaos: structure and novelty.


By translating the ‘evolutionary’ principles of quantity, variety, randomness and play into exercise for people in today’s world, De Vany is developing a science he calls ‘Evolutionary Fitness’. In his book on the cubject (which he hopes to finish this Summer) he writes:


‘The primary objectives for any exercise and diet program must be to counter hyperinsulinaemia (chronically elevated insulin) and hypoexertion (wasting the body's lean mass through inactivity).’


Not that the two are so easily separable. De Vany says the body ‘reads’ its food intake in the context of its activity patterns. For instance, he says, high energy-flux brings our appetite control mechanisms into the ‘ancestral’ range, where they are evolved to operate.


But he feels most modern exercise systems are not hitting the mark:


‘Chronic aerobic exercise overtrains the heart, reducing the chaotic variation in heart rate which is essential to health.’ He believes most weight training is too routine, too time-consuming, and does not train the right muscles for that ultimately attractive - and adaptive - quality of symmetry.


‘Symmetry...is a reliable evolutionary clue to health... Tumors and pathologies produce gross asymmetries, and our love of symmetry reflects the reproductive success of our ancestors who were sensitive to these clues.


‘I strive for the X-look - a symmetrical balance of mass in the shoulder girdle, upper (not lower) chest and back, the calves and lower quads.’


De Vany's advice to the modern exercise freak is to cut duration and frequency - and increase intensity.


‘Our muscle fibre composition reveals that we are adapted to extreme intensity of effort. And the energy sources of these fibres (the muscle phosphates quickly used up in intense exertion) show that the highly intense activities through which our ancestors “earned a living” were of short duration.’


De Vany combines ‘brief but intense gym workouts with a wide variety of activities that mix intensity and duration randomly’.


Given our well-defined sexual dimorphism - and that men traditionally hunt, and women gather - why doesn’t he recommend significantly different regimes for each gender?


'Women are opportunistic hunters who go after small game when they come across it. They also climb trees to capture honey and snare birds. Have you ever seen how much work it is to dig out a deep tuber?


‘[So] I typically recommend a mix of high intensity and endurance (sprint/walks and hiking) activities for both men and women, with the balance more toward endurance for women. But today's women are so weak [relative to their female ancestors], they benefit enormously from strength work. And, they get and stay leaner by building some muscle mass - and increase their bone density.’


De Vany gives his own workout a ‘chaotic’ character with ascending weights and descending repetitions - which exercises his fast-twitch muscle fibres.


The intermediate and slow-twitch zones (with brief excursions into fast-twitch) are worked by rollerblading, bicycling, walking, sprinting, tennis, basketball, power walking, hitting softballs, and trekking with a grandson on his shoulders.


Professor De Vany is 62. Though he remains a little skeptical of such assessments, three years ago he was rated by a fitness institute as having a ‘biological age’ of 32. The rating was based on such factors as blood profile and pressure, strength and flexibility.


‘Paleo-exercise’ is in its scientific infancy, so its practitioners avoid being overly dogmatic. De Vany acknowledges that humans are not all adapted to one terrain or climate - indeed  ‘Homo sapiens lives in a wider range of climates than any other creature but the cockroach.’


Cordain recognises that certain genetic changes (for example adult lactase persistence) have appeared in some human populations since the Palaeolithic. He also stresses that the genes of different populations will often endow different performances: for example East Africans seem to be better endurance runners, West Africans better sprinters.


But human genetic similarity greatly overshadows the variations. And genetic change since the Palaeolithic is much outweighed by the continuities. Because of this, the emerging science of evolutionary exercise may transform the way we think about fitness in the coming decades.


Further reading:


Physical Activity, Energy Expenditure and Fitness: An Evolutionary Perspective. L Cordain, RW Gotshall, S Boyd Eaton, S Boyd Eaton III. Int. J Sports Med. 19 (1998) 328-325.


Evolutionary Aspects of Exercise. L Cordain, R Gotshall, S Boyd Eaton. World Rev Nutr Diet. Basel, Karger. 1997, vol 81, pp 49-60.



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