The teaching first hypothesis

Most accounts of the origin of human cultural evolution focus on imitation or social learning. However there's another possibility - that the most relevant changes were in teaching ability - or inclination to teach.

The scenario I favor relating to the origin of social learning in humans involves walking. This scenario is described in my essay walking made us human. Walking is a socially-transmitted trait. Learning it promptly is extremely important for modern humans. Walking is also widely taught to offspring by their parents. This observation suggests another scenario for the early cultural evolution of humans - in which changes in teaching ability are more significant than changes in learning ability.

Teaching ability is easier to change via cultural evolution than infant learning ability is. It is probably easier to change via DNA gene evolution too. Since the trait looks as though it is probably easier to modify, there's at least a fair chance that the main difference between the early walkers and the non-walkers was that the walkers put more effort into teaching their offspring.

Teaching is not involved in all types of cultural transmission. However it is involved in transmission of walking. Acceptance of the scenario described in Walking made us human makes this "teaching first" hypothesis more likely.

The focus on learning seems fairly ubiquitous among students of cultural evolution to me. Susan Blackmore in The Meme Machine promoted the importance of imitation. Lee Alan Dugatkin reviewed Susan's book and then went on to write The Imitation Factor. While both books are excellent, if the teaching first hypothesis is correct then an emphasis on imitation may be misplaced.

Can we test the idea? The detailed history is probably lost in he mists of time. However, we can probably test the idea that teaching ability is easier for cultural and genetic evolution to produce. If so, the teaching first hypothesis becomes favored by Occam's razor - conditional on the ideas described in walking made us human.

Memesis

Memesis refers to the origin(s) of meme(s). Its etymology derives from the terms 'meme' and 'genesis' - it's a contraction of meme-genesis. It can refer to the origin of a particular meme - or more generally to the origin of evolving culture.

The origin of cultural evolution is an area which has been studied extensively in academia. For some reason, many academics in the field seem to have specialized in the pre-history of cultural evolution - an area where we have a paucity of data and which it is difficult to explore experimentally. Why this happened is another story, but it did happen - and as a result we know more than we otherwise would about the origin of cultural evolution. In particular the work of Boyd and Richerson - as reported in their 2005 books - significantly illuminates this subject area.

They speculate that the glacial climate of the current ice age provided a challenging, spatio-temporally varying environment for our ancestors - and a variable environment increases the benefits provided by rapid cultural adaptations. They also suggest that the mild climate in the modern inter-glacial period led directly to the modern flourishing of humanity.

The doctrine of common descent suggests that all living things share a common ancestor. If taken literally, this means that the first memes came from evolving ideas within minds - and these ultimately arose from DNA genes. The initial dependence of cultural evolution on DNA-based evolution suggests that cultural evolution doesn't violate the common descent doctrine.

However the origin stories of individual memes can certainly involve external influences that are neither genes nor memes. A classic example of this is "the face on mars" (see right). While elements of this meme arose within human brains and involved cultural artifacts - such as spaceships and telescopes - it is hard to deny that an important part of the meme originated on Mars.

Ultimately, the origins of cultural evolution should be traced back beyond our common ancestor with chimpanzees (since these also carry a significant cultural inheritance with them).

References

• The 1996 Memesis symposium

Cultural kin selection may have driven imitation capability

What drove the human ability to transmit culture with high enough fidelity to support the current cultural explosion?

There are a couple of common explanations for this:

• One explanation invokes DNA evolution. This explanation says that acquiring intact memes was beneficial to their hosts - and so acquiring them without error was favoured.

• The other explanation involves cultural evolution. This suggests that culture evolved in order to improve its copying fidelity. Gesticulation led to grunts, which led to speech, which led to writing, which led to printing, which led to the internet - with the copying fidelity increasing at every step. Here the benefits of high-fidelity copying accrued primarily to the memes involved - not to genes.

These explanations are not mutually exclusive - and fairly clearly each played a role at different points in time.

Recently, I've seen another kind of explanation which involves cultural kin selection:

In DNA-based kin selection, your genetic relatedness to another human is an accident of birth - something that you can't easily change. The best you can do is to try and manipulate perceived relatedness cues. In cultural kin selection, the situation is a bit different. The proportion of memes you share with another human is not fixed. You can fairly easily increase your memetic relatedness to another human - by the process of acquiring memes from them - or perhaps their teachers or associates.

It has long been known by psychologists that humans manipulate other humans by imitating them. Interview technique books are full of advice about mirroring your interviewer's posture and copying them in other ways - in order to appear more similar to them. The idea is that this process may have actively pressured humans into improving their imitations skills - in order to appear more similar to other humans, so as to better manipulate them. The improvement could have involved DNA-based genetic evolution, cultural evolution - or a combination of the two.

This is an intriguing story - partly because we can see the process involved acting today. However, I think the idea needs more comprehensive study and quantification. Chimpanzee studies are one area which might illuminate the issue. Chimpanzees have the ability to transmit information down the generations culturally. However do they also imitate each other - in order to appear more like kin to each other? It is an interesting question.

I came across the idea in this article while researching my article on homophily. The paper is in the references for this article. I'm not yet sure where the idea originated.

References

• Haun, D. B. M., & Over, H. (2013). Like me: A homophily-based account of human culture. [paywall] In P. J. Richerson, & M. H. Christiansen (Eds.), Cultural Evolution: Society, technology, language, and religion.

Meme liberation and the modern cranial shrinkage

The general trend in brain size among our immediate ancestors over the last three million years has been upwards, as this graph illustrates:

However, recently, there are some signs that this trend has abated. In particular Neanderthals had larger brains than modern humans.

Is this consistent with the idea that big brains are meme nests? Surely memes have been on the up-and-up - while brain size has not.

The modern brain shrinkage corresponds to the rise of modern agriculture and increased population densities. Here's a quote from a 2010 article on the topic:

Bailey and Geary found population density did indeed track closely with brain size, but in a surprising way. When population numbers were low, as was the case for most of our evolution, the cranium kept getting bigger. But as population went from sparse to dense in a given area, cranial size declined, highlighted by a sudden 3 to 4 percent drop in EQ starting around 15,000 to 10,000 years ago. “We saw that trend in Europe, China, Africa, Malaysia—everywhere we looked,” Geary says.

Through most of human history the meme pool had to fit in a single brain. There wasn't much in the way of specialization - all the tribe members played similar roles (except perhaps for the doctor). There was probably some gender-based specialization, but that was about it - the meme pool mostly had to fit in a single mind.

With the advent of agriculture, large populations and exchange and specialization - and more advanced language - all this radically changed. Memes were liberated from the confines of a single mind, and the meme pool was able to expand enormously. Towns could support far more memes that any hunter-gatherer tribe could manage. The process of meme liberation eventually led to writing - another major move to liberate memes from the human skull.

The meme pool not being effectively confined to a single mind would have massively reduced the selection pressure on minds to grow to accommodate more memes. Now minds only had to accommodate the memes associated with a given specialization.

Other theories may have something going for them too. Modern humans have been domesticated by their institutions - and domestication often results in smaller brains - since the domesticated creatures have their defensive and foraging needs supplied for them. Also agriculture led to poorer diet - and that might have had a negative effect on brain size too (though re-feeding modern humans doesn't give them much bigger brains).

However, the idea of big brains as meme nests is at least consistent with the modern cerebral downturn. The modern cranial shrinkage corresponds to the liberation of the meme pool from the mind of a single hunter-gatherer mind. The division of labor that came with large populations would have meant that each specialization had its own, much smaller and largely-independent meme pool. The pressure on the brain to grow to accommodate the entire meme pool of the human race was off - and stupider humans could thrive.

The liberation of memes led to a removal of the size limit on cumulative cultural evolution. Now that they were no longer effectively confined to a single mind, the modern meme explosion began to gather speed.

References

• Tyler, Tim (2011) Big brains as a meme nests
• Tyler, Tim (2011) The big brain as a meme nest

Walking made us human

Walking was part of our lineage from the point where it split from chimpanzees - as far as archaeologists can tell.

The idea that walking made us human probably seems naive these days. However, tools, fire and language followed much much later - and the significance of walking gets quite a shot in the arm from memetics.

As I explain in considerable detail in my 2011 memetics book, walking was one of the earliest socially transmitted traits in our ancestors. The need to walk put pressure on infants to master the social skills needed to learn to walk from their parents and caregivers.

Chimpanzees socially transmit use of tools such as hammers. However, there's nothing similar to walking in demanding early learning and so profoundly affecting development.

It was walking that kicked the race to develop social learning into a high gear in infants among our early ancestors. There was cultural transmission before walking - but is wasn't so profoundly life-changing. It is true that the expansion of the human cranium corresponding to colonization by memes didn't begin for another three million years - but that seems consistent with walking having a high significance in the development of social learning. Walking generated pressure for social learning skills to develop early. It was a while before this started having knock on effects that led to an expansion of the skull-bound meme pool - as the size limit on cumulative cultural evolution in our ancestors gradually began to rise.

References

• Tim Tyler (2011) Memes and the upright gait hypothesis
• Nicholas Humphrey (2006) The Family that Walks on All Fours

Universal Darwinism and the origin of life

One of the more coherent critiques of universal Darwinism I am aware of comes in the first part of the book Genetic Takeover: And the Mineral Origins of Life by A. G. Cairns-Smith. The author argues in some detail that there's no such thing as "prebiotic evolution", or "chemical evolution" - and the origin of life represented the dawn of the era of adaptation. He rejected the idea that you could draw on the concept of adaptation before the first self-reproducing agent existed.

We now know that this idea is wrong. There was copying with variation and selection before the origin of life. Evolutionary theory applies to a variety of non-living systems that preceded the first living things. The concept of "adaptation" also applies to such systems.

The rest of the thesis in this book seems little-affected by these more recent developments. Crystals still look as though they are the most likely candidate substrate for the first living things. The idea of a genetic takeover still seems to be highly significant.

Probably, universal Darwinism makes the probability of the origin of life seem larger - since invoking adaptation before the origin provides new paths and mechanisms via which life could arise.. However our main evidence relating to the likelihood of life's origin still consists of observations about its history on the planet and astronomical observations of other worlds - rather than arguments from physics or chemistry. So perhaps this doesn't make much difference.

However, universal Darwinism might help to illuminate possible pathways towards the origin.

Nicholas Humphrey: The Family that Walks on All Fours

This is a documentary called "The Family that Walks on All Fours". Nicholas Humphrey is the presenter. It presents evidence that relates to a theory that I covered in my 2011 book on Memetics - that the distinctively human bipedal gait is partly culturally-transmitted.

This is an important hypothesis for students of memetics, since it places cultural transmission at the origin of our species. Maybe memes were present in a big way from the beginning. Maybe memes contributed to human speciation via symbiogenesis.

The documentary covers a family with multiple individuals that never learned to walk. By the end of the documentary, a number of them learn to do so, via social learning. These individuals are mentally handicapped - but it still adds to the evidence on the topic from feral children.

Another family that Walks on All Fours has also been found.

The external womb

As discussed extensively on this site, memes prefer to have an enlarged human cranium in which to swarm.

However, how did they engineer things so that they had one? Probably a big part of the answer was that they created an external womb in which the human brain could be better incubated.

This external womb took the form of baby slings. These slings created a protective environment for the human cranium after birth - allowing more premature birth to take place - before the skull bones had fully formed. The result was a marsupial-like phase of human evolution - with the newborn living in a synthetic pouch.

Baby slings are ancient - and the relaxed selection pressure on the skull was probably highly significant. This idea has been covered in more detail by Timothy Taylor and Duncan Caldwell.

The next-most significant factor letting memes inflate the human cranium was probably reduced nutritional constraints - a hypothesis covered in some detail in the book The Driving Force: Food, Evolution and the Future by Michael Crawford and David Marsh.

Memes in the driving seat

It is widely believed that cultural evolution goes much faster than the evolution of human DNA can manage.

In my book on memetics, I discuss the "upright gait hypothesis" and the hypothesis that much speciation in the hominid lineage was assisted by memes.

Looking at the changes memes have produced in us, I think it is reasonable to propose the following bold hypothesis:

Practically all the significant differences between chimpanzees and modern humans are the consequences of human cumulative cultural evolution.

We can see the normal rate of morphological and behavioural change in primate lineages - by looking at our nearest relatives. Human evolution has been like a rocket by comparison - and memes explain why.

Much modern evolution is cultural evolution - memes explain all the interesting evolutionary change, while genes plod along at a glacial rate which is hardly noticable.

Coevolution between memes and genes mostly takes the form of memes dragging genes around in the adaptive landscape. The memes lead, while the genes follow. Genetic evolution is thus the delayed consequence of cultural evolution. The practice of drinking milk led to lactase genes being active an adults; the practice of talking led to larynx changes, and the practice of walking upright led to modified knees and ankles - and so on.

This idea also explains why our brains swelled up and why humans are ultrasocial.

It is an old idea in memetics. For example, Susan Blackmore (1999 p.80) raps on the Lumsden-Wilson "leash" metaphor - of memes being held on a leash by genes - saying:

In this way the memes are, as it were, dragging the genes along. The leash has been reversed and, to mix metaphors, the dog is in the driving seat.

The hypothesis here is the polar opposite of the position of Coyne 1999 who wrote:

Similarly, the self replication of memes does not mould our biology and culture; rather, our biology and culture determine which memes are created and spread.

Of course memes and genes coevolve, but the point is that the memes lead, and the genes are dragged along in their wake. This is an example of large organisms using small symbiotes to adapt quickly.

Since this "memes-lead" hypothesis explains so much of human evolution so well, I think the challenge is to look for puzzle pieces which it doesn't explain. I've looked, and haven't found very much - thus the bold hypothesis above.