Neotony, Prozac and Human Evolution

Why did the dog bark in the night? With apologies to Sherlock
Holmes, not for the reason you might think. The answer is: because he
is a domesticated animal. "What?", you say, why does that make a
difference? Simply put, domestication changes an animal's behavior and
his looks. This is called neotony, which means the retention of
juvenile characteristics in the adult. Juvenile wolves bark, adults do
not. The dog, which is a domesticated wolf, stays in a perpetual state
of juvenile behavior, therefore: he barks.

An elegant 40 year experiment by a Russian researcher has revealed much
of the process of domestication and the resulting neotony in foxes.
Fascinating biochemical changes and changes in features occur merely
from selecting for "friendly" behavior. Coat color changed, ears became
floppy, and the foxes would seek human interaction by barking and
whining. These foxes were playful as well. Domesticated foxes also have
higher serotonin levels. This is the chemical that increases in the
brains of Prozac takers for feelings of calmness and well-being.
Another biochemical that changes from domestication is thyroxine,
placing more stress on the domesticated animal's thyroid.

Most domesticated animals exhibit morphology connected to neotony by
relatively rounded features, with larger eyes and shorter muzzles,
compared to their wild relatives. Juvenile behaviors, such as barking
in foxes and wolves, and continued curiosity and fearlessness for a
longer stage in infancy, before fear reactions begin, are also part of
the changes brought about by domestication.

Humans are also affected by neotony. Some scientists even call humans
developmentally retarded apes! Others go so far as to suggest that
staying in a juvenile state is what has allowed human's brains to learn
and develop throughout our lives. Some humans have more extreme
characteristics of neotony than others. Models are one example of this.
They have more childish features than the average human female of the
same age, according to research on facial features and age. It would be
an interesting experiment to determine if humans displaying more
extreme juvenile features also had biochemical and behavioral changes,
similar to the fox experiment.

Another interesting idea for research would be to examine features of
humans using Prozac versus similar groups that are not. Perhaps using
Prozac is a way to domesticate the user's emotions.

Yet another way to research changes in humans associated with neotony
would be to look at skulls from archaeological digs from
hunter-gatherer societies versus more agricultural and urban societies.
One wonders if the pressures placed on human society in the change from
nomadic hunter-gatherers to a more agricultural and settled society
would have been a contributing factor to human neotony. Perhaps more
cooperative, ( ie. "friendly"), behavior was necessary for this change.
If it can occur in 40 years in foxes, strictly due to selection for
behavior, then changes in humans may have occurred faster than is
currently believed. Larger societies require more sophisticated
behavioral interactions. Examining skull features would allow us
determine if changes in skulls were associated with changes in social
group size.

It might be that some of this research would help us find more pieces
to the puzzle that is humanity, our origins, our disparate natures, why
we are who we are, and more importantly, who we are becoming.