The Creative Neurons

Creativity generates novel solutions to tasks by processing information. Imagination and mental representations are part of the creative process; we can mull over ideas of our own making, and construct algorithms or scenarios from them. Social scenario-building can be viewed as a human cognitive “super-power” that involves abstraction, meta-representation, time-travel, and directed imaginative thought. We humans have a “theater in our minds” to play out a near-infinite array of social strategies and contingencies. Here we propose an integrative model for why and how humans evolved extraordinary creative abilities. We posit that a key aspect of hominin evolution involved relatively open and fluid social relationships among communities, enabled by a unique extended family structure similar to that of contemporary hunter-gatherer band societies. Intercommunity relationships facilitated the rapid flow of information—“Culture”—that underpinned arms-races in information processing, language, imagination, and creativity that distinguishes humans from other species.

Does Legal Origin Matter for Arms Control Treaty Ratification?

This chapter examines whether the legal origin of a country influences the likelihood of ratification of multilateral international treaties concerning arms control. We theorize that ratification of an arms control treaty signals a country’s intention to avoid arms races and wars. We know only little about the variation in the ratification of such agreements. One possible element that may explain this variation is the legal origin or tradition of a country. Since treaties are legally binding agreements between two or more states and/or international governmental organizations, they cannot be adapted to local needs and circumstances. Treaties are therefore generally an uneasy fit with the gradual, organic evolution of law that is essential in the common-law system. By contrast, the civil-law tradition neatly distinguishes between legally binding obligations and non-binding guidelines or directives. Consequently, civil-law countries are expected to be more likely to ratify treaties than common-law countries. The empirical results clearly confirm this expectation. In particular, civil-law countries have ratified about nine percent more treaties than common-law countries.

Neofunctionalization of an ancient domain allows parasites to avoid intraspecific competition by manipulating host behaviour

Intraspecific competition is a major force in mediating population dynamics, fuelling adaptation, and potentially leading to evolutionary diversification. Among the evolutionary arms races between parasites, one of the most fundamental and intriguing behavioural adaptations and counter-adaptations are superparasitism and superparasitism avoidance. However, the underlying mechanisms and ecological contexts of these phenomena remain underexplored. Here, we apply the Drosophila parasite Leptopilina boulardi as a study system and find that this solitary endoparasitic wasp provokes a host escape response for superparasitism avoidance. We combine multi-omics and in vivo functional studies to characterize a small set of RhoGAP domain-containing genes that mediate the parasite’s manipulation of host escape behaviour by inducing reactive oxygen species in the host central nervous system. We further uncover an evolutionary scenario in which neofunctionalization and specialization gave rise to the novel role of RhoGAP domain in avoiding superparasitism, with an ancestral origin prior to the divergence between Leptopilina specialist and generalist species. Our study suggests that superparasitism avoidance is adaptive for a parasite and adds to our understanding of how the molecular manipulation of host behaviour has evolved in this system.

Human vs. Deep Neural Network Performance at a Leader Identification Task

Control of robotic swarms through control over a leader(s) has become the dominant approach to supervisory control over these largely autonomous systems. Resilience in the face of attrition is one of the primary advantages attributed to swarms yet the presence of leader(s) makes them vulnerable to decapitation. Algorithms which allow a swarm to hide its leader are a promising solution. We present a novel approach in which neural networks, NNs, trained in a graph neural network, GNN, replace conventional controllers making them more amenable to training. Swarms and an adversary intent of finding the leader were trained and tested in 4 phases: 1-swarm to follow leader, 2-adversary to recognize leader, 3-swarm to hide leader from adversary, and 4-swarm and adversary compete to hide and recognize the leader. While the NN adversary was more successful in identifying leaders without deception, humans did better in conditions in which the swarm was trained to hide its leader from the NN adversary. The study illustrates difficulties likely to emerge in arms races between machine learners and the potential role humans may play in moderating them.

The evolution of targeted cannibalism and cannibal-induced defenses in invasive populations of cane toads

Biotic conflict can create evolutionary arms races, in which innovation in one group increases selective pressure on another, such that organisms must constantly adapt to maintain the same level of fitness. In some cases, this process is driven by conflict among members of the same species. Intraspecific conflict can be an especially important selective force in high-density invasive populations, which may favor the evolution of strategies for outcompeting or eliminating conspecifics. Cannibalism is one such strategy; by killing and consuming their intraspecific competitors, cannibals enhance their own performance. Cannibalistic behaviors may therefore be favored in invasive populations. Here, we show that cane toad tadpoles (Rhinella marina) from invasive Australian populations have evolved an increased propensity to cannibalize younger conspecifics as well as a unique adaptation to cannibalism—a strong attraction to vulnerable hatchlings—that is absent in the native range. In response, vulnerable conspecifics from invasive populations have evolved both stronger constitutive defenses and greater cannibal-induced plastic responses than their native range counterparts (i.e., rapid prefeeding development and inducible developmental acceleration). These inducible defenses are costly, incurring performance reductions during the subsequent life stage, explaining why plasticity is limited in native populations where hatchlings are not targeted by cannibalistic tadpoles. These results demonstrate the importance of intraspecific conflict in driving rapid evolution, highlight how plasticity can facilitate adaptation following shifts in selective pressure, and show that evolutionary processes can produce mechanisms that regulate invasive populations.

Red queen's race: rapid evolutionary dynamics of an expanding family of meiotic drive factors and their hpRNA suppressors

Meiotic drivers are a class of selfish genetic elements that are widespread across eukaryotes. Their activities are often detrimental to organismal fitness and thus trigger drive suppression to ensure fair segregation during meiosis. Accordingly, their existence is frequently hidden in genomes, and their molecular functions are little known. Here, we trace evolutionary steps that generated the Dox meiotic drive system in Drosophila simulans (Dsim), which distorts male:female balance (sex-ratio) by depleting male progeny. We show that Dox emerged via stepwise mobilization and acquisition of portions of multiple D. melanogaster genes, including the sperm chromatin packaging gene protamine. Moreover, we reveal novel Dox homologs in Dsim and massive, recent, amplification of Dox superfamily genes specifically on X chromosomes of its closest sister species D. mauritiana (Dmau) and D. sechellia (Dsech). The emergence of Dox superfamily genes is tightly associated with 1.688 family satellite repeats that flank de novo genomic copies. In concert, we find coordinated emergence and diversification of autosomal hairpin RNA/siRNAs loci that target subsets of Dox superfamily genes across simulans clade species. Finally, an independent set of protamine amplifications the Y chromosome of D. melanogaster indicates that protamine genes are frequent and recurrent players in sex chromosome dynamics. Overall, we reveal fierce genetic arms races between meiotic drive factors and siRNA suppressors associated with recent speciation.

Gorbachev and the Abandonment of Anti-Imperialist Struggle

Gorbachev knew that reform at home could not be accomplished while the US-Soviet relationship remained confrontational and marked by arms races. His interactions and negotiations with President Reagan led Gorbachev continuously to augment Soviet concessions, even unilaterally, in hopes of ending the Cold War. He succeeded in doing so. Moreover, Gorbachev’s long-standing unwillingness to use military force to prevent democratization in Eastern Europe led directly to the collapse of these communist regimes in 1989.

Host–parasite co-evolution

Macroevolutionary patterns concern phylogenies of hosts and their parasites. From those, co-speciation occurs; but host switching is a common evolutionary process and more likely when hosts are close phylogenetically and geographical ranges overlap. Microevolutionary processes refer to allele frequency changes within population. In arms races, traits of hosts and parasites evolve in one direction in response to selection by the other party. With selective sweeps, advantageous alleles rapidly spread in host or parasite population and can become fixed. With antagonistic negative frequency-dependent fluctuations (Red Queen dynamics) genetic polymorphism in populations can be maintained, even through speciation events. A Red Queen co-evolutionary process can favour sexual over asexual reproduction and maintain meiotic recombination despite its other disadvantages (two-fold cost of sex). Local adaptation of host and parasites exist in various combinations; the relative migration rates of the two parties, embedded in a geographical mosaic, are important for this process.