The Chicken Egg as an Embryo, The Avian Flu and other reasons why the chicken is significant to the development of a human culture
The chicken egg played the key role in the development of the field of embryology. Ancient Egypt aound 1400 B.C. is the starting point for informed embryonic curiosity, which is of intriguing relation to the history of humanity; even at the darkest of times babies were born and it would be difficult not to engage in some slight speculation on the growth and development of an embryo. Early Egyptians are credited with the discovery that chick eggs could be artificially incubated in ovens after being removed from their nests. Thus, humans could control their observations of chick embryos during different periods of development within an incubated egg. A historically reoccurring consideration we’re still debating today began its train of thought in Egypt. This consideration is the problem of deciding at what point life begins in an embryo.
A hymn from the 18th dynasty in Egypt, Needham notes it having an interesting resemblance to the one hundred and fourth psalm, goes like this:
(Needham, 1959, pp. 1 – 8)
Aristotle (384 BC–322 BC) studied the embryo growth of different organisms by opening up bird eggs at different stages of development, most of which were chicken eggs for their availability and convenience. His recognized dedication to observational science of bird eggs was responsible for the continued growth of embryology (Needham, 1959, pp. 13 – 55).
The scientific study of embryology for hundreds of years was seemingly dead until the early 1200s. Albertus Magnus is known for the scientific revival of embryology. Like Aristotle in scientific observation and attention to detail, embryology was often discussed in Albert’s books. Albert studied and wrote extensively about chick and fish embryo development, helping to bring embryology back into the jurisdiction of scientific observation (Needham, 1959, pp. 67 – 90).
In the 17th century as early as 1652, William Harvey dissected and examined deer and chicken embryos using low powered microscope lenses. Harvey is known for his discoveries about blood and introducing the term “Epigenesis” or the morphogenesis and development of an organism. Harvey also rejected the idea of spontaneous generation in communicating how even the lowest organisms arise from eggs (Needham, 1959, pp. 96 – 140).
The domesticated chicken egg was the perfect, controllable embryo to study and make possible numerous intuitive observations and later dynamic experiments on the egg as a way of understanding human development and our relationship to other animals and, according to Needham, it influenced the “coming 20 centuries of scientific research (Needham, 1959, p. 54).”
Whereas embryology studies the normal development of an organism, Teratology seeks to study abnormal development of an embryo. Thus, teratology attempts to infuse irregular development in chicken egg embryos so the abnormalities can be studied. Camille Dareste (1959) started engaging in experiments in the late 1800s and his results emerged with the perspective that evolution should be known as “an expanding horizon of variability, an open ended exploration of the possibilities of life (p.85).” Two years later Sherwood Anderson in his short story, “The Triumph of the Egg” wrote a tale in which, “a hen’s egg serves as an embodiment of both the sublime potential of life and its limitations offers a first-person narrative of a young boy’s struggle with identity, sexuality, and the passage to adulthood (p.87).” At the end of the story it is concluded that the wondrous developmental possibilities explored by 19th century teratology are dispelled by pragmatic realism of modern commercial society.
Speaking of embryology…
For a month over summer before entering my 11th grade year I attended “Governor School for Agriculture.”
Blakely, my roommate, analyzing the development of chicken embryos.
Far right: a bovine (cow) embryo. I never thought an opportunity to share it would come. The first two photos: we have just squeezed developing eggs out of a hen’s reproductive tract. Back then I did understand science and genetics but not the influences of our culture. It was a cold morning and I remember my hands were cold coming to class. They killed the hens as we arrived so their bodies made my hands nice and, toasty. Biology’s frozen frogs were much less actual. I did learn a lot about the inside of a chicken and the reproductive system (seriously, the frog was lame) but it was a strange feeling to walk in a barn, put on your gloves, and dissect a very-real dead chicken in the name of education.
The experience amounted to a new appreciation for where my eggs come from – literally and biologically. It marks a way of objective scientific learning dominant in our society today and fueling genetic and biological discovery.
The new Avian Flu H7N9
Electron micrograph of Influenza A H7N9 from the CDC.
The CDC explains, Avian influenza is an infection caused by avian (bird) influenza (flu) A viruses. These influenza A viruses occur naturally among birds. Wild birds worldwide get flu A infections in their intestines, but usually do not get sick from flu infections. However, avian influenza is very contagious among birds and can make certain domesticated bird species, including chickens, ducks, and turkeys, very sick and kill them.
Although this is “natural” it may point to interesting understandings of our new and modern relationships with our domesticated chicken. In our process of domestication and genetic improvement of chickens we made them more suitable to disease and perfect vectors for spreading said disease to their human companions (Barbato, 1999, p. 445).
Most human contractions of the avian flu are a result of either handling dead infected birds or from contact with infected fluids, says the CDC. Most wild birds have a mild form of some bird flu strain. Once domesticated birds such as chickens or turkeys are infected, it becomes much more deadly because the birds are often within close contact of one another. There is currently a large threat of this in Asia with infected poultry due to low hygiene conditions and close quarters, says the CDC.
A new type of flu has made the jump from birds to people in China – it is known as H7N9, explains this BBC article from May 3, 2013.
The World Health Organization says it as an “unusually dangerous virus”, but it is still too soon to say whether it will pose a global threat to human health. There is no doubt H7N9 is a dangerous infection and scientists consider it a “serious threat” and a “cause for concern”. Since the first case a month ago, was detected, more than 100 people have been infected. The article notes this is an unusually high rate for a new infection. A 20% of the patients have died, a 20% have recovered and the rest remain critically ill.
Viruses jump species quite regularly. The last major bird flu, H5N1, made the jump to people in 1997 and has since killed more than 300 people. But H5N1 also remains unable to spread between humans. The most infamous pandemic – the 1918 Spanish flu, which killed perhaps 40 million people – is thought to have come from birds. The fear is that eventually a new virus will sweep the world in a similar fashion. It is a numbers game. Eventually it will happen. Some would argue we are overdue.
The good news is that it’s not yet time for worry, the BBC article explained. It is a virus that can spread only from a bird to a person, but this can change as the virus mutates. It has been detected in chickens, ducks and pigeons at markets in China. Unless you have close contact with birds in the regions affected, the risks are low.
The Guardian on May 1, 2013 explained, there are worries that it could mutate into a form that could be passed from one person to another. Five mutations are known to be necessary for that to happen – H7N9 already has two of them. If that occurred, it could spread worldwide with lethal effect. “The WHO considers this a serious threat. We’re on an alert and we’re developing diagnostics and vaccines specifically against the virus.”
The first comprehensive genetic analysis of the virus is published in the Lancet medical journal. The findings of the avian influenza H7N9 virus were that “it originated from multiple reassortment events. The HA gene might have originated from avian influenza viruses of duck origin, and the NA gene might have transferred from migratory birds infected with avian influenza viruses along the east Asian flyway. Detailed analyses also showed that ducks and chickens probably acted as the intermediate hosts leading to the emergence of this virulent H7N9 virus. Unknown intermediate hosts involved might be implicated, extensive global surveillance is needed, and domestic-poultry-to-person transmission should be closely watched,” said the authors.
One of the biggest problems is that the virus does not cause illness in chickens, so it is impossible to know which are infected and which are not. In the past, China has slaughtered flocks to eradicate bird flu viruses, but H7N9 is now known to be present in chickens in all 31 provinces of China.
Channel News Asia published an article, Immunologists expressed concern Friday about the “dangerous” work of scientists in China who created a hybrid bird flu virus that can spread in the air between guinea pigs, and now lives in a lab freezer.
The team from the Chinese Academy of Agricultural Sciences and Gansu Agricultural University wrote in the journal Science they had created a new virus by mixing genes from H5N1 “bird flu” and H1N1 “swine flu”. Flu hybrids can arise in nature when two virus strains infect the same cell and exchange genes in a process known as reassortment, but there is no evidence that H1N1 and H5N1 have done so yet.
Wain-Hobson and others fear the risk may far outweight the scientific value of the research. “You do not do these things unless there is some call of extreme emergency,” he said. “We are encountering a real and present danger with extremely dubious benefits to the public.” The findings held little value for finding a vaccine or treatment that would take years to develop — probably long after an outbreak, they argue.
Virologist John Oxford from the Queen Mary University of London, however, said the experiment was a valuable wakeup call. It showed that the two viruses, both still infecting people around the world, can swap genes. “Mathematics will tell you that sooner or later a person will get co-infected,” he said — possibly leading to a hybrid virus “that will start spreading”.
What’s going to happen when the first American chicken catches the flu?
So, now what??
The history of the domestic chicken shadows that of humans. The French philosopher Simone Weil understood the autonomy of nature:
The beauty of the world gives us an intimation of its claim to a place in our heart. In the beauty of the world brute necessity becomes an object of love. What is more beautiful than the action of gravity on the fugitive folds of the sea waves, or on the almost eternal folds of the mountains? (128-9)
Weil identifies the thing of love and beauty that which many have tried to subdue: the autonomy of nature, and its mechanisms of necessity. It almost seems natural to want to command nature’s every part. However, perhaps, it is too natural for us to delight in nature’s independence. I have experienced both desires for the chickens owned by my family. Regardless of my desire I cannot radically control them. I can erect fences, tell my chickens “stay” and set a Havahart trap for the fox. Ultimately, however, I cannot master them. They have their own nature
We can, however, enter nature, engage with nature, even change nature. This recognition is important, for it recommends that we exercise caution when we interact with nature. Many environmentalists of good will dedicate their lives to what they understand as protecting nature, that vast, pristine wilderness away from human activity. Yet as long as we maintain a vision that separates humans from nature, we will fail to live peaceably and responsibly as natural creatures with other creatures within nature.
What might this mean for me? Perhaps I can see a bit differently. For example, perhaps I can see a bird and be struck by a reality that exists apart from me and, at the same time, acknowledge the sun and soil and water that we share. Perhaps the next time I am tempted to use pesticides on my flowers or Drano in my sink, I’ll think about the shared home and how other creatures, which otherwise live quite apart from me, are affected by me.
Perhaps I’ll think differently.
Weil notes that “being seems to us less and less concentrated the farther it is removed from us” (159). What if distance could be reduced by thinking about our backyards differently? If we see the land around our home—our house, our apartment building, our dorm—as shared. Could we grasp the significance of the cliche, “it’s a small world,” and begin to respect the reality of other homes and other habitats far away? Our backyards, the view and habitat outside our windows, have much to teach us. My early relationships with chickens have brought my attention to my backyard. And truly paying attention is a skill society needs; chickens can help us develop it.