For our first June article Brian Thomas writes People Not Quite as Clever Anymore. Intriguingly this title seems to lack the usual hyperbole (anyone remember those “edible eggs”?) but this doesn’t mean that the article is correct.
Tying in with their conception of the Fall, young Earth creationists often talk about the concept of “genetic load,” or mutational meltdown. The Curse, they believe, caused mutations which they claim will go undetected by natural selection and build up over the generations until they eventually render organisms non-functional. This would exhibit itself in the form of genetic diseases, and also traits such as intelligence – it’s the root source of the common out when challenged on how Noah could have built such a large, seaworthy vessel: “people were smarter back then,” they say, “look at the pyramids.” An implication of this is that Victorians (such as Charles Darwin) would have been smarter than people living today – like the current batch of young Earth creationists, for instance. This may have something to do with their tendency to point to even older scientists, like Newton, who they claim believed as they did.
A more anti-evolution argument (as opposed to being defensive of their own narrative) made on this basis is that, if mutations keep building up in this way, species wouldn’t be able even to survive millions of years let alone evolve (therefore the Earth is young). My biggest problem with the genetic load idea in general is that we should really have seen it in fast reproducing species – like Lenski’s bacteria* – already, if it was an actual concern. If your model contradicts the data in this manner the model is probably wrong. We also have the issue that they tend to be defining all mutations as being bad, and equally so (most are pretty close to neutral). From a more theological standpoint, meanwhile, this concept goes beyond the idea that life has decayed from the pre-Fall perfection of Eden to suggesting that God’s creation is inherently flawed. After all, creationists praise what they see as the benevolent design of the mutation-correcting systems we do have, which implies that God foresaw their necessity, but if they are insufficient for the task…
Returning, however, to this specific case, Thomas opens his article by saying:
Wouldn’t it be interesting to compare our cleverness to that of our ancestors? It would only be possible if today’s researchers could use the same measuring tool in the same way that previous generations did. A team of European researchers believe they have done just that, and those convinced that evolution tends to generate higher IQs may be dumbfounded at the results.
I’m not sure who thinks that “evolution tends to generate higher IQs,” at least in the short run, but the paper – Were the Victorians cleverer than us? The decline in general intelligence estimated from a meta-analysis of the slowing of simple reaction time (pdf) – is certainly interesting.
The most well-known test for intelligence, the IQ test, gives scores based on how your performance compares with that of others. If you perform at exactly the average of the population you get given a score of 100, and scores are arranged around this value in a normal distribution with a difference of 15 usually representing 1 standard deviation – approximately 95% of the population, therefore, can be expected to have scores between 70 and 130. The IQ test has to be repeatedly recalibrated as people given old tests tend to score consistently better at a rate of a couple of points every decade: this is known as the Flynn effect.
This would on the surface appear to completely contradict the idea that intelligence is going down, but there are a number of other explanations ranging from the fact that we’re eating better (or, at least, more) when we grow up than we used to, to the possibility that we might just be getting better at taking IQ tests. The authors of this paper seem to be convinced that, masked by whatever is driving the Flynn effect, there ought to be an underlying decrease in inherited intelligence, though for a very different reason. At least since the Victorian era, they claim, poorer, less educated, and less intelligent people have had more children, and therefore natural selection is selecting in favour of less intelligence. They call this “dysgenic fertility,” but you might also recognise it as the central premise of the movie Idiocracy.
Because IQ doesn’t support their thesis they use a different metric, namely reaction time tests. Fast reaction times are apparently correlated with other measurements of intelligence, and records of tests go back into the 19th century. They found that reaction times had dropped, and translating this into IQ change they estimated that average IQ was in fact dropping 1.23 points per decade (about 14 points over the period of time for which there was data).
There is reason to be sceptical of this result: for one, just as with the Flynn effect, there could be other reasons for the change. A blog post by Patrick Rabbitt points out some more, including that while the data does indeed go back to the 1800s there isn’t really enough of it to draw such a conclusion, and that before the 1970s the equipment available for measuring time wasn’t all that precise and potentially even biased towards producing lower numbers. That post drew a response from one of the original authors, which has been replied to in turn in a post-script to the original post.
Resting on these foundations of sand, Thomas wants to extrapolate further:
And like other studies showing high rates of mutational buildup in the human genome, this high rate of IQ loss fits the Bible’s timeline much more closely than evolutionary ideas of human history. Losing one IQ point every ten years would reduce a genius population averaging 180 IQ points to a truly dull group of people in less than two millennia.
In fact, the drop of 1.23 points per decade over 2000 years would reduce that genius score to a cool negative 66 points. Remembering the properties of the IQ distribution it can be calculated for context that the the group of living people with an IQ score of 180 or above make up around 0.000 005% of the population, while those with -66 or lower would be more like the dumbest 0.000 000 000 000 000 000 000 000 001% – while that’s a lot of zeros, it ain’t a lot of percents (nor people). While the 14-point drop since (and beginning at) the Victorian era is at least plausible, this conclusion is absurd. Thomas tries to get out of it:
It’s quite likely IQs lowered at a slower rate in the past than today. But for mankind to have maintained any respectable level of intelligence for the more than two million years that evolutionists imagine mankind to have lived, some miracle must be invoked to preserve that intellect against extremely prolonged exposure to dysgenic trends.
To back up the “slower rate in the past than today” claim he says in a footnote that “If more reaction time data were available, they might show an accelerating rate of IQ decline, similar to the recently accelerating rate of genetic differences shown in the diagram in reference 3.” This seems more wishful thinking than “quite likely.” That reference is this old article, and the reason why genetic diversity “explodes” is because the population explodes at the same time – not that individuals are becoming more mutated at a faster rate.
Really, if mutations are causing genomes to decay the rate of decay should be decreasing over time. This is because the more of the genome that gets scrambled by mutations, the more likely it is that any individual mutation will effect something that’s already been scrambled. The result is an exponential decay curve, which happens to be similar to what creationists propose for magnetic fields and the like.
If mankind is less clever today than yesterday, then it comes as no surprise to those familiar with the Bible’s timeline and its teaching of the Curse.
(From Genesis chapter 3, KJV)
3:14 And the LORD God said unto the serpent, Because thou hast done this, thou art cursed above all cattle, and above every beast of the field; upon thy belly shalt thou go, and dust shalt thou eat all the days of thy life:
3:15 And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel.
3:16 Unto the woman he said, I will greatly multiply thy sorrow and thy conception; in sorrow thou shalt bring forth children; and thy desire shall be to thy husband, and he shall rule over thee.
3:17 And unto Adam he said, Because thou hast hearkened unto the voice of thy wife, and hast eaten of the tree, of which I commanded thee, saying, Thou shalt not eat of it: cursed is the ground for thy sake; in sorrow shalt thou eat of it all the days of thy life;
3:18 Thorns also and thistles shall it bring forth to thee; and thou shalt eat the herb of the field;
3:19 In the sweat of thy face shalt thou eat bread, till thou return unto the ground; for out of it wast thou taken: for dust thou art, and unto dust shalt thou return.
That is what the bible says about the “curse” – it says nothing of intelligence (quite the contrary: this was the Tree of Knowledge of Good and Evil after all, and Adam is cursed to eat of it “all the days of [his] life”), and claiming otherwise is an unbiblical invention. Perhaps people really are getting dumber.
*If you remember, the same lineage that evolved aerobic citrate metabolism also ratcheted up its own mutation rate in the process. Even without that, Lenski has run his experiment for more than 40,000 bacterial generations by now so I think we’re safe for at least a while.