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by Sean B. Carroll

Hope many of you can join in a discussion of The Serengeti Rules by Sean B. Carroll.

The subtitle sounds fascinating to me.

Here is that subtitle: The Quest to Discover How Life Works and Why It Matters.

Here are some questions listed on the back cover:

How does life work?

How does nature produce the right numbers of zebras and lions on the African savanna, or fish in the ocean?

How do our bodies produce the right numbers of cells in our organs and bloodstream?

Here are other books by Sean B. Carroll:

Endless Forms Most Beautiful

Brave Genius

Remarkable Creatures. This book was a finalist for the National Book Award for nonfiction.

I love his dedication:

For the animals,
and the people looking out for them.


Let's all try to look out for the animals, including the human ones.

Here are three interesting questions from the Introduction that came about when "a second revolution" in biology occurred:

1. Why is the planet green?

2. Why don't the animals eat all the food?

3. What happens when certain animals are removed from a place?

The first revolution had to do with molecular rules. The second revolution based on those questions above led to "ecological rules that regulate the number and kinds of animals and plants in a given place." The author calls them "the Serengeti Rules."

And he also states "We have done a very poor job in considering and applying these Serengeti Rules in human affairs."

So we apply molecular rules to medicines. About 85% are rejected in testing. But we hunt, fish, farm, burn, forest whatever we please with little or no consideration of what we are doing to other species or their habitats.

Chapter 1 deals with the life and discoveries of Walter B. Cannon who served in WWI. He was disturbed by the number of soldiers who died after they were brought to him for help. He came up with the idea that regulation is the key to maintaining a healthy human body. The job of medicine, therefore, was to find ways to correct abnormal regulation in sick humans.

This becomes a metaphor for the planet as a whole. The earth needs to be regulated as well. For example, there are only so many food and water sources. This fits in well with our discussions about over population. There are way too many humans to survive on this planet.

I am reminded of the concept of a keystone species by the question above: What happens when a species is removed from an area? It was the zoologist Robert T. Paine who first wrote about the concept in 1966 and 1969. He probably should have won a Nobel Prize. Now that idea is critical.

Here is a Wiki article about keystone species:

Chapter 2 discusses Charles Elton, known to biologists as the founder of modern ecology. He wanted to know how the numbers of animals are regulated. He is not as famous as Darwin or Malthus, but he should certainly be more famous than he currently is.

Elton went to the Arctic to study the food chain. He observed the importance of food, scarce on land but plentiful in the ocean. So it all starts with the oceanic food sources. Creatures eat fish, and land animals eat those creatures, and the droppings promote land growth. Numbers depend on what part of the chain you are on.

Elton came up with phrases like "food chains" and "food-cycles" and "food-webs." He drew a schematic of these chains with Summerhayes in 1923.

Here are some photos:



And other chains:

Elton found out that foxes and owls increased when the lemming population was high and vice versa. There were also forces that could make large populations crash. (Humans some day?) His 1926 book Animal Ecology became a classic written in just 85 days while he worked on it at a breakneck pace.

A pyramid is also formed with the dominant predator at the narrow top. Elton was fond of Chinese proverbs like "One hill cannot shelter two tigers." Predators need to stake out their territory. I can't imagine how much territory a snow leopard needs with its scarcity of food in the Himalayas. Must make it so difficult now to save them.

It was commonly believed, even by Mr. Elton, that lemmings engaged in mass suicide when they overpopulated. There is actually no evidence of that, but the belief persists. The 1958 Disney film White Wilderness showed lemmings leaping off a cliff to their demise. The scene was faked: the animals were flung off the cliff by the filmmakers. The movie won an Academy Award.

"Anything that is found to be true of E. coli must also be true of elephants."--Jacques Monod and Francois Jacob.

Chapter 3: Jacques Monod almost died in a shipwreck. Fortunately, he lived to become a co-founder of the new field of molecular biology. He and his collaborators would discover some of the first general rules of the regulation of life at the molecular level, a feat that would earn him a Nobel Prize.

Monod had to deal with WWII for six years. Then, like the others I mentioned, he asked great questions. Like, How did a bacterium, so tiny it was barely visible in a microscope and without any nervous or endocrine system--just a bag of chemicals inside a membrane--"know" to make the right enzyme for whatever sugar was available? It all came down to "regulation." All life is "governed by longer chains of interactions than we first imagine, with more links in between."

What I find fascinating about all this is how it gets back to us and our feelings of free will. We are also "governed by long chains of interactions." Free will is a feeling not based in scientific reality.

Francois Jacob became Monod's partner and helped him to move further in his discoveries. Together they would crack the logic of enzyme regulation. Monod would famously say, "I think I have discovered the second secret of life." DNA was the first secret of life, and "allostery" would be the second. There would be connections to cancer and why it occurs.

Gradually, these discoveries led to the conclusion that what people eat makes them sick. It led to the use of statins for managing cholesterol.

Chapter 5 deals with Janet Davison Rowley, a pioneer in cancer research. She wanted to establish that cancer was a genetic disease. She took the same approach: find how the rules of regulation have been broken. Leukemia is a disease of regulation. The metaphor is used of a stuck accelerator so a car careens out of control.

Rowley herself was diagnosed with ovarian cancer in 2010. Throughout her treatment, she had biopsies and other samples of the tumor to her colleagues. She died on December 17, 2013. She had pre-arranged her own autopsy so researchers could study the progress of her disease.

For the remainder of the book, the author looks at rules that regulate populations: Chapter 6 about pioneering discoveries in various parts of the world, Chapter 7 about how those rules and a few others operate in the Serengeti, Chapter 8 about places where the rules have been broken, and Chapter 9 and 10 about extraordinary efforts to restore entire ecosystems.

"You push an ecosystem too far and suddenly all the rules change."--Robert Paine.

In Chapter 6 we learn about Mr. Robert Paine, an ecologist who deserves much more popular fame. As a young man, he asked questions like "Why is that tree green?" And then when someone answered "Chlorophyll," he responded, "Why isn't all of its greenery eaten?" Once again, it's the great questions that take these scientists to new places.

Paine discovered that the predatory starfish of Washington and New Zealand were "keystones" in the structures of intertidal communities. He coined the term "keystone species." What a great accomplishment.

He began tinkering with nature to make even more remarkable discoveries. He termed a new phrase "trophic cascades." It showed the cascading effect of the decline of a predator like the sea otter in an ecosystem. Many other examples of trophic cascades are given in the chapter.

Paine summed up his knowledge with a quote from George Orwell's 1984: "Some animals are more equal than others."

Serengeti Rule #1: Keystones: Not all species are equal. Some species exert effects on the stability and diversity of their communities that are disproportionate to their numbers or biomass. The importance of keystones species is the magnitude of their influence, not their rung in the food chain.

Serengeti Rule #2: Some species mediate strong indirect effects through trophic cascades. Some members of food webs have disproportionately strong (top-down) effects that ripple through communities and indirectly affect species at lower trophic levels.

About half way through--fascinating, but needs to be digested in small chunks.

I am learning a lot. I'd like to see young scientists reading this book.

Chapter 7 deals with Tony Sinclair and the Serengeti. Rinderpest was a virus that killed many buffalo and wildebeest. As rinderpest was eliminated, more wildebeest meant more predators, less grass, more trees, fewer fires, more giraffes in a trophic cascade. Fascinating.

Serengeti Rule #3: Some species compete for common resources. Species that compete for space, food, or habitat can regulate the abundance of other species.

Serengeti Rule #4: Body size affects the mode of regulation. Animal body size is an important determinant of population regulation in food webs, with smaller animals regulated by predators (top-down regulation) and larger animals by food supply (bottom-up regulation).

Serengeti Rule #5: The regulation of some species depends on their density. Some animal populations are regulated by density-dependent factors that tend to stabilize population size.

Serengeti Rule #6: Migration increases animal numbers. Migration increases animal numbers by increasing access to food (reducing bottom-up regulation) and decreasing susceptibility to predation (reducing top-down regulation).

Tony Sinclair would be given the nickname "Mr. Serengeti."

The summaries on P68 and P153 comparing regulation of life and regulation on the Serengeti are very instructive.

And when you come down to it, doesn't it all remind you of how we talked about the overpopulation of humans? Isn't the day coming when we will have a gigantic crash?

Overpopulation has been caused by removing the down regulation by death due to famine (the green revolution) and poor health care and hence a huge decrease in infant mortality. The natural compensation that people twill have few children when they can expect more of their offspring to be alive to help them in old age takes a long time to take effect. It is already seen in the developed world where the fertility rate dropped dramatically in the 20th century sometimes to below replacement. Climate change has a more rapid effect:
Temperature rise-->drought-->famine-->death (esp. infants)
also: famine-->war-->death.
We are seeing this happening already.

Chapter 8: "It is failures in regulation of numbers of animals which form by far the biggest part of present-day economic problems in the field."--Charles Elton.

A major American city needs about 80 million gallons of water daily to survive. That's why Lake Erie and other water sources are critical to the survival of life. The spread of algae in such a lake is an ecological cancer.

Another example of Indonesia where tons of pesticide were used to kill brown planthoppers on rice. The predator of the insect was also killed, so there ended up being more planthoppers!

Another example is given of sharks and their critical role in the environment.

Chapter 9: The study of lakes (limnology) began at the University of Wisconsin in Madison in 1875. Lake Mendota would use some Serengeti Rules to cure some of its ills. To stop algae blooms, scientists who were proponents of trophic cascades proposed increasing predator fish. The result was a success story, and the details are fascinating. One key was that local fishermen supported the scientists and government regulators.

Another success story was the reintroduction of grey wolves at Yellowstone. They are many great videos available on Youtube. Preventing elk from browsing, willows and aspen flourished again.

Chapter 10: Focus on Ken Tinsley's efforts to save Gorongosa Park in Mozambique. Then a civil war drove people to poaching. Man, am I ever sick of revolutionaries. In 2002, Greg Carr came and focused on increasing tourism as a way to save the park. He brought in animals to start again. Important point: he helped the people in the surrounding areas. Want to help? Here's a tip: Buy shade-grown coffee from Mozambique like I do. Carr also focused on law enforcement.

In his Afterword, Carroll suggested some optimistic notes from the book House on Fire by Bill Foege:

1. Global efforts are possible.
2. Smallpox eradication did not happen by accident.
3. Coalitions are powerful.
4. Social will is crucial, and must be transformed into political will.
5. Solutions rest on good science, but implementation depends on good management.
6. The objective may be global, but implementation is always local.
7. Be optimistic.
8. The measure of civilization is how people treat one another.

Here is my negative takeaway as I read that list. It is time to fight back hard against "libertarianism." That ideology has caused more problems, at least here in America.

Enjoyed this book immensely.