I've already done some research on the character 也, but I haven't find something that pleased me. I've seen explanations going from "horn" and "snake" to "vulva" and "around".
Where did it come from? How did it get the meaning of "also" and what does it have to do with the characters 他 and 地?
Thanks in advance!
商
甲
合集33170戰國・楚
金
曾侯乙鐘
集成325戰國・楚
簡
信1・039
秦
簡
睡・秦106
西漢
隸
定縣漢簡10
今
楷
「也」originally depicted a child「子」with an emphasised mouth「口」, indicating the meaning to wail, cry. This word was later written as「嗁」and now written as「啼」. The meaning also is unrelated, and is a phonetic loan, derived from an early usage of「也」as a modal particle.
Please take note of the phonetic component of「嗁」;「遞」and「地」are homonyms in Mandarin, and the latter uses「也」as a phonetic component.
The arms of the child were later omitted, possibly to reduce the chance of confusing「也」and「子」. For reference,「子」appeared as
商
甲
甲2903
合集20576戰國
金
曾子𨘕簠
集成4488楚
簡
包2・66
秦
簡
睡・秦62
今
楷
References:
Note: much of this is based on the answer by Altair at Chinese-Forums.
It may be worthwhile to answer the 也 / 他 / 地 / 池 question first.
Character Mandarin Cantonese Hokkien Middle Ch. Old Ch.
也 yě jaa5 / yáh iā yæX *lAjʔ
他 tā taa1 / tā tha/thaⁿ tha *l̥ ˤaj
地 dì dei6 / deih tè/tē/tōe/tī dijH *[l]ˤej-s
池 chí ci4 / chìh tî drje *Cə.lraj
Although in standard Mandarin, each initial, each final, and each tone is different, one can see that they are more similar in other varieties of Chinese. Comparing this with the rime tables of Middle Chinese (from between the Sui and Song dynasties), the vowels vary between /a ~ æ ~ je ~ ij/. The orthography thus points to a similar enough pronunciation in Old Chinese when the characters were formed that 也 was thought to be an appropriate phonetic in the semantic-phonetic scheme.
In addition, there is a rather well-known orthographic quirk that 也, 它 and 㐌 were viewed as the same logograph in Bronze script of the Zhou. So we can add (Mandarin is standard Hanyu Pinyin; Cantonese is Jyutping and Yale; Hokkien is Peh-oe-ji; Middle and Old Chinese are from Baxter-Sagart 2014):
Character Mandarin Cantonese Hokkien Middle Ch. Old Ch.
蛇 shé se4 / sèh chôa / siâ zyæ *Cə.lAj
施 shī si1 / sī si/sì sye *l̥ aj
馳 chí ci4 / chìh tî drje *lraj
紽 tuó to4 / tòh tô da *lˁaj
匜 yí ji4 / yìh î ye *laj
The modern Chinese readings can start to be grouped then, roughly corresponding to modern standard Mandarin shi/chi/she, tuo/ta, ye/yi, and finally di.
Is there a deeper connection to all of these besides the sound? Some of them may be derived from each other via the usual word-formation processes of Old Chinese.
The characters from the oracle bones seem to point to a "hooded snake" being the 'original' meaning of what was depicted by 也/它/㐌 (and the original 虫, which was retained in 虺 as opposed to 蟲; hence, 蛇 is a double snake), and the principal conjecture seems to be that this meaning of a snake and its hood extended to "spreading".
Many of the modern meanings could conceivably be traced from this idea of spreading. 地 would therefore be "that which is spread" (based on applying the *-s nominalising suffix in Old Chinese) = "land, ground".
It may also be that the meaning of "also/too" may simply be a phonetic loan (假借), but it is very likely that this transfer of meaning was the motivation for adopting 他 and much later 她、牠、祂 based on the third person being the "other". This shift must have happened later after the Mandarin varieties split from the more southern Chinese tongues.
也，它，虫 have the same origin, meaning 蛇 snake.
也 means vulva, 女阴. This meaning is related to totem worship and reproduction worship.
I think it's also possibly related to the ancient Chinese mythology : Nüwa (女娲) who is known for creating mankind and repairing the pillar of heaven (Fig. 1 and 2), and Fuxi (伏羲) who is credited with (along with his sister Nü Wa) creating humanity and the invention of hunting, fishing and cooking as well as the Cangjie system of writing Chinese characters (Fig. 2). From this mythology we can see how 蛇 snake was related to the reproduction worship.
The evolutions of characters of 也，它，虫，and 蛇 are listed beneath Fig.1 and 2. (complete reference)
As how the meaning of 也 extends to "also, too, as well, either", I don't know...
Fig. 1
Fig. 2
也
它
虫
蛇
Let me quote one guy:
同意评友呵呵“也”是“匜”的初文的观点。认为“也”表示低的意思：匜，古代洗手用具，有低凹面可盛水；池，存水的低处为池；地，地面以上的疙瘩墩为土，土以下即低于疙瘩底面为地；弛， 张弓即拉紧弓弦则弓背高，放松弓弦则弓背低为弛；驰，马飞奔则头与身段表现为低；扡同拖，把物体从低处拉出；他，认为比我们低一级的第三人称，古含贬义。猜：低凹的可存水的洗手用具是共用必须品，你洗手，我洗手，使得“也”有了“同样的并列的”意思。
I thinks it's a good model of the evolution of 也.
P.S. the quote is taken from a comment section under the glyph at http://www.vividict.com/ So, it's not reputable in any way :(
