review by Jack Kittredge
Fred Provenza is a lifelong westerner. Born and educated in Colorado, he was a university professor for 35 years in Utah before retiring to Colorado and Montana. He brings an amazing observational acumen, as well as a thorough knowledge of plants, herbivores, and their grazing habits on both wild and domestic fodder, to this book.
His basic insight about the existence of ‘nutritional wisdom’ is something most of us at some level already know. He perhaps states it best early in the book, discussing his experiences as a young college sophomore, collecting and identifying hundreds of plants along a Colorado stream and meadow.
“Plants are the glue that links soil with herbivores, omnivores, and carnivores. Land is a cascade of energy, flowing from the sun through plants into soil and animals below and aboveground. A species is a strand in a web, linked with millions of other strands.
“Plants are also the founders of the feast – all creatures ultimately eat plants. So no discourse on nutritional wisdom can be complete without considering not only how animals eat but also how plants procure the sustenance they need. And beyond that, we must also consider: How do plants manage to provide for the needs of animals and also sustain themselves?”
The most important way that plants have managed to do both through the last almost half billion years of life on earth has been to evolve themselves as organic chemists. A typical example, one of the earliest plants to appear in a Colorado spring, soon after snowmelt, is the pasque flower Pulsatilla ludoviciana. Fresh pasque parts are toxic if eaten or even touched to the skin. Dried, however, the plant is used as medicine in Europe and North America for menstrual pain, skin diseases, asthma and eye infections. It is also used as a diuretic and expectorant to clear airways. Homeopaths used it for measles, toothache, earache and indigestion. It contains compounds found to be antibacterial, antimalarial, antifungal, and to have cytotoxic effects as well.
This is just an example. Provenza details how plants, ‘dumb’ organisms as they are, create not only primary compounds containing the energy, proteins, vitamins and minerals they need to grow and reproduce, but also create secondary compounds – such things as phenolics, terpenes, alkaloids and many, many more metabolites – which inhibit competing plants while increasing their own strength through drought tolerance, pest resistance, larger tiller numbers and biomass, greater seed mass and quantity, and faster germination rates.
Some of these compounds, like lignins and tannins, help build soil organic matter and humus. Antioxidants protect plants from free radicals produced during photosynthesis; flavors, aromas and colors attract pollinators and fruit eaters. Other metabolites boost recovery from injury and enhance regrowth. Secondary compounds also serve to regulate loss of plant tissue to predators – bacteria, fungi, insects, birds and mammals – by limiting how much each can eat before experiencing ill effects. Limiting intake results in encouraging diversity among grazed species and locations.
Just as plants, as stationary organisms, evolved their thousands of secondary metabolites to attack and defend, entice and repel, heal and sicken, the herbivores eating them equally evolved responses to help them sort through the hundreds of unique grasses, forbs, shrubs and trees in any meadow or glen. Animal nutritional needs change seasonally, with age and condition, when pregnant or infested with parasites, when ill, hot or cold. To meet their changing needs, herbivores must sort through a bewildering array of biochemically active plants when making grazing decisions.
Certainly grazers need to make the right primary choices, fluctuating daily as they do, for energy, protein, vitamins and minerals to survive. But these choices necessarily include the secondary compounds in every mouthful – some parasiticides, some analgesics, some stimulants, some sedatives, some bitter, some sweet – often with several metabolites combining to create uniquely new effects.
Do herbivores wander aimlessly through these choices? Certainly not, Provenza shows. Evolution is too tough a master. The continual contest between secondary metabolites and grazer intelligence quickly abandons those who do not keep up. The many animal behavior studies Provenza discusses are convincing evidence that animals have evolved very sensitive preferences and feedback loops which guide every choice of mouthful.
Some of his most fascinating stories demonstrate this ‘nutritional wisdom’. For starters, far more animal nerves ascend from the gut to the brain than the other way. Is the body voting what sorts of information are the most important? Many studies in animal behavior show the clear preferences of grazers for certain plants at certain times, with those preferences changing based on what has just been eaten. These choices of animals are not inherited but learned, as many cleverly designed studies show. Sheep or goats newly introduced to an area will sample the fodder naively until post-digestive body feedback kicks in to inform them about what they have just eaten. Kids grazing with their mothers will quickly pick up the maternal preference patterns and repeat them, whereas those separated from such instruction will struggle to find what satisfies and what disturbs them.
In some of the more unusual of Fred’s stories he cites the well-documented cases of food preferences associated with organs or even cells. It is not uncommon in transplant cases, he shows, for the recipient of a new organ to have strong cravings for food items that person has never preferred and in many cases had disliked. When investigated, it turns out the previous owner of the organ expressed exactly those strong food preferences!
Provenza also discredits the widely held practice of creating animal rations based on an ‘average’ livestock animal. The range of variation among individuals in a herd, he says, is so large that any one nutrient can be needed by one animal at a rate five times as high as another similar animal. Since animals will eat until their nutritional needs are met, if given ‘total mixed rations’ (TMR) some will overeat nutrients for which their need is small in order to satisfy their need for others. Each animal in a herd given rations on a ‘free-choice’ basis, however, will consume what it needs and no more, averaging a 24% savings in feed costs over a herd given TMR.
Does this ‘nutritional wisdom’ carry through to omnivores, carnivores, and humans, you ask? Without a doubt, Fred feels. Plant secondary metabolites are passed along up the food chain and their presence or absence is well documented in human food cravings such as for vitamin C among sailors with scurvy or iron for women suffering from anemia or vitamin B12 for vegetarians. (Interestingly, Provenza is opposed to most food supplements and fortification, feeling that vitamins and minerals should come through the food chain in a natural form, produced by living organisms.)
Fred is well aware of the forces that militate against humans exercising their innate nutritional wisdom. Human food quality has fallen significantly in the last generation or two, because of choices by plant breeders to select for crop size, yield and appearance as opposed to healthful qualities such as secondary metabolites, the use of artificial compared to natural forms of nitrogen, phosphorus and potassium fertility the marketing requirement that crops be picked green and shipped to market rather than fully maturing before harvest, and elevated atmospheric carbon dioxide that has resulted in lower crop protein levels
These losses in crop quality (Provenza has a simple definition of quality in crops — it is equivalent to phytochemical richness) combined with the efforts of the food industry to refine, sweeten and otherwise alter foods to confuse our innate sense of taste have badly damaged human health by disconnecting our ability to discern healthy foods. This, of course, is a fundamental problem that must be addressed by returning to eating whole foods raised in a more natural state.
It is hard to give justice to this book. I took many pages of notes, so many things were interesting that I wanted to return to again. His story is told intermixed with tales of his life experiences in the mountains and high plains of the west so you get a good sense of the man, the living landscape which shaped him, his love for nature, his inexhaustible curiosity about life, and his Zen-like ability to observe and learn from what is around him.
In his eighties now, Fred writes the last chapters as if he wanted to leave more than a scientific testament. Exceedingly well read, he reaches into various religions and cultures for wisdom, citing philosophers and psychologists and physicists and seers as needed.
This is a hopeful book, at bottom. You cannot read it without a deep sense of the wisdom of nature and how mankind’s efforts to thwart and control it must seem to be laughably childish when looked at clearly. Provenza is well acquainted with the Earth’s great extinctions, recognizes that 99.99% of all species that have existed are no more, and yet has a convincing faith in the vast power of nature and life to continue to manifest their beauty and mystery.