June 14, 2010

  “I’m going to study microbiology.” Ko Ye-eun suddenly decided to change her major. Her classmates were puzzled by her abrupt decision. “I thought being a food researcher was a good career, but the competition for food research positions in Seoul is intense. So, I’ve decided to focus on microbial research.” Professor Gamamusa nodded at her decision. “The origin of microbiology mainly comes from animals. Today’s TMI will be about animals and domestication.” The professor wrote “Animals and Domestication” on the chalkboard. “First, let’s look at how animals were domesticated. Many animals are domesticated today. There are birds like chickens, turkeys, and ostriches; small mammals or rodents like rabbits, hamsters, and dogs; and even reptiles like lizards. However, the animals that truly serve human needs—producing meat, wool, eggs, milk, etc.—number only 19 species. Among them, microbes similar to those living in humans come from large mammals.”

  The professor wrote “Large Mammals” on the board. He listed them comprehensively. “Globally, 148 species of large mammals have been identified, but only 16 have been domesticated. These include horses, donkeys, zebu cattle, Bali cattle, yaks, water buffalo, gayals, sheep, goats, reindeer, Bactrian camels, dromedary camels, pigs, llamas, and alpacas. Of these, 14 originated in Eurasia, and the remaining two, llamas and alpacas, come from South America’s Andes Mountains. Domestication is difficult because animals must meet strict conditions. Six factors hinder domestication: two physical and four behavioral. The physical issues are ‘diet’ and ‘growth rate.’ Herbivores and omnivores can eat a variety, but carnivores require other animals, making feed efficiency poor. Thus, carnivores cannot be domesticated. Growth rate refers to how fast an animal matures. Gorillas or elephants take decades to reach adulthood for slaughter, so while raising them is easy, using them for resources is another matter. The four behavioral issues are ‘shy temperament,’ ‘aggressive temperament,’ ‘fearful temperament,’ and ‘lack of hierarchy.’”

  The professor took a sip of water and continued. “For domestication, animals must reproduce in captivity anytime, anywhere. However, animals like vicu?as and cheetahs don’t breed in confinement. Vicu?as are one example, but cheetahs require males to chase females for days to court, making captive breeding impossible. Aggressive temperaments harm humans. For instance, the Ainu raised bear cubs to eat young, as grown bears would attack them. Fearful temperaments lead animals to escape enclosures, sometimes dying in the process. Gazelles, for example, may run themselves to death, so they aren’t domesticated recklessly. Lastly, humans don’t domesticate animals without hierarchies. Horses follow adults from a young age and thus obey humans, but most animals prefer to divide territories and fight, making hierarchy essential for domestication.”

  The professor circled the Americas and Australia. “Of the 148 large mammals, only 24 exist in the Americas, and just one, the kangaroo, in Australia. This is because farmers, crossing wastelands (Siberia, Indonesia’s rainforests, and Australian deserts), became hunter-gatherers with advanced hunting skills, decimating animals. Africa has 51 large mammals, not far from Eurasia’s 72. Yet, no animals were domesticated in Africa because, as they slowly adapted to humans, behavioral flaws became prominent. Humans hunted animals, leaving only those with fearful or aggressive temperaments. Hierarchical animals were slaughtered in groups, and those breeding freely were hunted mid-reproduction. The dodo, never having seen humans, followed them to extinction, and modern penguins’ trust in humans suggests behavioral flaws stem from human interaction.”

  Stolen from its rightful author, this tale is not meant to be on Amazon; report any sightings.

  The professor wrote “Crops and Domestication” on the board. “As you know, humans need carbohydrates. After securing carbohydrates, they need protein. Thus, humans have long practiced ‘gathering’ and ‘hunting.’ After agriculture settled, they began raising livestock.” He wrote “Farmers and Pastoralists” on the board. “As I’ve said before, farmers and pastoralists differ. Farmers live off agriculture, while pastoralists live off herding. But both raise animals. The difference is that farmers keep livestock in one place, while pastoralists move them. What we must understand is that raising livestock began after agriculture. Pastoralists raised sheep or goats for milk and wool but traded with farmers or plundered on horseback to survive. This is because grains are essential for pastoralists.”

  The professor drew a world map, adding animals. “Humans began raising animals where agriculture started. In the Fertile Crescent, five large mammal species were domesticated, spreading across Eurasia. As agriculture spread to other Eurasian regions, domestication followed. With the Fertile Crescent’s crops, Tibet’s yaks, Siberia’s reindeer, Central Asia’s horses, and Bactrian and dromedary camels emerged. As rice spread, water buffalo, banteng, and pigs appeared. Since livestock couldn’t exist before agriculture, animals spread or emerged where crops did. In Africa, the Americas, and Australia, which had no livestock, horses, goats, sheep, pigs, and cattle from the Fertile Crescent and Europe were raised, finally achieving domestication.”

  The professor wrote “Animal and Bacterial Evolution” on the board. “Initially, animals carried microbes different from humans. But as humans domesticated animals, they began experiencing the transfer of livestock microbes.” He began explaining how livestock bacteria infected humans. “At first, livestock bacteria couldn’t adapt to human bodies because they were too different. Over time, some bacteria coincidentally adapted to humans.”

  He drew a cow on the board. “Cowpox, found in cattle, resembles smallpox, which spreads among humans. They may share a distant ancestor. Zoonotic diseases transmissible between animals and humans were quite common. The Black Death spread between humans and rats. Eventually, bacteria adaptable to humans began spreading to other humans, becoming fully adapted.” He drew the final stage of bacterial transmission. “A tiny fraction of these bacteria began spreading solely among humans, called pandemics. Smallpox is a prime example. Ironically, since smallpox only infects humans and not animals, it became the first bacterium eradicated by humanity.”

  The professor connected Asia, Europe, and the Americas and Australia. “Since 99.9% of human genes are identical, diseases spread easily. Unfortunately, human populations living far apart struggle to adapt to each other’s bacteria. The Black Death, starting in China’s Yunnan Province, spread to India and Europe, killing countless people. When diseases crossed from Europe to the Americas and Australia, the impact was devastating.” He erased the board. “Thus, animal diseases are a gradual tragedy born from human domestication.”