Guns, Germs, and Steel: Part II: Chapters 4-7

My fellow farmhands were, for the most part, tough whites whose normal speech featured strings of curses, and who spent their weekdays working so that they could devote their weekends to squandering their week’s wages in the local saloon.

But, as we’ll see, food production was indirectly a prerequisite for the development of guns, germs, and steel.

Among wild plant and animal species, only a small minority are edible to humans or worth hunting or gathering.

Most species are useless to us as food, for one or more of the following reasons: they are indigestible (like bark), poisonous (monarch butterflies and death-cap mushrooms), low in nutritional value (jellyfish), tedious to prepare (very small nuts), difficult to gather (larvae of most insects), or dangerous to hunt (rhinoceroses).

Several domestic animals yielded animal fibers—especially wool from sheep, goats, llamas, and alpacas, and silk from silkworms.

Only with the introduction of trucks and tanks in World War I did horses finally become supplanted as the main assault vehicle and means of fast transport in war.

Infectious diseases like smallpox, measles, and flu arose as specialized germs of humans, derived by mutations of very similar ancestral germs that had infected animals (Chapter 11).

It should come as no surprise that food production never arose in large areas of the globe, for ecological reasons that still make it difficult or impossible there today.

This method is based on the slow decay of radioactive carbon 14, a very minor component of carbon, the ubiquitous building block of life, into the nonradioactive isotope nitrogen 14.

Plants take up atmospheric carbon, which has a known and approximately constant ratio of carbon 14 to the prevalent isotope carbon 12 (a ratio of about one to a million).

Increasingly today, archaeologists are circumventing this problem by a new technique termed accelerator mass spectrometry, which permits radiocarbon dating of tiny samples and thus lets one directly date a single small seed, small bone, or other food residue.

In this way, measured radiocarbon dates can be "calibrated" to take account of fluctuations in the atmospheric carbon ratio.

The site where it appeared earliest may be its site of initial domestication—especially if the wild ancestor also occurred there, and if the dates of first appearance at other sites become progressively later with increasing distance from the putative site of initial domestication, suggesting spread to those other sites.

In reality, only for today’s affluent First World citizens, who don’t actually do the work of raising food themselves, does food production (by remote agribusinesses) mean less physical work, more comfort, freedom from starvation, and a longer expected lifetime.

Still other hunter-gatherers in contact with farmers did eventually become farmers, but only after what may seem to us like an inordinately long delay.

Before we can answer these questions, we must dispel some misconceptions about the origins of food production and then reformulate the question.

Another supposed dichotomy that becomes blurred in reality is a distinction between food producers as active managers of their land and hunter-gatherers as mere collectors of the land’s wild produce.

For example, New Guinea peoples who never domesticated sago palms or mountain pandanus nevertheless increase production of these wild edible plants by clearing away encroaching competing trees, keeping channels in sago swamps clear, and promoting growth of new sago shoots by cutting down mature sago trees.

Their digging to extract the tuber loosened and aerated the soil and fostered regrowth.

The underlying reason why this transition was piecemeal is that food production systems evolved as a result of the accumulation of many separate decisions about allocating time and effort.

Foraging humans, like foraging animals, have only finite time and energy, which they can spend in various ways.

One suggested function of the first gardens of nearly 11,000 years ago was to provide a reliable reserve larder as insurance in case wild food supplies failed.

Conversely, men hunters tend to guide themselves by considerations of prestige: for example, they might rather go giraffe hunting every day, bag a giraffe once a month, and thereby gain the status of great hunter, than bring home twice a giraffe’s weight of food in a month by humbling themselves and reliably gathering nuts every day.

People are also guided by seemingly arbitrary cultural preferences, such as considering fish either delicacies or taboo.

Nevertheless, over the last 10,000 years, the predominant result has been a shift from hunting-gathering to food production.

This is a long-debated chicken-or-egg problem: did a rise in human population density force people to turn to food production, or did food production permit a rise in human population density?

That is, the adoption of food production exemplifies what is termed an autocatalytic process—one that catalyzes itself in a positive feedback cycle, going faster and faster once it has started.

Within the present decade, even they will have been seduced by the attractions of civilization, settled down under pressure from bureaucrats or missionaries, or succumbed to germs.

To achieve that goal, they plant many different seeds or roots, select the best progeny and plant their seeds, apply knowledge of genetics to develop good varieties that breed true, and perhaps even use the latest techniques of genetic engineering to transfer specific useful genes.

To achieve that goal, they plant many different seeds or roots, select the best progeny and plant their seeds, apply knowledge of genetics to develop good varieties that breed true, and perhaps even use the latest techniques of genetic engineering to transfer specific useful genes.

How, then, did early farmers domesticate plants unwittingly?

It may come as a surprise to learn that plant seeds can resist digestion by your gut and nonetheless germinate out of your feces.

Many wild seeds evolved to be bitter, bad-tasting, or actually poisonous, in order to deter animals from eating them.

The explanation is that occasional individual almond trees have a mutation in a single gene that prevents them from synthesizing the bitter-tasting amygdalin.

Were that to happen, the seedlings might all be killed by a single drought or frost, leaving no seeds to propagate the species.

Like the changes in seed dispersal, these changes in germination inhibition characterize wheat, barley, peas, and many other crops compared with their wild ancestors.

By all these means, ancient farmers, who didn’t understand plant reproductive biology, still ended up with useful crops that bred true and were worth replanting, instead of initially promising mutants whose worthless progeny were consigned to oblivion.

By all these means, ancient farmers, who didn’t understand plant reproductive biology, still ended up with useful crops that bred true and were worth replanting, instead of initially promising mutants whose worthless progeny were consigned to oblivion.

Big seeds that can take advantage of the good conditions to grow quickly will now be favored over small seeds that were previously favored on dry, unfertilized hillsides where seeds were sparser and competition less intense.

Instead, those trees must be grown by the difficult technique of grafting, developed in China long after the beginnings of agriculture.