0021 The authors’ focus on actuality₂, rather than potential₁, is typical for modern sciences.

There is an alternative to the two-level interscope for gene-culture co-evolution.  The alternative has the same situation-level nested form, but a different content level.

To start, genes_2a are a content-level actuality_2a, corresponding to DNA [codes for] brains_2a.  Culture [informs] brains_2b is a situation-level actuality_2b that emerges from… um… the potential ‘situating content’_1b.  But, does that situation-level potential_1b virtually emerge from (and situate) the potential of brain function or plasticity_1a?  Or, does it_1b virtually situate another potential, such as the potential of ‘whatever is happening at the time’_1a?

0023 Is there a hidden ingredient to gene-culture co-evolution?

That hidden ingredient is expressed on the content level of the following two-level interscope.

0024 Now, this hidden ingredient must be very important for the “sauce” of the story that Newson and Richerson tells.

It is as if culture informs brains_2b allows the creature to fill in the blanks on the content level.

0025 But, I suppose before our lineage has big brains, then that content level is not culture oriented.  Something much more… um… primal tells the story.

If I go back to a common ancestor between the chimpanzees and our lineage, say seven million years ago, then that obvious actuality_2a involves a behavior common to all mammals.

Chapter two begins with an interlude, a story about mother-infant “culture”.  When the infant drinks its mother’s milk_2a, the mother-infant interaction stimulates hormonal responses_2b.

0026 Here is the hidden ingredient two-level interscope for mother-infant interactions.

0027 If the situation-level normal context is sociality_3b, then the potential of situating content_1b could be called, by psychologists, the possibility of ‘an mother-infant bond’_1b.

0028 Mother-infant bonding_1b situates the physical act of the infant suckling_2a, which is innate for mammals.  So, the content level for the hidden ingredient dovetails into the content level for gene-culture co-evolution.

0029 The normal context of suckling_3a can be viewed as a facet of body development_3a.

The infant’s behavior_2a must be genetic_2a, since an infant is too young to culturally figure out anything.

The innate physical act_1a has a function_1a, so plasticity offers no advantage.

0030 What does this imply?

The secret message of the hidden ingredient of the “gene” side of gene-culture co-evolution is that our brains have the potential to construct the hidden ingredient.  A content level_2a obviously must be going on when content is situated_1b in the normal context of sociality_3b.  So, the potential of function or plasticity_1a corresponds to the (innately gifted) ability of the individual to isolate the potential of ‘whatever is happening at the time’_1a, as well as the normal context_3a and the actuality_2a of the hidden ingredient.

0031 How complicated is that?

There is a huge advantage to Newson and Richerson’s theoretical sleight of hand.  The situation-level actuality_2b arising from mother-infant bonding_1b has the same hylomorphic structure (of two contiguous real elements) as culture [informs] brains_2b.  Indeed, one may say that these two dyads are the polar ends of a continuum of behaviors that rely on pure function (for stimulation) at one end and pure plasticity (for information) on the other.

0032 Finally, the authors complete their picture by claiming that the emotional attachment_1b increases reproductive success_1c.

The problem?

The potential for ‘reproductive success’_1c is necessary, but not sufficient, to explain the actuality of an adaptation_2c.  A niche₁ is required to honestly account for any particular adaptation₂ in the normal context of natural selection₃.  However, the authors are not aware that humans have a niche or that the human niche may have anything to do with the hidden ingredient composing a content-level nested form that does not appear in their theoretical framework.

0033 Here is a picture of the authors’ big picture, applied to the last common ancestor of the chimpanzee and human.