Behavioural ecology explains the rise of the AfD

On Sunday 6 September, in Saxony-Anhalt, Alternative für Deutschland secured 43.8 per cent of the vote and 39 out of 83 seats. This is the best result in the AfD’s history and comes in one of the states which, for historical rather than political reasons, seemed to possess particularly robust defences against the resurgence of a radical right-wing movement built around identity, borders, enemies and the promise of swiftly restoring a lost order.

One can, of course, discuss the German causes of this outcome, just as one might discuss the American, French, Italian or British causes of similar phenomena. There is, however, something more general at play, which unites different societies and concerns the way in which our species makes decisions when it perceives itself to be in danger. Just as the problems requiring in-depth analysis, the ability to distinguish between competing causes, quantitative risk assessment and a willingness to revise one’s conclusions are on the rise, so too is the political demand for rapid answers, simple causes, clear-cut allegiances and leaders capable of making decisions without too many obstacles. When we need rationality most, we become more vulnerable to the shortcuts that undermine it.

An animal must constantly decide whether what it sees, hears or smells poses a danger. The information is almost always incomplete, whilst the potential costs of errors vary greatly. Mistaking a bush swaying in the wind for a predator results in a pointless flight; mistaking a predator for a bush can cost a life – it is no coincidence that predators seek to induce precisely this type of error. When the second error is vastly more costly than the first, natural selection does not necessarily favour the organism that makes the fewest errors overall. Instead, it favours a response threshold shifted in the direction that minimises the most costly error.

Randolph Nesse called this logic the ‘smoke detector principle’. A properly calibrated smoke detector goes off even when we’re simply frying a steak, because the cost of a few false alarms is negligible compared to the cost of failing to detect a fire. Pain, coughing, nausea and many other biological defences operate according to the same asymmetry. Signal detection theory allows us to formalise the problem: as the cost of failing to react to a real danger increases, the amount of evidence required to trigger a response decreases.

An organism that assesses the probability of a catastrophic loss as high therefore has good evolutionary reasons to become less demanding before reacting. False positives increase, because waiting for better information may be more costly than acting immediately on the basis of mediocre information. The resulting response may appear irrational if judged solely on the basis of the accuracy of the prediction; however, in an environment where a false negative entailed a much greater loss of fitness than a false positive, such a threshold might instead have been favoured by natural selection.

In humans, this solution goes hand in hand with an extraordinary dependence on information produced by others. Learning individually is costly: it requires exploration, making mistakes, and investing time; and in certain circumstances, the very mistake needed to learn may be the one that proves fatal. A highly social species can use the behaviour of others as information. If many members of the group avoid a certain area, eat a particular food or follow a specific path, copying them allows one to benefit from knowledge acquired by others without bearing the full cost. Experiments by Thomas Morgan, Luke Rendell, Micael Ehn, William Hoppitt and Kevin Laland have shown that humans do indeed modulate their use of social learning according to, amongst other things, the difficulty of the task, their own confidence and the consensus observed among others, in line with predictions derived from evolutionary models of learning. 

This very solution contains a vulnerability. Copying others works as long as the behaviour of others contains information about reality. If everyone starts copying those around them, an initially poorly-founded decision can spread until it becomes the majority view; at that point, the majority itself becomes a reason to adopt it. The rule that allows a population to accumulate culture can thus produce cascades in which a great many individuals share a choice that very few have independently verified.

The threat also affects the effectiveness of coordination. When the danger is collective, the existence of many incompatible individual strategies can be disastrous, even if some of them are excellent. In a situation where one must flee, defend a territory or resist an attack, it becomes advantageous to quickly agree on a common course of action and to be able to predict that others will do the same.

Patrick Roos, Michele Gelfand, Dana Nau and Janetta Lun have demonstrated, using evolutionary game theory models, that higher levels of threat can foster stronger norms, greater compliance and harsher punishment for deviance, both in problems of cooperation and in those of simple coordination. A thirty-day experiment, published in 2021 by Aron Szekely and colleagues, provided complementary evidence of causality: a higher risk of collective loss led to stronger cooperative norms, which were more resistant to erosion when risk conditions changed.

The exploratory individual, willing to try out new solutions and to diverge from others, can be invaluable when the environment allows for the cost of mistakes to be borne and for the benefits of innovation to be reaped. Under an immediate threat, however, the value of coordination increases, whilst behavioural variability can become costly. The pressure shifts towards conformity and the punishment of deviance. Just how profoundly rules can influence human behaviour was demonstrated once again in 2025 in a series of experiments by Simon Gächter, Lucas Molleman and Daniele Nosenzo involving over 14,000 participants: between 55 and 70 per cent complied with an arbitrary and materially costly rule even when acting alone and anonymously, without harming anyone through their own breach of the rule.

Leadership resolves another recurring problem in group life. When a collective decision needs to be made quickly, a hierarchy can reduce the cost of coordination. There is no need to imagine some sort of ‘authoritarianism gene’ – a category devoid of biological meaning: it is enough to recognise that leadership and followership can reduce uncertainty about who makes the decisions and how others will behave. Furthermore, if circumstances suggest a conflict with another group, the apparent effectiveness of a dominant leader – capable of imposing coordination and confronting the opponent – increases. In 2025, a study involving 5,008 people across 25 countries tested four independent predictions derived from this evolutionary hypothesis, finding overall that the presence or perception of intergroup conflict increases the preference for dominant leaders.

Under threat, therefore, several parameters of decision-making may change simultaneously. It becomes advantageous to react on the basis of less reliable signals; uncertainty makes social information more valuable; collective danger increases the returns from coordination and the cost of deviance; conflict between groups may increase the value attributed to dominant leadership. This is not a single ‘instinct’, nor is it a political programme encoded in our genes. These are different systems, produced by different selective pressures, which under certain conditions can drive behaviour in the same direction.

Natural selection, after all, does not produce universally correct decision-making procedures. It favours mechanisms that exploit the regularities of the environment in which they are selected and which, on average and under relevant conditions, increase the reproductive success of their bearers. If the relationship between the available signals and the consequences of different responses changes, a mechanism that was previously advantageous may begin to produce systematic errors. Behavioural ecology has long studied cases of this kind in animals exposed to rapidly changing environments, in which perceptual and decision-making systems shaped by a previous selective history may respond inadequately to new signals.

A predator attack, a raid by a rival group or a local resource crisis all present circumstances in which rapid decision-making, cohesion and a reduction in behavioural diversity can offer enormous advantages.

The European demographic crisis, immigration, industrial competition from China, the transformation of the labour market brought about by artificial intelligence, climate change, a pandemic or the funding of a pension system, however, belong to a different category of problems. The causes are widespread, interact with one another, produce effects on different time scales and respond to interventions through feedback loops that often generate unforeseen consequences. To tackle them, we need to keep multiple hypotheses open, gather independent information, tolerate dissent, experiment with competing solutions and wait long enough to measure their effects: precisely some of the steps that become more difficult to sustain politically when a situation is perceived as an urgent threat.

The growing complexity of the threats facing Western societies therefore calls for greater analytical rigour, whilst at the same time the perception of those very threats may encourage a decision-making approach geared towards acting swiftly, aligning with the group and rapidly reducing uncertainty. This paradox does not stem from some mysterious degeneration of contemporary cognitive abilities. It arises from the fact that a set of responses with an evolutionary logic can be triggered by problems whose solutions require very different behaviours.

Populist politics, almost by its very nature, has tools at its disposal capable of fuelling this dynamic. A complex phenomenon is portrayed as an immediate threat; a diffuse cause is attributed to the actions of identifiable actors; these are grouped together as an external or internal group to which the blame can be laid; dissent can be portrayed as weakness or disloyalty; finally, a leader promises to remove the obstacles that would prevent a swift response.

Such a portrayal produces something that serious politics can hardly promise with the same speed: a subjective reduction in uncertainty. A statement such as ‘the problem is immigrants’ has infinitely less explanatory power than an analysis of the demographic, economic and fiscal transformations of a European society; yet, in a matter of seconds, it identifies a cause, pinpoints a group to blame and suggests a course of action. The solution may be ineffective in addressing the problem itself, yet highly effective in creating the impression that the problem has become understandable and manageable.

The practical failure of a policy does not necessarily mean it loses its appeal. If part of its function is to demonstrate that the group is responding, that a boundary is being re-established or that someone is exercising command, this outcome can be perceived immediately, long before the tangible consequences become measurable. Furthermore, any failure may be interpreted as evidence that the threat is even more serious, that the enemies are more numerous or that the action has been thwarted, thereby providing fresh fuel for the demand for strength and coordination.

A self-sustaining cycle is thus formed. The threat increases the demand for simplification; simplification identifies an enemy; the enemy makes the threat more tangible; the heightened threat increases the value placed on cohesion and leadership. The discussion regarding the complexity of the causes may end up appearing suspect in itself, because those who raise doubts and qualifications seem to be holding the group back whilst danger looms.

There is therefore no need to imagine that millions of citizens in so-called liberal democracies have suddenly lost the ability to reason. Reacting swiftly to dangers, utilising information from others, coordinating with one’s group and modifying behaviour in accordance with the costs of error are all part of the normal repertoire of a social species. Their effectiveness, however, depends on the structure of the environment in which they are employed.

The scientific method, statistical analysis, cross-examination, the separation of powers and the institutional procedures that keep dissent alive long enough to allow hypotheses to be tested are all part of a much more recent history. These are cultural mechanisms that enable us to correct the errors to which biologically ancient decision-making systems may expose us when the world presents problems different from those that shaped their evolution.

Independent verification, specialist expertise and procedures that prevent a single individual from making an immediate decision come at a cost in terms of time, coordination and simplicity. During a crisis, it is precisely this cost that becomes particularly apparent and frustrating. It is also the moment when those procedures prove most valuable, because they protect a society from the risk of turning a perfectly understandable response to a threat into a collectively disastrous decision.

The difficulty with major modern crises lies in preserving the cognitive, informational and institutional conditions in which solutions can be sought, precisely at the very moment when the perception of danger makes speed, conformity and authoritarianism seem more appealing. It is then that we need reason most of all, and it is then that our evolutionary history makes it easier to choose something different.