Field of Science

The Future of Human Evolution

For much of the history of life, evolution worked a certain way. Organisms competed for the chance to reproduce. An individual with an advantageous mutation would produce more offspring, which would inherit the advantageous gene, and in this way life continually improved upon itself.

But I would argue that for humans, in the world as it is today, this process is more or less defunct. We are not, by and large, competing with each other to produce more offspring. It's true that some people lack reproductive ability or die before their time, but most people who reach adulthood with their health intact can have as many babies as they want. It is a matter of choice more than a competition. Furthermore, people with genetic defects, who may never have survived in times past, can now (sometimes) lead healthy procreative lives thanks to modern medicine.

This means that the best genes no longer produce more copies. There is no longer a way for advantageous mutations to spread through the population. If these trends continue, we can expect that our gene pool will no longer improve, and may even degrade a bit thanks to advanced health care. The human body and mind are currently as good as they will ever get.

So have humans stopped evolving? As individuals, I would say yes. But our society is clearly still evolving, due a mechanism we evolved in the past million years (back when we were still evolving the normal way): language.

Language allows for the evolution of ideas rather than genes. A person with a good idea can communicate it to others, who, if they like it, can communicate it further. In this way good ideas, rather than good traits, spread through the population.

Here's another way of seeing the difference: for conventional evolution, DNA carries information about traits that successfully spread themselves. For this new form of evolution, language (both oral and written) carries information about ideas that successfully spread themselves.

I don't think any of the above ideas are terribly original. But it occurred to me today that while there are many mathematical models for genetic evolution, I don't know of any good models for the evolution of ideas. And more generally, how does a society that progresses by idea-based evolution differ from one that evolves genetically? The question is so vague I can barely conceive of how to frame it, but it seems very important to the study of humanity's future.


  1. I think something else interesting to consider is the environment of ideas. When dealing with organisms it's fairly obvious, and factoring the breeding pool into play with genes isn't much of a leap. With ideas however they almost completely shed the environments of genes and organisms. Do they "live" in our head, or in our speech, what about books, television, and the radio waves we send out into space?

  2. Excellent question! I think that ideas live in our collective consciousness---that is, a single idea will live multiple lives in the minds of multiple people. In this way ideas are like viruses: they live inside hosts and reproduce by infecting other hosts.

    The environment for an idea would consist of all the other ideas that are out there in people's heads. The success or failure of an idea depends on the current intellectual environment, as well on the idea's intrinsic worth.

  3. But what is there to say about storage media like books and movies? I think the ability to be archived and unearthed at a much later date is a significant difference as well. For a gene to survive it has to constantly be within a living organism and keep reproducing.

  4. Hi, great post and topic, but I disagree that the process of genetic evolution for humans is defunct.

    It is true that the idea of humans dealing with 'natural selection' may mostly be considered obsolete (save a few stubborn diseases), but that's only one of the processes of evolution. Genetic drift, mutation, gene therapy, cultural behaviors, and more random (esp. catastrophic) events will still change the gene pool. Our traits as a species will always evolve genetically, just under societal rules and not necessarily in a positive or beneficial way (see: Idiocracy).

    Part of the semantic problem is that the word 'evolution' has come to imply improvement, something the field of biology never intended. The process of evolution makes no distinction in whether a trait is beneficial or not, because every change in a species' inherited traits (whether good, bad, random, neutral, homogenizing) is considered evolution.

    Having said that, the real question you raise is how an advancing society of ideas will evolve with and around us and how it will affect our evolutionary path. Describing ideas as viruses might actually work very well in existing models, with different cultures or individuals as hosts with varying degrees of susceptibility and distances measured only in access to communication.

    I bet if you plugged in numbers for the spread of ideas into similar disease models, we'd be facing endless epic epidemics since the internet hit.

  5. Yes, selection may be defunct — or, rather, many of the selective pressures may have been nullified — but mutation and drift are likely still at work.

    Interesting subtleties arise when one tries to model the spread of ideas by analogy with the dynamics of genes. For example: genes are coded onto physical objects, snippets of nucleic acid, which are passed from one organism to another, either by reproduction or via horizontal gene transfer. Genes acting in concert produce a phenotype, which then has a greater or lesser chance of success in the organism's environment (part of which, of course, is formed by the presence of other life-forms carrying their own genes). Selection changes allele frequencies by acting on phenotypes.

    Now, suppose we try to think about ideas and culture in the same fashion. How does an act "go viral"? Consider a case where it's very clear whether the "phenotype" is present or not: wearing one's baseball cap backwards, say, or wearing a carnation in one's lapel. Encountering that phenotype may influence me to emulate it, stealing a carnation from a flowerbed and poking its stem through the otherwise useless buttonhole in my lapel. No physical object was passed from Clifton Webb to me, nor did I really receive an explicit set of instructions. The "idea gene" reproduced via its phenotype.

  6. @samineru-Also a good point. The existence of semi-permanent media means it is very hard to kill any idea completely. There is a biological parallel here as well: some bacteria, upon finding that their environment cannot support them, go into a "dormant state" where they shut off all life functions and encase themselves in a hard shell, preserving their DNA for better times.

    @paz & blake-Evolution, as I've been taught in my classes, requires three ingredients: variation, reproduction, and selection. With the third ingredient removed I don't think we can say we're still evolving genetically, though our genome is certainly changing.

    There are models out there that use epidemiological methods to study the spread of ideas. There are also more explicit models where individuals can choose to imitate each other's behavior, and some behaviors are more likely to be imitated than others. But I don't think I've seen a big-picture study of how idea evolution advances a society differently from genetic evolution.

    Here's one more interesting question: what makes an idea likely to spread? One could say that ideas spread if they provide some utility to the idea's holder. (Or if they appear to provide utility, as in "Hey, that tattoo looks cool! I should get the same one!") But what defines utility in this context? Evolutionary biologists usually think of utility in terms of an increase to reproductive fitness, but as we've discussed, this doesn't much apply to us anymore. So to understand the evolution of ideas, it is important to think about which ideas are valued by humans and why.

  7. I agree with your post and the nuanced points made in the previous comments. To add to the discussion, I'll suggest that the evolutionary process as shaped by selection and drift, is going on all the time at all levels of organization. However, as higher levels emerge from lower, the higher level constrains the dynamics (including evolutionary) at the lower level. Thus from an absolute and relative standpoint it appears as if evolution stops or slows to a crawl at the lower level, even though it doesn't. An example worth noting is somatic evolution (i.e. the population of cells in the body or soma) which has been constrained by the multicellular level of organization, but at times speeds up and we recognize that as cancer.

    As for the levels of organization above human, there are many, and they are overlapping and intersecting. Language and culture play key roles and can be seen as evolutionary systems if you model them appropriately to meet the evolutionary preconditions. Dawkins was the first to do this by positing a population of agents called "memes" which are essentially ideas. They live in the minds of humans, reproduce with differential fecundity, etc. Disappointingly, memetics has not been fleshed out or formalized much since the concept was introduced. But there is some work on it, including extensions into the technological and economic realms.

    The most prolific thought leader in generalized evolutionary is, of course, your professor, Martin Nowak. What does he have to say about linguistic/cultural evolution as it relates to human evolution?

  8. Good point! I hadn't thought to frame the transition from genetic to cultural evolution as a "scaling up" analagous to cells within an organism, but the analogy may be quite useful.

    I haven't heard Nowak talk specifically about the qualitative distinction between genetic and cultural evolution, though he has talked about each separately. I'll see if I can pry some thoughts out of him some time.

  9. may be because you are in 10% of people who can "choose to mate". If you really want to check your claim (that we are not competing for mating) may be you should check with many other societies of different cultures.


Markup Key:
- <b>bold</b> = bold
- <i>italic</i> = italic
- <a href="">FoS</a> = FoS