Teaching made us human

Like my Walking made us human idea, the idea on this page takes on the dominant "culture made us human" meme - pithily expressed by Richard Dawkins in 1976:

Most of what is unusual about man can be summed up in one word: 'culture'.

That idea is dominant - at least among most students of cultural evolution. Walking, talking, tool use, our big brains and even our opposable thumbs are largely the product of cultural evolution - plus some meme-gene coevolution.

However, cultural evolution is fairly ubiquitous among other animals. This had led to people to seek out other answers to the question of "what made us human?". Cumulative cultural evolution is one common answer. However, an issue with this answer is that chimpanzees have cumulative cultural evolution too. Teaching is much rarer in non-human animals. This helps to make it an interesting candidate for what makes humans special.

Here I want to examine another possible answer to this question - an idea based on what I have previously referred to as the "Teaching First" hypothesis. To recap, the "Teaching First" hypothesis turns the usual story about the evolution of cultural evolution on its head. It is usually thought that some change in social learning abilities was responsible for the modern explosion in cultural evolution. Maybe a slightly bigger brain, maybe slightly less aggression - something affecting social learning. The the "Teaching First" hypothesis represents a considerable shift away from this perspective - a shift from social learning to teaching.

In some respects, teaching is more a product of cultural evolution than social learning is. Teaching requires some age, experience and previous social learning. Because teaching is cultural, it is more subject to rapid change. Cultural evolution is an example of large organisms using small symbiotes to adapt quickly. The short reproduction cycles of memes (relative to their human hosts) is part of the reason why it is faster.

We know that in many cases, memes lead and genes follow. If meme-gene co-evolution can be characterized as genes holding memes on a leash, then the memes are often dragging the genes around. The the "Teaching First" hypothesis would be another example of this kind of dynamics.

Teaching could have helped create a positive feedback loop - where improved culture relating to teaching leads to more teaching-related improvements in the future. The corresponding loop for learning exists too - but more learning capacities (than teaching capacities) are coded in DNA genes - so progress there is harder and slower.

Academics have don't seem to have looked into the idea that the cultural evolution of teaching drove cultural evolution very much. One related idea is the cultural evolution of cultural evolvability. An example of this is Cecilia Heyes' video: Cultural Inheritance of Cultural Learning. The corresponding paper is Grist and mills: on the cultural origins of cultural learning. This is more about social learning - but it has the idea of positive feedback on cultural learning capacities via cultural evolution. It is some of the nearest literature I know about.

Memes and host lifespan

Cultural evolution has led to increased lifespans among many modern humans.

Symbiology has some basic models of how symbiotes affect host lifespan which seem likely to be applicable to cultural evolution. When a symbiont usually dies with its host, it can sometimes pay for it to divert resources from host reproduction into host maintenance processes. That makes the host live for longer and results in more opportunities for the symbiont to reproduce before it perishes with its host. Copies of individual memes do perish with their hosts - and this model is broadly consistent with the observed longer lifespans produced by cultural evolution to date.

However, there's an alternative scenario described by the same kind of model. If there's a lot of horizontal transmission of symbionts between hosts, the symbionts can sometimes profit by converting the hosts' resources into copies of their own heritable material as quickly as possible. This is the strategy employed by the Ebola virus, for example. Rather than increasing host lifespan, these types of parasite dramatically decrease it.

When does this latter scenario arise? The models are fairly specific about when this type of scenario is likely. It happens when the host density is high or when there's a lot of opportunities to spread between hosts.

The ability of memes to leap from host to host has dramatically increased over the last century. These days, mobile phones deliver memes pretty directly into peoples' brains in a near-constant stream. Horizontal meme transfer has increased dramatically in modern times - and it looks set to continue to rise. Our ability to pack humans together in huge cities has also continued to rise.

This raises some questions. What can be done to avoid going into an era in which memes shorten host lifespans - and rip through host resources like the Ebola virus does? Also, we have been seeing a lot of horizontal meme transmission for a while now. Yet if you look at the most meme-rich areas of the planet - such as Japan - host lifespans are excellent. Why are we not in an Ebola-like era already?

The most obvious answer is that memes that quickly kill their human hosts are selected against in various ways - by host immune systems, and by active suppression by groups of humans. People do get sucked into meme-spreading cults that rip through their resources Ebola-style - but education defends against this fate - and so do nearby friends and relatives.

An important reason for studying these dynamics is to see whether we can avoid problems. Will we see plagues of parasitic memes mirroring the 1918 flu epidemic? Will we see persistent draining influences - mirroring the effect of the HIV virus on lifespan in Africa? What about mixed bag pathogens? For example, smallpox helped Europeans to conquer native American tribes - while simultaneously killing many Europeans.

So far the influence of memes on lifespan seems consistent and positive. More memes are strongly correlated with longer lifespans. However I think it is too early to say whether this positive trend will continue without interruption. We should strive to understand these dynamics in order to help us to avoid problems in the future.

The eusociality symbiont hypothesis and epistemic hygiene

The eusociality symbiont hypothesis relating to the evolution of eusociality pictures a positive feedback loop of interactions between hosts and symbionts, with each new symbiont pulling the colony tighter together as the symbionts manipulate their hosts into coming into contact with each other in order to reproduce.

The positive feedback loop involved in the hypothesis is counteracted by negative interactions involving hosts and symbionts - in other words by parasitism. As hosts interact more closely parasites can also spread horizontally between them. Since horizontal transmission promotes misalignment between host genes and parasite genes, after a certain point, parasites start to dominate more helpful symbionts - and then the hosts start to behave as though they want to live further apart from one another.

The significance of parasites is evident in most social insect colonies. These are vulnerable to parasitism - due to the close proximity of the members - and it is not uncommon to see nests obliterated by parasites. On the other hand, because of the parasite threat, the nests themselves are often policed by cleaning squads. Disease eradication is a big theme. Sick individuals are exiled and everything is kept remarkably clean.

Humans are a case study for the eusociality symbiont hypothesis. Our symbionts are typically cultural, but the basic dynamics are much the same - the cultural symbionts manipulate the humans into coming into contact with each other in order to reproduce. The result is human ultrasociality.

We know that humans living in close proximity are more vulnerable to horizontal transmission of genes. We can see this by comparing sick city dwellers with their more healthy country cousins. Parasite transmission favors situations where humans are crowded together. We have institutions to deal with this - such as hospitals.

Close proximity also favors horizontal memetic transfer. Assuming that humans want to avoid exploitation by deleterious memetic parasites, we are going to need organizations and institutions that promote epistemic hygine. These will involve schools, as well as other types of training more focused on the memetic immune system.

The negative effects of memetic parasites are clearly evident today. We have an obesity epidemic driven by fast food advertising. There are smoking, drinking and caffination epidemics which are widespread. Over the counter drugs are widely abused. Paranoia epidemics are fostered by the news media with resulting scares about terrorism, global warming, vaccination, resource depletion, and so forth.

Epistemic hygiene can reasonably be expected to become a big focus. Not necessarily the 'thought police' pictured by George Orwell - but other government-level infrastructure to protect populations against the negative effects of bad memes.