This ambiguity and uncertainty can also be found when it comes to Nietzsche’s assessment of Darwinism

Friedrich Nietzsche on the Origin of Language and Consciousness
from Shared Symbolic Storage by (Michael Pleyer)

Friedrich Nietzsche (1844-1900) is mostly known for his famous sentence “God is dead” and his concept of the “Übermensch”/”Superman” which later was horrendously misinterpreted and misused by the Nazis. In fact, some of the widespread misinterpretation of Nietzsche’s works are really his own fault, because he often expressed himself in very dark and obscure ways open to several readings. There is a joke in the Nietzsche scholarship community that everybody who is quoting a single excerpt of Nietzsche’s writing to make his case has to be lying, because you just as easily could find a section in which he says the exact opposite.

This ambiguity and uncertainty can also be found when it comes to Nietzsche’s assessment of Darwinism. Although he seemed to be convinced of the theory of evolution through common descent, he seemed to have differing views on the mechanisms of evolution. There are several aphorisms in his unpublished works and notes titled “Anti-Darwin,” but at least from the view of modern evolutionary Theory his criticisms are mostly due to a misunderstanding of evolutionary theory and terms like “fitness.”

I do not know in which way Nietzsche’s criticisms applied to 19th century Darwinism. You should probably ask John Wilkins for that. Nietzsche took the side of biologists like Wilhelm Roux who argued that there had to be internal, systemic selection prior to external selection, something readily acknowledged in modern evolutionary theory, especially the systems theory of evolution.

Nietzsche also thought that life wasn’t only about self-preservation and mere survival (a position he took Darwinists to be arguing for) but that life was intrinsically aiming toward multiplication and extension, that it was governed by fundamental “a will to power” (here we have another very problematic concept of Nietzsche which no one really seems to understand).

Be that as it may, there is quite a bit of evolutionary theorizing in Nietzsche’s work and sometimes he even invokes notion akin to fitness and survival in order to explain how a certain cognitive property came about.

In Nietzsche’s 1882 “The Gay Science” (Part V, Aphorism No. 354) there are even some speculations about the function and evolution of language and consciousness and their interrelated nature.

For Nietzsche, thinking, feeling, wanting, recollecting and acting need not be conscious in order to be performed, but can come about sub-consciously. Nietzsche then asks:
“What then is the purpose of consciousness generally, when it is in the main superfluous?”

Nietzsche proposes that consciousness is always in proportion with an animal’s capacity for communication. This capacity again is seen as being related to an animal’s need for communication:
“where necessity and need have long compelled men to communicate with their fellows and understand one another rapidly and subtly, a surplus of the power and art of communication is at last acquired, as if it were a fortune which had gradually accumulated, and now waited for an heir to squander it prodigally."

Language then, is seen as an adaptation that evolved gradually and provided a selective advantage in a hostile environment in which quick and efficient group coordination and cohesion were of utmost important. This is eerily familiar with the perspective of Evolutionary Psychology, especially Steven Pinker’s view of language as a gradual adaptation that evolved for the communication of complex propositions. Interestingly, Pinker also has written about our intrinsic “urge to communicate" (Pinker 1994).

Nietzsche sums up his hypothesis thus: “consciousness generally has only been developed under the pressure of the necessity for communication "

Furthermore, consciousness is mainly necessary in social settings:
“consciousness is properly only a connecting net between man an man, - it is only as such that it has had to develop, the recluse and wild-beast species of men would not have needed it.”
Humans are seen as the “most endangered animal” in need of help and protection. This is also eched in famous German philosophical anthropologist Arnold Gehlen's concept of humans as "Mängelwesen" (deficient creatures), i.e. organisms with deficient instincitve capacities which leave them ill-prepared to respond to challenges from their environment. I think formulated in the way Gehlen does it the notion is crap, but it is certainly true that human are adapted for the "cognitive niche" and do not rely on predatory skills such as lions, etc, and are much more fragile and helpless to such attacks.

In order to express and coordinate this need, they needed to make themselves understood, and they needed to have a capacity for conscious introspection in order to know and communicate what they needed and wanted. In modern terminology, this would probably be called metacognition. To be more precise, given modern terminology, Nietzsche would probably hold that animals may display metacognitive regulation, e.g. higher-order sub-conscious uncertainty monitoring, as it has been shown in macaques and dolphins (Smith et al. 2003). This sort of higher-order subconscious thought would probably be what Nietzsche would refer to as unconscious thinking. However, together with other modern philosophers, he would probably hold that only humans display metacognitive knowledge (a distinction introduced by Flavell 1979, see also Hurford 2007: 23ff.).

Again, this neatly fits with the perspective of evolutionary psychology and Steven Pinker who see language and consciousness as “adaptation to the cognitive niche”, which then led the ‘environmental’ niche humans constructed for themselves: culture.
Nietzsche’s view on the evolution of language and consciousness even links to concepts such as Ernst Cassirer’s “homo symbolicus” or Terrence Deacon’s “Symbolic Species” as well as to the Social Intelligence Hypothesis, which holds that the driving motor of primate brain evolution as well as of human conscious cognition were large social groups:
“The sign-inventing man is at the same time the man who is always more acutely self-conscious, it is only as a social animal that man as learned to become conscious of himself“”
The term social animal of course can be traced back to Aristotle’s notion of man as a zoon politikon, which basically means “social aninmal.”

Now here’s the catch: according to Nietzsche:
“consciousness does not properly belong to the individual existence of man, but rather to the social and gregarious nature in him; […] as follows therefrom, it is only in relation to communcal and gregarious utility that it is finely developed; and that consequently each of us, in spite of the best intention of understanding himself as individually as possible, and of “knowing himself”, will always just call into consciousness the non-individual in him, namely, his “averageness.”"

This sounds similar to neuroscientists who see the conscious self as an illusion, a fiction that just came into existence as a regulatory social mechanism. They see that consciousness in essence as a socially and culturally imposed and imprinted idealized role model we link and ascribe our actions and states to. (see e.g. Metzinger 2000)
But Nietzsche goes even further: given that conscious is essentially something that develops in group interactions, if we translate our actions into conscious decisions, they all have to adhere to the same conscious group format, and thus lose their personality, uniqueness, and individuality:

“The nature of animal consciousness involves the notion that the world of which we can become conscious is only a superficial and symbolic world, a generalised and vulgarized world; […] everything which becomes conscious becomes just thereby shallow, meagre, relatively stupid, a generalisation, a symbol, a characteristic of the herd; […] with becoming conscious of something there is always combined a great, radical perversion, falsification, superficialisation, and generalisation.”
Nietzsche’s closes with a sceptically remark that is very similar to the viewpoint of modern, evolutionary epistemology, and which is also close to the following fear expressed by Charles Darwin:
"But then with me the horrid doubt always arises whether the convictions of man’s mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy.”

Nietzsche also shares this scepticism. If consciousness is merely a group function and not responsible for higher-order thought, then
“we have not any organ at all for knowing, or for “truth”: we “know” (or believe, or fancy) just as much as may be of use in the interest of the human herd, the species; and even what is here called “usefulness,” is ultimately only a belief, a fancy, and perhaps precisely the most fatal stupidity by which we shall one day be ruined”

P.S. The translation I took these quotes from is pretty shitty. I have also looked at the original text and asked myself how I could translate it better, but Nietzsche’s idiosyncratic style is sometimes hard to follow if you’re a native speaker of German, and my English skills are wholly deficient for the task I’m afraid.

References:
Flavell, John. (1979). Metacognition and cognitive monitoring: A new area of cognitive-developmental inquiry. American Psychologist 34, 906–911.
Hurford, James M. (2007): The Origins of Meaning: Language in the Light of Evolution. Oxford: OUP.
Metzinger, Thomas (2000): The Subjectivity of Subjective Experience: A Representationalist Analysis of the First-Person Perspective. In: Thomas Metzinger (ed.): Neural Correlates of Consciousness – Empirical and Conceptual Questions. Cambridge, AM: MIT PressPinker, Steven 1994. The Language Instinct: The New Science of Language and Mind. London: Lane Penguin Press.
Smith, J. D., W. E. Shields, and D. A. Washburn (2003a). The comparative psychology of uncertainty monitoring and metacognition. Behavioral and Brain Sciences 26, 317–339.