Stand on a ridge in the Appalachians and rain falling on your left boot ends up in the Mississippi, bound for the Gulf of Mexico. Rain on your right boot ends up in the Atlantic. Nothing marks the line. What is a watershed is exactly that: the land area that drains to a single common … Read more
A teaspoon of healthy soil contains more microorganisms than there are people on Earth. That is the first clue that soil is not simply dirt. What is soil, properly defined, is a porous mixture of mineral particles, organic matter, water, air, and living organisms, structured into layers and capable of supporting plant roots. Soil Is … Read more
A cow eats roughly 20 pounds of plant matter to put on one pound of body weight, and a person eating that cow gets back about a tenth of the energy the cow stored. By the fourth or fifth transfer there is so little energy left that supporting another level is not viable — which … Read more
Antibiotic-resistant bacteria did not appear because bacteria needed to resist antibiotics. Resistant variants already existed by chance; the drug killed everything else and left them to multiply. That is the whole mechanism in one example. So what is natural selection, precisely? It is a filter, not a force — and once you see it that … Read more