Sunday, 5 July 2015

In light of cultural evolution

There's a recent trollish article doing the rounds titled:

The Theory Of Evolution Does Not Apply To Modern Human Beings.

Basically it argues that humans don't behave as the theory of evolution dictates. For example, the more resources you give a human, the fewer children they have.

I think this article nicely illustrates the confusion associated with a lack of understanding of cultural evolution. Almost everything in the article makes me think: "yes: but only if you ignore cultural symbionts".

It's well-known that parasites can reduce host reproduction - and even drive hosts extinct. The demographic transition is driven by cultural symbionts that reduce host reproduction. This has been extensively modeled by cultural evolution enthusiasts. This isn't contrary to the theory of evolution - you just have to include the evolution of memes in order to understand it.

If you add resources to a human population the memes absorb the resource faster than the human hosts do - and more memes often means less host reproduction.

Something very similar happens in the organic realm - if you add sugar to a human population. A little sugar might help with reproduction - but beyond a certain point, fertility begins to decline. Instead of making more human genes, the sugar fuels the reproduction of gut microbes at the expense of the genes of the human host. The host's belly swells up to accommodate them all. Eventually the host is effectively sterilized.

This all illustrates the dictum: Nothing in human evolution makes sense - except in the light of cultural evolution.



  1. I too, have been very guilty of hammering this point out to everyone. Honestly, the meme as a visceral parasite is an intriguing, yet certainly not uncontroversial hypothesis to account for this.

    However, If one considers epigenetics as a part of evolution, then both ideas are perhaps compatible. I am always of the opinion that evolution be defined as "allele frequency change across generations". Given the additional constraints on genetics imposed by epigenetic markers, and indeed by the very cutting edge of cell-by-cell genetic variance, makes evolution in the short term demonstrably more Lamarchian.

    I'll produce at the very least some citations if prompted. I'm sure I have the articles lying around somewhere.

  2. Damn, Lamarckian. I even googled it to check spelling and didn't actually correct it.