user471: The following sutta AN 5.191 is a bit unusual, because it seems to highlight the moral decadence of newer generations of brahmins / brahmans, compared to the older generations.
However, to my understanding, the Buddha was not concerned with intercaste marriages firstly. Secondly, I don't think there was sex slave trade in ancient India. Thirdly, brahmins who were not monks, need not collect almsfood, because they can store and cook their own food. Fourthly, it looks like an ad hominem attack.
So, to me, this looks like a polemical sutta that was inserted later, and not originally spoken by the Buddha.
Was there any commentaries or scholarly opinions on this topic?
Or is this sutta indeed coherent with the rest of the Buddha's teachings?

“Monks, these five ancient brahmanical traditions are now observed
among dogs but not among brahmans. Which five?
“In the past, brahman males mated only with brahman females and not
with non-brahman females. At present, brahman males mate with brahman
females and with non-brahman females. At present, male dogs mate only
with female dogs and not with female non-dogs. This is the first
ancient brahmanical tradition that is now observed among dogs but not
among brahmans.
“In the past, brahman males mated with brahman females only in-season
and not out-of-season. At present, brahman males mate with brahman
females in-season and out-of-season. At present, male dogs mate with
female dogs only in-season and not out-of-season. This is the second
ancient brahmanical tradition that is now observed among dogs but not
among brahmans.
“In the past, brahman males did not buy or sell brahman females, but
took up cohabitation for the sake of reproduction simply through
mutual attraction. At present, brahman males buy and sell brahman
females, and take up cohabitation for the sake of reproduction simply
through mutual attraction. At present, male dogs do not buy or sell
female dogs, but take up cohabitation for the sake of reproduction
simply through mutual attraction. This is the third ancient
brahmanical tradition that is now observed among dogs but not among
brahmans.
“In the past, brahmans did not make a stash of wealth, grain, silver,
or gold. At present, brahmans make stashes of wealth, grain, silver, &
gold. At present, dogs do not make a stash of wealth, grain, silver,
or gold. This is the fourth ancient brahmanical tradition that is now
observed among dogs but not among brahmans.
“In the past, brahmans searched for alms for their morning meal in the
morning, and for their evening meal in the evening. At present,
brahmans, having eaten as much as they like, swelling their bellies,
leave taking the leftovers. At present, dogs search for alms for their
morning meal in the morning, and for their evening meal in the
evening. This is the fifth ancient brahmanical tradition that is now
observed among dogs but not among brahmans.
“These, monks, are the five ancient brahmanical traditions that are
now observed among dogs but not among brahmans.”
AN 5.191


user13992: If you look at the original:

“Pañcime, bhikkhave, porāṇā brāhmaṇadhammā etarahi sunakhesu
sandissanti, no brāhmaṇesu. Katame pañca?
Pubbe sudaṁ, bhikkhave, brāhmaṇā brāhmaṇiṁyeva gacchanti, no
abrāhmaṇiṁ. Variant: sudaṁ → pubbassudaṁ (mr)Etarahi, bhikkhave,
brāhmaṇā brāhmaṇimpi gacchanti, abrāhmaṇimpi gacchanti. Etarahi,
bhikkhave, sunakhā sunakhiṁyeva gacchanti, no asunakhiṁ. Ayaṁ,
bhikkhave, paṭhamo porāṇo brāhmaṇadhammo etarahi sunakhesu sandissati,
no brāhmaṇesu.

Then the root word used to refer to dogs is sunakh-, where the words used to refer to dog, as in the animal species, in Pali are usually koṭṭhu° or Kukkura (hence the modern Hindi  कुत्ता. Kuttā). So this is an interesting choice of word, since this root word is found in the Petavatthu meaning or alluding to something completely different:

sunakho te khādati: a constituent part of a whole or system or collection (Pv II.1210, 13, 18)
in °sunakha, the Dog of Purgatory (Pv 152) of a dark, i.e. miserable, unfortunate birth, or social condition

So it's very plausible this text is wordplay to compare the behavior of the highest cast in the contemporary society (brahmin) to the lowest cast. I probably do not need to remind anyone that even today the lowest cast in India is referred to as "untouchables". As such, it's interesting that the word sandissati forms an idiom with the sunakh- root, so that sunakhesu sandissanti，can also mean "they are of no more value"( J．VI，217 )
We actually have the same wordplay in modern English vernacular: everyone knows what "you dog, you!" is referring to. It's not suggesting the person is an actual dog, but alluding to behavior.

471: <p>The following sutta <a href="https://www.dhammatalks.org/suttas/AN/AN5_191.html" rel="nofollow noreferrer">AN 5.191</a> is a bit unusual, because it seems to highlight the moral decadence of newer generations of brahmins / brahmans, compared to the older generations.</p>
<p>However, to my understanding, the Buddha was not concerned with intercaste marriages firstly. Secondly, I don't think there was sex slave trade in ancient India. Thirdly, brahmins who were not monks, need not collect almsfood, because they can store and cook their own food. Fourthly, it looks like an <em>ad hominem</em> attack.</p>
<p>So, to me, this looks like a polemical sutta that was inserted later, and not originally spoken by the Buddha.</p>
<p>Was there any commentaries or scholarly opinions on this topic?</p>
<p>Or is this sutta indeed coherent with the rest of the Buddha's teachings?</p>
<blockquote>
<p>“Monks, these five ancient brahmanical traditions are now observed
among dogs but not among brahmans. Which five?</p>
<p>“In the past, brahman males mated only with brahman females and not
with non-brahman females. At present, brahman males mate with brahman
females and with non-brahman females. At present, male dogs mate only
with female dogs and not with female non-dogs. This is the first
ancient brahmanical tradition that is now observed among dogs but not
among brahmans.</p>
<p>“In the past, brahman males mated with brahman females only in-season
and not out-of-season. At present, brahman males mate with brahman
females in-season and out-of-season. At present, male dogs mate with
female dogs only in-season and not out-of-season. This is the second
ancient brahmanical tradition that is now observed among dogs but not
among brahmans.</p>
<p>“In the past, brahman males did not buy or sell brahman females, but
took up cohabitation for the sake of reproduction simply through
mutual attraction. At present, brahman males buy and sell brahman
females, and take up cohabitation for the sake of reproduction simply
through mutual attraction. At present, male dogs do not buy or sell
female dogs, but take up cohabitation for the sake of reproduction
simply through mutual attraction. This is the third ancient
brahmanical tradition that is now observed among dogs but not among
brahmans.</p>
<p>“In the past, brahmans did not make a stash of wealth, grain, silver,
or gold. At present, brahmans make stashes of wealth, grain, silver, &amp;
gold. At present, dogs do not make a stash of wealth, grain, silver,
or gold. This is the fourth ancient brahmanical tradition that is now
observed among dogs but not among brahmans.</p>
<p>“In the past, brahmans searched for alms for their morning meal in the
morning, and for their evening meal in the evening. At present,
brahmans, having eaten as much as they like, swelling their bellies,
leave taking the leftovers. At present, dogs search for alms for their
morning meal in the morning, and for their evening meal in the
evening. This is the fifth ancient brahmanical tradition that is now
observed among dogs but not among brahmans.</p>
<p>“These, monks, are the five ancient brahmanical traditions that are
now observed among dogs but not among brahmans.”</p>
<p><a href="https://www.dhammatalks.org/suttas/AN/AN5_191.html" rel="nofollow noreferrer">AN 5.191</a></p>
</blockquote>
 13992: <p>If you look at the original:</p>
<blockquote>
<p>“Pañcime, bhikkhave, porāṇā brāhmaṇadhammā etarahi <strong>sunakhesu</strong>
sandissanti, no brāhmaṇesu. Katame pañca?</p>
<p>Pubbe sudaṁ, bhikkhave, brāhmaṇā brāhmaṇiṁyeva gacchanti, no
abrāhmaṇiṁ. Variant: sudaṁ → pubbassudaṁ (mr)Etarahi, bhikkhave,
brāhmaṇā brāhmaṇimpi gacchanti, abrāhmaṇimpi gacchanti. Etarahi,
bhikkhave, <strong>sunakhā sunakhiṁyeva</strong> gacchanti, no <strong>asunakhiṁ</strong>. Ayaṁ,
bhikkhave, paṭhamo porāṇo brāhmaṇadhammo etarahi sunakhesu sandissati,
no brāhmaṇesu.</p>
</blockquote>
<p>Then the root word used to refer to dogs is <em>sunakh-</em>, where the words used to refer to dog, as in the animal species, in Pali are usually <em>koṭṭhu°</em> or <em>Kukkura</em> (hence the modern Hindi  कुत्ता. Kuttā). So this is an interesting choice of word, since this root word is found in the <em><a href="https://en.wikipedia.org/wiki/Petavatthu" rel="nofollow noreferrer">Petavatthu</a></em> meaning or alluding to something completely different:</p>
<ul>
<li><em>sunakho te khādati</em>: a <strong>constituent part of a whole or system</strong> or collection (Pv II.1210, 13, 18)</li>
<li><em>in °sunakha</em>, the Dog of Purgatory (Pv 152) <strong>of a dark, i.e. miserable, unfortunate birth, or social condition</strong></li>
</ul>
<p>So it's very plausible this text is wordplay to compare the behavior of the highest cast in the contemporary society (brahmin) to the lowest cast. I probably do not need to remind anyone that even today the lowest cast in India is referred to as &quot;untouchables&quot;. As such, it's interesting that the word <em>sandissati</em> forms an idiom with the sunakh- root, so that <em>sunakhesu sandissanti</em>，can also mean &quot;they are of no more value&quot;( J．VI，217 )</p>
<p>We actually have the same wordplay in modern English vernacular: everyone knows what &quot;you dog, you!&quot; is referring to. It's not suggesting the person is an actual dog, but alluding to behavior.</p>
