Carnivores cannot survive on cellulose. They may on occasion eat grass, but they use it medicinally, usually as a purgative to clear their digestive tracts of parasites. Ruminants, on the other hand, have evolved to eat grass. They have a rumen (hence, ruminant), the first in a series of multiple stomachs that acts as a fermentative vat. What’s actually happening inside a cow or a zebra is that bacteria eat the grass, and the animals eat the bacteria.
Lions and hyenas and humans don’t have a ruminant’s digestive system. Literally from our teeth to our rectums we are designed for meat. We have no mechanism to digest cellulose.
So on the carnivore side of the fence, starvation will take every animal. Some will last longer than others, and those some will end their days as cannibals. The scavengers will have a Fat Tuesday party, but when the bones are picked clean, they’ll starve as well. The graveyard won’t end there. Without grazers to eat the grass, the land will eventually turn to desert.
Why? Because without grazers to literally level the playing field, the perennial plants mature, and shade out the basal growth point at the plant’s base. In a brittle environment like the Serengeti, decay is mostly physical (weathering) and chemical (oxidative), not bacterial and biological as in a moist environment. In fact, the ruminants take over most of the biological functions of soil by digesting the cellulose and returning the nutrients, once again available, in the form of urine and feces.
But without ruminants, the plant matter will pile up, reducing growth, and begin killing the plants. The bare earth is now exposed to wind, sun, and rain, the minerals leech away, and the soil structure is destroyed. In our attempt to save animals, we’ve killed everything.
On the ruminant side of the fence, the wildebeests and friends will reproduce as effectively as ever. But without the check of predators, there will quickly be more grazers than grass. The animals will outstrip their food source, eat the plants down to the ground, and then starve to death, leaving behind a seriously degraded landscape.
The lesson here is obvious, though it is profound enough to inspire a religion: we need to be eaten as much as we need to eat. The grazers need their daily cellulose, but the grass also needs the animals. It needs the manure, with its nitrogen, minerals, and bacteria; it needs the mechanical check of grazing activity; and it needs the resources stored in animal bodies and freed up by degraders when animals die.
The grass and the grazers need each other as much as predators and prey. These are not one-way relationships, not arrangements of dominance and subordination. We aren’t exploiting each other by eating. We are only taking turns.
That was my last visit to the vegan message boards. I realized then that people so deeply ignorant of the nature of life, with its mineral cycle and carbon trade, its balance points around an ancient circle of producers, consumers, and degraders, weren’t going to be able to guide me or, indeed, make any useful decisions about sustainable human culture. By turning from adult knowledge, the knowledge that death is embedded in every creature’s sustenance, from bacteria to grizzly bears, they would never be able to feed the emotional and spiritual hunger that ached in me from accepting that knowledge. Maybe in the end this book is an attempt to soothe that ache myself.