“The most common form of social organization for group-living monkeys is the multigenerational matrilineal group (Silk, 1987). In this type of system, males, and females have very different life histories. Females stay in the natal group and their mothers and female kin for life, while males leave at adolescence and transfer to neighboring groups for breeding.” (Lynn Fairbanks, “Influences on Aggression in Group-Living Monkeys,” in Endocrinology of Social Relationships, eds. Ellison and Gray, pp. 160-161.)

“In spite of abundant evidence documenting intergroup conflict over the past 10,000 to 15,000 years, there is no evidence of warfare in the Pleistocene. Such absence of evidence is not evidence of absence, but it helps to explain why many of those who actually study hunter-gatherers are skeptical about projecting the bellicose behavior of post-Neolithic peoples back onto roaming kin-based bands of hunter-gatherers, and why anthropologists refer to the Pleistocene as the ‘period of Paleolithic warlessness.’” (Hrdy, Mothers and Others, pp. 19-20.)

For the last few years, I’ve reveled in the indulgence of reading several books at the same time, and often they were books seemingly unrelated. Sometimes synergies result. Exploring details regarding the endocrinology of relationship in primates in one book and the power of social structures that encourage alloparenting, resulting in cooperative evolution, in another book leaves me feeling like I’m reading about the same process from two different perspectives.

Central to understanding Hrdy’s work focusing on humans evolving in response to females raising children cooperatively, and the evidence that supports these conjectures, is the understanding that males, not females, are often moving to where they can procreate. Females are relatively stationary, with sisters and mothers working cooperatively to raise the children. This is in stark contrast to post-Neolithic developments that encouraged males to form alliances with other males that would result in land and resources staying within the control of a male and his male progeny. Females moved away from mothers and sisters to the location of their husband.

I’ve been exploring the endocrinological implications of matrifocal evolution for 12 years. When I started these explorations, Marija Gimbutas’ work was often derided. Gimbutas hypothesized that humans evolved in matrilineal societies. It seems Hrdy and her colleagues are finding support from colleagues as they make connections between matrilineality and our aboriginal forebears.

From my perspective, central to the realization that humans evolved in a matrifocal context is the understanding that natural selection was not the primary selective process that was in play. Though it is fairly easy to intuit that hormones adjust as social structure adjusts, it is when it can be understood that it is larger patterns of maturation rates and timing that are guiding both hormone levels and social structures, with hormone levels and social structures influencing maturation rates and timing, that we achieve insight into how evolution actually unfolds.

Reading Hrdy, I’m feeling stirred that humans evolving in matrifocal societies is a concept now receiving respect. If this shift in our origin story continues to gain followers, there will be impacts on other disciplines and popular culture.

My wife introduced me to Ken Wilber’s work about three years after the Serpentfd.org website went up.  That was around 2003.  From there I read maybe six of his books (he’s written close to 20) and listened several times to the 10-CD interview he conducted.

In the previous piece, I noted the prerational and transrational distinction he makes that clearly demarcates the differences between aboriginal prepersonal points of view and more recent spiritual transpersonal experiences.  The two are often confused.  Wilber efficiently parses out the differences, using a system of seven stages of maturation that apply to both individuals and societies.

Wilber looks at some feminist inclinations to view ancient times as more evolved in human relations as another case of comparing seemingly positive aspects of earlier stages of societal evolution, or maturation, with later-stage negative features.  For example, human sacrifice was common in matrifocal agricultural society, a fact usually ignored by those seeking synthesis in the past.  Wilber suggests that some feminists pick and choose what they want to emphasize when comparing female-centered societies with contemporary patrifocal examples.

Paying close attention to similarities between evolution and maturation on both individual and social scales, Wilber, guided by the work of…

Social structure and the environmental effects upon social structure feel central to how species change cascades across an ecosystem.  I just typed “social structure” and “testosterone” into Google, wondering who might be discussing relationships among the environment, social structure, testosterone, estrogen and evolution.  I expected one of my postings to come up first, but preceding that there was a book I’d not heard of, Social Structure and Testosterone.  I just ordered it.  It seems to be carrying a sociobiological banner, but perhaps there are patterns the author is uncovering that will offer insight.

Most evolutionary psychology or sociobiological theorizing seems to assume or emphasize male impact.  Tanner, Hrdy and others have pioneered female influence.  I’ve written often about the heritage of our patrifocal society creating stories that emphasize a male’s influence.  I’m now encouraging myself to view animal evolution as heavily influenced by social structure, with female sexual selection perhaps understandable in a context of social structure that only sometimes makes it obvious that female choice or female sexual selection is in play.

It is possible that my estimation that estrogen is managing the timing of testosterone, heavily influencing directions in evolution, is integral to understanding the relationship among the…

“The prevalence of twilight-state thinking, our very susceptibility to the condition, argues for its evolutionary importance.  In extreme cases it results in pathology, derangements and delusions, persisting hallucinations and fanaticisms.  But it is also the driving force behind efforts to see things whole, to achieve a variety of syntheses from unified field theories in physics to blueprints for utopias in which people will live together in peace.  There must have been an enormous selective premium on the twilight state during prehistoric times.  If the pressures of the Upper Paleolithic demanded fervid belief and the following of leaders for survival’s sake, then individuals endowed with such qualities, with a capacity to fall readily into trances, would out-produce more resistant individuals.”  (J. E. Pfeiffer, The Creative Explosion (New York:  Harper & Row, 1982), p. 213.)

The power of art to inform culture receives relatively little attention in current times.  Any anthropologist studying aboriginal society finds art central to how a culture operates.  In that context, always, art and spirituality are closely tied.  Perhaps art feels separate from society today because religion has been contextualized as important, but not essential, to how we understand society.  So, art often finds itself ignored.

“Furthermore,

…

“The entire scheme represents a hierarchically organized system of increasing size, differentiation, and complexity, in which each component affects, and is affected by, all the other components, not only at its own level but at lower and higher levels as well.  Thus, the arrows in Figure12-2 not only go upward from the gene, eventually reaching all the way to the external environment through the activities of the organism, but the arrows of influence return from the external environment through various levels of the organism back to the genes.  While the feedforward or feedupward nature of the genes has always been appreciated from the time of Weismann and Mendel on, the feedbackward or feeddownward influences have usually been thought to stop at the level of the cell membrane.  The newer conception is one of a totally interrelated, fully coactional system in which the activity of the genes themselves can be affected through the cytoplasm of the cell by events originating at any other level in the system, including the external environment.”  (G. Gilbert, Individual Development and Evolution (New York:  Oxford University Press, 1992), p. 145.)

The article appearing in the 11/8/09 BBC News, “Early Life Stress ‘Changes’…

“In a study of alcoholism, it was noted that alcoholism is a significant health concern for lesbians, with an incidence rate perhaps three times that of the general population.  The relationships among the development of alcoholism in women, the experience of stigmatization and the complex facets of lesbian identity and lesbian community are explored.  This exploration provides for a more comprehensive and critical analysis of alcoholism in lesbians.  As a phenomenon of women’s health, alcoholism is examined using the perspectives of developmental theory, symbolic interactionism and critical theory.  The author offers insights and implications for health care, research and theory building.”  (Hall, J. M., “Alcoholism in Lesbians:  Developmental, Symbolic Interactionist, and Critical Perspectives,” Health Care for Women International 11(1) (1990):89-107.)

“Yalom et al. (1973) studied 20 16-year-old boys of diabetic mothers, who had received estrogen or progesterone during pregnancy.  These boys showed less heterosexuality and less masculinity than 20 control boys.  Netley and Rovet (1982) showed that among 33 males with 47,XXY syndrome, 24% were nonrighthanded, compared to 10% of a control group. …  In the present study, as well as in Lindesay (1987), only homosexual men were studied.  In Rosenstein and Bigler (1987) and McCormick et al. (1990), both

…

A professor recently wrote me that she introduced the ideas described in my blog to her class on Neanderthals and Human Evolutionary Theory.  Her email asked or suggested several questions or expressed her class’s confusion in the following areas:

Are you proposing that testosterone levels are driving evolution of mammals in general or primates specifically?

The evidence that testosterone is driving evolution mostly comes from anomalies emerging in neuropsychology around progeny maturation changes that result from environmental influences upon a pregnant mother and other studies in the neuropsychological literature.

An interesting primate study was as follows…

“In a 5-year longitudinal study, we examined the effect of disrupting the neonatal activity of the pituitary–testicular axis on the sexual development of male rhesus monkeys.  Animals in a social group under natural lighting conditions were treated with a GnRH antagonist (antide), antide and androgen, or both vehicles, from birth until 4 months of age.  In antide-treated neonates, serum LH and testosterone were near or below the limits of detection throughout the neonatal period.  Antide + androgen-treated neonates had subnormal serum LH, but above normal testosterone concentrations during the treatment period.  From 6 to 36 months of age, serum LH and testosterone were

…

I received an email from Jon Gluckman, who follows this blog, suggesting that there is another interpretation of human developmental stages and political milieu, one that suggests that Right Wing orientations and perhaps fascism have their origin in the maturationally delayed.

My interpretation of the power of neoteny to impact culture holds to the view that the prolongation of infant features into the adult of our species can be observed to be influencing society as aboriginal aspects emerge in contemporary times.  I describe the horizontalization of society, with female frames of reference and bonobo-like qualities.  Horizontalization is fanning out from its source among young people, the Internet.  In other words, many features of the very young, including playfulness, curiosity, affection and sociality, are becoming primary features of current society, particularly when examined from the view of the new communications technologies.

One could also view contemporary trends to withhold information, engage in secrecy, offer reverence to the leader, engage in systemic selfish behavior and associate only with those who are like you as traits exhibited by children, traits which many adults also exhibit.  That being the case, the neoteny premise of a horizontal society being one featuring the traits of young…

“Environmental factors can be an important source of nongenetic influences on laterality.  Since the effect of a gene is to play a role in some form of chemical reaction, it is not surprising that genetic determination is not absolute.  Every chemical reaction can be modified by alterations in pressure, temperature, pH, light, the presence of other substances, the availability of chemical precursors, and the rate at which products are removed.  With growing sophistication of molecular genetics, it has become increasingly clear that nongenetic effects can play a powerful role; methylation, for example, has been shown to suppress expression of many genes.  We will now consider some of the random effects that might modify lateralization.  One implication of our hypothesis is that even if the genetic endowment of any particular fetus were known precisely, it would not be possible to make predictions concerning the distribution in a population basis.  One of the reasons for this relative freedom from genetic determination is that if hormones do play a role in determining laterality, then the effects of testosterone or related substances on the developing brain will be modified by factors not under the control of the fetal genes.  Androgens are produced not only

…

Maturity is not the same as progress.  To pass through a series of ontological stages evidencing the look, sound and behavior of the personal epochs that have been experienced is not progress.  It is life.

All mixed up in contemporary theorizing are three things:  the exact nature and difference between that which transforms over time that is changing as a result of random interconnections, that which is changing as a result of progress or improvement over time and that which is changing as part of a larger pattern of maturation.

Evolutionary biology tends to take the position that evolution follows Darwin’s wedges metaphor, with every feature of every being emerging as a direct or indirect result of what is necessary to survive to procreate.  Features acquired by individuals are random, unconnected to the environment or the parents’ experience, making random feature survival the central focus of evolution.  There is no such thing as progress.  There is no larger picture to inform what survives to procreate.

Society, religion and spirituality tend to focus on the idea that either we are on a pathway toward improvement or we are not.  Those saying not are often atheists, and often they find themselves sympathizing…

“Before Agassiz, recapitulation had been defined as a correspondence between two series: embryonic stages and adults of living species.  Agassiz introduced a third series: the geologic record of fossils.  An embryo repeats both a graded series of living, lower forms and the history of its type as recorded by fossils.  There is a “threefold parallelism” of embryonic growth, structural gradation, and geologic succession.  ‘It may therefore be considered as a general fact, very likely to be more fully illustrated as investigations cover a wider ground, that the phases of development of all living animals correspond to the order to succession of their extinct representatives in past geological times.  As far as this goes, the oldest representatives of every class may then be considered as embryonic types of their respective orders of familiar among the living.’”  (1857, 1962 ed., p. 114)  (Stephen J. Gould, Ontogeny and Phylogeny (Cambridge:  Belknap Press, 1977), pp. 65-66.)

Stephen J. Gould’s Ontogeny and Phylogeny lies at the heart of many of the interconnecting concepts of this thesis.  Ontogeny and Phylogeny made sense of many of the disciplines I’d been studying for many years, showing how evolutionary theory informs many levels of experience.  Central to Gould’s thesis…

Explorations of societies displaying matriarchal, or matrifocal, tendencies often struggle with a definition that will adjust to very different examples of the paradigm.  Often, a woman’s exercise of authority within a culture can be profound but not obvious, as if there were an agreement that men look like they are in control.  There are different areas where authority manifests such as home, work, market, social situations.  Female authority may vary depending on the context.  Shared authority can look very different in different societies.

What I am calling “The Orchestral Theory of Evolution” is a feminine theory of evolution insofar as both sexes share the ability to inform change and both foundation hormones have profound impact.  “Feminine” suggests sharing and cooperation.  In the context of evolutionary theory, a feminine paradigm is a cooperative paradigm with both a male and female command of process.

Nevertheless, from our Western perspective, provide a woman any control in a hierarchical context where men have traditionally called the shots, and the female anomaly often receives negative attention.  Evolutionary theory traditionally focuses on the male.  Some exceptions with a focus on the female have emerged over the last 40 years, mostly from female theorists, but so long…

I have found that definitions of neoteny that I provide to friends often don’t easily stick in their mind.  To ask someone to think of an automobile accelerating is easy.  It is not too difficult to ask people to make a picture in their mind’s eye of an accelerating automobile changing its model year to acquire future features while speeding up, decelerating to change shape to look like an older model.  But it is more difficult to ask them in their mind’s eye to perform this animation while considering a long succession of automobile models, each succeeding vehicle behaving a little different from the one before, different in a fashion where its ability to change model year with speed is enhanced or compromised with time.  Minds’ eyes sometimes can use a little training.

Neoteny, one of six heterochronic dynamics described by Gould (1977), is the biological process that prolongs ancestor embryo, infant and childhood features and displays them in the physical bodies and behaviors of descendant adults.  The classic examples are our ancient chimpanzee-like forebear infant features of small jaw, small teeth, big head, relatively large brain, upright stature, vertical skull positioning, playful disposition, curiosity, social dependency and displays of…

If heterochrony is the study of the rates and timing of maturation, with testosterone levels impacting rate and estrogen levels controlling timing, then those environmental or social structure adjustments that influence levels of testosterone and estrogen determine the speed, timing, features and direction of evolution.

Central to the dynamic that winds its way throughout this work, and what I am now calling the Orchestral Theory of Evolution, is the idea that biological evolution and social evolution are the same.  The present paradigm behaves like there has been so profound an effect upon society and consciousness by self awareness and language that culture now seems separated from biology.  This work seeks to integrate biology and culture.  This integration is made possible by an understanding of how evolution proliferates variation outside of natural selection.  This is an old idea, one that emerged in the nineteenth century.  Stephen J. Gould, in his 1977 Ontogeny and Phylogeny, sought to codify this idea.  He focused on the principle of heterochrony, a word coined by Ernst Haeckel.  Heterochrony is a process that describes the dynamic of progeny variation, a process that is not random.

The natural selection paradigm hypothesizes that the progeny produced by a parent…

Several themes run through this blog.  Several related melodies play off each other as I explore how they are connected and the way that the melodies seem to transform when approached from different directions.  Perhaps this work’s most influential theme is the power of play to inform understanding.  I am not an academic.  I have no affiliations with an established institution or connections with groups that compel me to defend specific beliefs or conjectures.  I feel like a grown-up surrounded by toys, ideas that represent patterns in our experience, and I’m reveling in the process of letting myself be led to what feels like unique ways for the ideas or patterns to interact.

Like a child, I presuppose that what I am exploring, I can understand.  Engaging, I intuit and experience connection, and I estimate that my participation will be rewarded with my having learned something I didn’t know before.  Many themes carry through this work, but perhaps the core idea is that everything is connected and that those connections can be understood, or at least intuited, by a nonacademic.

I maintain a deep reverence for what might be called “fun.”  When I feel attracted to something, I take that…

“Again, masculine characters generally lie dormant in male animals until they arrive at the proper age for procreation.  The curious case formerly given of a Hen which assumed the masculine characters, not of her own breed but of a remote progenitor, illustrates the close connection between latent sexual characters and ordinary reversion.”  (The Variation of Animals and Plants under Domestication, Charles Darwin, 1868, V2, p. 394)

Freud was inspired by his contemporary evolutionary biological theorists to take the emerging paradigm equating the fossil record displaying species transformation with embryology and cultural variation.  Biology, ontogeny and society were thought to be allied.  Western prejudices assumed aboriginals were less “evolved.”  They were looking at evolution as a process displaying “progress.”  Nevertheless, this threefold parallelism was embraced by many a hundred years ago.  Freud added a fourth layer by theorizing that individual human development could follow pathways, influenced by incidents over the course of a lifetime, that would align themselves with paths at the biological, social and ontological scales.  Central to Freud’s thesis was the power of adult reversion to early developmental stages to then have early childhood (and earlier human-society) features manifest in the lives of adults, informing their behavior and experience.…

I’ve been playing with the idea that the genome is not a blueprint or a computer algorithm or a structured plan designed to take into consideration information provided by the environment.  I’ve been toying with the possibility that the genome is closer to a musical script, sheet music, designed to only make sense when integrated with the scripts or compositions of other beings of the same and other species.

First, perhaps a genome makes no sense as an isolated single gnome.  I am suggesting that a genome is but a puzzle piece among puzzle pieces, each piece appearing in a different being.  Seeking answers from within a single genome is like trying to understand a symphonic composition by reading the sheet music of the timpani.

Second, if the genome is like sheet music, then perhaps the musician is something science has been ignoring.  I’m thinking that it’s not that our genome is supplying content for the artist to then display, but that the genome is creating context whereby content and artistry can both emerge.  This is difficult to even consider without the first point successfully absorbed.

The genome is like a nationwide train-track system, with each city a different individual,…

After several hundred pages of describing biological anomalies that didn’t fit his theory of natural selection, on page 350 of his second volume of The Variation of Animals and Plants under Domestication, Darwin said the following, “Under this point of view I venture to advance the hypothesis of Pangenesis, which implies that every separate part of the whole organization reproduces itself.  So that ovules, spermatozoa, and pollen-grains, – the fertilized egg or seed, as well as buds, – include and consist of a multitude of germs thrown off from each separate part or unit.  In the First Part I will enumerate as briefly as I can the groups of facts which seem to demand connection; but certain subjects, not hitherto discussed, must be treated at disproportionate length.  In the Second Part the hypothesis will be given; and after considering how far the necessary assumptions are in themselves improbable, we shall see whether it serves to bring under a single point of view the various facts.”

Darwin is wrestling with observations that don’t fit an established paradigm, the one that he and Wallace introduced in 1858 called natural selection.  He is hypothesizing movement across a body and between generations of something…

I have been playing with the idea that genetics guides ontogeny, that how our genes inform an individual’s unfolding has far more to do with how music is made than with how a computer is programmed.  Once again, I’m finding these ideas emerging in my dreams.

Two nights ago, while dreaming, I was seeking to understand the mathematics of words, searching for the equations in language, wondering how music connects them both.  In the dream, the answer felt to be related to evolution.  The answer emerged.  The answer is the price of homemade baked goods at the farmer’s market. (I don’t know what that means.}

Scientists are stumped by how few genes there are in the human gnome.  Some less somatically sophisticated species display a far larger library of genes.  Having a complete gnome is not leading to deep insight as regards our disabilities, diseases, talents or evolution.  Over and over again, difficult-to-understand genetic riddles are ascribed to not-yet-understood, multiple gene effects.

Consider this.  By understanding music, we can understand how genetics works.  This is because the human connection to music is a direct reflection and result of the ontogenetic processes created by our genetic algorithm.

Genes engender a growing…

Light moves at a speed of 186,000 miles per second.  Speed as a concept is also integral to biology.  I hypothesize that the speed with which information passes between the two cerebral hemispheres impacts consciousness, behavior and personality.  And, whereas the basic unit of speed in physics is the kilometer or mile, in biology that unit is a generation.  Though maybe not.

Bernard Crespi has written a paper, Psychosis and Autism as Diametrical Disorders of the Social Brain, which focuses on several neurological features as influential in the etiology of particular diseases and conditions.  Corpus callosum size (the corpus callosum is the primary brain bridge between the two cerebral hemispheres) and anomalous dominance (differing cerebral hemisphere sizes) are two of those features, aspects of cerebral lateralization.  I would consider that corpus callosum size not only influences the ease and speed of information transfer, but that corpus callosum size influences the experience of self awareness or split consciousness.

There are correlations between degrees of cerebral lateralization, how much the two cerebral hemispheres vary, and conditions characterized by maturational delay (autism, Asperger’s, stuttering).  Degrees of handedness are influenced by this variable.  Other diseases and conditions are associated with right cerebral hemispheres not…

Where you draw the line between individual and species or individual and society has a lot to do with our ability to understand ourselves and evolution.  This line is not an arbitrary line but characterizes what we perceive as the primary unit.  As humans, we maintain individual self awareness and so view the world as composed of those units that create the foundation of the structure of our world.

Dawkins and his colleagues have played with the gene as the foundation unit and have come up with some interesting conjectures.  Though I disagree with many Neo-Darwinians that behave compelled to believe that the level of the gene is the only important level of selection, I agree that there is usefulness in taking a gene perspective.  What interests me now is not just the Neo-Darwinist perspective, or even the Gould position that evolution occurs in numerous levels, including gene, individual, species, groups and larger systems.  The idea that is playing with me at this time is that using units to explore evolution strips the process of the dynamic hidden at its core.

I’m feeling that just as in physics, in biology, by assuming that there are patterns that play across the…

It interests me how Einstein perceived the relationship between speed and time by identifying with the kind of Doppler effect that he imagined to occur when a light beam left a train station, compelling two different rates of time.  He then capitalized on this exercise of imagination by conceptualizing it as equations, music of the spheres.

I’ve been playing with a concept that I’m feeling integrates a lot of the various patterns I’ve been observing and exploring over the last 12 years.  It is as follows… If heterochrony is the study of the rates and timing of maturation, with testosterone levels impacting rate and estrogen levels controlling timing, then those environmental or social structure adjustments that influence levels of testosterone and estrogen determine the speed, timing, features and direction of evolution.

This is a description of the influence of time on biology.  Maturation is usually understood to be associated with the stage-like development of an individual.  Maturation in an individual is also an unfolding of the maturational record of all preceding individuals in the lineage of life on earth.  I’m not just describing Haeckel’s recapitulation, but the back and forth play of waves of both neoteny and acceleration, waves paradoxically…

An aspect of neoteny just struck me that has never crossed my mind before.  It perhaps suggests a basic principle in evolution.  I’m not sure.

Two days ago, I posted a piece exploring a paradox of recapitulation that focuses on an odd possibility.  When a species is in an accelerated phase and withdraws adult features backward over generations to eventually appear in the infants of descendants, adults may exhibit features of ancient forebears.  If the species lineage had in the past gone through a similar cycle, then that genetic inheritance would have been available, emerging when a similar hormonal disposition became engaged.

Haeckel may have been focused on that very dynamic as he obsessed on recapitulation as a source of new behavioral and physical characteristics.  What strikes me now is that though recapitulation (acceleration) is not considered at this time as a relevant description of evolutionary process, it does seem to be half of a process that results in a seemingly natural biological dynamic that not only withdraws species backward through ontogeny to conception but at the same time carries forward or prolongs features of this planet’s earliest species forward into adults.

There are two waves or currents moving through…

There is an idea I’ve been wrestling with for several years that I don’t think is going to get resolved by putting it into words, but I still want to describe the conundrum.

Alpheus Hyatt was a contemporary of Darwin. In Hyatt’s view, all species transformations could be explained by acceleration, with the apparent withdrawal or reversion into former stages, neoteny or paedomorphosis, being explained by a natural reemergence of early ontogenetic stages very late in an accelerated process, an exhibition that might be compared to senility in human development.

I’ve hypothesized that humans and many other species evolve over time by delaying and accelerating maturation (influenced by higher and lower levels of testosterone and estrogen).  Both the environment and sexual selection informed by social structure can influence these hormone levels.  Imagine a roller coaster or a snake’s wavering path revealing periods of time in a species’ transformation that evidence relatively high male testosterone, for example, and relatively low male testosterone.  Over time we might observe several peaks of high testosterone, reflected, we might hypothesize, by far more male-against-male control of procreation competition and shorter life spans with higher mortality.

Let’s hypothesize that humans have followed something like this meandering…

There are the interpretations of evolution that emphasize mutation.  Evolutionary developmental biologists are exploring ways life may be evolving that are unrelated to mutation, pathways influenced by the environment.  My work concentrates on how the rates and timing of maturation are influenced by hormones, with sexual selection or environmental changes transforming individuals and then species over time.

In the river analogy that preceded this piece, there is no explanation for how a species might leave the groove provided by the trajectories set up by maturational delay and acceleration.  This river chatters, making music as it flows downstream.  What might be the music of evolution?

A species could evolve over time, prolonging infant features into adult descendants, and then it could reverse that trend by withdrawing adult features into descendant infants.  Then repeat.  It would seem, like a teeter totter, that over great periods of time there would be no real movement, just variation between two polarities.

Indeed, in some cases this may be what occurs.  Nevertheless, unique variations keep emerging, species that have never been observed.

Some reasons for this come to mind.  What might these reasons sound like?

Species don’t just prolong infant features to adult descendants.  Aspects of…