How Did We Get Here?

by Luke Muehlhauser on August 9, 2009 in Reviews,Science

I’m blogging my way through Sense and Goodness Without God, Richard Carrier’s handy worldview-in-a-box for atheists. (See the post index for all sections.) In my previous post, I wrote about the meaning of life. Now, I discuss Carrier’s section on How Did We Get Here?

If nobody planned the universe, how did it manage to produce a complex, reasoning, self-aware creature like homo sapiens? Isn’t that just too improbable to believe in?

Yes, our existence is extremely improbable. But the universe is so old and vast that it was actually inevitable it would produce something like us. Even if consciousness is only produced in one out of every million galaxies (each of which contain billions of star systems), then we’d expect there to be thousands of instances of conscious life in the universe. The thing is, the distances between these galaxies are so great that we would never expect them to communicate with each other.

The scientific story of how we got here is told in 5 parts. First, the universe began and evolved, which we discussed earlier. Second, simple chemicals capable of reproduction formed (biogenesis). Third, natural selection acted on these molecules, and built more and more complex forms of life. Fourth, evolution finally hit upon the most flexible and powerful adaptation: a thinking, conscious mind. Fifth, these conscious minds created culture, a new environment on which natural selection could act. This time, the fittest ideas were selected as they were reproduced among conscious minds. These ideas eventually led to art, philosophy, science, and technology.


Everything we are made of – amino acids, sugar, water, sulphur, oxygen, carbon, etc. – has been found in space in great quantities. Moreover, there are probably trillions of planets in the universe, and planets are the very place we would expect such elements to congregate. So the stage was certainly set for life.

We’ve also discovered that amino acids naturally chain themselves into proteins, and that some very simple proteins will naturally reproduce themselves. And once reproducing proteins exist, mutation inevitably occurs.

So, given the vast size and age of the universe, it seems plausible that biogenesis has occurred not just once, but many times. Every month scientists discover something new that makes the origins of life clearer.

Isn’t this an “atheism of the gaps”? Am I not just holding out for scientific answer where there isn’t one, yet?

Not quite. There is at least one very good reason to suspect that biogenesis will eventually be explained by science, not supernaturalism. In the words of Tim Michin, “every mystery ever solved has turned out to be…not magic!” This is the Inference to Naturalism, and it has stood the test of time (unlike the vast majority of supernatural claims). Elsewhere, Carrier puts it this way:

The cause of lightning was once thought to be God’s wrath, but turned out to be the unintelligent outcome of mindless natural forces. We once thought an intelligent being must have arranged and maintained the amazingly ordered motions of the solar system, but now we know it’s all the inevitable outcome of mindless natural forces. Disease was once thought to be the mischief of supernatural demons, but now we know that tiny, unintelligent organisms are the cause, which reproduce and infect us according to mindless natural forces. In case after case, without exception, the trend has been to find that purely natural causes underlie any phenomena. Not once has the cause of anything turned out to really be God’s wrath or intelligent meddling, or demonic mischief, or anything supernatural at all. The collective weight of these observations is enormous: supernaturalism has been tested at least a million times and has always lost; naturalism has been tested at least a million times and has always won. A horse that runs a million races and never loses is about to run yet another race with a horse that has lost every single one of the million races it has run. Which horse should we bet on? The answer is obvious.

So when looking for an explanation for biogenesis, I’m betting on the horse that always wins: naturalism. Besides, the scientific case for natural biogenesis gathers more evidence every day.

Evolution by natural selection

When a collection of molecules reproduces itself, there will inevitably be mutations – random changes or mistakes. Most of these mutations are fatal. Many will have no effect. And a few of them will actually be beneficial, meaning that this slightly different molecule will more successfully reproduce itself in its environment than the original. This is evolution by natural selection.

In fact, evolution by natural selection is inevitable any time you have (1) replication, (2) variation, and (3) certain variations being more useful for replication than others. As such, biology is not the only place you find evolution by natural selection. We also see it in the world of ideas (ideas mutate as they replicate between human brains, and some mutations make these variations more successful replicators than others) and computer programs (evolutionary algorithms have been used to ‘design’ everything from better aircraft wings to more successful computer viruses).

But I won’t spend much time on this. The evidence for evolution is so insurmountable that only religious fundamentalists deny it. Some quick links for the doubtful: observed instance of speciation, Why Evolution is True, The Theory of Evolution Made Easy, The Greatest Show on Earth, and Evolution: What the Fossils Say and Why It Matters.

Evolution of mind

Every brain reasons in some sense. Every brain responds in one way to some sensations, and in another way to other sensations. The more complex the brain, the more subtle and adaptable these responses can be. Finally, “after hundreds of millions of years of trial and error, a brain developed so complex that it was capable of perceiving itself and its own thought, and this made… self-knowledge possible… which also made a recognition… of other minds possible (by analogy to our own), as well as a recognition and comprehension of abstractions. [And] this made sophisticated language possible… as well as advanced reason.”

This story makes sense to me, but of course the evidence for it can’t be easily summarized. So, I provide you with Carrier’s list of suggested reading on the topic:

Cultural evolution

Since the development of language, not just molecules but now ideas (“memes”) are reproduced and mutated on a grand scale, and inevitably some of these variants copy to new minds more successfully than others, depending on the peculiarities of the human mind.

Of course, there are important differences between genes and memes. Genes can be encoded, combined, and mutated in a limited number of ways, but with memes the possible patterns are virtually infinite. You can even combine klezmer and modern chamber music or philosophical fiction with a first-person horror shooter!

According to Carrier, memetic selection occurs at two levels:

First, memes will survive, or die out, in relation to how they affect the biological survival of individuals and societies. For instance, false knowledge, and poor methods of acquiring and testing knowledge [are often deadly], whereas true knowledge and good methods [will lead to] more useful ideas. Second, memes will survive, or die out, in relation to their own battle for ideological survival. For instance, to survive and be passed on, ideas must not only confer some advantage to the recipient [such as the use of fire or emotional comfort] but [also] they must contain with or within them the seeds that inspire the recipient to pass them on, and the audience to gladly take them up.

This is why certain beneficial cultural and technological memes take hold. But it is also why certain virus-like memes (like nationalism or racism or superstition) can replicate themselves despite certain disadvantages. The promise of an eternal life of bliss is a very successful meme because it is so comforting, even though this falsity may confer certain disadvantages on its recipients.

And that is the heavily abbreviated story of How We Got Here. But perhaps the best way to experience this story is potholer54′s astounding Made Easy series on YouTube, beginning with History of the Universe Made Easy and ending with Human Ancestry Made Easy.

Next, we look at section III.9, The Nature of Reason.

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{ 7 comments… read them below or add one }

IntelligentDasein August 9, 2009 at 2:07 pm

If you are into simplistic and enjoyable related reads, you should check out Paul Davies The Mind of God. It is a real interesting read that deals with Cosmology in science and philosophy. I am a history major (my area of history is religious studies. In particularly historic jesus, human sacrifice, and the development and criticisms for the religious proofs for God) but I am very literate in science, in particularly cosmology and evolution.  If you ever want any book suggestions, I would be glad to make some. You are one of the only athiests (besides myself obviously) who takes religion seriously and I would be happy to help you out.


Haukur August 9, 2009 at 3:54 pm

Wait, that gets too vague there at the end. What sort of disadvantages are you talking about for racism? Is racism even a meme?* It doesn’t seem like just an arbitrary cultural idea, it seems connected to a basic evolutionary strategy that I would think is pretty much hard-wired into every creature, i.e. a preference for beings related to us over others.
* I’m not convinced ‘meme’ is even a useful concept to begin with but I’m assuming that here for the sake of argument.


Ryan August 9, 2009 at 5:38 pm

I just wanted to chime in with something: Carrier also tells us that another good reason to accept a natural origin of is that “current theory” explains why life is made of the particular elements it is made of. I expanded on this in an article I wrote on directed panspermia:

“[R]esearchers have determined that the last universal common ancestor of all life (‘LUCA’) used proteins constructed with amino acids, and these amino acids can easily be produced in experiments meant to recreate early Earth conditions[4]. Note: the last common ancestor was not necessarily the very first living thing. It probably evolved from an even simpler organism.

Another way of describing this is by the Miller experiment: in 1953, Stanley Miller attempted to recreate the early Earth’s atmosphere[1]. In the end, he produced several amino acids. Dozens of experiments like his have been done since then, many of them correcting mistakes that he made (for example, he assumed the atmosphere was composed of methane and ammonia, while recent evidence suggests that early Earth atmosphere was mainly composed of carbon dioxide and nitrogen[6]). The amino acids that these experiments produce in abundance are the most frequently used amino acids of the LUCA. This is surely to be expected if life arose naturally from the chemicals on the early Earth. Later organisms could’ve evolved ways to synthesize amino acids which were not readily available in the environment. Yet the very first organisms would not have had the ability to synthesize just any amino acid. They would have had to use what was readily available – the simple amino acids generated by Miller-type experiments. The fact that the LUCA predominantly used these simple amino acids means it likely evolved from an organism which used these simple amino acids exclusively (or almost exclusively). This is what we would expect if this form of life originated naturally.”


Reginald Selkirk August 10, 2009 at 5:34 am

We’ve also discovered that amino acids naturally chain themselves into proteins, and that some very simple proteins will naturally reproduce themselves. And once reproducing proteins exist, mutation inevitably occurs.

Personally, I think the RNA World theory is the way to go. These days, specifically coded proteins are the result of ribosomal synthesis (with some post-translational modification). Nucleic acids have the advantage of base pairing, which is at the heart of replication, transcription and translation.

IntelligentDasein: If you are into simplistic and enjoyable related reads, you should check out Paul Davies The Mind of God.

Paul Davies is a Templeton Prize winner, which I hold against him.

Haukur: I’m not convinced ‘meme’ is even a useful concept to begin with but I’m assuming that here for the sake of argument.

I have no difficulty accepting memes as useful; but I question whether meme theory is rigorous.


lukeprog August 10, 2009 at 7:39 am

I also think “meme” is a useful concept, but I haven’t seen any rigorous work done on it yet.


Fortuna August 10, 2009 at 11:36 am

What sort of disadvantages are you talking about for racism? Is racism even a meme?
Well, assuming arguendo that memes are a useful concept and that racism can be treated as a meme; racism has the disadvantage of discouraging disparate parties from entering into mutually beneficial relationships. On the flip side, it also has the disadvantage of encouraging disparate parties to enter into mutually deleterious relationships. If you survey history, I think you can find plenty of examples.
On a side note, I think you can treat racism as a meme that propagates culturally, rather than the result of hardwired xenophobic instincts, at least to some extent. The evidence I’d cite for that would arise from situations in which racially diverse people grow up side-by-side, without a preponderance of authority figures expressing racist views. Such people don’t tend to grow up into hardline racists.


Reginald Selkirk August 25, 2009 at 7:12 am

The current issue (Sept. 2009) of Scientific American is a special issue on Origins. It contains a review article on The Origin of Life on Earth by Alonso Ricardo and Jack W. Szostak which covers the current status of biogenesis research.


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