Consciousness and Natural Selection

If one is a physicalist, then presumably one thinks that consciousness emerged as a result of naturalistic evolution. From this, it would seem to follow that consciousness was selected for, i.e. that it provided some kind of adaptive advantage, which lead to conscious organisms out-competing non-conscious ones. (If consciousness is a purely physical process, then it would likely depend on rather complex biological systems, and so it is unlikely to be a spandrel that simply piggy-backed on some other adaptive trait.) 

However, this claim seems to be rather suspicious. After all, it is obvious that non-conscious organisms are perfectly capable of doing all the things required for survival, such as finding food and avoiding predators (e.g. about two-thirds of philosophers do not regard flies as conscious, yet they seem to be doing alright for themselves). At the same time, there are a number of behaviors which are highly detrimental from an evolutionary perspective, and which only conscious beings are capable of. Among these would seem to be: committing suicide, developing a mental illness, having an existential crisis, using contraceptives, adopting antinatalism, and committing oneself to celibacy as part of a religious ordination. 

The upshot, then, is this: there seem to no highly adaptive traits that only conscious beings possess, whereas there are numerous non-adaptive traits which only conscious beings possess. It is thus difficult to see why a naturalistic evolutionary process would have selected for consciousness. And of course, this is completely separate from any concerns one might have about emergence (serious though these worries are). I have no idea whether this is a good argument against naturalistic physicalism, but it is interesting to think about.