This is perhaps the most undermined study on canine ethology in existence and the epitome of the expression, "Don't throw the baby out with the bath water."

"Expression Studies on Wolves" was a groundbreaking insight into the expressive behavior of captive wolves (and dog) behavior.  Despite every repeated study on captive wolves yielding similar results, Schenkel's work is largely referred to as "outdated" when compared to the work of David Mech's wild wolf observations who simply decided to veer away from accurate terminology in the field of ethology and replace it with more "politically correct terms" when bringing to public light that most wild wolf packs consisted of "wolf families" and therefore the leaders should simply be called the "breeding pair" or parents instead of "Alphas".  This caused widespread confusion in the dog training community in particular, and Schenkel's work has mostly become a footnote of outdated and debunked information since.

Mech likely distanced himself from the term "alpha" due to the negative associations with the term and poorly applied dog training references and techniques.  This "debunking" of the word alpha happened during the release of Mech's newest book and the emerging commercial success of Cesar Milan who liberally misused the term.   Other commercial competitors of Milan jumped on the bandwagon of "debunking" not only the term but the whole concept of dominance and even any relationships between dog and wolf behavior.  The rhetoric has spread like a virus through professionals, that do not bother to check their references, and it has since become widely accepted "truth".

Mech later wrote in a letter to Psychology Today that:

"This misinterpretation and total misinformation like Kelley's (referring to an article about "dominance debunked") has plagued me for years now. I do not in any way reject the notion of dominance." (you can read more on this subject here)

David Mech's observations revealed significant insight to the behavior of wild wolves which form packs that are more similar to the nuclear families of humans, compared to the concentration camp-like structure of the captive wolf studies (similar aged unrelated wolves with no option of dispersal).  Mech's studies occurred long after Schenkel's and for sure David Mech did benefit from the earlier insight gained by that research.  This embed of Schenkel's is refurbished from Mech's archives, and it is likely Mech's pencil highlights that are viewed in the photocopy.

Even though David Mech's studies are a better example of the natural behavior of wolves in their natural environment, it nonetheless does not disprove objective observations made by Schenkel in a captive environment.  This represents an extreme difference in scientific control which only proves the differences caused by this variable, but not the potential behavior itself of both captive and wild canines which will vary depending on the environment in which they are placed.

Rudolph Schenkel admitted that there was not, yet, any scientific studies on wild wolf behavior at the time of his work.  He instead offers the best references available at the time including the mention of family units by Young and Goldman which predated Mech's own observations, yet CREDITED to Mech 55 years later:

The mentioned work of Young & Goldman (1944) bring to light another possibility of inter-relationship:
The parent animals form the center of a tightly closed family with their own area, living a monogamous permanent union. This family encompasses the young animals until they reach reproduction age, so that a family, i.e. a pack, encompasses "generally a pair of wolves and their yearling or two-year old offspring". (P. 120).

Moreso,  the dismissal of this study and reference to Mech's research is often used to "debunk" the importance of "dominance" and "leadership" in domestic dogs, which fails to recognize that neither Mech or Schenkel ever dismiss these behaviors.  In both scientists works, it merely mentions the differences in how these hierarchies are formed and maintained.

Why is it essential that this study is not merely referred to as "outdated"?

• We are often faced with the challenges of managing "captive" unrelated canines of domestic or hybrid sub-species more so than their truly wild counterparts which run free without the restraints of human intervention (i.e. dog on dog aggression cases within a household)
• Adaptive and coping behaviors of unnaturally managed canines can be learned from this study, which will show similarities or at the very least the most primitive form of behaviors that may need to be understood before interpreting the actions of the wolves domesticated counterparts.

We must always remember that ethology is the objective (free of opinion) study of behavior from an evolutionary point of view.  Often, beliefs and emotions unrelated to the study itself (in this case commercialized dog training competitors) will skew the fact that these observations are objective and should remain that way, and what Schenkel observed with his owns eyes and recorded is no less fact then as it is today since no one has ever disproven his observations on captive wolves.

For those that are not satisfied with believing rhetoric should form their own opinions. Below is Schenkel's famous "outdated" study, that should be read in its entirety along with Mech's studies referenced above: