The answer can be both 'yes' and 'no'. The jury of scholars is still out, how can I student take it upon myself to answer the query. However, by logically analyzing the evidence presented by both schools, the answer tends towards "Yes. Uttara Kaanda is a later interpolation."
Based on the prime evidence in Chapter IV of Baala Kaanda and Chapter CXXVIII (...
Mahabharata contains 100 parvas which are further grouped into 18 major parvas
Adi Parva gives list of 100 parvas which includes Santi as well:
Then the coronation of the wise Yudhishthira. The next is called the 'Grihapravibhaga'. Then comes 'Santi', then 'Rajadharmanusasana', then 'Apaddharma', then 'Mokshadharma'. Those that follow are called ...
Are there some foolproof methods of differentiating the originals from the interpolated texts in such cases? If yes, what are those?
There are some accepted methods explained further below but they are not perfect.
Are those methods mentioned in Hindu scriptures themselves?
For how the integrity of the Vedas is preserved, see this answer. I'm not aware ...
Not likely to be interpoloated.
There doesn't seem to be any strong enough reason for that.
"How can a serious philosophical treatise like Bhagavad-gītā contain verses like these that talk about astrology?"
It's not talking about Astrology, but liberation (Moksha). It's explained in description in How can we know that an Aatma got Moksha?. Below ...
It's a new theory proposed by modern scholars of Vālmīki Rāmāyaṇa based on textual criticism. As noted by Robert and Sally Goldman in their translation of Uttarakāṇḍa, the same traditional commentators who wrote commentaries on the previous kāṇḍas have also commented on Uttarakāṇḍa. So, it's unlikely they were aware of problems with the Rāmāyaṇa text passed ...
Yes, Uttara Kanda of Ramayana is an interpolation.
Srimad Ramayana was written much earlier to Mahabharata. In the 272-289 Sections of Vana Parva of Mahabharata, the story of Sri Rama was narrated to Yuddhistara by Sage Markandeya. Though the story contains minor variations compared to the story told in the Srimad Ramayana, those episodes describe the story ...
The critical edition of Vālmīki Rāmāyaṇa available at bombay.indology.info doesn't list the verse in question.
1004001a प्राप्तराज्यस्य रामस्य वाल्मीकिर्भगवानृषिः
1004001c चकार चरितं कृत्स्नं विचित्रपदमात्मवान्
1004001a prāptarājyasya rāmasya vālmīkir bhagavān r̥ṣiḥ
1004001c cakāra caritaṁ ...
I think not. The critical edition mentions 500 chapters in the text but most probably not the number of shlokas.
The table below shows the number of chapters and shlokas we have in
the Critical Edition. The Critical Edition has 606 chapters, 106 more
than 500 sargas mentioned in the text itself. And there are 18,670
shlokas. If one considers ...
One method had been used by Aacharyas is to prepare and check Anukramani.
For protecting the Vedas, and keeping the tradition of mantras well-organized, ancient Rishis has made sorted indices or index according to the topic/subject.
In these index Suktas, Padas, Seear of each and every mantra, Chhand (meter) of richa (hymns) and Devatas of Samhitas are ...
Virata war is NOT an interpolation according to the BORI scholars. Beacause Critical Edition Prepared by Scholars at Bhandarkar Oriental Research Institute BORI > Devanagari (and other Indian scripts from each sarga page) > ४ विराटपर्वम् > ५६ contains the below verse:
ततो वैकर्तनं जित्वा पार्थो वैराटिमब्रवीत् |
Is Shanti Parva an interpolation?
Mahabharata itself says that originally it had 24,000 verses exclusive of the episodes. Only later there was another compilation that extended it to 100,000 verses.
Vyasa executed the compilation of the Bharata, exclusive of the
episodes originally in twenty-four thousand verses; and so much only
is called by the learned as ...