slime and minds

My intellectual career began with the reading of two books under the guide of an excellent teacher: Jeffrey Wallin.  The Crisis of the House Divided, by Harry Jaffa, convinced me that the principles of the Declaration of Independence, as articulated by Abraham Lincoln, provided a solid foundation for an understanding of justice.  All human beings are in fact created equal, endowed by the laws of nature to certain unalienable rights. 

Natural Right and History, by Leo Strauss, convinced me that the account of justice articulated by the Socratic philosophers-Socrates, Plato and Xenophon, and Aristotle, was superior to the relativism and historicism that then still dominated the historical and social sciences.  At the bottom of this choice was a fundamental metaphysical question: are human beings part of the natural order, such that human nature can be understood in the way that the nature of other living things can be understood?  Or are the human things-individual psychologies and collective cultures-somehow sequestered, walled off from our biological nature? 

There was never any good reason to believe the latter.  It has become increasingly untenable.  By contrast, the Socratic approach now has compelling support from modern biology.  Just as human beings share much of our natural endowment with other living organisms, so those organisms should present at least elemental forms of our highest spiritual capacities.  If anything unifies the Socratic approach it is the idea that the nature that surrounds, if not possessed of logos, is at least logical. 

Powerful support for that idea is found in recent research into the humble slime mold.  Slime molds are republics of amoebae.  The citizens of that republic are single eukaryotic cells.  As they grow they form clusters and then tubes that squeeze columns of their brethren alone, like tooth paste squeezed out the nozzle.  These tubes grow out in search of food. 

The current episode of NOVA is a marvelous account of how intelligent these slime mold colonies are.  They can navigate a maze.  They can explore corridors and quickly abandon fruitless routes.  They can learn where they have been before and learn that certain unpleasant routes (a salt covered bridge for example) are nonetheless the routes to plentiful food sources.  How they do all this is the next mystery, but they do it. 

I am hesitant to call this behavior intelligence, as the scientists interviewed are tempted to do.  For my part, that is a translator’s bias.  I translate the Greek nous as intelligence, and nous indicates an understanding of what something really is.  That requires a conscious mind.  Slime mold amoebae have no brains or nervous systems.  It is unlikely that they are conscious. 

I have no hesitation in saying that the slime mold colony presents a mind.  The colony acquires information about its environment and processes that information into action strategically.  If that’s not mind, I don’t know what is. 

I am, I would like to tell myself, capable of nous.  This is because my brain is a much more sophisticated thing than a slime mold colony.  In one respect, it is much the same.  My brain has about eighty-six billion neurons.  These are just single cells capable interesting electro-chemical reactions, but they are wired together in such a way as to allow me to read Plato’s Republic.  This doesn’t mean that my thinking is reduced to mere slime.  It means that the slime had the potential for philosophy.

Contra Genetic Determinism

 One of the things you are warned against if you study (or dare to teach) logic is the strawman argument.  This informal fallacy occurs when someone more or less deliberately constructs a weakened version of her opponent’s argument (the straw man) in order to easily knock it down.  You say that people have a right to bear arms.  Should we really allow anyone to walk around with a grenade launcher? 

My least favorite strawman argument is expressed in the phrase it’s not all in the genes.  When I searched for that phrase a moment ago, Google reported one hundred and fifty-three million results.  It is apparently a popular straw man. 

It is always deployed as if it were a response to someone who claims that it is “all in the genes.”  That phrase indicates the idea of genetic determinism.  It is conceivable that individual minds and behaviors are largely controlled by genes in the same way that a player piano is controlled by the holes in a rotating scroll.  I say largely because I wish to avoid building my own strawman. 

The reason that “all in the genes” indicates a straw man is that no one believes in genetic determinism.  Genes provide the fundamental elements of the recipe that an organism uses to build itself from its beginning and maintain itself during its life.  That is indeed most of the story of how I came to be and continue to be a human being.  It is not at all the entire story nor even the most dramatic part of the story.

Many of the “not in the genes” refer to epigenetics.  How genes are packaged in the nucleus of a cell can determine which genes are expressed and how they are expressed in the actualized individual.  Epigenetic changes frequently result of environmental influences.  A mouse whose mother is devotedly nurtured and fondled by her mother will not only do the same to her offspring, but those offspring will inherit the same tendency.  This is a very important discovery which should be but has yet to be integrated into social science. 

This implicates one of my chief interests as somewhat reconstructed Aristotelian: the concept of species.  This article by Peter Ward in Nautilus tells the story. 

Work along the Great Barrier Reef in the 1990s had shown that two different and accepted species are present. One, Nautilus pompilius, is the most widespread of all the nautiluses across their vast Pacific and Indian Ocean range. The second, Nautilus stenomphalus, is found only on the Great Barrier Reef. It differs from the more common N. pompilius in having a hole right at the center of its shell. (In N. pompilius, there is a thick calcareous plug.) There are also marked differences in shell coloration and pattern of stripes on the shell. But when the Australian species was first brought up from its 1,000-foot habitat alive, in the late 20th century, scientists were astonished to find that N. stenomphalus has markedly different anatomy as well on its thick “hood,” a large fleshy area that protects the interior guts and other anatomical soft parts when the animal pulls into its shell. In N. pompilius the hood is covered with low bumps of flesh, like warts. Meanwhile the N. stenomphalus hood is covered with a forest of brushy projections that rise above the hood like a thick carpet of twiggy moss, or tiny trees of flesh; the coloration of the hood is also radically different.

So we have not one nautilus but two different… what is the plural of nautilus?  The two were recognized as distinct species, but what does that mean? 

A species can be defined as an interbreeding or potentially interbreeding population of organisms (the most useful but not only useful account, in my opinion) or as branches of the phylogenetic tree.  Either way, you would expect the two to have distinct sets of genetic inheritance.  No. 

We caught 30 nautiluses over nine days, snipped off a one-millimeter-long tip of one of each nautilus’ 90 tentacles, and returned all back to their habitats alive (if cranky). All the samples were later analyzed in the large machines that read DNA sequences, and to our complete surprise we found that the DNA of N. pompilius and the morphologically different N. stenomphalus was identical. No genetic difference, yet radically different morphology.

Let’s repeat that: no genetic difference, yet radically different morphology.  Genes do not even determine the final physical structure of an organism such as this, though to be sure they heavily influence it and explain the common morphological traits.  So much for it’s all in the genes. 

I would add that the difference between the two species is not determined by the environment either.  It is determined by the interaction between the common biologically heritable factors and the environment.  The ontogeny, or development of these creatures is a dialogue, not a recitation. 

What is true of biological structures is much truer of minds and behaviors.  A human being becomes what she is by a series of dialogues between her genome and the environment and between herself and the human community with which she interacts.  In this series of dialogues, she is not the least of the dramatis personae. 

The Solid Natural Foundation for Human Moral Equality

I believe I heard this from Professor Harry Jaffa, but it was a long time ago and I am going from memory alone.  If my memory is wrong, neither Professor Jaffa nor Mortimer Adler bear any responsibility.

Adler was teaching a class on classical texts during the Second World War.  As so many young men were missing from the home front, Adler’s class consisted entirely of women.  He was trying to illustrate the concept of human nature with this scenario.  “Suppose a creature entered the room.  He is eight feet tall, covered in hair, with fangs.  He sits down in one of these chairs and discusses the classical texts with us.  Would that be a man?”  After a brief pause for thought, one of the young ladies replied: “Well, Mr. Adler, times are hard.”

That joke, as I remember it, perfectly expresses the point I was making in my last post.  Adler’s imaginary monster may not belong to the biological species Homo sapiens, but he shows clear signs of being human in a moral sense.  He can read and communicate in auditory symbols, which suggests the uniquely human power (on this planet in this age) of logos. 

Is this a secure foundation for the doctrine of unalienable rights expressed in the Declaration of Independence?  I submit that it provides the most secure foundation possible: it works for anyone who can recognize the difference between plants, non-human animals, and human beings.

There is a very good reason why we recognize that animals and plants have a very different moral status.  We are concerned enough about animals that we punish people who abuse them.  We live in weird times but, so far as I know, no one has been arrested for abusing a carrot.  The reason is that the two kinds of organisms occupy very different levels on the existential pyramid.  Plants can flourish or wither, but they cannot suffer.  Animals can suffer and because we recognize that we do or should care about how we treat them.  This moral fact is a robust as the difference between a horse and a horse chestnut. 

The same order of distinction presents between human beings and animals.  Perhaps we shouldn’t exploit animals at all, let alone eat them, the way we do plants.  Some people believe that.  No reasonable person can say that we ought to give a dog the vote or allow her a space for liberty and the pursuit of happiness.  Dogs are, by nature, capable of no such things. 

The phrase “all men are created equal,” understanding “men” to mean all human beings, is grounded in such distinctions.  I can conceive of no better ground for human rights than in the nature of the creatures that we encounter in this world. 

Biological Species & Natural Kinds

If I have one big idea it is that one can understand Platonic and Aristotelian ontology and metaphysics better (or perhaps at all) by comparing them with modern evolutionary biology and vice versa.  I think I began to understand Aristotle much better, after decades of reading the Physics and the Metaphysics, when I realized that many contemporary debates in the philosophy of biology were recapitulating problems already present in Aristotle. 

Two days ago, I grabbed a book off my self on the way to the toilet.  Some of my biological processes seem to require reading material.  Darwinism and Philosophy [ed. Vittorio Hösle and Christian Illies (2005)] included an essay by Michael T. Ghiselin.  The latter is most famous for his answer to one of the great questions of modern biology: what is a species?  Is it a natural kind, like oxygen in the periodic table of elements?  Is it a group of (potentially) interbreeding organisms like elk?  Is it merely a customary grouping, like red pieces of laundry?  Each of these answers has its proponents. 

Ghiselin’s answer is that a species in an individual.  If that makes no obvious sense, you are in good company.  It made no sense to me until, sitting on porcelain and doing God’s work, I realized that Aristotle had joined the conversation.  By the time I finished the paperwork and returned to my desk, I was convinced that I understood Ghiselin’s argument and I was convinced that he was right. 

An individual is something that is located in space and time and, for that reason, has a history.  The Garmin fitness tracker on my left wrist is an individual; this one is mine, not somebody else’s.  The same is true of my wrist and me.  I had a beginning in time and my being traces a continuous path from that time and place to now.  The same is true of Homo neanderthalensis.  That species had a beginning, spread out across portions of the globe, and came to an end. 

Natural kinds are not located in time and space the same way.  Gold is gold wherever it occurs, whether it was dug up in California or discovered on Mars or produced in a supercollider.  As opposed to individual lumps of gold, gold has no history; it has only essential properties. 

Aristotle covered this same ground.  There are things that have properties-horses for example-and there are the properties that such things have-shape, weight, and species forms.  The things that have properties would seem to be the things that are real.  A horse can change color (age happens, even to Seabiscuit) and yet remain a horse; its color exists on in the horse and the color ceases to exist when the color has changed. 

This suggests one answer to the question: what is most genuinely real?  For the purposes of biology, at least, it is the individual organism.  From the horse one can abstract downward to its properties (color and size), its matter (meat and bone), and its parts (limbs and organs).  Likewise, one can abstract upwards to its species form, which links it to the other horses.  All of these are abstractions because they exist only in analysis; they depend for their reality on this here animal. 

Aristotle might have rested with this had he not inherited the central problem of Greek philosophy.  What is most real should be what is most knowable.  It is not clear that I can know anything about individual organisms.  Is she short or tall, young or old, alive or not.  On the other hand, I can know that horses are mammalian quadrupeds in a rather more secure way. 

Ghiselin’s view that species are individuals seems to address this problem.  If species are not eternal, they are not knowable in the same sense that triangles are knowable.  They are at least more knowable that a particular horse.  His account points, however, toward a solution to the problem. 

Ghiselin does not deny that the species as natural kind account points to something real.  The species horse is an emphatically real thing: there are lots of horses.  The natural kinds horse, mammal, etc., are real in so far as horses really are horses and mammals.  He just insists that natural kinds of this sort are properties of individual species. 

A good indication that we are on the right track is that our account to solve problems that once seemed too difficult.  I was raised, intellectually speaking, in a hotbed of natural rights theorists.  Under the guidance of Harry V. Jaffa, we took the Declaration of Independence very seriously.  In that I have not wavered. 

The Declaration speaks of the Laws of Nature and of Nature’s God.  Inferred from such laws is the self-evident truth that all men are created equal in so far as they enjoy certain unalienable rights.  Here I understand “men” to mean human beings.  My colleagues who reject evolutionary biology do so on the grounds that undermines confidence in the existence of a stable human nature that can bear such properties as unalienable rights. 

In the evolutionary scheme, species seem to differ not in kind but only in degree.  For example, lions and tigers can mate and produce ligers, hybrids that are not capable of having offspring.  This means that the two species share a large percentage of their DNA but not enough to produce a lineage.  So lions and tigers differ, genetically, only in degree.  Species as individuals emerged from common ancestors and so differ only in their unique history and genomic families.  From that point of view, the critics appear to be correct. 

Not so fast.  Individual species also present real differences in natural kind.  A particular lion may be so much a tiger, genetically speaking, and he may be bigger than more aggressive than another male lion when he squares off on the field of reproductive competition.  He is, however, no more a lion than any one of his competitors.  Socrates, Aristotle insists, is no more a man than any of his interlocutors. 

To bring this back to the Declaration, allow me to indulge in a little science fiction.  Suppose we encounter living organisms on another world.  Assume that these organisms emerged historically through the same evolutionary processes as life on earth.  We will find there no organisms that belong to the same species as those on our planet, at least in Ghiselin’s terms.  None of those species will have a common history with any of our species.  Yet the fact that we recognize them as living organisms means that they do share something vitally important.  The living organism is a natural kind.

Now suppose that we encounter Vulcans or something of that sort.  Green blood and distinct biological history notwithstanding, they are capable of symbolic communication and moral responsibility.  They can recognize mutual obligations between themselves and us newcomers.  They are capable of making contracts.  Are they “men” as the Declaration means that term?  Of course.

Human beings are certain kinds of beings.  Our species has its unique biological history, just as do individuals and populations of individuals within that larger individual that is our species.  While we are diverse in many respects, no son or daughter of humankind is more an organism, or a mammal, or a human being than any other.  I find the distinction between species as individuals and natural kinds to be worth thinking about.

Police Shootings & Racial Bias

The fundamental assumption underlying the protests and riots that followed the death of George Floyd is that racism in police departments across the US is responsible for the fact that a disproportionate number of Black males are shot by the police.  I say “death” and not “murder” not because I have any doubts about the facts because I suspect that the constant use of the latter term, especially by such persons as the Minneapolis chief of police, may make it harder for a court to do justice in this case. 

My purpose here is to question that assumption.  About twice as many White persons are shot and killed by police officers as Black persons, according to the Washington Post database.  That is obviously not a very useful statistic.  Non-Hispanic Whites make up about 76% of the US population; Blacks make up a little over 13%.  The WaPo helpfully explains that Black Americans “are killed by police at more than twice the rate of white Americans”.

A very good and recent summary of the statistics for fatal officer-involved shootings (FOIS) can be found in “Risk of being killed by police use of force in the United States by age, race–ethnicity, and sex.”  The authors do not address causation but confine their study to outcomes.  Here is a fascinating chart of FOIS restricted to males. 

The chart measures deaths by police per 100,000, controlling for population share, and tracks the numbers by age.  Unsurprisingly, the fatality rate rises dramatically at the teen years and drops steadily after 30 for all the age groups.  The most important fact is that the hump for Black males is much steeper than for any other defined group, and much lower than for White males. 

Does this chart point to a racial bias in FOIS nationally?  There is one anomaly that doesn’t support that explanation.  Asian Americans are proportionately less likely than Whites to be killed by police.  If the difference between the White and Black curves is evidence of racial bias against the latter, wouldn’t the low incidence for Asian Americans be evidence for a pro-Asian bias on the part of police forces across the country?  That hardly seems plausible. 

A more significant problem is that the racial bias explanation relies on a generally silent and implausible assumption: that, in the absence of racial bias, the FOIS stats for each demographic group would be perfectly proportional to its share of the total population.  That, in turn, assumes that all the demographic groups are exactly the same for all relevant characteristics.  That is also implausible. 

Another chart leads us in the right direction. 

This is about as robust a difference as one ever sees in social science.  Males are far more likely than females to be killed by police for all groups measured here.  This not, let me go out on a limb, gender bias on the part of the police.  It is a consequence of the fact that men are more likely than women to commit the violent crimes that might bring them into contact with the police and far more likely to escalate once they are exposed to the police.  Here is a bit from the Bureau of Justice Statistics (2011) tracking stats between 1980 and 2008. 

Males represented 77% of homicide victims and nearly 90% of off enders. Th e victimization rate for males (11.6 per 100,000) was 3 times higher than the rate for females (3.4 per 100,000). The offending rate for males (15.1 per 100,000) was almost 9 times higher than the rate for females (1.7 per 100,000).

Is there a connection for the Black/White differential FOIS rates and a difference in rates of violent crime?  Again from the BJS:

Blacks were disproportionately represented as both homicide victims and offenders. The victimization rate for blacks (27.8 per 100,000) was 6 times higher than the rate for whites (4.5 per 100,000). The offending rate for blacks (34.4 per 100,000) was almost 8 times higher than the rate for whites (4.5 per 100,000).

Two recent papers examine the relationship between police shootings and criminal activity among Blacks and Whites: here and here.  Here is a bit from one of them:

We first reproduce the well-known finding that Blacks are more likely to be fatally shot than Whites given population proportions… the odds were 2.5 times higher for Blacks to be killed by police compared to Whites given their population proportions.

However:

When fatal shooting data are benchmarked against the number of murder/nonnegligent manslaughter reports and arrests, the odds ratio obtained when benchmarking against population proportions flips completely. The odds were 2.7 times higher for Whites to be killed by police gunfire relative to Blacks given each group’s SRS homicide reports, 2.6 times higher for Whites given each group’s SRS homicide arrests, 2.9 times higher for Whites given each group’s NIBRS homicide reports, 3.9 times higher for Whites given each group’s NIBRS homicide arrests, and 2.5 times higher for Whites given each group’s CDC death by assault data.

In other words, given rates of homicide reports and arrests, across three databases, Whites were more likely to be shot by police than Blacks. 

The fundamental assumption underlying the current wave of civil unrest is false.  This might be an important fact.  One would hope that a responsible press would report it.  One should not expect that it will be mentioned by any major news outlet. 

Face Masks & Bad Science

Virginia Governor Ralph Northam has decided that all Virginians must wear face masks in “indoor public areas.”  An enlightened authority, he declares that he has good reason for his decision. 

“I am taking this step because science increasingly shows us that the virus spreads less easily when everyone is wearing face coverings,” Northam said during a press conference.

It’s nice to know that science shows this.  It would be helpful to know where we go to consult science.  Perhaps to one of science’s spokespersons, such as Dr. Anthony Fauci. 

"I want to protect myself and protect others, and also because I want to make it be a symbol for people to see that that's the kind of thing you should be doing," Fauci, the nation's top infectious disease expert and a member of the White House's coronavirus task force, told CNN's Jim Sciutto on "Newsroom."

Fauci said he believes that while wearing a mask is not "100% effective," it is a valuable safeguard and shows "respect for another person."

There are two very different argument in favor of face masks here.  One is that face masks serve as a symbol of virtuous intent.  It serves as a symbol for what people should be doing and it shows respect for other persons.  I confess that I am skeptical.  I happen to think that public health policy should be designed to advance public health and not to send signals. 

At any rate, it is surely not within the powers of the governor of Virginia to force people to wear cloth over their faces in order to show respect for others.  As Joe Biden might put it, there’s that thing… the thing in this case being the Free Speech clause of the First Amendment. 

The second argument is that a face mask is “a valuable safeguard,” even if not “100% effective”.  Okay.  Only an idiot would suppose that this practice is perfect.  But if not 100%, then what?  Does science tell us that face masks are 75% or 50% or 15% effective?  A little more precision would help in evaluating Governor Northam’s dictate. 

Dr. Fauci gives us none, but the British Guardian is more helpful.  Here we find a report from “a multidisciplinary group convened by the Royal Society called Delve – Data Evaluation and Learning for Viral Epidemics.”  This is what Delve has to say:

Our analysis suggests that [face mask] use could reduce onward transmission by asymptomatic and pre-symptomatic wearers if widely used in situations where physical distancing is not possible or predictable, contrasting to the standard use of masks for the protection of wearers,” the report notes. “If correctly used on this basis, face masks, including homemade cloth masks, can contribute to reducing viral transmission.

Someone should ask Governor Northam if when he says science, he means Delve.  It turns out that Delve isn’t exactly science.  The Guardian piece goes on:

The [Delve] report prompted other scientists to express their reservations, warning that it amounted to no more than opinion and overstated the available evidence.

Dr Simon Clarke, associate professor in cellular microbiology at the University of Reading, Dr Ben Killingley, consultant in acute medicine and infectious diseases at University College London hospital, and Dr Antonio Lazzarino of the Department of Epidemiology and Public Health at University College London all had the same view of the Delve Report.  To quote Dr. Killingley:

The report is overly optimistic about the value of face coverings and it is incorrect to conclude that the evidence shows that face covering can reduce viral transmission in the community,” he said. “There is in fact no good evidence that face coverings achieve this.”

Dr. Lazzarino goes further:

Based on what we now know about the dynamics of transmission and the pathophysiology of Covid-19, the negative effects of wearing masks outweigh the positive.

We might also consult the World Health Organization:

If you are healthy, you only need to wear a mask if you are taking care of a person with COVID-19.

Is that science? 

I am not competent to judge the science here, but Governor Northam’s dictate was a political act and there I have some expertise.  He knows no more about science than a hog knows about Sunday. 

A Foundational Library for Biopolitical Science

As an addendum to my last post, I can recommend three recent collections of scientific papers by a large number of scholars that will provide anyone with a solid foundation for reading and exploring biopolitical science. 

First and most important, The Princeton Guide to Evolution, ed. by Jonathan B. Lobos.  This is easily the best general guides to an academic subject that I have ever seen.  It is extraordinarily broad and at the same time thorough in each of its chapters.  It is generally accessible to non-specialists, though it may require some attentive reading. 

Second, Chimpanzees and Human Evolution, edited by Muller, Wrangham, and Pilbeam.  If you want to enjoy the benefits of the books I mentioned in my last post, just look up the author’s contributions to this one.  Both volumes were published as recently as 2017. 

Third, The Evolution of Primate Societies, edited by… everyone.  It’s the most dated of the volumes, being published as far back as 2012.  If you want to know what is natural in human social behavior, the best way is to consider our nearest relatives.  To read this book is to swim in that sea of questions. 

Finally, I would be remiss not to recommend one of the first general guides to biopolitical science: Handbook of Biology and Politics, ed. by Steven A. Peterson and Albert Sommit.  If biology and politics overlap anywhere in the realm of thought, this book will have a chapter on it.  I would also be remiss not to point out that the author of Chapter 13, “Political Ethics and Biology,” is very wise. 

A Biopolitical Science Library

I am returning to this blog after a hiatus of more than two years.  I am working on a book with the tentative title: Darwin and the Declaration of Independence.  My thesis is that contemporary research in the evolution of human social, political, and moral behaviors supports a natural right tradition that stretches from Aristotle and Plato, through Locke and the American founders, to Lincoln and Martin Luther King, Jr. 

In this post, I am going to list some of the books and papers in contemporary biosocial science that I lean on heavily.  They constitute a library in what I call biopolitical science. 

First and foremost, Christopher Boehm’s two magisterial works: Hierarchy in the Forest, and Moral Origins.  Boehm establishes that forager societies were characterized by what he calls an egalitarian ethos.  Every (male) member of the band in good standing (not a free rider or a bully) enjoyed the protection of the group and enjoyed more than less equally in whatever resources the group had at its disposal and got the group’s protection against any member who tried to push his weight around.  Group decision making was also egalitarian: each “citizen” gets his say and each abides by the consensus.  Boehm argues that the sanctioning of bullies and free riders (hungry but unwilling to contribute to the hunt) amounted to social selection.  Human moral emotions were shaped by selection pressure as individuals internalized the egalitarian ethos.  For a shorter introduction, see his paper “Egalitarian Behavior and Reverse Dominance Hierarchy”. 

Second, Michael Tomasello’s Why We Cooperate is a pretty good introduction his work on the innate human capacity for cooperation that distinguishes us from other social primates.  Tomasello’s work frames Boehm’s, showing how we got from individuals collaborating out of convenience to a species capable of generating the concept of “we” and “our” good.  For a shorter introduction, see his paper “Two Steps in the Evolution of Human Cooperation”. 

Third, Bernard Chapais’ Primeval Kinship, a forceful argument that it was pair-bonding, stable relationships between one male and two or more females, that transformed our early ancestors from typical social apes into a network of related individuals including aunts, uncles, and cousins.  Unlike our nearest relatives, the chimpanzees and bonobos, humans had a much better idea who their fathers were and that opened up the network of family relations.  When our ancestors began to recognize affinal relationships (in-laws) the network of familial relationships expanded indefinitely.  For a brief introduction, see “Monogamy, strongly bonded groups, and the evolution of human social structure”.   

Fourth, Richard Wrangham’s The Goodness Paradox.  Human beings are the best of animals and the worst of animals.  We get along within our groups and commit atrocious violence against other groups.  Wrangham answers the old question whether human beings are violent by nature or not with “yes.”  He does so by distinguishing between reactive violence (spontaneous irritation) and proactive violence (we could sneak up on them and…).  Most importantly, he invests in the domestication syndrome, the theory that selection against reactive violence produces a range of physical changes that present in human beings and other domestic animals.  We are the self-domesticated species.  See “Two types of aggression in human evolution”.  

These works, read together, provide a foundation for political science and political theory that has so far been sorely lacking in the discipline.