Was prehistoric tool use in the genes?

Our ancestors have been making stone tools for millions of years. They were probably using organic tools for millions more. This sort of technology helped them take over the world. Armed with Oldowan and Acheulean tools, Homo erectus spread across the Old World. But what prompted them


A handaxe, nicknamed Excalibur. Does it have a genetic root?

A handaxe, nicknamed Excalibur.

Our ancestors have been making stone tools for millions of years. They were probably using organic tools for millions more.

This sort of technology helped them take over the world. Armed with Oldowan and Acheulean tools, Homo erectus spread across the Old World.

But what prompted them to make these tools in the first place? Was there some great pioneer? Some particularly clever innovator? A Steve Jobs of the Palaeolithic?

Or does the actual answer lie in the genes of our ancestors?

Testing chimps

Culture is the ability to learn technology and behaviour from one another. This “saves the progress” of civilisation; ensuring each generation doesn’t have to start from scratch.

Some of the chimp cultures currently identified, along with the behaviours practised by each (you're probably going to want to click to see a bigger image)

Some of the chimp cultures currently identified, along with the behaviours practised by each (you’re probably going to want to click to see a bigger image)

Ultimately, culture means that innovations can accumulate over time. Each generation builds on the inventions of the previous. As such, culture is kind of a big deal. And chimps have it (further proof of their imminent, evil attempt at world domination). For years, scientists had knew that different chimpy groups made different sets of chimpy tools. But whether or not this counted as culture was hotly debated.

A series of rigorous tests finally confirmed that the variation in chimp technology really was a case of culture. They did this by ruling out all the alternatives. For example, compared the culture of chimps living in similar environments; showing that the variation wasn’t just a response to the environment. The scientists even compared the genes of the chimps to show that the variation in technology didn’t have a genetic basis.

All of this showed that chimps really do have culture. But crucially, we haven’t demonstrated this in our ancestors.

Homo erectus genes

Around 1.8 million years ago our ancestors began making a set of fancy tools called “handaxes“. They’re pretty cool. So cool that Homo erectus kept making them for a million years.

Could this be because the drive to make handaxes was actually in there genes? That’s what a new paper suggest. It notes that the alternatives explanations (like genetics) for the the transmission of these tools hasn’t been ruled out. We only accepted chimp culture because they were ruled out, so why should we accept it for Homo erectus if they haven’t?

Environment can be ruled out as handaxes don’t change much, despite the fact that the environments their manufacturers lived in did. The tools made by Homo erectus in France are recognisably the same as those from South Africa. This leaves two alternatives for the transmission of handaxes from one generation to the next: culture or genetics.

Genes can’t really be ruled at this time since we don’t have any genetic material from Homo erectus. They were making these handaxes more than a million years ago. By contrast, the oldest DNA we’ve managed to recover from our hominin family is only ~400,000 years old.  

There may be some alternative ways to test for the influence of genetics. For example, you could compare the tools made by two nearby groups of Homo erectus. Such groups would likely be interbreeding, so their toolkit should be identical if genes are responsible for it.

Arguments for genes

As well as pointing out that genetics hasn’t been ruled out, the authors of this new paper also note there is some positive reasons to think that genetics may be involved.

The key piece of evidence is the consistency of handaxes. They remain very similar for a very long period of time. On top of that, there isn’t as much variation as would be expected between the tools. The fact that people don’t learn from each other perfectly means that there should be slight differences between how people make tools. Yet this degree of variation isn’t present in the tools.

Personally though, I think this is mostly bollocks.

For starters, there’s the fact that these handaxes are a minority of the tools made by these people. Whilst there are some exceptional sites, many sites from this period don’t even have any handaxes. Of those that do, they typically represent <20% of the artefacts recovered. Clearly, they may not be the most representative way to study our ancestors. On top of that there are many alternative explanations for why handaxes remained unchanged (like people rectifying the mistakes they may have picked up when they initially learnt how to make them).

Nevertheless, I do think the authors raise some very interesting points about the fact that genetics and tool use hasn’t even been considered; let alone ruled out. I think it’s very likely that there are some key genes linked to our ability to make tools. Maybe even specific tools. I’m just very doubtful you could find a handaxe in the genome.

So don’t let my casual use of profanity fool you. I’m very interest in seeing where this goes.

tl;dr

Genes could have influenced tool making, but it hasn’t been shown. One way or the other.

References

Corbey, R., Jagich, A., Vaesen, K. and Collard, M., 2016. The acheulean handaxe: More like a bird’s song than a beatles’ tune?. Evolutionary Anthropology: Issues, News, and Reviews, 25(1), pp.6-19.

Santonja, M. and Villa, P., 2006. The Acheulian of Western Europe. Axe Age Acheulian Tool-making from Quarry to Discard Approaches to Anthropological Archaeology. London: Equinox, pp.429-478.

Whiten, A., Goodall, J., McGrew, W. C., Nishida, T., Reynolds, V., Sugiyama, Y., … & Boesch, C. (1999). Cultures in chimpanzees. Nature399(6737), 682-685.

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21 thoughts on “Was prehistoric tool use in the genes?”

  1. Randall Fears says:

    There are just too many errors in your posts! Simple spelling mistakes or the use of incorrect verbs, subject-verb agreements, etc. are too prevalent. You sure need a better copy editor or you need to get your first one! It detracts from your academic work or even just your writing, if it’s not academic as such. It hurts your influence on this very important subject.

    1. Adam Benton says:

      Those are all tests to keep you on your toes.

  2. Francesco Piccardi says:

    How could this ability have been fixed in the genome?

    1. Adam Benton says:

      How it would have been fixed is easy: natural selection. Those with the genes for handaxes would have had an advantage, so their genes would be passed on more often.

  3. Wyrd Smythe says:

    The is also the idea that form follows function, so perhaps very similar “discovered” tools for similar tasks converge on a most workable form. Tool use, in general, might simply follow from opposable thumbs and an inquisitive and expansionist nature.

    1. Adam Benton says:

      They dismissed that on the grounds that there should still be more variation between examples

      1. Wyrd Smythe says:

        In their opinion, or did they provide comparative examples? Just how much variation can there be in a hand axe?

        1. Adam Benton says:

          They cited a paper where volunteers recreated a handaxe (albeit digitally). They noted that there was ~3-5% variation between the source and what the volunteer produced. Yet when handaxes are compared in general, variation less than this is seen.

    2. Adam Benton says:

      There is big debate over just how much function influenced the form of the Acheulean. You can get a cutting tool just as good without it being nearly so symmetrical; yet they made it that way anyway. Of course, this also raises some questions for the genetic point of view. Why would such non-adaptive characteristics rise to fixation?

  4. Brian says:

    I’ve always imagined that Homo Erectus made hand axes like birds make nests. Out of instinct rather than real understanding of what they’re doing.

    1. Adam Benton says:

      The authors of the paper actually make explicit comparisons to birds nest, pointing out how such complex behaviour can be innate. However, the had to have had some real understanding of the tools and their functionality because they were used for practical, deliberate activities.

  5. Charles A. Bishop says:

    I fall into a different camp. First, contrary to many primatologists, I do not believe that chimps have culture even though they make tools and that tools vary from region to region. This is because I define culture as consisting of a system of symbols (linguistic and otherwise) that is manifest in variant forms of behavior and their material products. Chimps and gorillas are highly intelligent and have a rudimentary capacity for culture (symbolism) if taught by humans (eg. Koko the gorilla, and many chimps). Learning while important to the transmission of information is insufficient in and of itself, unless what is being learned can be transferred via symbols in the absence of context. For example, one chimp cannot tell another how to operate a water fountain in the absence of one on which to demonstrate. Second, like you, I believe the connection between genes and bifaces is “bollocks.” If it were that simple, shouldn’t we be able to make a case that genes are responsible for other forms of materials and even behavior? An interesting hypothesis, but like those associated with evolutionary psychology, untestable and unprovable.

    1. Adam Benton says:

      Whilst you might not think they have culture by your definition; most people discussing primate culture are using a different one (which I suspect you would agree chimps meet). What makes you opt for yours over there’s?

  6. Jim Birch says:

    I’ve alway found these gene arguments magical. Do we have enough genes for a hand axe gene along with everything else? Or, more likely, a hand axe gene constellation, because it’s a bit hard to see how a single new protein could generate multiple behaviours required to fabricate and use an axe. It’s not obvious how a gene/protein translates into behaviour but it’s going to be quite complex and in the case of humans – cf, insects – there are multiple layers of intervening learning.

    It seems infinitely more likely that general improvements in the brain that allowed planing, design and cultural transmission facilitated development and retention of tool-use and tool-making skills.

    1. Adam Benton says:

      Also, I’ve tried to make a handaxe. It’s not something you can do by rote. Every strike, every time, it’s different. How much variability in behaviour can a gene deal with?

  7. Jim Birch says:

    Charles, that seems a like an extreme definition of culture, why are are symbols so special? For example, a human child typically learns the grammar of the language it is raised in without ever having it explained/taught symbolically. (Ape hear, ape do.) AFAIK formal symbolic grammar rules don’t exist in many languages. Your definition of culture seem to exclude language acquisition.

    It seems to me better to use a simpler functional definition of culture: behaviour that is learned, and, transmitted. The mechanisms aren’t a required part of the definition and can be discovered rather that proscribed. Symbols are obviously a big part of human culture but not all of it: there are tacit components.

  8. Francesco Piccardi says:

    I didn’t understand really well how could this ability have been transmitted through genes.. how did they acquire it?

    1. Adam Benton says:

      The acquisition of this trait is very interesting. Presumably chimps would have a more archaic version that coded for their simpler tools; and this was built upon that.

  9. Chris Reynolds says:

    One possible reason to the apparent failure to advance the making of stone handaxes that never seems to be considered in the fact that our brains are made up of neural nets and these provide constraints on what can be done. In simple term filling a neural-net brain with the knowledge it needs to support the host animal through life takes time and normally that knowledge is lost when the animal dies. So no species will evolve a brain bigger than will suffice for one lifetime’s learning.
    My research shows how a neural-net brain might morph from simple pattern recognition, via simple set theory, a very basic rules based system and onto something resembling a stored program computer which can carry out extremely complex tasks. The learning time restraint means that no (non-human) animal can learn enough in a lifetime to get much beyond the basic rules level and this puts a natural cap on animal intelligence. It seems likely that that simple tool-making is about as sophisticated as species with a single neural-net brain can get.
    Once significant amount of information can be transferred between generations a major tipping point is reached, and the invention of a simple rule based language could be enough to reach the tipping point. One suddenly moves from a single neural-net brain to multiple neural-net brains working together.
    This is a very simple summary of the research but what it predicts is that humans start making simple tools and as a result they evolve bigger brains, and modified lifestyles, to make it possible to make slightly better tools – pushing at the neural-net brain’s natural cap. Suddenly a small group invents a simple language tool which allows knowledge to be transferred efficiently between generations – and it is as if a damn has burst. One now has a network of neural-net brains working together to build up a culture. The simple language is a tool which allows the user to build better tools – which means that language can modify itself to become a more effective tool. What is more language allows the brain to store information more efficiently – so there is no longer any pressure to evolve a bigger brain.
    So a neural-net model suggests a slow a painful struggle over millions of years to make slightly better tools, as the brain gets fractionally bigger, followed by an accelerating explosion of tool making (?about 150,000 years ago??) with no further increase in brain size.

  10. Anonymous says:

    Enjoyable article, I appreciate the humor

    1. Adam Benton says:

      I’m glad someone does

Leave your filthy monkey comments here.

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