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Knowing the molecular basis of a behaviour is not a prerequisite for understanding its evolution or many of its evolutionary consequences. Evidence about transmission is essential for claims of inherited change, while detailed genetic architecture becomes essential for particular mechanistic predictions. The claim therefore depends on what is meant by a genetic basis and on the explanatory question being asked.

Tinbergen's four questions distinguish mechanism, development, adaptive significance and evolutionary history. Identifying a neural or molecular mechanism helps explain how a response is produced; it does not automatically show why a variant spread, whether it currently increases reproductive success, or whether the same mechanism generated the ancestral transition. Conversely, a well-supported evolutionary explanation can begin with experimentally demonstrated biological fitness consequences and transmission without a complete molecular account. These explanatory levels are complementary rather than substitutes. ^[ref]

The phrase genetic basis can refer to several different achievements: identifying inherited variation; estimating the number and effects of contributing genetic loci; finding a causal nucleotide change; or describing every gene required for development of the relevant sensory and motor systems. These are not equivalent. Many genes can be necessary for an animal to perform an action while none explains variation in that action within the studied population. Knocking out a broadly required neural gene and eliminating courtship does not identify an evolutionary substitution for a naturally varying mate preference.

quantitative genetics can predict a response without naming the causal molecular variants. Under the appropriate additive, generational and environmental assumptions, the multivariate breeder's equation gives:where $\mathbf{G}$ is the additive genetic covariance matrix and $\mathbf{\beta }$ the vector of phenotypic selection gradients. Behavioural measurements, pedigrees, repeated observations and reproductive success can therefore estimate whether and in what direction a response is expected. The covariances matter: selection favouring exploration can produce a correlated response in aggression or constrain the response when their biological fitness effects conflict. Naming an exploration-related gene would not replace this population-level information.

These estimates require strong controls. behavioural repeatability is consistency among observations of the same individual; it can reflect persistent environment as well as inherited differences and is not equivalent to heritability. Parent–offspring resemblance can also reflect teaching, maternal provisioning or shared habitat. cross-fostering, common garden experiments and appropriately structured breeding designs help separate these alternatives. heritability is conditional on the sampled population and environment, not a measure of immutability. A response measured in one environment may fail elsewhere because of genotype-environment interaction or altered selection. Thus ignorance of exact molecular variants is compatible with informative prediction, but ignorance of transmission and its confounders is not.

Molecular work adds power when it establishes a causal link to naturally occurring variation. In Drosophila melanogaster, rover and sitter food-search variants were connected to the foraging gene, which encodes a cGMP-dependent protein kinase. Mapping, enzyme activity and transgenic rescue linked the molecular difference to behavioural performance; comparable locomotion without food helped exclude a general activity explanation. ^[ref] This is much stronger than finding a statistical association between a gene and a behavioural score. Nevertheless, the experiment alone does not establish which ecological conditions historically maintained the polymorphism. That requires biological fitness comparisons across resources, densities and frequencies, with genetic-background controls.

genetic architecture is particularly informative when animal behaviour changes gene flow. In Heliconius melpomene and Heliconius cydno, mapping identified several major regions associated with male mating preferences; one lay close to the wing-pattern regulator Optix. Tight genetic linkage can help maintain associations between a mating cue and preference despite exchange between lineages. It does not establish pleiotropy, and courtship assays must distinguish attraction from the female's response and subsequent mating. ^[ref] Here molecular localization helps evaluate whether a proposed route to reproductive isolation is genetically feasible. A preference could still have been shown to reduce heterospecific mating before its contributing regions were mapped.

The influence of one individual's animal behaviour on another's development further complicates a simple own-genotype explanation. Maternal provisioning in Onthophagus taurus was studied using a breeding design that separated direct and maternal genetic contributions to offspring traits. ^[ref] An indirect genetic effect occurs when another individual's inherited properties alter the focal individual's phenotype. Such effects change the environment in which selection acts and can alter expected evolutionary responses. Identifying only the offspring's molecular variants would miss an important part of the causal system. Conversely, an observed maternal effect is not automatically a maternal genetic effect; provisioning can vary for environmental reasons.

Transmission need not follow genetic parentage. In wild great tits, experimenters trained demonstrators to use alternative puzzle-box techniques and followed the spread of the introduced variants. Persistent local traditions and preferential adoption of the common local technique supported social learning and conformist transmission. ^[ref] The experiment established a route of behavioural inheritance without identifying a molecular difference between the techniques' users. It did not prove that learning ability has no inherited basis, or that the new tradition changed allele frequencies. Rather, it shows why an account of behavioural change needs to identify the relevant transmission process instead of assuming it.

Even a learned response with no demonstrated inherited differences can influence subsequent evolution. A new resource use can alter selection on digestion; a socially learned mating signal can alter assortative mating; habitat choice can change contact with other populations. The immediate causal effect can be tested by manipulating the action or its social transmission and measuring biological fitness or exchange. To claim ensuing genetic adaptation, one must additionally show inherited change. To explain exactly which variants can respond, how quickly, and with what correlated effects, information about genetic architecture becomes increasingly valuable.

The most productive programme therefore combines behavioural intervention, transmission studies, biological fitness measurement and molecular analysis when it addresses an unresolved mechanism. Candidate variants should be tested across natural genetic backgrounds and environments, preferably with targeted perturbation and rescue; historical claims also need comparative or temporal evidence. Exact molecular knowledge is neither sufficient nor universally necessary: the necessary evidence is the evidence that connects the particular behavioural difference, its transmission and its measured evolutionary consequence.

Lack of direct access to another animal's subjective experience limits some claims about consciousness, but does not prevent testable explanations of sensory processing, behavioural function or evolutionary history. The essential distinction is between occupying another individual's standpoint and explaining what information it acquires, how it uses that information, and the consequences for survival and reproduction. Thomas Nagel's argument concerns the subjective character of experience, rather than a claim that objective bat biology is inaccessible. ^[ref]

For behavioural biology, Tinbergen's four questions keep the explanatory targets separate. Mechanism asks what sensory and neural processes produce a response; development asks how it changes with maturation and experience; function asks how it affects performance or fitness; evolutionary history asks how it arose and differs among relatives. ^[ref] Not knowing a bat's exact experience does not make the latter questions equivalent to guessing its feelings. It does mean that a functional explanation, even a very successful one, is not by itself an explanation of the qualitative character of consciousness.

Echolocation illustrates substantial knowledge without shared phenomenology. Acoustic recordings and experiments on sensory access linked ultrasonic vocalization and hearing to obstacle avoidance in flying bats. ^[ref] Modern tests can vary echo delay, level or interference while measuring detection or flight responses. A prediction about ranging is available from propagation physics: for sound speed $c$, a round-trip echo delay $\tau$ from a stationary target at distance $r$ gives approximately:An illustrative $2\mathrm{ms}$ delay at $343\mathrm{m}{\mathrm{s}}^{-1}$ corresponds to $0.343\mathrm{m}$. The factor two comes from outward and return travel. Real ranging also depends on target motion, atmospheric conditions, filtering and the timing of emission. None of these testable relationships requires a scientist to experience an echo as the bat does.

The experimental controls matter because a successful animal can exploit an unintended cue. Changing a visual target might also change its acoustic reflection; changing an echo's delay might accidentally change its intensity. Appropriate comparisons manipulate the putative information while holding other cues constant, include sham manipulation, and measure baseline performance. A psychometric function across stimulus levels is more informative than a single success rate. Signal detection theory distinguishes sensitivity from response criterion, helping separate a sensory change from greater willingness to respond. Failure in an unfamiliar apparatus may reflect motivation or the required motor response rather than absence of the sensory capacity.

This approach also prevents treating human perception as the definition of available information. A stimulus invisible to us or outside our hearing range can be salient to the animal. The correct physical description must use the animal's receptors, spatial and temporal resolution, and ecological setting. Human photographs, displays and loudspeakers can omit relevant information or introduce artefacts. Conversely, an animal's failure to categorize objects in our preferred way need not show poor understanding: the experimental categories may not correspond to the distinctions its biology makes useful. Sensory ecology is therefore a substantive constraint on design, even though the animal's qualitative viewpoint remains partly inaccessible.

Causal intervention can connect sensory machinery to behaviour without settling phenomenology. The adult squirrel-monkey opsin-addition experiment demonstrated improved chromatic discrimination following a specified alteration of receptor input. ^[ref] That supports a functional inference about information use. It cannot report the appearance of the new colours to a monkey. Distinguishing these claims makes the experiment more, rather than less, informative: its conclusion is tied to an observable prediction instead of an assumed human-like experience.

Similarly, we can study affect-like influences on decisions without claiming to have measured a feeling directly. In bumblebees, unexpected sucrose reward altered responses to ambiguous cues, with evidence for a dopamine-dependent component and tests of behaviour in more than one context. ^[ref] Such judgement bias is evidence of an internal state influencing decisions; it is not a direct readout of happiness. Changes in activity, hunger, reward valuation or stimulus discrimination can produce superficially similar results and require control. Nor is an unexplained behavioural difference stronger evidence for subjective experience merely because an experimenter finds it familiar.

Evolutionary explanations require an additional bridge. Showing that a bat uses echoes establishes a mechanism; showing improved capture or obstacle avoidance under relevant conditions tests a current function. Demonstrating historical adaptation additionally requires comparisons, inherited variation and an account of the selection pressures or ancestry involved. One can test the prediction that signal structure differs with clutter or prey characteristics while allowing for shared ancestry and body size. A useful hypothesis should predict differences under specified circumstances, rather than explain every outcome retrospectively by invoking what the animal “wanted”.

There are nevertheless real limits. Different internal models can generate the same choice, and an animal cannot necessarily provide the linguistic reports that make some human experiments possible. Success with one discrimination does not reveal the complete content of a representation, and a neural correlate does not uniquely specify an experience. Questions about felt intensity, emotional quality or a reflective awareness of self demand converging behavioural and physiological evidence and may remain underdetermined. This is an epistemic limitation, not evidence that the corresponding experiences are absent.

A productive position avoids both unconstrained anthropomorphism and an equally unsupported denial of mental processing. Specify which sensory information or internal state the model requires, derive predictions, test alternatives and state the level of inference. We can explain much of the evolution and function of animal behaviour through objective relationships among information, decisions and fitness, while remaining uncertain about precisely what those processes feel like to the animal. The residual uncertainty should limit the wording of our conclusions and improve experimental design, rather than stop the research.