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 serpentine evolution pathway with lineages revealing a history characterized by sometimes a more matrifocal, gracile, cooperative society vs.  periods featuring a patrifocal, robust, competitive community.  A span of a million years of Homo erectus and Homo sapiens evolution may have had several mild and more severe such roller coaster ups and downs.  Separate lineages would exhibit separate histories, histories that would genetically converge when geographically separated bands of hominids met and merged.

Now, consider that the dynamics of neoteny and acceleration compel a prolonging or withdrawing of features forward or backward, revealing a change in features in descendants over time.  If, over time, your lineage is transforming back and forth between gracile and robust versions, maturationally delaying and accelerating over time, then consider that when impacted by sexual selection or the environment, species are sliding backward and forward along an established maturational trajectory.  In other words, we don’t just mature ontogenetically, delaying or accelerating within a life span.  Our maturation follows a very specific species history, reproducing the roller coaster, serpentine path of evolution.

To a degree, ontogeny does recapitulate phylogeny, or, to be more exact, ontogeny reenacts our hormonal past.

The conundrum emerges during acceleration and has to do with Hyatt’s observation that perhaps there are features of neoteny that can emerge as a result of acceleration.  I’m not convinced that this is the case, though it is an interesting conjecture.  What has my attention is that if, for example, a male is exhibiting high testosterone and is pushing the envelope regarding his society’s hormonal constellation, does that male then begin exhibiting features of the last time his lineage explored a high testosterone peak?  When there is an established species/lineage maturational experience of high testosterone, do features of the last time it occurred now reappear in the lineage?  In other words, though moving forward in maturational time, withdrawing adult features back toward infancy, can features of ancestors emerge?

This feels like an important question, one that has plagued me for almost a dozen years.  What is suggested is that we as individuals within a species with a maturational pathway history might find ourselves with access to forebear features by both maturationally delaying and maturationally accelerating.

I have already hypothesized (sexualselection.org) that in current human patrifocal social structures, those of us with matrifocal predilections, cooperative males and commanding females, can find ourselves propelled backward by environmental effects, resulting in a return to ancient aboriginal hormonal constellations and neurological structures.  Further decreasing male testosterone or increasing female testosterone can result in a slide backward in time down the lineage roller coaster.  This is because I estimate males have become less neotenous over the last 50,000 years while females have become more neotenous as we have shifted from matrifocal to patrifocal social structures.  Paradoxically, evolving forward can also be to evolve backward.  Forward and backward become somewhat difficult to discern when evaluating evolution as a maturational condition that features movement along an established track.

What is at issue is that it is not clear to me that acceleration, when pushing the limits of what we can easily hormonally tolerate, doesn’t also propel individuals and species backward.  This seems like classic Haeckelian recapitulation.  Not only are adult features drawn backward in ontogeny over time, but features emerge that echo features of the past.

Although it feels like this is almost making sense, it still doesn’t quite click and come together.  By maturationally delaying, we bring new features into ontogeny, yet by accelerating or withdrawing features backward, we regress to manifest ancestor adult traits in contemporary youth.  Yet, the same thing can happen with neoteny.  Ancestor infant traits can appear in adult contemporaries and we slide backward, compelled by hormone changes, to a past that reveals neotenous characteristics.

It seems to me that Tourette’s syndrome may be explained to some degree by these conjectures.  Individuals experiencing acceleration may be presented with features exhibited by ancient forebears.  Whereas a male with decreasing testosterone may show autistic tendencies, a male with increasing testosterone may reveal Tourette’s tendencies, the difference between ancient gracile and ancient robust hormonal constellations.

The fog-filled roller coaster pathway that got us to where we are leaves many questions as to how this process works.  Perhaps with time this fog will lift.


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