Human Natures: Genes, Cultures, and the Human Prospect

Rating:
Summary: A "must read"
Review: "Human Natures" is far and away the clearest, most comprehensive, and most compelling synthesis of what is known about the co-evolution of humans, their cultures, and the rest of nature currently available. The title subtly reflects the important distinction between human "nature" and human "natures" - the plural implying that our species has many and varied natures - not a single unitary nature. This pluralism is in stark contrast to the stilted and unrealistic assumptions about a singular human nature embodied in both the reductionist biological model and the conventional economic model. The biological reductionist idea that all human behavior can be reduced to a genetic basis is clearly insufficient in light of the massive importance of cultural evolution in shaping human behavior. Likewise, the all-knowing, perfectly rational economic utility or profit maximizer of the conventional economic model may be convenient for mathematical tractability, but it is so far from the reality of human natures that it is laughable. The only mystery is why, given what we know about human natures, more economists are not laughing. The case of Phineas Gage, described by Ehrlich in the book, serves to illustrate the size of the chasm between the conventional economic model and reality. Gage was a railroad worker who had a large portion of his frontal lobe removed when a 1.25 inch-thick tamping rod shot through his head in a freak railroad accident in 1848. Amazingly, Gage survived and was not even knocked unconscious by the accident. But he was a changed man. He had lost the part of the brain that we now know is dedicated to emotional responses. A surprising result was that while he could think, talk, and calculate perfectly well - he was completely "rational" - he simply could not make a decision. It turns out that rationality without emotions leads to swamping with details and the inability to make any decisions at all, even ones so trivial as what to eat for dinner. That emotions are necessary for decision making is an interesting part of real human natures, but is in direct contradiction to the conventional economic assumptions about decision-making, which considers emotions to be a hinderence to "rational" decision-making. But as Ehrlich points out: "Human emotional capacities evolved along with our cognitive capacities. Without the ability to respond to stimuli with appropriate emotions, critical decision making becomes impossible" (pp. 121-122). The challenge is to build economic models that incorporate the realities of human natures, rather than to assume them away. The weakest aspect of the book is the imbalance between its treatment of genetic and cultural evolution. While Ehrlich takes pains to acknowledge the large and growing importance of cultural evolution in shaping human natures, he gives very little space in the book to the details of how cultural evolution works and does not attempt to synthesize the research in this area in anything like the completeness with which he treats human genetic evolution. For example, he notes that cultural evolution has several unique characteristics relative to genetic evolution. Most importantly, learned behavior can be passed on through the culture to genetically unrelated individuals and changes in culture can occur with light speed relative to genetic evolution. But how does this work and what does this mean for human natures and for the future of our society? This and several other key questions about the details of the relationship between genetic and cultural evolution are hinted at in passing, but left largely unaddressed in the current volume. For example, conventional biological evolution theory is largely circular and descriptive, not predictive. It is one thing to describe how alligators evolved, but quite another to be able to predict the emergence of alligators. To do this one would need to know the underlying criteria for success in evolution that can be specified before the fact. From a predictive point of view, it doesn't help much to say that those individuals that reproduce best will survive, unless one can say why particular individuals will be able to reproduce better than others in particular situations. Most human evolutionary ecologists work on time scales that make this question moot, but it is essential for understanding cultural evolution, the results of which are observable in units of years rather than thousands of years. To use the evolutionary paradigm in predictive modeling, we require a quantitative measure of fitness (or more generally performance) that can be specified before the fact, in order to drive the selection process. Another important question has to do with the "reflexive" nature of cultural evolution - because we are capable of at least some degree of conceptualization and foresight, we can exert at least partial control over our own selection environment. The process then becomes one of conscious design and tinkering with the cultural evolutionary process rather than passive response to externally determined criteria. How does this process work and what are it's limits? Devising policy instruments and identifying incentives that can translate foresight into effective modifications of the short-run cultural evolutionary dynamics is the key research challenge. In cultural evolution, we have the unique potential to first envision our goals and then modify the selection criteria in order to achieve them. Ehrlich's book provides a solid basis for addressing these and countless other questions that are critical to understanding our human natures and how we can actively participate in changing them. Adequately understanding and controlling our complex human natures is essential to the continued survival of our so far exceptionally successful species.

Rating:
Summary: Excellent reading for both the scientist and lay person
Review: Ehrlich has added to a number of good inter-disciplinary books that have been published in the last few years that all bring together the social and hard sciences. This is a well written and brilliantly engaging work. Few readers will fail to come away after reading this without some sort of intellectual reward.

Culture as a model of human evolution is emphasised, not to overtake genetics, but to add another dimension. The implications of this effect many fields, including biology, genetics, psychology, history and anthropology. Ehrlichs intelligent and clear writing, persuasive analysis and excellent footnotes make reading "Human Natures" a worthwhile effort. A joy to read.

Rating:
Summary: Thorough--and perhaps too objective
Review: Ehrlich is a well-reasoned scientist who examines the entire history of humanity to provide plausible explainations for our many behaviors and natures. His research is (mostly) thorough (one critic accuses him of dismissing research that details differences among different races of humans; e.g., the variety that asks why blacks are better at sports than whites, and why Asians are better mathematicians), and I noticed Ehrlich repeatedly refraining from stating absolute truths about human behaviors. Instead, he acknowledges our many differences and why we can't ultimately insist that humanity is what the Euro-American-centered view of it often makes it out to be, but rather, that as multiple cultures evolved over time, we adopted many cultural differences (as well as our genetic structures evolving) that make us unique within our species.

In his stressing humanity's multiple traits, he also states that we are not automatically predisposed to enlightenment any more so than we are predisposed to self-annihilation: Both are characteristic of humanity and always have been, so to assume one over the other as a way of being for all of humanity is rather ridiculous.

Of most importance, however, is Erhlich's examination of humans as tribal creatures. The presenting problem of our world today is that even though we are small-group peoples, "we are ... trying to maintain health, happiness, and a feeling of connectedness in an increasingly impersonal world in which individual natures are based on ever small fractions of society's cultures." But I wish Ehrlich would have explored the point more in depth: What are the specific and wide-ranging ramifications of our large-group aspirations when, historically, we have lived in small-groups? Does this mean globalism will be our undoing? Is Ehrlich implying that we should "go local"? He presents these issues while refraining from exploring some the potentially controversial consequences of our 10,000-year-old behavior, when we began to change from tribal/small-band people to sedentary agriculturists.

Despite these few minor criticisms, Human Natures explains perhaps more about humanity in a single volume than at least what I've ever read--with very current references no less. And his treatment of this vast subject is fairly objective which both benefits and slightly detracts from the book in the end. Nevertheless, Human Natures is a valuable addition to any who work with people or are open to rethinking how we will look back on ourselves 3 million years from now, assuming there are any of us left by then.

Rating:
Summary: Once more into the breach . . .
Review: Paul Ehrlich enters the lists of "nature vs nurture" by fulminating against the straw-man of "genetic determinism". One would have thought this joust would have been called for "time" by now. In his attempt to triumph over this rather ephemeral opponent, Ehrlich has performed a prodigious task. This well-written and comprehensive view of human evolution is a valuable resource. A massive footnotes and references collection grants this book value far above the narrative itself. Ehrlich, a practiced writer and researcher, brings many years of work and observations of the human condition to this massive overview. He strives to explain who we are and how we arrived at our current stature. He further warns that our lack of understanding of our backgrounds may threaten our future.

"Human nature" is often cited as a foundation for many behavioural traits. The fallacy of that moral expression is revealed in the variety of our habits. Ehrlich recognises that variation in his title and goes on to explain it in this book. While the genetic foundation of our behaviour is being solidly established by much field research, he ultimately concludes much of that basis is overriden by our cultural influences. Much of our confusion about "nature versus nurture", he contends, lies in the rapid pace of humanity. Compared to most other species, our mental development raced past the other animals - with language as the accelerator pedal. Since the genetic base for most traits is so slow and nearly muted, our development agriculture, religion and urban society virtually overwhelmed our "animal instincts". The prime example, of course, is the massive impact we have on our environment.

Ehrlich's key in assessing genetic versus cultural input lies [logically!] in the structure of the brain. When he wrote this book, the human genome was thought to be comprised of 100 000 genes. With that figure halved, he concludes the genome hasn't the power to command the billions of neurons with their trillions of connections that comprise the human brain. This "gene" shortage, he avers, suggests the genome hasn't the capacity to drive human behaviour to any significant degree. This rather simplisitic enumeration ignores the fact that the entire genome, whatever the number of genes, must be highly interactive in many areas of the body - the brain is simply another part of the mechanism. He is apparently unaware of the brain research showing how similar interactions have been mapped within the brain. Genes merely kickstart the process, they don't need to "control" our behaviour.

Ehrlich takes the usual swipes at Richard Dawkins as he builds his narrative. Like so many others, Ehrlich's reading of "The Selfish Gene" appears to have ceased at the title. To him, the "Great Leap Forward" of some fifty thousand years ago emancipated us from the shackles of our genetic heritage. With the development of language [which wouldn't have happened without a biologically endowed "voice box"], human cognition, hence behaviour, launched on a new course. Ehrlich asserts we've never looked back, but also warns our capabilities should be adapted to now look forward. Our abilities threaten the biosphere with an intensity and scope no other species possessed.

In his conclusion, the author nearly reverses all his prior narrative. He urges humanity to develop a better understanding of its place within nature. That, of course, means a full programme of understanding animal behaviour and the mechanisms animals and plants use to stay alive and reproduce. Our evolution, particularly the cultural input, has led us to believe we are distinct from Nature. Ehrlich recognises the dangers of such an attitude and urges us to overcome it. Although an excellent synthesis and supremely comprehensive, it's unfortunate that Ehrlich's prejudices blinded him to create a problem that doesn't exist. Nobody argues for "biological determinism" in an absolute sense - certainly not Dawkins. Where Ehrlich is correct is that we must increase our knowledge of how nature works and undertake the tasks needed to stop and reverse the spoilage under way.
[stephen a. haines - Ottawa, Canada]

Rating:
Summary: For the true believers only
Review: Paul Erlich is usually introduced as the author of "The Population Bomb", so it's not unreasonable to look back for a moment at that book- and Erlich's intellectual history- in considering this new book. Back in the 1960s Erlich was a mainstay of the popular media- sort of a Carl Sagan of population- and a regular guest on the Tonight Show, where he spelled out his apocalyptic vision.

"The Population Bomb" was a polemic that dictated a series of prescriptions for society, without which we were racing headlong to all sorts of disasters, notable shrtages of all strategic resources, massive starvation involving millions of people, food riots that destroyed governments and the downfall of western society as we knew it. This was prophisized to happen in the 1970s, and as most of us recall, none of it happened. He went on to predict that *billions* would die of starvation in the 1980s. Erlich also made a famous bet with economist Julian Simon,in which Simon challanged Erlich to pick 5 commodities that he felt would go up in price because of shortages. Erlich took the bet, and all five fell drastically in price.

In fact, nothing that Erlich prophasized ever happened. Erlich's predictions had little to do with science and much do do with ad-hoc justifications for his political prescriptions. Now Erlich has jumped onto the nature/nurture bandwagon, which has generated a lot of renewed interest in recent years owing to some major breakthroughs in the understanding of, and potential control over, the genetic makeup of humans. And once again, Erlich sees a lot of reasons we should follow his particular social agenda.

There's nothing particularly new or original in the discussion of nature and nurture in this book, which isn't surprising as Erlich has never done any research in this area. Most of the book is a fairly elementary rehash of the last twenty years of genetic research. Unfortunately it's not a terribly good one. His understanding of issues like human language is elementary at best. Even as science continues to discover just how much of our nature and our biology is, in fact, genetically determined, Erlich's position is that the contribution of genes to behavior is all but trivial, and that leads into the real intent of this book, which is to say his prescription for how society should be run. And not surprisingly, it's the same prescription he was making in the 1960s.

Erlich's problem is that he wants to be a social philosopher. He longs to dictate his notion of an ideal society- but he doesn't have any good social arguments. Instead he gives us specious arguments rooted in questionable scientific interpretations. The result is a poor introduction to either the nature-nurture debate or social philosophy.

Rating:
Summary: For the true believers only
Review: Professor Paul Ehrlich strikes back! Long recognized as the West's response to Lysenko, his list of scientific publications includes "The Population Bomb" and "Betrayal of Science and Reason". This time, Ehrlich ventures into the fields of genetics, evolution, and human nature. The book is recommended to the true believers only. Everybody else should consult Stephen Jay Gould, Richard Dawkins, Steven Pinker, and the likes.

Rating:
Summary: An outstanding piece of scholarship
Review: The enthusiasm associated with major scientific breakthroughs such as the sequencing of the human genome needs to be tempered with a realist view of the complex relationships between genes, cultures and the natural environment. Paul Erhlich's "Human Natures" is a timely reminder of the dangers of reductionism and the importance of placing advances in molecular biology in a wider socio-cultural context. "Human Nature" is an outstanding piece of scholarship that will shape public policy discussions on the relationship between genetics and culture for a long time to come. It is a compelling argument that deserves attention among scholars, practitioners, policy makers and students of contemporary history.

Rating:
Summary: One of the best books on human evolution
Review: This ambitious work, the magnum opus of Paul Ehrlich, Bing Professor of Population Studies and of Biological Sciences at Stanford University, and the popular author of the best selling The Population Bomb (1968) and many other works, is quite a challenge for any reviewer. Perhaps I should begin with the footnotes. There are too many of them. On page 32, for example, Ehrlich writes "...twelve populations of a gut bacterium have now been tracked..." footnoting the word "bacterium." When one turns to the back of the book, one finds simply, "Escherichia coli." Perhaps it would be better to have written "Escherichia coli" in the first place! And something needs to be done about letting us know which footnotes are extensions of the text (afterthoughts, clarifications, etc., that we might want to go chasing after) and which are merely references. Of course this is a problem with all extensive works of scholarship. I suggest two sets of notes: one for references and one for clarifications, indicated perhaps by numbers for one and alphabetic letters for the other. There are 100 pages of footnotes here (1,909 footnotes!) and 76 pages of works referenced. The index--a particularly good one, by the way--covers 18 double-columned pages.

Footnotes aside, this is a book that in a sense summarizes a long and much laureled career written by a man whose work and accomplishments we can all appreciate regardless of whether we agree with his sometimes all too politically correct conclusions. Human Natures, despite Ehrlich's careful avoidable of such terminology, is about evolutionary psychology; that is, about how our understanding of evolution and our place as evolved and evolving beings affects how we view ourselves and our prospects. His "human natures" are derived from a survey of a vast literature including the work of anthropologists, ethnologists, sociologists, biologists, sociobiologists, psychologists, evolutionary psychologists, ecologists, demographers, geneticists, behavioral geneticists, historians, etc., etc. (This splintering and proliferation of disciplines as we enter the third millennium of the current era makes one long for consilience!) Most of these disciplines and many others have as their unifying principle the process of evolution. Ehrlich writes in the Preface (p. xi) "I want to show how a greater familiarity with evolution might contribute to our resolving...the human predicament." Ehrlich is referring to cultural evolution as well as biological. His primary thesis, that we are not of one "human nature" but of various "human natures," is implicit throughout. Made explicit on page 227, is his belief that since the beginning of agriculture 10,000 years ago we human beings have been, and continue to be, more subject to the forces of cultural evolution than we are to biological evolution. He writes, "cultural evolution...at this stage of our development begins to swamp the more gradual processes of biological evolution." It's clear that he wants to emphasize cultural evolution because we can do something about it, whereas to change our biological nature would involve human genetic engineering, a process that Ehrlich is understandably loathe to endorse (see especially page 66).

Ehrlich argues strongly for the plasticity of human behavior. He doesn't like generalizations about innate behavior. This can be seen particularly in his analysis of the causes of war in the Chapter 11. He insists with some exasperation that "It is senseless from any viewpoint for people to keep acting as if it were either possible or pertinent to determine whether human beings are innately aggressive or innately pacific" (p. 264). Ehrlich wants to encourage the idea that education can lead to more desirable behaviors. If our behavior is innate, then perhaps we can't be blamed for it, and furthermore (and worse) we can't do anything about it in terms of education, etc. It is this fatalism that Ehrlich is preaching against.

In short, Ehrlich takes what might be considered a caring, "liberal," politically correct view of human nature as opposed to some others who see us merely acting out our genetically and culturally derived destinies. His position is comforting, but strange to say I really see little or no difference between his PC version of "human natures" and, e.g., Edward O. Wilson's much maligned amoral view. I think a lot of the differences are really matters of terminology and emphasis.

I want to add a couple of clarifications. Apparently Ehrlich is unaware of the full significance of "the handicap principle"advanced by Amotz and Avishag Zahavi in their book of the same name (1997) which in part explains altruism beyond kinship and reciprocity, namely that altruism is sometimes an advertisement to potential mates of one's fitness. Also in the chapter entitled "Why Men Rule" Ehrlich points to men being bigger as one of the reasons they rule, and to their being freer (because they have less of a reproductive burden) as another. But as Bobbi Low has pointed out in her Why Sex Matters (2000) men rule because there is no reproductive advantage to be gained by women in taking the reigns of power. Whereas men have been able to gain greater sexual access to females by becoming rulers and thereby increase their reproductive fitness (Bill Clinton, notwithstanding), women gain little to nothing in securing access to more males.

Also there is the matter of the synchronization of menstrual cycles by women living together discussed on page 182. Ehrlich says the evolutionary significance is unknown. Actually it's fairly clear: in a harem situation if the females become fertile all at the same time, this provides an opportunity to more broadly mix the gene pool because the harem master can't possibly do it all himself, and so other males may get an opportunity. This embarrassment of riches for the harem master reminds me of the walnut tree producing so many seeds in a boon year that the squirrels can't possible eat them all.

This is a great book engagingly written by a man at the pinnacle of his career, a man I admire and respect.

Rating:
Summary: Must-read book for integrative thinkers
Review: This book is at once the most accessible and the most scholarly book available on human evolution. The first third is an incredibly clear synopsis of the current state of knowledge about hominid evolution, and this complex story is woven in exciting (no exaggeration) prose. This alone makes the book worth reading. But the way Ehrlich uses this biological background as a frame for exploring the much more rapid pace of cultural evolution makes this a new and penetrating examination of the human condition. Perhaps it is not surprising that it is an evolutionist who has put together the best synthesis of the relationship of biological and cultural factors, but I was surprised at the relative weight this author gave these themes. The importance of cultural evolution in determining the trajectory of human societies and, in fact, the fate of life on Earth is convincingly argued. At the same time, the critical biological "sideboards" that bound what is culturally possible is clearly articulated. This book supersedes the threadbare "nature vs. nurture" argument in a single bound, and it gives us a modern perspective that is more knowledgeable, more thought provoking, and it much more exciting.

And this is not one man's perspective. Ehrlich has drawn on an incredibly diverse group of scholars, as well as his own experiences at the forefront of research in evolution, ecology, and the environment. In diverse fields, he has read widely and discussed critical issues with the recognized experts. This depth of this research is conveyed in the extensive endnotes that take up more than a third of the printed pages. I read this book with two bookmarks, one for the text, the other tracking in the endnotes, which were every bit as readable and interesting as the main text. I've been through this book cover-to-cover once, and it is already one of the standard reference books on my shelf. It is a goldmine for anyone interested in what it is to be human.

Rating:
Summary: genetic and cultural coevolution
Review: This scholarly opus written in a conversational style by Paul R. Ehrlich, Professor of Biological Sciences at Stanford University, sets forth the thesis that human nature is the product of genetic and cultural coevolution. He states that while genes predispose and constrain human behavior, its cultural expression is undetermined and highly variable. This view leads him to advocate the use of the expression, "human natures," which denotes cultural pluralism. In effect, he also argues against the position that genetic determinism fully explains human behavior.

One example he gives concerns the nature of language. Human beings may have inherited the genetic capacity for language, but they do not develop languages according to predetermined forms. Development of languages in human populations thus illustrates the undetermined quality of evolution in human behavior.

The book is roughly divided into two parts, so that the first makes a gradual transition into the second. In the first part, the author offers a detailed and complete account of human biological evolution. In the second part, he explores the evolution of human behavior, from its primitive counterparts in the behavior of other primates to its complex modern manifestations.

All throughout, his approach, according to his own description, is to summarize the latest scientific research and then to offer his own opinion on issues that are largely inconclusive. As an in-depth compendium, the book makes a good reference.

In the second part, Ehrlich tackles intriguing topics in evolutionary psychology--the evolution of language, sex, war, religion, art, ethics, to name a few. I believe any careful reader will come away, as I did, with insights. For example, I was enlightened by his observation that while our hundreds of thousands of years of genetic evolution as small-group hunter-gatherers allow us the capacity for meaningful personal interaction with perhaps 90-220 individuals, we live in modern societies organized around millions or even billions of citizens. This fact explains the impersonality and alienation in modern states besides the incredible inhumanity of wars waged on a modern scale.

However, I came away somewhat dissatisfied with the second part for two reasons. First, Ehrlich does not offer any unified theory upon which to interpret cultural evolution. On this question, he says that human culture is indeed vast and it awaits the next crop of geniuses to construct such a theory a la Darwin. Second, it became apparent, at least to me, that while the author is in his element when he draws upon disciplines cognate to his own, such as cultural anthropology, he is limited in covering the contributions of less related disciplines like economics or art history to understanding cultural evolution. But I would not expect anyone, Ehrlich included, to be so complete in scope.

I might suggest that the most rewarding way of reading the second part is to treat it as little essays, from as long as a chapter to as short as a section, in which the author is guided throughout by the interpretative framework of genetic and cultural coevolution.

This book is worth reading--and keeping--for anyone interested in human evolution.