The biology of the alpha male: Can parasite infection explain aggression?

 

My 2018 post, Cognitive Manipulation by parasites, discusses the behavioral effects of parasite infection. It also speculates a possible role of Toxoplasma gondii infection in human psychology. A recent article in Nature, a premier scientific journal, provides a clear link between parasite infection to risk-taking and dominance. 

Sexual reproduction of Toxoplasma gondii occurs in a cat's body. As a result, the infected rodents lose their fear of cats, which allows the reproductory cycle to complete. However, warm-blooded mammals can catch the parasite by eating an infected animal or ingesting forms of the parasite shed in the feces of infected cats. After acute infection, semi-dormant cysts form in muscle and brain tissue and persist for the rest of the host's life. An analysis of over 200 North American wolves shows that parasite infection inspires leadership by boosting bold, uninhibited aggressive behavior. In addition, the infected animals are also more likely to leave their home packs and strike out independently.

Therefore, pathogens may have a significant role in the ecology and behavior of wild animal populations. In addition, it is estimated that up to one-third of humans might be chronically infected. Physical and behavioral changes found in people include increased testosterone and dopamine production, which leads to more significant risks taking.

Chemical signals from the fungi, such as secreted proteins, may target the host’s behavioral systems and control behavior like summiting and nest desertion. Pathogens may be taking advantage of preexisting behaviors governing molting, sleep, and molting — the process by which an insect sheds its protective exoskeleton to grow a new, bigger one. Insects have evolved behaviors for this time that can include wandering from the nest and summiting or grasping onto grass or leaves. Molting and sleep are controlled by the insect’s circadian rhythm.

Read my 2018 post: Cognitive Manipulation by parasites. 

Read the resource article: Meyer, C. J. et al. Commun. Biol. https://doi.org/10.1038/s42003-022-04122-0 (2022).

Gering, E. et al. Nature Commun. 12, 3842 (2021).

Copyright © 2022 by Eva Deli

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Can AI improve its ability of learning by adapting sleep?

Spiking neural networks have a complex, biologically-inspired design yet haven't been practical for widespread use because it's challenging to train them. Nevertheless, spiking neural networks are more energy-efficient, providing a considerable impetus for transitioning to more spiking network technology over the next decade. 

Many AIs can only master one set of well-defined tasks – they can't acquire additional knowledge later without losing everything they previously learned. However, interspersing focused training periods with sleep-like periods prevents forgetting. Sleep in the neural network occurs by activating the network's artificial neurons in a noisy pattern reminiscent of the training's neuronal firing pattern. This way, replay strengthens the connections related to the task. In addition, rapidly alternating sessions of training and sleep help consolidate the links from the first task that would have otherwise been forgotten.

Such a network can combine consecutively learned knowledge in intelligent ways and apply this learning to novel situations – just like animals and humans do.

Read more: AI uses artificial sleep to learn a new task without forgetting the last.

Image credit: Image by iuriimotov on Freepik

Copyright © 2022 by Eva Deli