Selfish Genes to Social Beings (Survival of the nicest): The complexity of self-replication in the natural world

Selfish Genes to Social Beings is the best talk about the complexity of cooperative behaviour in the natural world. For instance, although I’ve read a lot about biology, before reading this book I could never understand how RNA chains might have joined together and started the process of self-replication through which all life evolved. It is easy to talk about the compounds that make up your genes in Silvertown.

Silvertown uses examples from nature to emphasize that cooperation is very common in nature. The plants can use nitrogen from the air into a form that they can excrete, thanks to the growth of rhizobia in the legume’s root nodules. Some beetles will bury animal corpses that are too big for a single insect to manage, both reducing the risk of other animals stealing food and providing a nest for beetle families to live in.

And many bacteria indicate their presence to each other using a chemical-signalling system called quorum sensing, which is active only when members of the same species are tightly packed together. This allows each cell to adjust its gene expression in a way that benefits the individuals in the group — to release a poison to kill other species, for instance, when enough bacteria are clustered together to mount a decent attack.

Source: Survival of the nicest: have we got evolution the wrong way round?

Cooperation and piracy in the 19th century: Slaves versus fungi as parasites, or do they prefer to be adopted?

Silvertown claims that even eighteenth-century piracy is a good example of cooperation. Pirates worked together on their ships, and used violence more often against outsiders than as an internal mechanism for law enforcement.

The term ‘algam’ is used for organisms in which a alga or cyanobacterium lives in a fungus. Simon Schwendener, a Swiss botanist who discovered this relationship in the 1860s, claimed that a lichen was a parasites and that its slaves were green algals. Another way to view the relationship is that these algae and fungi are co-dependent — when they co-exist as a lichen, each grows better than it would alone. The line between parasitism and mutualism, competition and cooperation is not clear cut. It is a matter of perspective.

Our own cells have hazy boundaries in their biology. Cells evolved into structures that generate energy more than a billion years ago. Plants, animals and fungi have mitochondria, which are the parts of the cells that make up the body. They could be considered slaves with their cells. Or perhaps they are more like adopted family members.

Some animals will choose to help raise young children rather than having their own, according to Hamilton’s theory. Nature 547, 357–1362. The natural world has a lot of these phenomena, from slime moulds to termites. Dynamic environments help to shape social behavior and is part of the accepted theory of evolution.

This seems callous, but it’s indicative of the human tendency to apply moral frameworks to biological phenomena. The use of emotionally charged words such as ‘slave’ and ‘adopted’ takes us away from rigorous science and leads us to see biological interactions as ‘good’ or ‘bad’, rather than as the morally agnostic, transactional processes that they truly are.

The anthropomorphizing of biological processes is a deep and current problem. The tendency to imply agency in the natural world can be an easy trap to fall into, if you consider how often people say that a virus wants to be transmitted, for instance. I am not sure what Silvertown thinks about this category error. I thought he could have made his implicit understanding explicit in some places. In the past, he sacrifice carefulness for unnecessary jokes, such as the fact thatbacteria are essentially singletons who like to party.

Gordon says that the whole appears to be more than the sum of the parts because they do not sum up. The statement is a description of the ecological and evolutionary complexities that shape our world. All biologists need to keep in mind the complex issues.

Gordon suggested that the ideas of her were at odds with thevailing theory of social behavior. Inclusive fitness theory — an idea put forward by UK evolutionary biologist William Hamilton in 1964, and accepted widely in the field — suggests that social behaviours evolve when the benefits of cooperating with relatives exceed the costs (W. D. Hamilton J. Theor. Biol. 7, 1–16; 1964). Hamilton’s ideas stemmed from his observations of wasps, ants, bees and birds in their natural habitats, and are supported by strong experimental and theoretical evidence.

Gordon has spent decades studying the natural history of two ant species that live in very different environments, paying acute attention to how the insects’ stirring, dynamic habitats shape their behaviour. Her book is based on these observations.

Both pocos and turtle ants have distinct ways of solving problems. How they do it is dictated by their environment. Gordon borrowed network science concepts to explain how turtle ants use modules to keep communication local, meaning they can respond rapidly to changes in availability of resources. The centralized regulation of pogos is the epitome of low modularity, as it is the only source of communication.

Gordon says that the answer is simple. The ants follow the smelliest path — the one with the strongest pheromone signal — and keep reinforcing profitable trails until something tells them to stop, such as the presence of a predator or a broken branch. This ensures that the ants will find the most lucrative spot and change their behavior in a constantly changing environment.

First, she describes the red harvester ant Pogonomyrmex barbatus, which lives in the harsh, parched deserts of New Mexico. Affectionately known as pogos, these ants are deep red and around 10 millimetres long — an impressive size for an ant. They live in colonies, which contain more than 10,000 female workers, and rely on seeds scattered on the desert floor for both food and water. As plants fade, there is a gradual shift in seed sources, but mostly a plentiful and constant supply of food. But collecting seeds is hazardous. pogis live in a world that they have to risk desiccation to get the water they need.

Gordon shows that this delicate trade-off is achieved by a slow but robust mechanism through which foragers recruit nestmates in the search for food. When a female returns to the nest with her bounty, she releases hydrocarbons from her outer cuticle to indicate to her sisters that there’s food out in the desert.

A fleeting touch from a forager’s antennae sends others scuttling out of the nest. They head out in random directions, but that’s OK, because the seeds are spread out on the desert floor, not clustered in patches. It can be difficult for foragers to find new colonies because of the nice food and good environmental conditions. Less ants return to muster recruits under gloomy circumstances. In this way, simple positive feedback regulates the steady collective behaviour of thousands of ants.