I've made some speculation on this issue before, so I'll repost the gist of my interpretation.
There are clues in the novels - traditional dress for each gender that, for example, designates the chan
as warriors. The primary religion also assigns a spiritual “virtue” to each (as well as a Guardian). Extrapolating from what we get:
The gender which receive the traditional virtue of “strength” are the zhen,
the nursing sex - the zhavey
is outright stated to be the traditional "primary caregiver" for the children. That’s interesting, as it suggests the Andorian concept of strength differs from a lot of human constructs. Humans (forgive the "as you know, Bob" feel to all this
) traditionally saw strength as a trait associated with the provider/protector roles, the labour force, public leadership, etc - and so as a virtue to be promoted among males (in fact, most people still define strength in those terms no matter the sex of the person in the role), and they segregated it from the nurturing, child-raising role of the female. The virtues of the mother and the virtue of strength were both praised highly but were very much separate. The Andorians, though, equate strength with the child-bearing and child-rearing sex. Strength is more a "feminine" virtue to them, it seems.
My interpretation: enduring childbirth in the dangerous conditions of frozen Andoria, caring for offspring and installing in the children the basic lessons needed to further the fortunes of the clan required, in Andorian terms, strength - first biologically (for the strain of childbirth, and given a four-sex paradigm I assume they were giving birth a lot), and culturally/spiritually. Indeed, if we consider what we see of Andorian family life in Trek lit, I think we might make a case that traditional society on Andoria is “matriarchal”, in the literal sense of mothers being the head of the family and the model for political authority. The books suggest that children take the zhen’s
family name most of the time; Thirishar ch’Thane
, after all. And Thriss shared her name with her zhavey
too, if I remember rightly. Also, as a happy serendipity, Pava Ek’Noor Aqabaa becoming sh’Aqabaa where her mother is Undeieela zh’Noor offers an "retcon" explanation for her unusual name - ek’Noor is in there because she didn’t take her zhavey’s
surname. Perhaps she needs it in there in another fashion, because family lineage is read in a matrilineal fashion? If we consider characters like Charivretha zh’Thane and Sessathantis zh’Cheen, then the implications seem to be that the matron of the clan - the leading zhen
- is still at least unofficially the most powerful political presence. Was the great Empress Thalisar the Last a zhen
Anyway, moving onto that traditional clothing - for the two “female” genders a variety of dress, where chans
wear “warrior’s attire”, and the thaan
wear chain-mail. So, I was thinking; Andorian civilization developed as partly subterranean around hot-springs (both Jarman’s DS9 Andorians and Enterprise
Andorians established this prior to the two approaches’ reconciliation in later novels). The clan Keep is traditionally (in part at least) a warren of tunnels. The chans
, according to Thelin in “The Chimes at Midnight” are the sex traditionally least
involved in child-rearing - and if they wear warrior’s attire we can assume they were the hunter-gatherer/war-makers who operated outside the keep, so this makes sense. Their value in the religious mythology is “wisdom” - the wisdom of the hunter-tracker, learning to read the signs of the natural world as he moved through it, outside the safety of the caves and the keep? After all, his gender's Guardian is the Star Guardian, and the Tale of the Breaking insists he uses the stars as his guide
Then, the other default “male” sex, the thaans
, were perhaps closer to home and so more involved in family life, and formed a defensive perimeter perhaps (hence the chain-mail?). Their value is “passion” - the passion of standing their ground and fighting in direct defence of their family within the keep? I guess maybe thaans
also performed close-to-home labour professions. Their Guardian is associated with Fire - the fire of passionate defence AND of the forge?
Maybe some of this type of labour was performed by shens
too (as Andorian “females” are apparently as tall or taller than “males” and we don’t know how physical power works for them - they may have had “females” in those roles too). Either way, as we go further in, we have the shens
, who I guess maintain the home and keep the supplies running between the “males” on the edge and the zhen
and young deep inside. This makes sense - their Guardian is the Water Guardian, their virtue Blood. They are the flowing life-blood between the zhen/children and the males, the currents connecting it all. Then, deep in the centre of the keep, are the nurseries and schools, and the zhens
caring for the young - with the zhens
also having political authority and, perhaps, the leadership role, because it is their strength that allows them to succeed in the child-birthing nurturing role. That’s not to say there’s a hierarchy of moving inward - there’s no evidence that any of the sexes were considered “inferior” in any sense, only that zhens
were associated possibly with leadership, their mothering associated with strength. The zhen
, of course, have the Earth Guardian, strong protector -- as they, who embody strength, are buried in the earth, at the heart of the subterranean keep?
Tale of the Breaking:
From one, there shall be four. To one shall be given wisdom to be a protector - the cunning warrior who shall fight for the future. To another shall be given strength, providing a foundation upon which the others can build. One shall be given blood, the river of life that shall flow among the others, providing nurture and sustenance when the flesh longs to yield. And to the last shall be given passion, for the flame of desire will bring change to the others and warm them when the chill is bitterest”.
So Thirishar became four: Charaleas became wisdom; Zheusal became strength; Shanchen became blood; Thirizaz became passion. Together, the four are the First Kin.
Uzaveh banished the four to the farthest reaches of the kingdom and upon seeing them there, so far from the Thrones and utterly alone, appointed for each a guardian. For Thirizaz, the Fire Daemon fed the soul-consuming passion. Loving Shanchen became a vessel for the Water Spirit, forever bound to the Eternal love flowing from Uzaveh’s Throne. For strong Zheusal, Earth became protector. For wise Charaleas, the Stars became guides, their light defying darkest night.
PS: One of the Corps of Engineers stories establishes "Zhutanii" as the polite form of address for a quad as a whole (better than saying "Zha, Cha, Sha and Tha" everytime
). I notice it begins with "zh", reinforcing the idea that zhen
are the strong foundation on which the Whole is built.