Most of our ancient thinkers were of the opinion that only the male members of the brāhmaṇa, kṣatriya, and vaiśya varṇas were eligible to study the Vedas. And since the upanayana saṃskāra was primarily meant as an entry to the study of the Vedas, it was not applicable to women of all varṇas and to śūdras.
There are, however, exceptions to this rule. For instance, one of the ancient teachers, Ācārya Bādarī mentions that everyone, including śūdras, has the right to perform Vedic yajñas. As a consequence, they too would have the opportunity for upanayana. That apart, in the early Vedic period, there were only three varṇas – the first being the group of people mostly involved with the spiritual and ritualistic activities (brāhmaṇas), the second being the people involved with governance and warfare (kṣatriyas), and the third being the common folk (vaiśyas).
We find interesting statements in the smṛtis about whether the upanayana was performed for women and if they wore the yajñopavīta (sacred thread) or not. In the early days, they seem to have classified women into two types – Brahmavādinīs, students of sacred lore and Sadyovadhūs, those who straightaway marry. Of these, brahmavādinīs underwent upanayana, maintained the agni, engaged in Vedic study; they were expected to beg and maintain themselves but not in public, instead it was under the parental roof. In the case of sadyovadhūs when their marriage was drawing near, the mere ritual of upanayana was performed and only then was their marriage celebrated.
While speaking about the marriage rite, it is said, “Leading forward from the house towards the agni, the bride who is wrapped in a robe and wears the yajñopavīta slung from her left shoulder, the husband should recite a verse from the Veda.” So the girl wore the yajñopavīta as a symbol of the saṃskāra of upanayana.
Another clue is obtained from one of the rules laid down in the Samāvartana, the graduation ceremony. On the subject of applying an ointment, Aśvalāyana says, “After smearing both hands with the ointment, a brāhmaṇa should start by salving his face; a kṣatriya, his two arms; a vaiśya, his stomach; a woman, her private parts…” Women undertaking Vedic study might have not been common but one can definitely say that Aśvalāyana—who lived at least two thousand years ago—knew about such women.
In the case of women, Samāvartana took place before the appearance of menses. Brahmavādinī women had upanayana performed in the eighth year from conception; then they studied Vedic lore and finished student-hood at the age of puberty. Tying of the mekhalā of muñja (i.e. upanayana) was desired in the case of maidens. They were made to recite the Sāvitrī (the sacred Gāyatrī mantra) as well. Their father, uncle, or brother taught them, and not a stranger. Begging was prescribed for the maiden but in the house itself. Also, she was not to wear deer-skin or bark garment and was not to have matted hair.
Even Manu seems to know of this usage as prevalent in ancient times, if not during his own. Speaking about the saṃskāras from jātakarma to upanayana, Manu says “these ceremonies were to be performed in their entirety for women also, but without mantras” and adds “the ceremony of marriage is the only saṃskāra performed with Vedic mantras in the case of women; (in their case) attendance on the husband amounts to serving a guru (which a student had to do) and performance of domestic duties to worship of fire” (which the student had to perform by offering a fuel-stick in the evening every day). By the time of Manu, upanayana for women had perhaps gone out of practice but it was known to have been performed in former times.
Even in the case of those who were eligible, not everyone chose to have the upanayana performed. It seems that kṣatriyas and vaiśyas often neglected this saṃskāra or at least neglected the constant wearing of the yajñopavīta. This was so prevalent that the yajñopavīta was regarded as the peculiar indicator of the brāhmaṇa varṇa even from comparatively early times.
To be continued…
Thanks to Pradeep Chakravarthy for getting me to write this essay. Śatāvadhāni Dr. R Ganesh and Dr. Koti Sreekrishna, who have always supported and encouraged me, were kind enough to go through the essay and give their detailed feedback. Shashi Kiran B N, a young scholar-poet went through the essay and offered valuable suggestions. Yet another scholar-poet, Arjun Bharadwaj, helped me with getting some of the reference books needed for this essay. My heartfelt gratitude to all of them.
Achari, Sri Rama Ramanuja. Saṁskāras: The Hindu Sacraments. Srimatham, 2015 <http://www.srimatham.com/uploads/5/5/4/9/5549439/hindu_samskaras.pdf>
Devuḍu. Mahādarśana. Bangalore: Devuḍu Pratiṣṭhāna, 2009
H H Sri Rangapriya Swami’s lecture on the Gāyatrī mantra
Harshananda, Swami. Upanayana: Sandhyāvandana and Gāyatrīmantrajapa. Chennai: Sri Ramakrishna Math.
Harshananda, Swami. A Concise Encyclopaedia of Hinduism. Volume 3. R-Z. Bangalore: Ramakrishna Math, 2008
Kane, Pandurang Vaman. History of Dharmaśāstra. Vol. II, Part I. Poona: Bhandarkar Oriental Research Institute, 1941
Pandey, Rajbali. Hindu Saṁskāras: Socio-Religious Study of the Hindu Sacraments. New Delhi: Motilal Banarasidass, 1969
Ṛgvedasaṃhitā. Vol. 17. Ed. Rao, H. P. Venkata. Mysore: Sri Jayachamarajendra Vedaratnamala, 1948-62
Śatāvadhāni Dr. R Ganesh’s seven-part lecture series in Kannada titled Ṣoḍaśa-saṃskāragaḻu at Gokhale Institute of Public Affairs (GIPA) in December 2005
The Sixteen Samskaras <http://cincinnatitemple.com/articles/SixteenSamskaras.pdf>
 HDS, pp. 293-99
 Gautama calls the three higher varṇas dvijātis—having two births—while he calls the śūdra an ekajāti, having just one birth. (Gautama-dharma-sūtra 10.1 and 51). Āpastamba goes as far as to say that śūdras and criminals are not allowed to undergo upanayana (Āpastamba-dharma-sūtra 188.8.131.52) While there was doubtless a disdain towards the śūdras, it is also true that those who were talented attained recognition and came to the forefront, irrespective of their varṇa. Aitareya-brāhmaṇa 2.19.1 tells the story of Kavaṣa Ailūṣa, a śūdra who became a ṛṣi of the Ṛgveda. Mahīdāsa Aitareya was the son of Itarā, a śūdra woman. He is the seer of the Aitareya śākhā of the Ṛgveda. Chāndogyopaniṣad 4.4 tells the story of Satyakāma Jābāla, the illegitimate child of a śūdra woman, who goes on to become a great ṛṣi
 See Jaiminī’s Pūrva-mīmāṃsā-sūtra 6.1.27
 Further, we find that it was only the words of the Veda that were held back from the śūdras and not the message. Just as an example, the Gāyatrī being a Vedic mantra was forbidden to the śūdra; instead he was taught a Paurāṇic mantra—Yo devaḥ savitāsmākaṃ dhiyo dharmādigocharāḥ. Prerayettasya yadbhargaḥ tadvareṇyamupāsmahe.—that has the same meaning as the Gāyatrī
 Yattu hārītenoktaṃ dvividhāḥ striyo brahmavādinyaḥ sadyovadhvaśca. Tatra brahmavādinīnāmupanayanamagnīndhanaṃ vedādhyayanaṃ svagṛhe ca bhikṣācaryeti. Sadyovadhūnāṃ tu upasthite vivāhe kathāñcidupanayanamātraṃ kṛtvā vivāhaḥ kāryaḥ. – Hārīta-dharma-sūtra quoted in Smṛticandrikā I, p. 24; also see Saṃskāra-prakāśa, p. 402
 Ṛgveda-saṃhitā 10.85.41
 Prāvṛtāṃ yajñopavītinīmamyudānayan japet ‘somo dadadgandharvāyeti’ – Gobhila-gṛhya-sūtra 2.1.19; the commentary says ‘Yajñopavītavatkṛtottarīyām.’ ‘Na tu yajñopavītinīmityanena strīṇāmapi karmoṅgatvena yajñopavītadhāraṇamiti hariśarmoktaṃ yuktaṃ strīṇāṃ yajñopavītadhāraṇānupapatteḥ.’ – Saṃskāra-tattva, p. 896
 In the Mahābhārata, a brāhmaṇa is said to have taught Kunti many mantras from the Atharvaśiras. Tatastāmanavadyāṅgīṃ grāhayāmāsa sa dvijaḥ. Mantragrāmaṃ tadā rājannatharvaśirasi śrutam. – Vana-parva 305.20
 Anulepanena pāṇī pralipya mukhamagre brāhmaṇo anulimpet. Bāhū rājanyaḥ. Udaraṃ vaiśyaḥ. Upasthaṃ strī. Ūrū saraṇa jīvanaḥ. – Āśvalāyana-gṛhya-sūtra 3.8.11
 Prāgrajasaḥ samāvartanam. Iti hārītokstyā – Hārīta quoted in the Saṃskāra-prakāśa, p. 404
 Yamopi. Purākalpe kumārīṇāṃ mauñjībandhanamiṣyate. Adhyāpanaṃ ca vedānāṃ sāvitrīvācanaṃ tathā. Pitā pitṛvyo bhrātā vā naināmadhyāpayetparaḥ. Svagṛhe caiva kanyāyā bhaikṣacaryā vidhīyate. Varjayedajinaṃ cīraṃ jaṭādhāraṇameva ca. – Yama quoted in the Saṃskāra-prakāśa, pp. 402-3
 Amantrikā tu kāryeyaṃ strīṇām āvṛdaśeṣataḥ. Saṃskārārthaṃ śarīrasya yathākālaṃ yathākramam. – Manu-smṛti 2.66
 Vaivāhiko vidhiḥ strīṇāṃ saṃskāro vaidikaḥ smṛtaḥ. Patisevā gurau vāso gṛhārtho’gniparikriyā. – Manu-smṛti 2.67
 HDS, p. 295
 Apart from kṣatriyas and vaiśyas proper, those who belonged to other groups like the anuloma jātis (e.g. rathakāra, ambaṣṭha &c.) too were eligible for the rite (see Manu-smṛti 10.41)