Murray’s “response 2” to the issue of animal suffering is the suggestion that the pain of non-human animals is like what Murray calls “lobotomy” pain. 
More precisely, on this account, non-human animals do feel pain, but the pain is not undesirable, in the sense that it would not have a “negative mental valence”.
Murray suggests that the distinction is based on the human prefrontal cortex (PFC) which he claims – citing research published in “Trends in Cognitive Science” - is “absolutely, obviously, and tremendously” different from the PFC of any other animals, and claims that those differences are destroyed in a lobotomy, so that if that’s what makes pain that is felt negatively possible, non-human animals do not feel pain negatively.
The article he cites actually compares the PFC of humans with that of chimpanzees, so in particular it would apply to chimpanzees.
The suggestion fails, for at least the following reasons:
a. It’s clear that chimpanzees do feel pain negatively. If they didn’t and they experienced pain like Murray’s lobotomy patients, then they would not react to pain like normal humans do, i.e., with a strong aversion. In fact, if they felt pain but did not care about it, they would usually feel no motivation to avoid it, and wouldn’t cry, fight or run away when exposed to it.
The same goes for bonobos, orangutans, gorillas, their ancestors for millions of years, as well as several species of australopithecines, Homo Habilis, etc.
In fact, this proposal leads to an absurd idea that chimpanzees, australopithecines, etc., are either pretending to find pain undesirable, or alternatively, their minds are trapped in P-zombie bodies that act as if they found pain undesirable – since, again, their expressions, screams and general behavior expresses what obviously appear to be emotions associated with unpleasant – sometimes, horribly negative – feelings.
Now, someone might suggest that chimpanzees, gorillas, australopithecines, etc., do not experience anything at all, taking a Cartesian stance. I do not think this is tenable, but in any case, it would not be Murray’s response 2, which holds that they do feel pain, but do not experience it in a negative fashion.
The points above suffice to conclude Murray’s response 2, and I think but I would like to add a couple more points, just to highlight some of the absurdities.
b. Murray claims that the human PFC is “absolutely, obviously, and tremendously” different from the PFC of any other animals. However, even if that’s the case of extant animals, the fact is that there is a chain from PFC very different from those of humans to human PFC through gradual changes, from parents to their offspring.
Now, Murray does not define “human”, and the word is not precise enough, in my assessment, for arguments involving a “first human”, i.e., it does not make a sharp distinction between two categories of humans and non-humans, but a fuzzy one – as usual with our language.
However, if a theistic reply to the problem of suffering distinguishes between the suffering of humans and the suffering of non-human animals (even if to deny the latter), it seems to me it’s implicitly assumed that there are no actual past individuals such that the categories of human and non-human are not precise enough to classify them, because otherwise what would the reply say about them?
So, I will assume that there is such precision for the sake of the argument.
Also, I will use numbers to simplify the matter, but being able to give a numerical value on some scale to the negative value of pain is not required.
So, of our subspecies Homo Sapiens Sapiens (HSS) finds pain negative, though how negative the pain is depends on the intensity of the noxious stimuli, type of pain, and the individual. But still, let’s say that PHSS is a rough average for how HSS individuals negatively feel pain, which varies of course with the stimuli. So, Pain(HSS, x) would have some negative value, for each noxious stimuli x that can be experienced by HSS.
On response 2, in the case of our most recent common ancestor with chimpanzees (CHLCA), there is no negative experience – else, response 2 fails, since we can run the problem of suffering on the suffering of CHLCA -, and so, Pain(CHLCA, x) = 0 for all x that can be experienced by CHLCA.
For example, if Pain(HSS, placing a hand in a fire)=-1000, we get Pain(CHLCA, placing a hand in a fire)=0, where we may consider the conditions for placing the hand to be specified. There are also individual functions, like P(Bob, placing a hand in a fire)=-1013, etc. (Bob is human).
That’s absurd of course, since our ancestor would not have avoided fire in that case, and would not have avoided pain in general, which obviously is not true. But that’s point a.; let’s now consider the period – which lasts from 5 to 8 million years – from the CHLCA to the present day.
We may consider two options.
b.i. Jump from 0 to Pain(HSS, x) in one generation.
b.ii. Gradual change.
Then, there is a mother (say, Alice), and her daughter Mary , such that Mary experiences pain negatively (roughly) like we do, whereas Alice does not find pain undesirable at all. So, here we have an extremely similar PFC, pretty much the same behavior in reaction to pain, etc., they both cry, recoil, avoid pain, etc., but only Mary finds it negative. Alice feels indifferent.
Of course, if Alice’s hand were to be put on fire, she would desperately cry, show the signs of suffering that we would see in humans, like her daughter Mary – who is human, otherwise she would not feel pain negatively on response 2.
But Alice does not mind at all. It looks like Alice is trapped in a zombie body that behaves in a way that is not at all linked to Alice’s actual feelings. The absurdities should be apparent in this case. For that matter, we might as well suggest that our grandparents were zombies.
We have that Pain (CHLCA, placing a hand in a fire)=0.
On the other hand, Pain (HSS, placing a hand in a fire)=-1000.
How about, say, Homo Habilis (HH)?
If, say, Pain(Homo Habilis, placing a hand in a fire)<-500, then they felt that pain at least half as negatively as we do, on average. But then, placing a hand in a fire feels horrible, and half as negative as that is still very negative. So, if the value is between -1000 and -500, then we may run an argument from suffering based on H. Habilis, and Murray’s response 2 fails because of that.
Similarly, we may consider other kinds of horrible pain, like being literally torn apart by a clan of hyena while still alive, or things like that, and run an argument based on H. Habilis if they felt at least half as bad as we do.
At this point, it might be argued that Homo Habilis were human in the sense in which Murray uses “human”, so response 2 does not apply to them. But in that case, we may run a problem of suffering based on H. Habilis, anyway. What’s the defense? It’s not response 2, so someone might try the Fall of humans. But the Fall of Homo Habilis?
But moreover, if Homo Habilis did not find pain half as horrible as we do in any cases of great pain, one would have expected that they would have been somewhat less averse to it. But how or why their reaction to pain diminished like that, from the time of CHLCA?
What if they did not find pain so unpleasant?
We can still run the argument with, say, -300, or -200, or even -100, etc., (that still would require a response, given that the theist posits that God is running the world), or alternatively ask: how about Homo Erectus?
If a theist holds that maybe Homo Erectus was human and the Fall explains it, then let's consider the mother of the first primate who, say, Fell.
From a slightly different perspective, let’s consider a present-day person, Alice, then her mother, grandmother, great-grandmother, etc., and the same for other people. The result would be either humans who do not find pain negative (but then, why would they avoid it so eagerly? Are they trapped in P-zombie bodies?), or alternatively, non-humans who find pain negative (then, response 2 fails because of that, since we may run an argument from suffering on their suffering).