thesis in 1921 on the social structures of birds, he called this the pecking order. When Schjelderup-Ebbe became a zoology student at the University of Oslo and wrote his Ph.D.
And so it went down the line, with each hen pecking the birds ranked below her and in turn being pecked by those above her. The second-ranking bird, on the other hand, was able to peck any subordinate but dared not try to assert herself against the dominant bird. And this was not based solely on size: The older, savier hens were often able to dominate even bigger, naive birds. The dominant hen at the top got first choice at all the food and the best roosting spot, and if any other bird tried to infringe on those prerogatives, she would quickly peck the usurper into submission. Through years of recorded data, he realized that there was a hierarchy within the flock. Then, peace would reign once again.īut it wasn’t until young Schjelderup-Ebbe began his years of observations, however, that anyone finally began to get a clear picture of how this flock order was established and maintained. Farmers knew that if anything happened to disrupt this order-introducing a new bird to the flock or removing one of the dominant birds-there would be a brief period of discord as birds fought with each other to re-establish dominance. Then, the more submissive birds got their chance, and finally, the least dominant got whatever was left. At feeding time, the dominant birds in the flock would eat first, picking out the best morsels. Schjelderup-Ebbe had a keen interest in nature and animals, and as he began to carefully watch the behavior of the chickens, he wrote down detailed descriptions and observations in a daily journal.įor more than 4,000 years, since the red jungle-fowl was first domesticated in Southern Asia, farmers had noticed that a flock of hens was a very orderly group. In 1904, 10-year old Thorleif Schjelderup-Ebbe was placed in charge of caring for his family’s flock of chickens in Kristiania, Norway (which is now the city of Oslo). Through the careful observation of a backyard chicken flock, one of the most important principles of social biology was uncovered-one that applies equally well to humans. More than just a food source, though, the humble chicken has taught us some important lessons. The only other terrestrial vertebrate that might rival the chicken in sheer numbers is the Norway rat. Statistically, every human on the planet eats the equivalent of 27 individual chickens every year. Apparently, “tasting good to people so they’ll protect you” is a pretty effective evolutionary strategy-aside from that whole “they eat you” thing. There are an estimated 20 billion chickens alive right now-almost three times as many as there are humans. In evolutionary terms, the domestic chicken is one of the most successful species on Earth.
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