Consequently the hymns in which these passages occur should be assigned to the period of the later Vedic literature. Other passages that similarly sh… - Kshetresa Chandra Chattopadhyaya

... Consequently we can safely infer that wherever the general scheme has been disturbed we have reasonable grounds for suspecting interpolations .... To give an ins- tance, the original Indra collection of the III Mandala was . hymns 30-50, the first hymn (30) containing 22 verses, and the last (50) only 5; the three supplementary Indra hymns (51-53), having respectively 12, 8 and 24 verses, seem to have been added in two instalments, hymn 53 (24 verses) having been added some time after hymns 51 (12 verses) and 52 (8 verses) had been appended to the original Indra collection. There are many more such additions, in some cases of entire groups of hymns. Now these later additions are not necessarily all later compositions. They may have been added later, because they were discovered later. But some of them certainly can be compositions of later times. Then there are six verses in the accepted text of the Rgveda-Samhita, 1.99.1, VII.59.12, X.121,1O, X.190.1-3, whose Pada-Piitha is wanting. The only inference that we can make from this fact is that these verses did not form part of the Rgveda-Samhiui when Sakalya compiled its Pada-Piuha. Consequently they have been added even so late as after the time of Sakalya. In this case too it is not possible to say that they were all composed after Sakalya, particularly when VII.50.12 and X.121.10 are found in the various Yajurveda-Samhitas. But we can presume this for X.190.1-3, which bear on their very face the impression of lateness. We do not find these three cosmogonic verses, showing knowledge of the Kalpa theory, till the very late Taittiriya Aranyaka (X.1.13), a text which shows know- ledge of Smrtis (1.2.1) ....

I have said above that the chief ground for placing the greater portion of the Rgveda-Samhita in a very early period is the archaic character of its language. But the Samhita is not lacking in late linguistic features as well. It well known that the word usura means "a good spirit", "a god" or "God" in the Rgveda-Samhiui as its cognate ahura means in the Avesta, and that in the later Vedic literature and in classical Sanskrit the word has undergone semantic deterioration, acquiring the sense of "demon".

These beings have also been called 'not divine' (a-deva) and 'not human' (a-miin~a), which shows that they were something between men and gods, i.e., they were demons.