CARTA: Violence in Human Evolution – Richard Wrangham: Parallel Evolution of Humanity and Savagery

Summary

The speaker explores the dichotomy of human aggression through an evolutionary lens, distinguishing between proactive and reactive aggression. Proactive aggression is likened to strategic, planned violence akin to chimpanzee warfare, while reactive aggression is impulsive and explosive. The talk suggests humans have evolved to exhibit both types but have also developed mechanisms to downregulate reactive aggression, contributing to a decline in violence over time.

Takeaways

• 🧬 The script discusses the evolutionary perspective on human violence, suggesting that humans have been subject to different selective pressures regarding two types of aggression.
• 🤔 It contrasts two historical views on human nature: Thomas Hobbes' view of humans as inherently violent and needing governance, and Jean-Jacques Rousseau's view of humans as inherently cooperative and gentle.
• 🐵 The speaker introduces the concept of 'proactive' (predatory, premeditated) and 'reactive' (impulsive, explosive) aggression, suggesting these are two separable forms of aggression in humans.
• 🔬 Developmental psychologists and psychiatrists use the distinction between proactive and reactive aggression as a diagnostic tool, especially in understanding domestic abuse and certain explosive disorders.
• 🧬 There is a difference in brain activation between proactive and reactive aggression, with the former being associated with lower prefrontal cortex activity.
• 🦍 Chimpanzees exhibit a pattern of intergroup violence with a large group targeting a lone individual, which is an example of proactive aggression.
• 🏞️ The script suggests that in the Paleolithic era, humans may have exhibited similar patterns of proactive aggression when there was an extreme imbalance of power and low risk of death for aggressors.
• 🌍 It is proposed that peaceful relations among hunter-gatherers are strategic and do not negate the possibility of proactive aggression in the past.
• 📉 There is a significant difference in rates of physical aggression between chimpanzees and humans, with humans showing much lower rates of face-to-face fighting.
• 🕊️ The script concludes by noting the decline in rates of violence, suggesting that the peaceful, cooperative nature (downregulated reactive aggression) can influence our proactive aggression style.

Q & A

What are the two different kinds of aggression discussed in the script?

The script discusses two types of aggression: proactive predatory premeditated aggression, which is planned and strategic, and reactive impulsive explosive aggression, which is impulsive and occurs in response to a perceived threat or provocation.

What is the role of government or a king according to Thomas Hobbs' view on human nature?

According to Thomas Hobbs, humans are inherently selfish and violent, and thus require a 'leviathan', which could be a government or a king, to control and manage this violence.

What does Jean Jacques Rousseau believe about the inherent nature of humans?

Jean Jacques Rousseau believed that humans are inherently cooperative, gentle, and nonviolent.

How does Chris B propose a resolution to the debate between Hobbs and Rousseau's views?

Chris B suggests that both views are true, indicating that humans possess both cooperative and violent tendencies, and that these traits can coexist within the same species.

What is the imbalance of power hypothesis in relation to chimpanzee behavior?

The imbalance of power hypothesis suggests that chimpanzees engage in unprovoked killings when there is a significant power imbalance, such as a large group attacking a lone individual, and the aggressors face a very low risk of death.

What is the significance of the Andaman Islands example in the script?

The Andaman Islands example illustrates a form of warfare where surprise attacks are made to kill one or two individuals and then retreat, which is similar to the proactive aggression seen in chimpanzees.

How does the script suggest that humans differ from chimpanzees in terms of reactive aggression?

Humans exhibit significantly lower rates of face-to-face fighting compared to chimpanzees, suggesting a strong downregulation of reactive aggression within human societies.

What is the role of alcohol in reactive aggression as discussed in the script?

The script implies that alcohol can exacerbate reactive aggression, making individuals more prone to impulsive and explosive behavior.

What is craniofacial feminization and how is it related to aggression according to the script?

Craniofacial feminization refers to the softening of male facial features over time. The script suggests that this may be an indication of reduced aggression, particularly reactive aggression, as humans have evolved.

How does the script relate the decline in violence to the concepts of proactive and reactive aggression?

The script suggests that the decline in violence is due to the downregulation of reactive aggression, which allows for the peaceful and cooperative tendencies to influence human behavior, including the proactive aggression style.

What are the challenges to the imbalance of power hypothesis as presented in the script?

The script acknowledges that there is variation among hunter-gatherer societies, and that some maintain peaceful relationships with their neighbors, which could challenge the hypothesis that proactive aggression was universally favored by natural selection.