The Serengeti Rules: The Quest to Discover How Life Works and Why It Matters - With a new Q&A with the author

The Serengeti Rules: The Quest to Discover How Life Works and Why It Matters by Sean B. Carroll“The Serengeti Rules” is a very good book that looks back at how the revolution in understanding the rules that regulate our biology unfolded and to look at where it is heading. Professor of molecular biology and genetics and member of the National Academy of Sciences, Sean B. Carroll takes the reader on adventure of amazing people who took on great challenges and accomplished extraordinary things. This captivating 288-page book includes ten chapters broken out into the following three parts: I. Everything is Regulated, II. The Logic of Life, and III. The Serengeti Rules.Positives:1. An engaging, well-written book.2. Interesting topic, how life works at different scales and what we can do with such knowledge. Dr. Carroll is a gifted writer.3. Good use of photos and charts to complement the excellent narrative.4. In the introduction Dr. Carroll doesn’t waste time in laying down the expectations of the book. “The most critical thing we have learned about human life at the molecular level is that everything is regulated.”5. Complex topics written at an accessible level for the masses. “And when cells escape the controls that normally limit their multiplication and number, cancer may form.”6. A lot of interesting findings throughout the book. “In his own laboratory, Cannon aimed to figure out how emotions affected digestion. He observed that emotional distress also ceased digestion in rabbits, dogs, and guinea pigs, and from the medical literature that also seemed to be true of humans.”7. At its heart this book is about extraordinary people who through determination overcome amazing challenges to make extraordinary discoveries. “Charles Elton is nowhere near as famous as Darwin or Malthus, but he is known to biologists as the founder of modern ecology, and the central mystery that gripped him was how the numbers of animals are regulated.”8. Stories of how rules of physiological regulation were discovered. “But it turns out that life—from the molecular scale all the way up to the ecological scale—is usually governed by longer chains of interactions than we first imagine, with more links in between. We need to know about each of those links and the nature of the interactions between them to truly understand, and to intervene in, the rules of regulation on every scale.”9. A look at the discovery of the link between heart disease and serum cholesterol levels. “Men with levels greater than 260 milligrams of cholesterol per 100 milliliters of blood had five times the heart attack risk of those with levels below 200. The Seven Countries study found the same at the five-year mark. For example, the average cholesterol level of east Finlanders was 270, and they had more than four times as many heart attack deaths as Croatians with cholesterol levels below 200.”10. Janet Davison Rowley’s impact to cancer research. “Rowley’s discoveries of specific but different chromosomal changes in two different types of leukemia was strong evidence that at least some cancers were caused by specific, perhaps unique, genetic mutations.”11. Rules of regulation on the larger scale. “The proposal that predators regulate herbivore populations is now widely known as the “HSS hypothesis” or “Green World Hypothesis.””12. Explains the Serengeti Rules. “Some species exert effects on the stability and diversity of their communities that are disproportionate to their numbers or biomass. The importance of keystone species is the magnitude of their influence, not their rung in the food chain.”13. A look at the Serengeti. “And indeed, the Serengeti is biologically very special. It is a vast ecosystem of almost 10,000 square miles that is bounded by natural barriers on all sides.”14. How key creatures have the biggest impacts. “The wildebeests’ many direct and indirect effects on grasses, fire, trees, predators, giraffes, herbs, insects, and other grazers reveal that they are a keystone species in the Serengeti, with disproportionate impacts on the structure and regulation of communities. As Tony Sinclair put it, “Without the wildebeest, there would be no Serengeti.””15. The story of Lake Erie. “Spurred by the dire condition of Erie and other lakes, the US Congress passed the 1972 Clean Water Act that authorized the Environmental Protection Agency to regulate the discharge of pollutants into waterways and to set the acceptable limits for water quality for humans and aquatic life.”16. Find out how some species explode in numbers. “Microcystis, planthoppers, baboons, cownose rays. What rule or rules of regulation have been broken that enabled these organisms to explode in numbers?”17. A look at how the trophic cascades were manipulated to benefit the Wisconsin lakes.18. A look at the Yellowstone Restoration.19. The fascinating resurrection of the Gorongosa National Park. “In October 2004, he pledged $500,000 toward the park’s restoration to Mozambique’s Ministry of Tourism. That was to be a small down payment. In November 2005, he agreed to provide $40 million to the park’s restoration over a thirty-year period. But this would not be a matter of merely sending checks from the United States. Carr and his foundation were to co-manage the endeavor on the ground with the Mozambicans.”20. An excellent section on lessons learned. “Every scientific recommendation requires political action for implementation. Scientists must equip politicians with the information necessary for making good public policy. I would add that another approach to securing the necessary political will is for scientists themselves to pursue public office.”21. Extensive notes and bibliography.Negatives:1. Even at its most accessible, molecular biology is difficult and some readers may feel lost early on in the book but don’t give up as it progresses nicely and is ultimately rewarding.2. Missed opportunity to add supplementary material such as a table of all the animals currently in the Serengeti and their vitals and/or interesting facts.3. Not at the same level as his previous books, as an example Endless Forms and The Making of the Fittest are superior books.In summary, Dr. Carroll succeeds in presenting a compelling case for how life works at its different levels through interesting stories. It’s hard to match his previous works but overall this book is satisfying and makes an interesting link between physiology and ecosystems. Not perfect but if you are a layperson interested in how life works and why it matters this is a recommended book.Further recommendations: “The Making of the Fittest” and “Endless Forms Most Beautiful” by the same author, “The Extended Phenotype” and “The Greatest Show on Earth” by Richard Dawkins, “The Gene” by Siddhartha Mukherjee, “I Contain Multitudes” by Ed Yong, “Life’s Engines” by Paul G. Falkowski, “A Most Improbable Journey” by Walter Alvarez, and “A New History of Life” by Peter Ward.

As usual Carroll came up with a compelling book. Anyone interested in ecology will be provided with much to consider from Serengeti Rules. What he provides the reader with is how a food chain works. He describes not simply from the land animal perspective but also from several aspects of science and how an ecosystem works in all of the life sciences.This molecular biologist took his family to Africa where they explored the Serengeti and he developed an explanation for how systems keep in balance. He made his “Serengeti Rules” after examining how biological systems at several levels, consistently obey those rules. He did so by selecting several historical biological events and combining them with his own studies and the Africa trip, created a very readable and more importantly, plausible explanation.Ultimately the book is a combination of science (occasionally pretty deep for those without the academic background), history of science and what he discovered in Africa. He knows how to write a book, this being the third that I have read and never once disappointed.His ultimate point is that we are all in this together. By “we” I mean all things with carbon in them. Gainsayers as he notes, suggest “So what? We win, they lose. That is how nature works.” when a species becomes endangered or worse. That is simplistic but more importantly just wrong. Ecosystems are important for everything that exists within them as there is symbioses amongst them even if it seems too obscure. An occurrence with one piece of biota impacts another that will impact another and so on and in the end, will impact all. Carroll makes this his point.He wrote about historical scientific events, some fairly distant in the past and some more recent. They included studies on high blood pressure, post-traumatic stress syndrome from World War II and advances in finding a cure for CML Leukemia with the understanding of the Philadelphia Chromosome. Not only were these studies significant but the characters involved scientific icons as a result.Elton, Monad, Cannon are only a few of the names of people who studied their problem by looking at the many events that could be impacting that problem. They looked at issues like leukemia as being an imbalance in the systems that impacted the problem they were trying to resolve. The solutions they came up with all reflected how one thing impacted another thing which impacted another thing. They found imbalances.Then he discussed some important concepts at the more macro level found in places like the Serengeti. One is what is called “Trophic Cascade”. This concept describes the effects on food chains when a species is deliminated or expired. It is referred to as “bottom up” when a seemingly insignificant part of a food chain is gone and how that changes which organism eats another. It can impact negatively, a large beast because its element of the chain is disrupted. It is called top down when a large predator is limited or gone from an environment changing the structure of the food chain below it.Within the notion of trophic cascade comes the term “Keystone Species”. Those are the ones that impact all others in very significant ways. In our popular lore and well intentioned pleas for action, this species tends to be either big or cute. In fact a Keystone species may be a large predator that when endangered changes the food chain by introducing more food for another species with sometimes dramatic effects on the ecosystem. If a major predator is missing then another specie grows in numbers and they impact the ecosystem by what they eat which may ultimately be the ruin of the whole ecosystem. Like the trophic cascade, keystone species could be seemingly small ones in an ecosystem but their demise could work the same way because ultimately they are affecting the entire food chain as well.I came to understand this many years while working in my vegetable garden. My thoughts were much coarser than Carroll’s presentation but as I introduced lady bugs to rid my garden of aphids I began to think that something else will take its place. No aphids could well lead to an invasion of some insect or perhaps disease that the aphids kept in check. I did not know what they might be but did imagine that there are always tradeoffs in an ecosystem.He ended the book by describing the restoration of a massive park in Angola that has had more strife than could be expected over the last 30 years. Angola is a war torn nation with an assumed to be Marxist government and a civil war with its rebels. The latter group had pretty much destroyed Gorongosa, a park named for its mountain. While the levels of destruction were massive, you will only get the details when you read the book. What Carroll describes as the best solution to revitalizing this treasure is to “Focus on law enforcement, not reintroduction.” This is a sentiment dear to me. I find it perplexing and annoying when suggestions are made of re-introducing species to an ecosystem that they have been extinguished from. It is an idea that is too late. The trophic cascade has already changed the environment to the extent that it is impractical to reintroduce a species. Even worse is the call for introducing hybrid species via cloning. I think that is more of a nutty idea than anything else.The problems that Africa faces with their ecosystems is often a result of poachers who glean something valuable like ivory by killing elephants or some sort of idiocy such as sexual enhancers only found in a species that may be a keystone one.This book is rife with interesting and informative details. A part of me wants to reveal the six Serengeti Rules and to go into more detail about the historical stories of scientific innovation but I would be a spoiler. I would either provide a potential reader with enough information to not read the book or would be wrecking all the good parts. It is a book that I would recommend reading so that one could better understand homeostasis or balance in ecosystems. That can make anyone a better steward of our land.

There is no actual “Balance of Nature”: everything is growing, changing, evolving, in flux. Despite this, there is a kind of dynamic balance: our bodies maintain temperature, animal population numbers don’t tend to grow exponentially of collapse, and so on. These are dynamic balances, because they happen due to active processes.Here Carroll explains how those processes have much in common from the molecular to the species level: biological regulation is at play. The logic of this evolved biological regulation is different from our engineered mechanical regulators: rather than a positive logic of a process being switched on when needed, it is often of a negative form: one process is constantly suppressing another, and when that suppression is removed, the change occurs.Carroll gives many examples. Each chapter has a similar structure: take one aspect of biology, and the scientists involved, and describe how they discovered the regulation logic. We start at the beginning, with Cannon’s discovery of the concept of homeostasis, and Elton’s invention of ecology.After these two introductory chapters, demonstrating analogous regulatory processes on vastly different scales, we get several chapters on molecular level: lactose regulation, statins and cholesterol, and cancer. Some of these have a “double negative” pattern of regulation – X represses Y which represses Z, hence removing X increases Y, which then decreases Z – so a change in one place can have a corresponding change elsewhere, which will be unexpected unless the system is understood. Next there are chapters about animal population regulation, keystone species, and trophic cascades: it’s not just upward regulation by food abundance; there’s critical downward regulation by predators.The book finishes with some positive examples about how, once we understand these negative regulatory patterns, we can potentially reverse certain ecological collapses. We need to identify the relevant keystone species: wolves predate on elk, thereby allowing vegetation to survive to support other species; bass eat minnows, reducing predation on the plankton that eat algae, which would otherwise cause blooms. Knowing the system’s structure, we can potentially reintroduce, or at least stop destruction of, the relevant species, to allow the ecosystem to move a healthier state.This is a good account of a biological process that works over many orders of magnitude in scale. Understanding how biological regulatory processes are negative, rather than the more familiar engineered positive ones, explains many otherwise counter-intuitive effects. And understanding the web of interacting regulatory processes allows us to intervene in an effective manner, allowing us to work with, rather than fight against, the system.

In ambition, this book certainly impresses. Carrol takes in both the very small - the way that processes within the cell take place at the molecular level - and the very large - how whole ecosystems function. The back-cover blurb advertises that his aim is nothing less than an attempt to, "travel the globe in search of the logical rules that govern all of life" and to "explore the unity of biology...the rules that regulate life and the consequences when regulation breaks down". And, as his earlier book, "Endless Forms Most Beautiful" brilliantly showed, he is certainly competent to make the attempt.So my expectations were high - might Carrol have formulated a set of principles that could make us think anew about the underlying unity of life? Not perhaps as revolutionary as the theory of evolution, but maybe something that could be applied equally to the regulation of cellular biochemistry and complex populations of animal communities. To save you the suspense, here are the "Serengeti Rules":1. "Not all species are equal" i.e. some species are "keystones", and exert a disproportionate effect on a community compared to others2. "Some species mediate strong indirect effects through trophic cascades" - a variation of the above3. "Some species compete for common resources" - this results in systems of mutual regulation4. "Body size affects the mode of regulation" - smaller animals are regulated by predators, larger animals by food supply5. "The regulation of some species depends on their density" - some populations are regulated by density-dependent effects6. "Migration increases animal numbers" - by enabling migrators to access additional food and escape predatorsThe examples Carrol gives are fascinating and elegant - a real pleasure to read. However, it will not have escaped the reader's notice that these rules a) apply to animal populations, not to lower level systems b) are little more than restatements of well-known ecological principles. Although Carrol uses the term "regulation" extensively, the reality is that his quest to seek "how life works" and "the logical rules that govern all of life" has not resulted in a new paradigm.So overall, this is a thoroughly enjoyable read, but it is rather less than the puffery might imply.As a footnote, I have to confess to being annoyed at Carrol's misrepresentation of the history of Mozambique's Gorongosa National Park (which forms the basis for one of his chapters). Whilst he correctly claims that its wildlife suffered as a result of the prolonged war between government troops and the Renamo guerillas, it is grossly misleading to suggest that Renamo sprang up as a response to what Carrol describes as the "oppressive measures" of the new, post-colonial government. In fact, Renamo were set up and sustained by the apartheid Rhodesian and South African military in an attempt to maintain their own repressive regimes. Gorongosa suffered excessively after it was chosen as the Renamo HQ by the Rhodesian military because it was sparsely populated and therefore easier to conceal and defend.

This should be required reading for all Politicians and people concerned about the degradation of species. There is hope, if the correct actions are taken.

The first 100 or so pages are quite heavy going with a lot of scientific explanations about "ecosystems" within individual cells and then how different cells inter-relate within the human body. The rest of the book transposes these interdependencies within individual body cells and within the bodies of animals out into the systems of nature. It demonstrates how ecosystems are built up and that it's not always the predators that dominate them. If you're not into heavy science, start from page 105, although I would recommend reading the whole book. A must read for anyone not yet a believer in "Global Warming". This book adequately demonstrates that it's the "Human Animal" that is causing all the harm in the world. We are the ones damaging the ecosystems that survival of all species, including ourselves depend on. We need to change and this book demonstrates it. I found it absolutely fascinating.

👏🏾👏🏾👏🏾Bravo on a brave topic, life and congratulatulations on the smooth traditions between the vignettes that gently illustrate human complexities and endeavours that ultimately propel humanity forward. Sadly, the books lacks the courage or foresight or both, to state that, Western culture created much if not all of the ills to be cured in the first place. Not in a medical sense, but a cultural sense, a capilist sense, a greed sense. That said the learning from the book remains invaluable to all.