Sunday, February 25, 2018

Mate Choice and Human Evolution

Richard O. Prum has produced a fascinating look at the role of evolution in species development in his text The Evolution of Beauty: How Darwin's Forgotten Theory of Mate Choice Shapes the Animal World - and Us.

Prum reminds us that Darwin wrote two books that defined his concept of evolution.  The first, On the Origin of Species by Means of Natural Selection, proposed the view that most describe as “survival of the fittest.”   This firmly established the notion that species evolved via natural selection as individual characteristics best adaptive to the species given environment would propagate via sexual transmission and eventually become dominant in successive generations.  This became, in most people’s minds, an all-encompassing concept that excluded other contributions to species evolution.  Everything a member of a species did must be explained as an attempt to seek a better, more survivable version of itself.  Prum refers to those who attempt to explain all data on evolution as driven by better adaption to an existing environment as “adaptionists” or neo-Darwinians.

Darwin was never convinced that natural selection, as defined in his first volume, could explain everything that he had observed.  In particular, he was troubled by the evolved tail feathers of the male peacock.  Prum provides a revealing quote from Darwin.

“It took Darwin a long time to grapple with this dilemma.  He famously wrote, ‘The sight of a feather in a peacock’s tail, whenever I gaze at it, makes me sick!’  Because the extravagance of its design seemed of no survival value whatsoever, unlike other heritable features that are the result of natural selection, the peacock’s tail seemed to challenge everything that he had said in Origin.  The insight he eventually arrived at, that there was another evolutionary force at work, was considered an unforgivable apostasy by Darwin’s orthodox, adaptionist followers.  As a consequence, the Darwinian theory of mate choice has largely been suppressed, misinterpreted, redefined, and forgotten ever since.”

Darwin eventually published a second book on evolution: The Descent of Man and Selection in Relation to Sex.  Natural selection certainly is operative, but before genes can be sexually propagated there is a mate selection process that takes place.  The example of the peacock suggests that the outrageous and functionally useless tailfeathers are not a result of environmental adaptation, but of aesthetic choices by female peahens.  They preferred to mate with males they found attractive. The consequences of this can be enormous because such choices need not lead to better adaption; rather, they can easily lead to maladaption.

If one considers how modern humans go about propagating their genes, the idea that mate selection might have little to do with adapting to climate change, for example, is not very revolutionary.  However, in Darwin’s patriarchal era, the notion that female mate selection could alter the course of evolution was deemed absurd.  Critics were much more comfortable with concepts of male-on-male competition as being determinant.

Prum devotes much of his book to demonstrating the peacock/peahen dynamic was not the exception, but the rule.  His examples from the world of birds are fascinating—and compelling.  Mate selection was always important, but each species seemed to deal with the issue differently.  The critical issue seems to be the sexual conflict between males and females over who controls the mating process.

All species seems to deal with this conflict in different ways.  And the two genders seem to have different goals.  At one extreme there is the case where males dominate such as our relatives the chimps.  In most of these cases, the alpha males are merely satisfied with having access to all females who are in estrous.  Note that this is a random practice of mate selection and it is not likely to contribute to any change in species characteristics other than to propagate the male features that lead to dominance in the male hierarchy.  Females seem to have another approach entirely to mate selection.  They tend to find certain male characteristics attractive or pleasurable and will preferably select such males for mating.  This is not a random process because the mating will result in males more likely to have the admired characteristics, and females more likely to appreciate those characteristics.  There is a positive feedback mechanism that can grow and spread throughout the species, particularly if the majority of females settle in on the same set of characteristics. 

Prum’s beloved birds consist of a huge multitude of species where female sexual autonomy is almost complete.  Female birds have almost total control over mate selection leading males of each species to audition for females in an attempt to make themselves more attractive to any female who might wander by.  Evolution under these circumstances has led to exotic ornamentation patterns for males and demanding courtship performances on their part.  The result has been an explosion in species differentiation as localized clusters of birds of a given family have evolved in different ways from their relatives.  Interestingly, most birds are descended from an ancestor that possessed a penis.  Those birds no longer possess a penis.  Prum suggests that since a penis is almost necessary if a male is to forcibly impregnate a female, the dominance of females in this sexual conflict might have rendered a male’s penis no longer of any value and it disappeared.  Of course, there is no way to know if some other factor contributed to its loss and this allowed females to exert their sexual autonomy.

There are two cases of interest that are discussed by Prum in which male or female dominance are not fully resolved and both genders participate in mate selection.  The first case is that of certain duck species in which males continue to wish to copulate with anyone they choose, and females continue to resist any forced impregnation.  Prum describes in detail the manner in which male ducks have evolved ever longer, more complex, and more powerful penises in an attempt to defeat female defense mechanisms.  The females, on their part, have evolved ever more complex vaginal channels to inhibit deep penetration by any male other than one for which the female will assume an accommodating posture.  Scientists who study such matters have concluded that the females seem to be winning this battle, if they physically survive it, by preventing fertilization in all but a few percent of the forced copulations.  This battle of the sexes is an excellent example of maladaptive evolution caused by mate selection.  This mating process results in females being injured and killed; consequently, it results in a lower population for the species and an imbalance in gender ratio. 

The second interesting case of contentious mate selection is that of the human species.  Human males and females are both selective in who they choose to mate with, meaning each gender is capable of propagating its desired characteristics.  It is not possible to tell the story of mate selection and its associated evolution among humans with any great accuracy, but Prum provides some interesting speculations that are certainly food for thought.  Prum doesn’t draw such a distinct conclusion, but a reader of his might conclude that human physical evolution was greatly driven by the desire to enhance sexual pleasure.

In order to understand human evolution within the context of mate selection, one must enumerate the differences between us and the apes from which we evolved.  Scientists tell us that homo sapiens descended from a line that broke off from the chimpanzee line about six million years ago.  Chimps lead a male-dominated existence in which males compete for hierarchical dominance which produces benefits in terms of access to females.  This type of system encourages characteristics that support male dominance.  Males are considerably larger than females and are endowed with large canines that seem to be only useful in fighting other males or in intimidating females.  Males don’t practice coercive sex because they don’t have to.  When females go into estrus they mate with dominant males as well as many subdominant males over a period of several days.  For their part, males will mate with any available female.  This seemingly promiscuous female behavior is thought to be a minimal response to their lack of sexual autonomy.

Sexual conflict has caused a horrible maladaptive response from chimp males: infanticide.  Females chimps bear almost total responsibility for raising their young.  After estrus, a female will have months of gestation followed by three or so years of breast-feeding which inhibits ovulation.  Females are then sexually unavailable for about four years.  Often among chimps and other primates, a new male will become dominant and discover that there are few if any females available to impregnate.  In a display of his dominance he will often kill infants of lactating females in order to render them sexually available again.  This practice is quite common, and it can be the most significant cause of death for young chimps.  The apparent promiscuity of chimp females is interpreted as an attempt to convince as many males as possible that they might be the parent of an infant in hopes that this possibility will inhibit a male from killing his own offspring.  Fortunately, infanticide, as a male behavior, was eventually shed by our ancestors.

It is useful to note that there is another species of chimp that broke off from the main chimpanzee line even later than humans (a mere million years ago) and, being geographically isolated, evolved quite different characteristics.  Both male and female bonobos form social structures that seem to share dominance in group affairs.  Infanticide is thought to be nonexistent.  Neither gender seems to be very selective in mate choice because the incidence of sexual interaction is quite prevalent, including same-sex contact.  Bonobos have taken sexual pleasure and made it a foundation for their social order.  Bonobos will express friendship and gratitude by offering sex.  They will use sex as a means of lessening social conflicts.  As someone once said, when unfamiliar groups of bonobos encounter each other it is more likely that an orgy will ensue rather than any form of violence. 

Sexual motivations can drive a species in many directions.

Humans have clearly evolved considerably, both physically and socially, from the ape ancestors.  If the bonobos can evolve quite different characteristics from the common chimpanzee in a mere million years, it seems rather dangerous to interpret human characteristics as being derived directly from our even more ancient ancestor.

Before considering how mate choice among humans might have coupled with natural selection to produce humans as they exist today, we should note a warning provided by Prum.  Human evolution is a story of the sexual conflict between the sexes, and over the roughly six-million-year period since we set out on our own, female sexual autonomy grew dramatically.  The males and females to which we evolved might have possessed quite different sexual and social habits than those that society has recently imposed on us in just the past few thousand years.  The evolution of our bodies is more consistent with a bonobos-like interest in sexual pleasure than our recent history might suggest.

“….I think that the advances in female sexual autonomy that occurred over millions of years since our common ancestry with the chimpanzees….have been challenged by two relatively recent cultural innovations—agriculture and the market economy that developed along with agriculture….These twin inventions came into being a scant six hundred human generations ago and created the first opportunity for wealth and the differential distribution of wealth.  When males gained cultural control over these material resources, new opportunities were created for the cultural consolidation of male social power.  The independent and parallel invention of patriarchy in many of the world’s cultures has functioned to impose male control over nearly all aspects of female life, indeed human life.  Thus the cultural evolution of patriarchy has prevented modern women from fully consolidating the previous evolutionary gains in sexual autonomy.”

In other words, women are now struggling to get back to where they were a thousand generations ago before men began convincing them they were the weaker sex and that sex itself was a male preoccupation—not one women should expect to enjoy.

“Viewing pleasure as the central, organizing force in mate choice, and mate choice as a major dynamic in evolutionary change, the aesthetic theory holds that women’s pursuit of pleasure is at the very heart of the evolution of human beauty and sexuality.”

Darwin lived in an era where the discussion of human sexuality was not conducted in open print, but he did suggest that the loss of human body hair could possibly be attributed to sexual selection—humans with little or no body hair were deemed more attractive, probably by both sexes.  Prum suggests that this contention is possible, but unprovable.  He is more interested in patches of hair that have remained because they are reminiscent of the ornamental displays birds have evolved to make themselves attractive.  Also, the emergence of pubic hair and hair in the armpits at puberty suggests an explicitly sexual role for those adornments.

“Regardless of whether the reduction of body hair is an aesthetic trait or not, it is clear that another unique trait—the retention of specialized patches of hair in the armpits, pubic region, scalp and eyebrows—is ornamental.  The fact that the retention of these patches of hair is the same in both sexes….strongly implies that it evolved through mutual mate choice, like the bright beaks and plumage of male and female puffins, parrots, and toucans.  The hypothesis that underarm and pubic hair are evolved sexual signals is further supported by the observation that these patches of hair do not develop until puberty.  These unusual patches of hair likely evolved for the purpose of pheromonal, sexual communication between mates, which is very common in mammals.”

Note that the loss of body hair for females would have been a big deal for females.  Female chimps are in almost continual bodily contact with their infants.  Chimps are born with a grasping reflex that allows them to clutch their mother’s hair and hold on as she went about collecting food (human infants are still born with that grasping instinct).  The loss of that hair would mean that the mother would have to find another way of caring for her infant while she foraged.  This would have required a dramatic change in group society whereby other mothers agreed to accept some responsibility for the care of the children of others, and/or male mates would have to also play a greater role in providing for their offspring.  Such a male attribute would then become a mate selection factor for females as they preferred males who were more domesticable.

Prum suggests that requiring a greater contribution to child rearing would have the effect of making males more particular with regard to whom they would father a child with rather than having sex with any available female.  From this would arise selected characteristics for females.

“….aesthetic male sexual preferences in human males evolved along with the increase in male parental investment….The result of this sexual choosiness has been the coevolution of distinctly female sexual ornaments—like permanent breasts and distinctive body shape—which are completely absent in other apes.”

Human females are the only mammals that have developed permanent breasts.  Since all the other mammals reproduce and raise offspring successfully with breasts that come and go as needed, it is hard to view this feature as anything other than a desired sexual ornament.

“Among the more than five thousand species of mammals on earth, permanent breast tissue is unique to humans.  The mammaries of all other animals increase in size only during ovulation and lactation, and they are not enlarged at other points in the life cycle.  Human females, however, develop enlarged breasts with the onset of sexual maturity, and they retain enlarged breast tissue throughout their lives.”

Mate selection remodeled the female body internally as well externally.  Human females, at some point became the only ape that no longer signaled when they ovulated as an invitation to males that they were ready to be impregnated.  This would produce a profound effect on sexual interactions.  Sex and reproduction were now only loosely coupled given a low probability of fertilization, allowing sex to be an activity focused mainly on pleasure.  Humans who subsequently took a fancy to each other would then plan for many sexual experiences.  This would elevate the roll of sexual pleasure in the interaction and emphasize the ability to produce sexual pleasure in a partner as a selection factor in evolution.  One can only speculate about how the change to concealed ovulation came about.  It could have been an adaptive attempt to perhaps limit the frequency of impregnations, or it could have come about because, like the bonobos, humans concluded that sexual pleasure had uses other than mere reproduction.

Male orgasm is easily understood.  It is necessary that it occur in order to disperse sperm, and it is inevitable that evolution would deliver a pleasurable feeling in order to encourage the production of more offspring.  However, female orgasm seems to have no function in reproduction, no matter how hard adaptionists have tried to invent one.

Human females may be unique in their ability to achieve a sexual orgasm.  People who study such things are able to stimulate other female animals in laboratory situations until an orgasm-like response is attained, but because animal sex is usually of short duration it is not clear that the response is ever attained naturally.  Prum provides this background.

“For example, copulation duration in gorillas and chimpanzees is measured in seconds.  On average, human copulation lasts for several minutes and of course can continue for far longer than that.”

It is not difficult to anticipate women who face many sexual encounters with a prospective mate will select on attributions such as copulation duration in an attempt to maximize their own pleasure.

“Any evolutionary explanation for longer copulation times in humans is inherently about enhancing the pleasurable sensory experience of sex”

“….female sexual pleasure and orgasm are the evolutionary consequences of female desire and choice, and are ends unto themselves.”

Female mate selection would also have a role in remodeling the physical appearance of males.  According to Prum, the human male’s penis and scrotum may be his most outstanding features.  It seems again that males evolved in a manner designed to increase sexual pleasure.

“By any measure, the human penis requires a lot of explanation.  It is substantially larger—both in absolute and relative size—than that of any of the other apes, even though humans are intermediate in body size between gorillas and chimpanzees.  The erect gorilla penis is only an inch and a half long.  The chimpanzee penis is three inches long when erect, very thin, smooth, and finely pointed at the tip.  The human penis is both longer—averaging about six inches when erect—and wider than the penis of other apes.  The human penis is also characterized by a distinctly bulbous glans and coronal ridge at its tip.  Similar structures have evolved in other primates, but they are not present in African apes.  We should also note that in contrast to their greater penis size and elaboration, humans have testes that are both relatively and absolutely smaller than those of our closest chimpanzee relatives.”

Since chimpanzee females are impregnated via copulation with multiple males, it would be natural for the males to develop large testicles in order to produce enough sperm to give them a chance to win that game of chance.  Humans have no equivalent selection process operative.  Chimpanzees then have a large scrotum to contain their large testes.  Surprisingly, humans have an even larger scrotum to contain their smaller testes.  How does one explain that?

There is another puzzling feature to the human penis.  Humans are one of only two primates that have evolved away their penis bone, the baculum.

“The existence of a baculum in the other primates means that an erection is guaranteed by the presence of an ossified bone within the penis….we do know that aside from producing erections, the baculum functions in retracting the penis between erections.  What its other functions might be is still not clear.”

So, we have human males evolving to state where they have a large floppy penis—permanently exposed—and coupled with a larger than necessary scrotum containing highly vulnerable testes.  As the humans became bipedal and stood upright this ostentatious genital display would become even more pronounced.  Male anthropologists like to view human males as aggressive warriors in frequent combat with other surly males.  Given such a picture, how could these males have produced such a vulnerable genital package via natural selection.  According to Prum, they didn’t.  It evolved because females favored bigger penises and appreciated the visual display provided by a dangling penis and a large scrotum.

“The longer, thicker, broader human penis with the bulbous glans at the end is likely to have evolved through female preferences for mail copulatory organs that produce greater pleasure.”

It would seem likely that the males’ delight in observing large breasts would be matched by females’ delight at estimating the potential pleasure to be derived from a male’s genitals.

Human females’ sexual autonomy is not as complete as in the case of most birds.  Both sexes are using choice to provide different influences in evolution.  Males contribution to childrearing is significant, but it varies widely within humans.  The desired male and female characteristics are also highly variable.  Interestingly, females seem intent on diminishing what we see as dominant male features.  It is as if there exists a species memory of a past when males exercised more coercive mating habits.

“….there is consistent evidence that females do not prefer the most ‘masculine’ facial features, which have been characterized as prominent square jaws, wide prominent brows, thick eyebrows, and thin cheeks and lips.  Numerous studies have shown that women instead prefer intermediate or even what some researchers call ‘feminine’ facial features in men, and one study has shown that females prefer a light stubble over a more masculine full beard.  According to a handful of disparate studies cited by Gangestad and Scheyd, these facial preferences seem consistent with the evidence on what women like to see in male bodies.  They tend to like lean but somewhat muscular male bodies with broad shoulders and v-shaped torsos the most, and men with larger, more muscle-bound bodies the least.”

Richard Prum has produced a fascinating look at evolution, describing a process that is more arbitrary and more interesting than we had been led to believe.  After reading his book it is difficult to think of evolution—and sex—in the same way as before.

Monday, February 19, 2018

Curing Our Macroeconomic Ills: Raising Corporate Taxes

There are many reasons to be concerned about the wisdom of enacting the recent tax bill placed into law by the Republican majorities in the Senate and House.  This bill increases fiscal deficits, provides most of the tax relief to the wealthiest citizens who need it the least, and provides more profits to corporations who are already awash in more funds than they know what to do with.  It is the lack of wisdom related to lowering corporate taxes that is addressed in two papers provided by the Washington Center for Equitable Growth

The issue being addressed is the inapplicability of standard economic analysis to our current economy.  Traditional thinking assumes that consumption will lead to company profit which will be reinvested in greater production capability which, in turn, will provide increased wages and jobs leading—in a virtuous cycle—to even greater profits.  The evidence that this virtuous cycle is not operative has been obvious for many years as economic growth is low, wages are stagnant, and corporate investment in capital is falling.  The only thing that seems to be rising are corporate profits.

A detailed analysis is provided in Kaldor and Piketty’s facts: The rise of monopoly power in the United States by Gauti Eggertsson, Jacob A. Robbins, and Ella Getz Wold.  A short summary of the study’s findings is presented in How the rise of market power in the United States may explain some macroeconomic puzzles by Jacob Robbins.  We will utilize this latter article.

Robbins states that several things have been occurring over recent decades that are inconsistent with the assumption of an efficient marketplace.  Included are the facts that the financial values of companies have become much greater than the value of their assets, yet these companies have used their increased wealth, as driven by increased profits, not to invest in assets for greater production, but to diminish labor and other costs in order to maximize profits.  These are classic signs of companies that are not threatened by competition, but rather, are securely in control of their markets.  In other words, they have some degree of monopolistic power.

“….Gauti Eggertsson, Ella Getz Wold, and I at Brown University argue that these diverse trends are closely connected, and that the driving force behind them is an increase in monopoly power together with a decline in interest rates.”

“Here’s how it works: An increase in firms’ market power leads to an increase in monopoly rents-economic parlance for profits in excess of competitive market conditions-and thus an increase in the market value of stocks (which hold the rights to these rents). This leads to an increase in financial wealth and to what’s known as Tobin’s Q, the ratio of a firm’s financial value (market capitalization) to the value of its assets (book value).”

Robbins provides the following plots of US financial wealth and capital value divided by GDP over time.



Clearly a transformation in the macroeconomic character of the economy began in the 1980s.  Companies began investing less of their income in capital and wages and keeping more of it in profit.  What does Robbins believe is an appropriate response to this situation?

“Greater monopoly power tends to depress economic growth and increase income and wealth inequality. With high levels of monopoly profits, it may be optimal to have higher taxes on corporate income than would be suggested by analyses that assume perfect market competition.”

In other words, if the economy is suffering low growth because companies see no need to invest profits in greater production capability and higher wages, then the government must consider extracting those unused profits via higher corporate taxes and plan to use those funds for projects that do create jobs and assets.

This analysis seems right on target.  Yet, we have just done just the opposite.  Lowering corporate taxes allows for greater company profit with no increase in investment, and the increase in wealth will allow companies to gain even greater control of their markets.  Company profits have been increasing for many years while the share of income devoted to wages has been falling.  The supposed “trickling down” has not occurred in the past, nor will it in the future.

It seems that when intelligent people gather to choose leaders they tend to choose the most intelligent and knowledgeable among them.  However, when corrupt people gather together, they seem to prefer the most corrupt among them as leaders.

Tuesday, February 13, 2018

The Evolution of Beauty by Richard O. Prum

For most of us, the idea of heading out into the wilderness in hope of catching sight of some interesting birds likely seems strange and inevitably boring.  However, a new book, while probably not convincing many readers to head for the woods, will convince most that birds are pretty damned interesting.  Richard O. Prum is an ornithologist at Yale University who mines his knowledge of various bird species to provide some fascinating insights into the true nature of evolution in The Evolution of Beauty: How Darwin's Forgotten Theory of Mate Choice Shapes the Animal World - and Us.  You will never think of evolution in the same way again after reading this book.  You will probably never think of sex in the same way either.

Prum’s thesis centers on the mistake evolutionary theorists make in focusing on the conclusions of Darwin’s first landmark book On the Origin of Species by Means of Natural Selection, and ignoring the conclusions produced in his second great volume The Descent of Man and Selection in Relation to Sex. 

Focusing on the first book has led to the standard prescription of survival of the fittest.  From this perspective, natural selection enhances characteristics that best ensure the propagation of a given species.  It does this by providing a better means of adapting to whatever environmental conditions are operative.  Prum claims that adherents to this limited view of evolution call themselves Darwinists, but they have betrayed Darwin who concluded that such a view could not explain all features of evolution.  Prum refers to such people as neo-Darwinists, or adaptionists.

“I am convinced that most of those who think of themselves as Darwinians today—the neo-Darwinists—have gotten Darwin all wrong.  The real Darwin has been excised from modern scientific hagiography.”

The weakness of a strict adaptionist approach is that it does not consider that an animal with really great genes has to get them propagated by finding an animal of the opposite sex willing to mate with it.  We know from our own experience as human animals that mate selection is a complicated venture, one that does not necessarily focus merely on producing survivable offspring.  Generally, we will select and consider mating with someone to whom we feel a physical attraction—someone we consider “beautiful.”  Considerations of fitness as a parent of a subsequent child may or may not arise later.  In fact, humans have evolved to a state where sex and mating are essentially two separate considerations.

Are we so confident in our uniqueness that we can’t consider that animals may be driven by similar considerations?  Darwin wasn’t.

“Natural selection cannot be the only dynamic at work in evolution, Darwin maintained in Descent, because it cannot fully account for the extraordinary diversity of ornament we see in the biological world.”

“It took Darwin a long time to grapple with this dilemma.  He famously wrote, ‘The sight of a feather in a peacock’s tail, whenever I gaze at it, makes me sick!’  Because the extravagance of its design seemed of no survival value whatsoever, unlike other heritable features that are the result of natural selection, the peacock’s tail seemed to challenge everything that he had said in Origin.  The insight he eventually arrived at, that there was another evolutionary force at work, was considered an unforgivable apostasy by Darwin’s orthodox, adaptionist followers.  As a consequence, the Darwinian theory of mate choice has largely been suppressed, misinterpreted, redefined, and forgotten ever since.”

The neo-Darwinians of his era were also influenced by a bit of misogyny.  The obvious explanation of the peacock’s tail is that it evolved because the female peahen thought beautiful tail feathers were sexually attractive.  Peacocks with the best tail feathers were the most likely to be selected as a mate by a peahen.  There are three crucial considerations that follow from that conclusion.  The first is that the female of the species had attained autonomy in mate selection, something that a patriarchal society of male scientists might consider to be too outlandish to be true.  The second is that female mate selection has driven a pattern of coevolution in which females’ evolving choices have produced the evolution of the desired characteristics in the male.  The third thing that follows is that mate selection, and its consequences, need not lead to improvement in survivability of a species.  In fact, it can lead to the opposite.

Prum refers to evolution by mate selection as “aesthetic” evolution.

“Aesthetic evolution by mate choice is an idea so dangerous that it had to be laundered out of Darwinism itself in order to preserve the omnipotence of the explanatory power of natural selection.  Only when Darwin’s aesthetic view of evolution is restored to the biological and cultural mainstream will we have a science capable of explaining the diversity of beauty in nature.”

To fully grasp Darwin’s conception of mate choice as an evolutionary process, one must accept that there is innate sexual conflict between males and females of a given species.  One must also accept that females will strive to have freedom of choice as to who they will mate with.  That is not too difficult a concept from a human perspective, but for the Victorian males Darwin had to contend with, applying it to animals was what Prum refers to as “a bridge too far.”

Each species seems to resolve this conflict in its own way.  At one extreme there are species where female autonomy is essentially nonexistent.  That does not mean that sex is necessarily coercive on the part of the male.  In these cases, males will often contend against each other for dominance and the associated access to females.  At the other extreme are species where female mate selection is dominant and males must audition for females if they wish to copulate with them.  Most bird species fall into this category and provide the prototypes that drove Darwin to his conclusion and set off Prum to write his book.  However, there are also species where this sexual conflict has not been successfully resolved.  Prum provides an example that illustrates the potential power of female sexual autonomy and demonstrates that sexual conflict can drive evolution in directions that are maladaptive in terms of species survivability.

Prum devotes an entire chapter to the fascinating story of “duck sex” in which males have spent millions of years evolving the tools to allow them to coercively inseminate a female against her will.  Meanwhile, female ducks have spent millions of years evolving tools to allow them to be inseminated only by the male of their choice.  Many females are injured or even killed in the annual mating process as they try to resist undesired males.  It makes a fascinating story that needs recounting in detail.

So, mate choice is a potent force in evolution.  Once one sex develops a fancy for some characteristic in the opposite sex, and that sex has some degree of autonomy, possessors of that characteristic will become more successful at mating and that characteristic will be enhanced in subsequent generations.  The desire for that characteristic will also be enhanced by natural selection.  In fact, the initial degree of autonomy will also be enhanced.  An aesthetic choice on the part of members of a species alters the evolution of that species—for better or worse.

Except for the unfortunate duck situation, most bird species have settled into situations where the females exercise sexual autonomy, leaving the males to compete for the ladies’ favor.  This has resulted in males developing exotic ornaments such as feather displays and fancy color patterns as means of attraction.  Many also practice physical displays consisting of flight gymnastics or suggestive posturing.  In some cases, male birds will congregate in the equivalent of arenas maintained for auditioning before any female who wanders by.  Members of a species that become geographically isolated will develop regional peculiarities in ornamentation and in their mating rituals.

Curiously, although birds evolved from species that possessed a penis, most birds have lost their penis somewhere along the way (the unfortunate ducks are an exception).  Those who might be uncomfortable in a situation where females have absolute power over sex and reproduction might note that it is extremely difficult to coerce a female into having sex without a penis.  Copulation without one requires the cooperation of the female in the transfer of sperm.  Could the bird penis have disappeared as a result of female desire to eliminate the threat from forced copulations?

Prum does not hesitate to speculate.

“Birds originally inherited the penis from their dinosaurian ancestors, but then it was lost some sixty-six to seventy million years ago in the most recent common ancestor of the group known as the Neoaves, which includes over 95 percent of the world’s species of birds.”

“It’s possible that the neoavian penis was lost because females explicitly preferred males without penises.  Why?  If one of the primary functions of the penis is to subvert female mate choice through forced copulations, as it is in waterfowl, then female mating preferences against intromission could have evolved to reduce the threat to female sexual autonomy.”

Mere wishing cannot make the penis disappear.  There must be a mechanism that renders it of little or no value to the male.  Selection via female choice could lead to ever-smaller penises until they became ineffective.

“In the more than 95 percent of bird species that are penis-free, females can eject/reject unwanted sperm.  For example, barnyard hens can eject sperm after coerced copulations with unwanted males.  Attempts at sexual harassment and intimidation do still exist in birds without a penis, and the female birds may still suffer injuries by resistance, but the loss of the penis has resulted in a nearly complete end to forced fertilizations.  Through the loss of the penis, female neoavian birds have essentially won the battle of sexual conflict over fertilization.”

Birds have become the most differentiated of species as they generated an explosion of variations of plumage and other ornamentations.  Prum speculates that it was this complete victory of females resulting in the loss of a penis that forced males to evolve ever more effective means of attracting females, leading to an “aesthetic evolutionary extravaganza” among birds.

Birds are interesting, but humans are too.  Mate choice and the conflict over sexual autonomy are also part of human evolutionary history.  Prum devotes a significant section of his book to trying to address the extent to which aesthetic choices have had, and continue to have, impacts on human evolution.  That must be a topic for another day.


The interested reader might find the following articles informative:

Bonobos, Christians, Scandinavians, Atheists, and Government

Are Humans Inherently Warlike?

Change in Human Brain Size, Natural Selection, and Evolution

Brains, Energy, and Humanity’s Most Important Achievement: Learning to Cook

Tuesday, February 6, 2018

Inequality: The Great Compression Came After Thirty Years of Conflict; Is the Conflict Necessary?

Walter Scheidel assumed the task of applying a historian’s perspective to the history of economic inequality as it can be determined from early historical periods to the present day.  He presented his findings in the book The Great Leveler: Violence and the History of Inequality from the Stone Age to the Twenty-First Century.  His conclusions were rather grim.

“For thousands of years, civilization did not lend itself to peaceful equalization.  Across a wide range of societies and different levels of development, stability favored economic inequality.  This was as true of Pharaonic Egypt as it was of Victorian England, as true of the Roman Empire as of the United States….Four different kinds of violent ruptures have flattened inequality: mass mobilization warfare, transformative revolution, state failure, and lethal pandemics….Sometimes acting individually and sometimes in concert with one another, they produced outcomes that to contemporaries often seemed nothing short of apocalyptic.  Hundreds of millions perished in their wake.  And by the time the dust had settled, the gap between the haves and the have-nots had shrunk, sometimes dramatically.”

It seems that elites with some degree of power, however they accumulated it, would use their power to accumulate more wealth.  This conduct was apparent in the earliest states and persists to this day in modern democracies.  Peace and stability were the conditions under which inequality thrived and grew.  States provided the elites with protection of their wealth and business activities and provided them access to the levers of power so that they could enrich themselves further at the nation’s expense.  State collapse, such as that of the Roman Empire, can render the elites much poorer by eliminating state protection of assets and by withdrawing access to public wealth that might no longer exist.

Pandemics such as the Black Death provided a very direct mechanism for diminishing inequality: if up to half of the population of workers are killed, then those who survive will earn higher wages.  The laboring class had acquired the means to demand and receive greater compensation.  Population would always increase and return to greater inequality was inevitable.

Most revolutions were ineffective at bringing about significant leveling of inequality.  Only the Communist revolutions in Russia and China actually managed to pull it off.  However, only after the use of violence to attain goals.  Many people died in the course of these revolutions, and the leveling generally involved the destruction of wealth rather than its redistribution.  Equality was attained at great price, but it often meant everyone was in an equally poor state.

It would be only in the twentieth century that wars would grow sufficiently consequential that changes would occur that lessened economic inequality to a significant degree and kept it low for an extended period.  Scheidel provides this summary.

“For war to level disparities in income and wealth, it needed to penetrate society as a whole, to mobilize people and resources on a scale that was often only feasible in modern nation-states.  This explains why the two world wars were among the greatest levelers in history.  The physical destruction wrought by industrial-scale warfare, confiscatory taxation, government intervention in the economy, inflation, disruption to global flows of goods and capital, and other factors all combined to wipe-out elites’ wealth and redistribute resources.”

Scheidel combines his history of violent changes with the inability to provide change peacefully and reaches this gloomy conclusion.

“If history is anything to go by, peaceful policy reform will prove unequal to the growing challenges ahead.  But what of the alternatives?  All of us who prize greater economic equality would do well to remember that with the rarest of exceptions, it was only ever brought forth in sorrow.  Be careful what you wish for.”

While “mass mobilization warfare,” as evidenced by the two world wars, caused a great deal of death and much destruction of physical assets, a considerable fraction of the actual leveling in the Great Compression came about through social and political changes.  Could those changes have occurred without the warfare?  Could significant developments cause social change on a massive scale without the violence of war?

Let’s examine some data provided by Thomas Picketty in his Capital in the Twenty-First Century.  This figure utilizes the income share of the highest 10% of the wage earners as an indication of income inequality.  The data covers several European war-impacted countries and the United States from 1900 to 2010.



All the European nations tracked experienced decreases in inequality during the first world war.  Except for the UK, all then saw small upticks from 1920 to 1930 as normalcy was apparently making a comeback.  The US actually increased in inequality during the war years from 1910 to 1920.  All countries then experienced a significant leveling during the depression era of the 1930s.  Changes incurred during and immediately after the second world war were generally smaller than those encountered during The Great Depression.  It would be around 1970 that the elites began fighting back and propagated neoliberal concepts designed to reestablish their dominance.  This set the UK and the US off in a race to determine who would become the most unequal nation.  However, by this measure, Germany and France changed little over the period from 1950 to 2010.  Note also that Sweden, the European country least affected by the damage of war, continued to lower its level of inequality from 1960 to 1980.  Whatever policies the Swedes had implemented to cause that change seem to be under attack by the elites there as well.

The point of that survey was to suggest that policies necessitated by severe societal stresses were responsible for much of the leveling of inequality that occurred.  And in some cases, those policies have persisted into the current era.  These observations provide some degree of hope that societies in states of severe stress in the future would be able to address their problems without the violence brought by war.

Let us discuss the policy decisions necessitated by mass mobilization war and consider whether these are actions that could reasonably be taken in peacetime by a nation facing critical problems.

Wars are tremendously expensive.  The government quickly realizes the only source of such large amounts of funds is highly progressive taxation.  One must extract the money from where the money exists.  Progressive taxation is a well-known method of leveling economic inequality.  To efficiently extract wealth from those in possession of it, one must tax not only income but wealth itself.  Taxes on wealth and inheritance were also efficient means of leveling.

The need for dramatic increases in spending to support a war can easily feed inflation.  Inflation was extremely harmful to the wealthy who disproportionately invested in bonds and other capital investments.

Scheidel discusses at length the social and economic ramifications of asking a nation’s population to make sacrifices, and even risk their lives.  Such a situation is quite supportive of democratic rights.  He includes a long list of the instances where European nations followed a war with an expansion of electoral rights for their citizens.

“….modern scholarship has repeatedly linked mass warfare and the extension of political rights.  Insofar as raising mass armies requires societal consent, extensions of the franchise may be regarded as a logical corollary of intense military mobilization.”

“Broadly speaking, European peacefulness after 1815 had retarded political reform.  This changed dramatically with the unprecedently massive mobilizations of the world wars.  Full male suffrage was introduced in 1917 in the Netherlands and in 1918 in Belgium, Ireland, Italy, and the United Kingdom.  Universal suffrage became the law in Denmark in 1915; in Austria, Estonia, Hungary, Latvia, Poland, and (technically) Russia in 1918; in Germany, Luxembourg, the Netherlands, and Sweden in1919; in Anglophone Canada, the United States, and Czechoslovakia in 1920; in Ireland and Lithuania in 1921.”

Scheidel uses the example of President Woodrow Wilson seeking to sell suffrage for women as a consequence of wartime’s call to duty with this quote.

“….essential to the successful prosecution of the war of humanity in which we are engaged….We have made partners of the women in this war.  Shall we admit them only to a partnership of sacrifice and suffering and toll and not to a partnership of privilege and right?”

The social and political implications of asking the poorest paid to accept the greatest risks in a time of war can produce notable changes in the social contract.  Scheidel provides this quote from Max Weber.

“Military discipline meant the triumph of democracy because the community wished and was compelled to secure the cooperation of the nonaristocratic masses and hence put arms, and along with arms political power, into their hands.”

Scheidel provides this view of the mood of the affected peoples as they emerged from World War II.

“Widely diffused across national populations, these dislocations eroded class distinctions and raised expectations of fairness, participation, inclusion, and the acknowledgment of universal social rights, expectations that were fundamentally at odds with the highly skewed distribution of material resources that had characterized the prewar period.  Wartime state planning gave a boost to collectivist thinking.  A large body of scholarship concurs that the experience of the world wars was a crucial catalyst for the creation of the modern welfare state.”

Could these changes in social expectations have occurred without the death and destruction experienced by the major participants?  Sweden provides an example that suggests a positive answer.

Sweden was not a direct participant in the warfare of the 1940s, but it did experience the threat of war.  It found itself threatened by the allies who resented any assistance provided Germany on one side and the Germans who had to be ready to attack if the allies moved into Sweden on the other.  The result was that Sweden had to mobilize for full-scale war but escaped from its realization.

“Military spending increased eightfold in the course of the war.  Whereas fiscal responses to the Great Depression had remained modest, the tax reform of 1939 greatly raised top rates and created a temporary defense tax that became highly progressive only for the highest earners and that was further sharpened in 1940 and 1942.  In addition, the statutory corporate tax rate rose to 40 percent.  The strengthening of military capacity was the official rational for all these measures.  Thanks to the threat of war, in a telling departure from the fractious politics of the 1920s ad 1930s, these reforms were passed with little debate or controversy as an almost unanimous political decision.”

“Moreover, mass mobilization generated social effects well beyond the fiscal sphere.  It transformed what had been a right-wing military force into a people’s army based on mass conscription and volunteerism.  Some 400,000 men served out of a population of 6.3 million.  Shared military and civilian service helped overcome existing distrust and fostered teamwork and mutual dependency.  Sacrifice went beyond service as such: some 50,000 soldiers were invalided as the result of injuries, accidents, and harsh service conditions.  Rationing likewise served as a crucial means of leveling class differences.  The war thus promoted homogeneity and civic engagement.”

Sweden emerged from the war years as a changed nation.  The increased economic homogeneity and the experienced solidarity between its citizens became the basis for its postwar politics.  Henceforth, the political goal would be as follows.

“….the majority is liberated from dependence upon a few owners of capital, and the social order based on economic classes is replaced by a community of citizens cooperating on the basis of freedom and equality.”

The data presented earlier indicated that Sweden had kept its promise to its people and inequality continued to fall well after the end of the war.

As to the question of whether inequality can be levelled without the death and destruction inherent in mass mobilization warfare, Sweden provides a glimmer of optimism.  Sweden required a near-existential threat before it got its act together.  Could it, or any other country, have accomplished the same with merely an act of democratic will? 

One would like to believe that is the case in spite of history’s lessons.

It is sad to consider that only catastrophe, or at least the threat of catastrophe, is capable of producing a feeling of solidarity within a nation and of motivating it to produce a more egalitarian society.  If one chooses to believe that, and if one wishes to anticipate a day when more societies will take the path pursued by Sweden (and the other Nordic countries) there may yet be a few more catastrophes in store.

Global warming may induce changes on a catastrophic scale.  Rising sea levels and changing weather patterns are going to cause huge internal migrations and require wartime levels of government spending.

Automation coupled with artificial intelligence could soon cause an employment crisis in which even low-level work is disappearing.  Capitalism as we know it has no answer to such a situation.  Society will have to decide how it wishes to engage such a future.

Every flu season we are reminded that influenza can be a potent killer.  Every few years a new virus migrates out of some unknown place to scare us with its potential for a deadly pandemic.

There are still people out there who continue to believe that nuclear explosives are viable weapons in international conflicts.

The world’s population continues to climb, climate is changing, and conflict over resources is ongoing.  Malthus is out there patiently waiting.

Scheidel may be only partly correct.  Death and violence are not absolutely necessary for the leveling of inequality, but future historians are likely to agree with his assessment.

“….it was only ever brought forth in sorrow.  Be careful what you wish for.”


The interested reader might find the following articles informative:

Massive Violence, Widespread Death, and the History of Inexorable Inequality

The Creation of the Middle Class

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