There is a book written by V.R.Anil Kumar "Vivaha Samskara in Grihya-Sutras of the Four Vedas" has been reviewed
recently in many Religious Magazines. I give below relevent portion of review by S.Jagannatha,Research Scholar, ORI, Samskrita Department, Manasagangotri, Mysore, relating to Mangalasutra in the said book .
For any scholar, chapter 7 is very important because it is of comparative study. Usually in this type of works, all the points are put in a tabular form. But the author of VSG mentions all points one by one in detail. In some cases showing the points in paragraphs is preferable to placing them in a table. Even though repetitions are inevitable in this method, it helps the reader to understand the points vividly. Author writes every point in clear sentences. Suitable time for marriage, qualities of bride and groom, forms of marriage, kanyadana, bathing and dressing the bride, panigrahana (most probably the oldest ritual), saptapadi (mentioned in all Grihyasutras), ashmarohana, lajahoma, agni-parinayana (circumambulating around Agni), grihapravesha, triratravrata and caturthikarman are elaborated. Order of contents of vivaha samskaras follows.
Chaprer 8 is a compilation of major mantras with mentioning the known sources. Variants are shown.Summary follows in chapter 9. Analysis is the main subject of this chapter. It is clearly shown that some rituals were added in later periods. Further evolutions from Grihyasutras like dibbana (baraat in Hindi) are mentioned. Tali (in Kannada) or mangalasutra is not mentioned in any Grihyasutra. We are informed that this custom is taken from the tribal practice. This opinion is already in circulation among Indologists. But it is hard to believe that our ancestors, being staunch conservatives, imitated tribal communities in marriage rituals. Why they should follow lower-class people in only tali when they had so many customary injunctions in scriptures? ......
(Full review is available in the URL:
http://www.dkprintworld.com/product-detail.php?pid=1280857365
During the past century we find the Hindu marriage rituals have changed from purly sacrmental to social function by adding and deleting many rituals. Regarding wearing "Thali", it is better to leave the same to one's wish.
Brahmanyan,
Bangalore.