I was going to put this in the Farming thread months ago, but I detected a hint of ambivalence towards Farmers. People seem less judgemental about livestock so I'm putting it here - it is about cows but it's not Fortean, it is not new science (40 years old) but it was my first Scientific epiphany. It doesn't warrant a new thread unless a Mod with filing OCD wants to move it.
Cows : Evolved to eat grass* but not evolved to digest it. For Goodness Sake.
*(see also coat toggles, dahlias, yew berries, ragwort, psilocybin, plastic-coated tractor wires)
Mid 1960's Primary School : Cows eat grass, cows cannot digest grass. They have special bacteria in their tummy that release a chemical to break down the grass into sugars. Things were more altruistic in the 60's
Mid 1970's Big School: Cows eat grass, cows cannot digest grass. The bacteria still didn't get names but the enzyme they release is called cellulase. This breaks down the cellulose plant cell walls and the released sugars, together with some of the bacteria, passes into the first chamber of the cow's stomach. This didn't seem fair on the bacteria, things were more cynical in the 70's
Mid 1980' Polytechnic, Mature student majoring in Microbiology & Ecology: Cows eat grass, cows cannot digest grass. I was doing a little late-night background reading in Energetics which is the study of energy flow (calories) through an ecosystem. Typically you measure the amount of sunlight falling on a patch of growing grass and determine the conversion rate of solar energy into plant protein. The grass gets eaten (eg by a cow) and the plant protein becomes herbivore protein with energy lost through respiration, evaporation, excretion (cow pats have their own ecosystem) and so on. Herbivore protein ends up as carnivore and scavenger protein in the great Circle of Life.
There was a young Researcher (outstanding in his Field) about 5 years earlier who made two observations, both of which were already well known but he put them together. One concerned the nature of bacteria utilising a food source: bacteria are not altruistic, they do not share or ration food - they eat and eat and eat, multiply, multiply, multiply (or divide, divide, divide) until the food supply is exhausted and the population crashes through starvation. Were it otherwise, Adam and Eve would have been up to their non-existent navals in bacteria after Day One in the Garden. So the amount of "free" sugar released in a cow's stomach is very small.
His second observation was that, relative to the amount of free sugar available, a cow is very large (even when far away). That was the epiphany, the light-bulb moment when I went from bacteria enabling a cow to feed off grass to a cow eating grass to feed the bacteria. These are grown up in the multi-chambered stomach acting as a bio-fermenter and they are what the cow digests and thrives on.