When Did We Become Human?

Exploring what paleontology, archaeology and biology tell us about when our ancestors acquired uniquely human traits.

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When Did We Become Human?

I’m not sure I’m willing to grant the premise of that question, particularly given recent events.

Have we finished becoming human? I hope not. I think the best that can be said for us is that we’re a ‘work in progress’ – more human (and more humane) than we once were, but not as human (or as humane) as we could be.

I don’t think attempting to inscribe a ‘bright line’ on the shifting sands of human and primate history is particularly useful. And I’m not sure that trying to use “symbolic thinking” as that line is particularly healthy – in that it tends to imply that those of us with a greater alacrity for abstract, symbolic thinking are better and ‘more human’ than those of us with lesser alacrity.

For myself, as a follower of both Neil Gaiman and the late Sir Terry Pratchett, I’m happy enough to define my species simply as ‘the story-telling ape’, and leave self-bestowal of more elevated titles to others.

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Interesting discussion of actual data. It seems odd that any theological implications are never mentioned. Perhaps there aren’t any?

Regarding pigment: Certain species of hornbills carefully decorate themselves with pigment. Is that evidence of their humanity? Those yellow feathers are actually white.

Ook!

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@NLENTS and I just gave a talk on this topic at Christopher Newport University.

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Can you speak to why hornbills decorate themselves? A counter-argument would be that hornbills decorate themselves for a social or selective reason, not because they have an artistic eye. Associating color and decoration with an appreciation for beauty could be a human trait we’re projecting onto hornbills, after all we find a lot of things in nature beautiful.

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One could equally make the argument that humans frequently “decorate themselves for a social or selective reason” – it would after all explain many of the fads and fashions that we see better than an “artistic eye” would. :slight_smile:

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How would we determine that the “artistic eye” is fundamentally different from any behavior engaged in my any other organism for simple reason that it feels good?

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I can’t. Then again, can anyone speak to why early humans used pigment? We certainly can’t ask any of them.

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It seems to me that, given natural selection is involved, the “it feels good” or “it appeals to my arttistic sense” proximate reason for a behavior is perfectly compatible with a “selective reason” such as “it protects me from predators” or “ir on average results in greater success at mating”. So asking whether the coloring of the feathers is there for the one reason or the other is a false dichotomy.

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I recall discovering, when I was an activist vegetarian child who liked to argue with other kids (not a good idea in the mid-1970s!) about animal rights, that many people actually believe that other animals are completely devoid of any sort of internal cognition. This was then expressed to me as “animals do everything by instinct,” which even as a child I could tell was vague, useless rubbish. But I run into it in a lot of forms still. One of those takes the form of assigning functional reasons for behaviors when non-human behavior is at issue, but subjective reasons when human behavior is at issue.

There’s a sort of amusing essay by Thomas Huxley on whether animals are automata, which at least shows that this weird concept is fairly old. Essentially Huxley takes the “animals are automata” concept as meaning that animals merely respond to their circumstances, and says, yes, in that sense they are, and that we are just like the rest of them and so are also automata in that sense.

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That’s the point, though; human motivation is anything but simple. The fact that we can analyze why we do things in a conversation like this instead of simply doing them IS a fundamentally different behavior than most other organisms.

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Fair point.

I agree. However, it does not mean that the fundamental nature of our motivations is different from that of other organisms.

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Makes sense.

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Hi @swamidass, @Faizal_Ali, @John_Harshman, @Andrew_Christianson and @Puck_Mendelssohn,

Dr. William Lane Craig seems very concerned to show that there is a clear-cut dividing line between humans and non-humans, and that ultimately, language is that dividing line. While Craig’s bibliography is extensive, he appears not to have read my online article, "An A-Z of Unanswered Objections to Christianity: H. Human Origins", in which I argue that the available scientific evidence seems to indicate that there was no “magic moment” at which our ancestors became human. I summarize my case in a table (scroll down two screens to view it) called “The Ten Adams,” showing that depending on which criterion of humanity you pick, you can make a case that humanity emerged anywhere between 1.76 million years ago and 100,000 years ago. Regarding language, here’s a summary of my conclusions in my section on “Linguistic Adam”:

Overview: The ongoing academic controversy over exactly when the ancestors of modern humans acquired language boils down to a difference of opinion regarding what language is. On a broad view , language is a communication system in which symbols (such as sounds) are assigned definite meanings, but in which words can be combined freely to make an infinite number of possible sentences. On this view, a very powerful case can be made that not only Homo sapiens but also Neanderthal man was an adept language user, and that Heidelberg man, who lived half a million years ago, probably used language as well. On a narrow view , language (in the strict sense of the word) is defined in terms of sets of rules governing the way we construct sentences: more specifically, syntax and recursion. On this conception, hierarchical syntactical structure is a core feature of language. If we adopt this view, then language is most likely confined to Homo sapiens , and probably emerged during a 130,000-year window, some time between 200,000 and 70,000 years ago. However, recent research has shown that a single mutation is unlikely to have given rise to human language , and that it is much more likely that multiple mutations with smaller fitness effects were required to fix it within the human population. The key point here is that no matter which conception of language you happen to favor, it most likely did not magically emerge all at once , but over a period of tens of thousands of years.

While Craig is commendably familiar with the work of Dediu and Levinson on Neanderthal linguistic abilities, he appears not to have read the following very recent articles:

Pomeroy, R. (2020). Did Language Evolve With a Single Mutation? A New Study Says That’s Unlikely. Real Clear Science , January 17, 2020.

De Boer, B. et al. “Evolutionary Dynamics Do Not Motivate a Single-Mutant Theory of Human Language”. Scientific Reports (volume 10, 451 (2020)).

Bart de Boer et al. critique the proposal that a single macro-mutation gave rise to human language:

We find that although a macro-mutation is much more likely to go to fixation if it occurs, it is much more unlikely a priori than multiple mutations with smaller fitness effects. The most likely scenario is therefore one where a medium number of mutations with medium fitness effects accumulate. This precise analysis of the probability of mutations occurring and going to fixation has not been done previously in the context of the evolution of language. Our results cast doubt on any suggestion that evolutionary reasoning provides an independent rationale for a single-mutant theory of language.

While there is a pretty sharp dividing line between humans and other species living today, there’s no such line dividing us from our non-human ancestors. Or as Darwin put it in his work, The Descent of Man, and Selection in Relation to Sex (1871, London: John Murray, Volume 1, 1st edition, Chapter VII, p. 235)::

In a series of forms graduating insensibly from some ape-like creature to man as he now exists it would be impossible to fix on any definite point when the term ‘man’ ought to be used.

That said, I’d tend to agree with Craig’s point that the common ancestors of Homo sapiens, Neanderthal man and Denisovan man were mentally human in many important ways (even if they lacked religion, which seems to go back a mere 100,000 years, with the appearance of ritual burial with ochre). Craig refers to this species as Homo heidelbergensis, but as of October 2021, this taxon has been reserved for the European ancestors of the early Neanderthals. The common ancestor of the three species named above is variously referred to as either Homo bodoensis or Homo rhodesiensis (although some prefer the name Homo saldanensis). For more, read here and here.

My two cents.

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Consider also that language, if it indeed arrives all at once in a single macromutation, has no selective advantage, since it has benefits only if there are others already around with which to converse. Further, while the ability must evolve, the language itself must also evolve and can only do so in a population with the ability. Again, there is no advantage to the ability to use language until there is a language to use.

One could of course imagine a series of miracles, in which language ability and language itself are divinely granted to a population. But even so I don’t think a population of two would be sufficient.

I was thinking about my earlier “story-telling ape” comment, and wondered, what if it started with some form of crude mime to communicate plans for collective hunts, and bragging about successful hunts afterwards – the latter also serving the purpose of preserving knowledge about how to hunt successfully. The mime could easily involve initially-random excited vocalisations, with these vocalisations becoming ritualised over time, and starting to form part of the mimed communication, in turn forming the crude basis for a language. This improved communication and hunt coordination could easily have provided a selective advantage for those with a tendency and/or aptitude for such communication, and natural selection could have gradually snowballed this into language-use.

I’m not an anthropologist, let alone an evolutionary anthropologist, but this ‘just so’ story does seem to offer a possible explanation for how the whole language thing got started.

I don’t think the “crude mime” idea would be outside the realms of possibility for a cousin species to the chimpanzee.

It’s not only inside the realms of possibility for chimp-like animals, it’s similar to what happens within wolfpacks and meerkat tribes.

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