The unassuming chicken! I don't know about you, but I really don't spend much time thinking about chicken outside of its huge presence in the food industry. Can you believe that about 77 billion dollars were spent on poultry in 2022?!
Do you want to know what's strangely impressive about this bird? It has an unusually high number of contributions to the field of science. Our work with chickens has helped us develop vaccines, understand cancer, and many other scientific breakthroughs.
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First off, chances are pretty good that your most recent flu shot was derived from a chicken egg. The manufacturing process has been the same for the past 70 years! The CDC connects private manufacturers with the latest flu strains. Those viruses are injected into eggs and left alone for a few days. A fluid that contains virus antigen is removed from the egg, purified, and eventually sent along to doctors' offices.
Close monitoring of chickens in the early 20th century helped researchers spot a cancer-causing virus called Rous sarcoma virus. Scientists were able to monitor how healthy body cells transformed into cancer and explore ways to stop cancerous growth.
Did you know one of the first animals to have its genes sequenced was a chicken? Looking at chicken genes helped scientists identify a molecule called MHC. This molecule helps the bodies of chickens, and humans, figure out which body cells belong in the body and which do not. Studying the chicken's simple MHC molecule was huge in perfecting organ transplants and disease immunity.
Chickens also have a four-part heart like humans do, so their genes are also being studied to investigate the human "hole in the heart" genetic condition.
Do you know what else is impressive about chickens? Their sheer numbers. There are four chickens in the world for every person on the planet! There are more chickens today than any other land vertebrate. In fact, their bones might be evidence that, geologically, we are in new epoch marked by human influence.
Scientists who have proposed the "Anthropocene" epoch point to the number of chicken bones added to the soil since World War II as a part of a distinct layer in the geologic record. The vast quantity reflects that livestock now make up more than 60% of chordate biomass on Earth!
Here are some questions I'd ask my students if I brought this graph into class:
💡How do the percent of chordate biomass contributed by humans, wild birds, and mammals compare? The percent of biomass contributed by humans is 35.5% and the percent contributed by wild birds and mammals is 5.3%. The mass contributed by humans is almost 7 times greater.
💡Insects have an exoskeleton and are not chordates. Studies show that insect biomass could be up to 10x greater than livestock biomass. How would this graph look different if insect data was included? The pie chart would be dominated by insect biomass, with only a small portion showing livestock and other chordates.
💡Predict how the graph would have looked different 400 years ago. Justify your prediction. Predictions can vary, but students might state that a lower human population would decrease the amount of biomass contributed by humans. There would probably a far smaller amount of biomass coming from livestock. Wild bird and mammal biomass would likely be much larger, due to less hunting and more abundant habitat and resource access.
The next time you see a carton of eggs, just think of how different our world would be without chickens!
- Chris
