Customer Reviews

Evolving Brains (Scientific American Library)

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How has the emergence of the super-sized human brain depended on the evolution of a good set of teeth? Why are the stomach and brain closely linked across the brambles of genetic code? This book answers not only those intriguing questions but also many others concerning the emergence of the brain on this planet. Especially fascinating to me was the explanation of the homeobox phenomenon, a process by which very complex mutations can arise in an organism without the mutation risking certain disaster. Being a non-biologist, I found this homeobox material quite fascinating, for it opened my eyes to how evolution could generate incredibly complex features without requiring a hundred trillion years for all the right components to come together all at once. Equally interesting are the many vestiges of our evolutionary past that are still embedded in the way our brains process information. For example, the sectors into which our brains split each of our retinae today for the purpose of signal processing: these are left overs from the days when our ancestors were prey and not predators, back when our ancestors' eyes were mounted to the sides of their heads! In summary, I would like to say that in reading this book, while just sitting in my chair, I felt myself moving up another notch on the evolutionary tree. It gave me a whole new appreciation for the miracle that is the development of brains and conscious life on this planet. A very pleasant read.

This is a sweeping examination of evolution's path leading to that mass of gray matter behind your brows. Allman has synthesized a wealth of research in producing this study. He explains in a clear, interesting style how natural selection has spent the last 500 million years tinkering with life to build complex systems from simpler ones. He is a forceful writer, supplementing a fine text with superb illustrative material to build his narrative. It's a refreshing view of natural selection's power of innovation.

Allman draws on the detailed research undertaken in recent years that has mapped the brain and detailed its operations. Like all life, beginnings were simple, but small variations among organisms had the potential for important roles. Deep in the Precambrian, floating cells developed appendages leading to hair-like structures we call "cilia". The cilia adopted dual roles: sensing the environment and responding to it. Allman explains how gene duplication led to opportunities for experiments. This process demonstrates how we can track many of steps leading to today's life forms. The original genes are usually still resident, with enhancements providing new functions added over the passing generations.

The author's explanation of the workings of chemistry in brain functions is worth close attention. Behaviour is the result of brain activity, but the interactions of various parts and functions of the brain elude simple analysis. One example is the brain chemical [neurotransmitter] serotonin which is found throughout the brain. It's impact gives monkeys their social structure while adding to the risk of suicide in humans. Neurochemistry alone doesn't explain the expansion of the human brain, nor does the author stop there. He goes on to show how bipedalism, diet, language and social behaviour all working in self-reinforcing feedback loops led to the gob of tissue that takes a fifth of our body resources to keep working. Even global climate changes played a role, coming at a time when our species was just prepared to contend with them.

The number and impact of revelations in this book are almost beyond counting. The "urban myth" that women live longer than men because of improved health practices has been disproved both by history and anthropology. A study reaching back into the 18th Century demonstrates that women have outlived men at least that long ago. Among the great apes, chimpanzee females also outlive their mates. Orangutans and gorillas have nearly parallel life spans between genders. There are also studies showing how caring fathers have extended life spans. His analysis of the development of colour vision is another novel thesis. Colour perception arose only 40 million years ago, after the demise of the dinosaurs. This raises again, the question of whether the emergence of flowering plants, which were toxic to those creatures, helped speed their demise.

While this book is not a light read, it's an informative and edifying one. Allman deals with complex topics. Adding to the elaborate range of material involving the brain, behaviour and social issues is the background of the immense time spans required in dealing with these questions in the context of evolution. Given all these constraints, he has met the challenges of the task credibly and lucidly. [stephen a. haines - Ottawa, Canada]

This is a book to savor, to read again and again. After reading it, I found myself looking at the world and our place in it in a new, expanded way. A lot of scientific advances have been made in the past decade or so, and this book brings the reader up-to-date and ties together the advances made in various fields in an interesting, understandable manner. This book was written by a Professor of Biology at Caltech, who obtained his doctorate in anthropology. It has some chapters that take concentration to read, and others that one can breeze through. The pictures and graphics are great (this book will look good on your coffee table). No prior background in biology or anthropology is assumed. Probably what was most useful to me was that I learned a lot about evolution that I hadn't known before. Before reading this book, I thought that I had a basic understanding of evolution, but now I realize that the part I more or less understood was simply that of natural selection (Darwin). By walking the reader through the recent advances in genetics, this book explains in a clear and understandable way HOW NEW SPECIES ARE CREATED. (In my informal polling of knowledgeable friends and relatives, I found no one else who understood how new species are created... of course, with my new knowledge, I explained it to them!) Speaking of which, this book has resulted in some lively and engaging conversations: I now have a seemingly endless source of fascinating insights about humans, about animals, about the brain that I can talk to others about. Take dogs, for example. I have never been much of a dog-lover, but now I more fully appreciate how dogs (having evolved from wolves with the help of humans) and humans have worked together to ensure each other's survival... so now I don't mind it so much when my sister's dog jumps on my couch! Other examples: how the extended family structure (and therefore the role of females in general) has played in the survival of humans. How serotonin and the level of this chemical affects the brain (and thus why Prozac and other anti-depressants are effective). How our 'junk DNA' creates a fossil record of evolution. How our eyes and vision evolved... amazing! I could go on and on with such examples from the book, such wonderful things I learned. With my enhanced understanding I find myself noticing more about babies and how they learn, about animals... and tuning in to the new animal channel on cable more often. This book has excited a curiosity in me, and I want to learn more. I believe that everyone would benefit greatly from reading this book.

I enjoyed this review of the current state of knowledge of the human brain, both its various functions and their evolution. Best of all, I shared some of the ideas in it with my 12 year old son. He went away and a day or so later came back to ask me the kind of question that the young inquiring mind frames so well: (referring to the appositional placement of reptilian eyes), "Dad, how can a reptile see two different scenes at the same time?". I had no good answer to this question which was prompted by the discussion of vision in Evolving Brains....so I called Prof. Allman's office. He kindly called me back within the hour to help me with this seemingly simple question. Turns out the answer is not simple. Just let me say that this book evinces the wonderful personality of the author throughout. Highly recommended for those interested in the latest knowledge on the functions of the human brain and how these functions evolved. Geoff Noyes knoyes@snapsystems.com

John Morgan Allman wrote a book that can be enjoyed by anyone from a psychology 101 student to an accomplished neuropsychiatrist. The evolutionary perspective on the brain not only informs us about its anatomical development, but enlightens us about the process of being human. I dare anyone to read this book and not come away with a deeper appreciation of pet dogs and gormet food.

I have found myself delighting my children, friends, and patients with tidbits from Evolving Brains. Allman seamlessly weaves what is known about evolution and brains with his own hypotheses about function and adaptation. This makes for pleasant and stimulating reading, although sometimes the reader is lead unknowingly into the land of conjecture, such as when Allman states that the anterior cingulum is the seat of human self-awareness. Remember, Decartes thought the pineal was the seat of the sole!

But for the most part, Allman is right on. If you like brains, don't miss this book!

Among the recent books to come out on brain evolution, Evolving Brains presents the most readable, up-to-date, and extensive coverage. Attempts to trace the fascinating history of brain and behavior often begin only at the origin of mammals or early primates, neglecting the neural groundwork laid by earlier invertebrate and vertebrate predecessors. Instead, John Allman backs up all the way to shadowy beginnings in bacterial behavior and methodically works his way up to self-domestication in Homo sapiens. Along the journey, he weaves in many recent and exciting discoveries covering a broad range of topics, from homeotic genes and the Cambrian explosion to neocortical mapping (including his own research findings) and primate social behavior. Dr. Allman keeps the context grounded in biology, including his own provocative views. I enthusiastically recommend Evolving Brains as "must" reading for anyone -- not just scientists -- with even a passing interest in the origin and evolution of nervous systems and the behaviors they generate, including our own.

A well written and illustrated book full of interesting thoughts about the evolution of brains leading up to our own.

The level of writing is about that of a review paper. Although Allman covers a lot of subjects, from genetics, developmental biology, palaeontology to primate vision, all concepts are well explained and illustrated and the book makes good reading for a research biologist as well as for an interested layman.

Allman started his career as an anthropologist, which gives him a different perspective than the average neuroscientist's. He not only describes the workings of the nervous systems and behaviors of different animals, but puts them into perspective with their evolutionary roots and their ecological niche. All these insights are not hand-waving speculation, but well supported by comparative studies.

Another strong point of this book is how Allman guides the reader trough the evolutionary lineage leading from amphibians to reptiles, mammal like reptiles, mammals, primates to ourselves. At every branch point he points out the critical innovations, the evolutionary pressures that most likely lead to these innovations and the trade offs made. A key question he addresses is, "why isn't every animal equipped with a big brain?". It is our own experience, both phylogenetically as well as everyday life, that a big brain, and the resulting high level of intelligence, is an advantage. Allman points out the high cost of rearing big-brained young and of maintaining such an energetically expensive organ.

If you are interested in how animals use their brains to deal with ever-changing environments and why our brain evolved to be so much more powerful than any other species', then this book is for you.

Evolving Brains is an excellent book for the scientist and the lay person. I found the concepts to be innovative such as the the effects of serotonin in the brain.The chapter on care taking and survival is extremely fascinating because it demonstrates the relationship between the offspring and primary care taker. This book is a wonderful introduction in understanding behavior and brain evolution. Key concepts are highly comprehensive due to the explicit diagrams and graphs. I give this book my highist recommendation.

This book proceeds from molecules in bacteria with brain-like functions all the way to the very complex brains of primates. It explains the history of how the brains evolved in very understandable terms using pictures and graphs. It shows how various innovations in the nervous system created both new possibilities that could be explored by future animals as well as cutting other possibilities off. It talks about how having a complex brain is related to worm-bloodedness. In short, read and find out.

This book starts with some basics about the nature of brains, and a comparison of brains. Special mention is made of serotonin, which often "modulates the response elicted by other neurotransmitters." It seems that serotonin tends to reduce risk-taking and fighting. But it also reduces motivation, as well as sensitivity to opportunities for rewards that risk-taking can bring.

Next, there is a more detailed explanation of the different parts of the brain and nervous system as well as the senses of sight and smell. After that, we learn about brains in warm-blooded creatures and primates. And we get into the question of senescene (the risk of dying going up with advanced age rather than staying the same) and what brains have to do with that. As well as more about sight, and how our brains allow us to be so aware of patterns and motion.

There are all sorts of fascinating tidbits to be found. When babies cry out for their mothers, do they do so in a high-pitched voice? Well, in some mammals, they do so at such high frequencies that while their mothers can hear them (and find them), predators find these sounds to be ultrasonic, and thus do not notice. There is also a complex attempt to explain why primates tend to have specific alarm cries for aerial versus ground predators. I find this phenomenon totally unsurprising: sentries make an entire group safer, and since all group members are potential sentries, everyone benefits including the sentries. It's easy to imagine how such cries might have evolved, even though the individuals crying out might well call attention to themselves.

We humans have very large ratios of brain weight to body weight. And perhaps the most interesting part of the book deals with the evolutionary tradeoffs involved with bigger brains. By the way, the part of the body that is most sacrificed in humans to get the excess brain weight is the gut. The liver is also a little smaller than for a smaller-brained mammal.

At the end of the book, we get into the interesting question of why Women live longer than Men. Women definitely do tend to live longer, and often have the unhappy experiences of outliving not only their husbands, but even one or more sons. But why? There are, of course, some flippant answers (not discussed in this book, of course). Men are genetically inhibited from asking for directions, and as a result get lost, wander around, and die. Men are married to Women (actually, I think married men tend to outlive unmarried ones). Men tend not to wear panty hose, a marvelous invention that protects the legs against swelling and blood clots. More seriously, I thought a dominant reason might be the fact that Men generally weigh more than Women. Within a species, smaller mammals may tend to live longer. But Allman makes the point that in those mammalian species where males have major role in parenting (such as the owl monkey), the males live longer. And there's an evolutionary reason for this: a species does better if the caretakers of the young live longer. The author discusses a couple of mechanisms for this: Males take more risks, while in females, estrogen enhances the actions of serotonin, reducing risk-taking behavior. Another mechanism could be that females may tend to lose fewer hippocampal neurons, which "are richly supplied with receptors for the corticosteroid hormones, which are produced by the adrenal cortex to mobilize the body's defenses when subjected to stress." If that's true, it could explain the higher incidence of death in Men due to stress-related causes.

I enjoyed this book very much. I learned plenty from it, and I highly recommend it.