The Pre-Historical Fallacy

I am talking about the pretty much anything that refers without references to the idea that 'humans evolved to X' or 'it is human nature to X'. My background is in anthropology, with comparatively little exposure to evolutionary psychology, but in my experience the ethnographies, papers, and meta-studies that this information would ideally be based on are very clear about their shortcomings.

However, even when your data is a handful of surviving and marginalized ethnic groups, field notes from the 50s, and some promising bones, you can make some good strong statements about behavior, diet, etc. This leads to conclusions that are highly technical and precise, but with limited scope. Most science writers want exactly the opposite -- non-technical and broadly applicable. So they latch onto some factoids, make 'reasonable' generalizations, and ignore the fact that most anthropologists are very clear on what is known and what is supposed.

There are examples of anthropologists giving interesting theories and arguing with limited data -- the aquatic ape hypothesis is a perennial example (now long obsolete). But this is in no way a problem in the field; every science has hypotheses, and within the field the evidence, or lack of evidence, is clearly stated.

Whenever someone says "according to my priors, in the absence of evidence we should assume..." I hear "I know nothing about this but that won't stop me pontificating."

It may be true that we have areas in our brain that evolved not only 'consistent with holding religion', but actually evolved 'specifically for the purpose of experiencing religion'... but it would be very hard to prove this second statement, and anyone who makes it should be highly suspect.

To prove the second statement, we just need to find gene variants that are strongly correlated with religious beliefs.

No, the second statement hinges on a causal claim, so correlations alone can't prove it unless supplemented with strong causal assumptions. Gene variants being correlated with religious beliefs is consistent with three different causal hypotheses: (1) gene variants influence religious belief, (2) religious belief influences gene variants, and/or (3) gene variants and religious belief have some common cause. Correlations only tell us that at least one of the hypotheses is true; they don't allow us to conclude that hypothesis 1 is correct.

ETA: [does Fonzie thumbs-up] aaaayyyy!

| Are you saying the specific hypothesis is problematic, or that the whole logical structure is?

Both the hypothesis and the logical structure are appropriate. What is not appropriate is presenting weak hypotheses as explanations without identifying them as weak and without giving alternative hypotheses.

To exaggerate just slightly, you might compare the use of these explanations to the use of government conspiracies as explanations for major political events. It is easy to come up with explanations that assume conspiracy, and it is obviously true that the government is hiding information from us in some cases, but without strong evidence that we do not currently have, tales of the Illuminati are only amusing, not productive. Likewise, explanations based on human evolution are very easy to construct, and it is obvious that we evolved...

| To prove the second statement, we just need to find gene variants that are strongly correlated with religious beliefs.

This is a bit off topic, but interesting! So... That's not quite true. We might, for example, find that genes that are correlated with imagination, creativity, or schizophrenia are also correlated with religious beliefs. But that doesn't mean that either these genes or these traits evolved 'for religion' in any meaningful sense... any more than we would use that sort of rhetoric to prove that 'humans evolved specifically for the purpose of experiencing schizophrenia'. We are muddying teleology here just a bit, but in many cases that is exactly the purpose of these arguments.

Yes, but it would be fair, for example, to say that 'eyes evolved for seeing'. This is fair because for the last few billion years, that is indeed what they were being optimized for. This get more abstract when talking about things like religion, and much more dubious when you are talking about a period of perhaps a million years, but it is not quite to the point that I would call it 'obviously wrong'.

I would agree that the statement 'specifically with the intent of experiencing religion' would be wrong; if you hold 'purpose' to mean 'intent', I have no objection to changing my language -- perhaps 'primary function'?

It is not at all hard to prove the first statement in that paragraph -- although if you would like to use a word other than prove, I am okay with that. I certainly don't mean to suggest that evolution is 'just a theory', but rather to point out that just because we have an effective law of nature that explains large amounts of the world, we cannot pretend that it will explain everything that we are interested in talking about.

To be clear, I am not saying that something like 'spirituality' or 'humanity' is somehow apart from the physical laws or observed processes of nature. I am saying that when we talk about the effects of human nature on X, we need to remember that you do indeed need to consider what is the scientific evidence for 'human nature', and what is conjecture. Most people do not use 'human nature' and related terms in a way that is meaningful, even in science writing.