There's this great recurring "Saturday Night Live" skit from several years back where Phil Hartman plays an unfrozen caveman who goes to law school. He pontificates on the American judicial system while marveling at modern technology like "the tiny people in the magic box" (a TV). It fits a common stereotype: Human ancestors were, well, cavemen, and not as smart as we are today. A provocative new hypothesis from a Stanford geneticist tries to turn this stereotype upside down.
Human intelligence may have actually peaked before our ancient predecessors ever left Africa, Gerald Crabtree writes in two new journal articles. Genetic mutations during the past several millennia are causing a decline in overall human intellectual and emotional fitness, he says. Evolutionary pressure no longer favors intellect, so the problem is getting exponentially worse. He is careful to say that this is taking quite a long time, so it's not like your grandparents are paragons of brilliance while your children will be cavemen rivaling Hartman's SNL character. But he does posit that an ancient Athenian, plucked from 1000 BC, would be "among the brightest and most intellectually alive of our colleagues and companions."
His central thesis is that each generation produces deleterious mutations, so down the line of human history, our intelligence is ever more impaired compared to that of our predecessors.
Not surprisingly, the hypothesis, published in the prominent journal Trends in Genetics, has several geneticists scratching their heads.
"It takes thousands and thousands of genes to build a human brain, and mutations in any one of those can impair that process, that's absolutely true. And it's also true that with each new generation, new mutations arise ... but Crabtree ignores the other side of the equation, which is selection," said Kevin Mitchell, associate professor at the Smurfit Institute of Genetics at Trinity College Dublin, who operates the blog Wiring the Brain. "Natural selection is incredibly powerful, and it definitely has the ability to weed out new mutations that significantly impair intellectual ability. There are various aspects in these papers that I think are really just thinking about things in a wrong way."
Crabtree said he wanted to examine the cumulative effect of generation-to-generation mutation on intelligence, which is thought to be controlled by many genes. Using indices that measure X-chromosome-related mental retardation, he comes up with between 2,000 and 5,000 genes related to human intellectual ability. Using another index measuring average mutations that arise in each generation of children, he calculates that within 3,000 years, "we have all sustained two or more mutations harmful to our intellectual or emotional stability."
"There is a general feeling that evolution constantly improves us, but it only does that if there is selection applied," Crabtree said in an interview. "In this case, it is questionable about how much selection is occurring now compared to the process of optimizing those genes, which occurred in the jungles of Africa 500,000 years ago."
There's already evidence for this in other areas, he argues: Take our sense of smell. Humans have far fewer olfactory receptors than other animals, he said--we're guided by our intellect now, not by smell. We can think about where a piece of food came from, how it was processed, which plant it's from, who has been around it, and so on. A dog, on the other hand, simply sniffs something and either eats it or doesn't.
"Once you place pressure on intellectual abilities, and take it off of olfactory abilities, the olfactory genes deteriorate," Crabtree said.
Similarly, he believes evolution now selects for other traits--namely, the most healthy and the most immune, not the most intelligent. Human movement into communities and cities increased the spread of infectious diseases, and those with the strongest physical constitutions survived to pass on their genes, he argues. He said he wanted to publish this hypotheses because geneticists can test for this, in an expensive process that requires saving some genetic information that typically gets discarded.
But geneticists took issue with his claims, not to mention his citations and methods. Mitchell took issue mostly with Crabtree's characterization of genes--he describes them as links in a chain, with incredible overall disruptive power. They're like a bulb on a string of Christmas tree lights that conks out, taking out the entire strand with it: "It can be concluded that [genes related to intelligence] do not operate as a robust network, but rather as links in a chain, failure of any one of which leads to intellectual disability," he writes. Mitchell countered that this ignores other genes that don't cause intellectual disability.
"Biological systems are robust to degradation of several different components," Mitchell said. "Evolution has gone to a lot of trouble to craft your genome so it's finely honed to do its job, and it doesn't make sense that you would have all this random mutation in your brain cells. Also, you would have a very high rate of brain cancer."
Mitchell went on to say that it's true, mutations can lower intelligence-- "It's just, I don't think, true that the mutational load in the species accumulates over time, because selection weeds out the serious ones. That's the real distinction that I think gets lost here," he said. "There's a conceptual fallacy to his argument, that in effect makes it trivial as opposed to controversial."
Other geneticists were somewhat less magnanimous in their disagreement. Steve Jones, a geneticist at University College London, called the papers "arts faculty science" in an interview with The Independent. "Never mind the hypothesis, give me the data, and there aren't any," Jones is quoted saying. "I could just as well argue that mutations have reduced our aggression, our depression and our penis length, but no journal would publish that. Why do they publish this?"
Crabtree, for his part, said he was surprised at the reaction. He flew to Hawaii on a long-scheduled vacation the day after Stanford publicized his papers, but seemed bemused by some of the responses when I reached him at his hotel.
Perhaps another reason why this paper is getting so much attention is the connection it shares to eugenics. For some context, I turned to Nathaniel Comfort, a historian of medicine at Johns Hopkins University. Comfort's recently published book, "The Science of Human Perfection: How Genes Became the Heart of American Medicine," tackles this subject.
"The notion of the degeneration of our intellect and our mental faculty is a strong theme through much of the history of medical genetics," he said in an interview. The difference is that the early eugenicists had a more simplistic understanding of biology, he said.
Karl Pearson, a renowned statistician and eugenicist, said in a famous 1903 lecture that Britain was "ceasing as a nation to breed intelligence," according to In the Name of Eugenics: Genetics and the Uses of Human Heredity by Yale history professor Daniel Kevles. Britain suffered "a dearth of national ability," evidenced by the lack of any Britons inventing airplanes or automobiles. This was a result of lower, "unfit" segments of the population contributing a disproportionate supply of offspring, Pearson argued. He believed intelligence could not be taught or earned, but merely inherited. Natural selection, he argued, had been replaced by "reproductive selection," in which evolutionary winners were "the most fertile, not the most fit," Pearson said.
Comfort said he was intrigued by the similarities in the arguments--from a biological perspective--of Crabtree and early 20th century psychologists like Henry Goddard. Goddard, a prominent psychologist and eugenicist, argued human intelligence was fragile because it stemmed from a single dominant gene. In the new papers, Crabtree argues it's fragile because it stems from thousands of genes, a disruption in any of which can be detrimental.
"I think there are some serious flaws in the reasoning of that, that it's a chain, rather than a network," said Comfort, while noting that he's not a geneticist. "That seems like an enormous leap. When you're a historian like I am and you see big leaps like that, and scientific evidence isn't driving that leap, then something else is. Your politics, your worldview, etc. those are the questions that I start asking about."
Comfort said historical evidence shows non-scientific impulses can drive the way we look at ourselves.
"Science is never completely value-free. Some science is more value-laden than others--climatology is more laden than particle physics--but something like the genetics of intelligence, and the notion of a deteriorating intelligence, is down toward the value-laden end of the spectrum," he said. "As a historian, I would say there is no way to talk about it without politics and social issues clouding it. I think they necessarily do. When we choose to describe something like intelligence in terms of the number of genes that determine it, we're making a social and political choice about what kinds of things matter."
Crabtree said the argument doesn't have to wade into eugenics, however; if there is a problem stemming from our declining intellects, it'll solve itself.
"I think within hundreds of years, we will have ethical and morally acceptable solutions to these problems, if it is a problem. It will never be an issue that needs to be looked at from the standpoint of eugenics; it's simply a matter of moving along, moving forward," he said. "I think probably we will be able to deliberately correct any mutations that occur, quite easily, and the day will come when we won't even hardly think about this. One doesn't need to be concerned."
"Global warming is a concern," he continued. "This is more or less a playground for curious minds."
If Neanderthal man had no or little written communication, then preservation of knowledge would be dependent upon remembering and some type of rough communication by storytelling. The Neanderthal brain is considered larger than the current human brain.
As the Sumerians recorded in our history of how the Gods\being from above created humans, perhaps they enhance traits they found most useful for them; since we were design to serve the GODS. We humans lost our fur and so our outer appearance was less ugly to the Gods and we could communicate better, to better do what we are told. In these upgrades we might of lost some memory abilities and the Gods decided to help us by teaching us written language, math, calendars and other useful tools; all to better serve them.
No DUHH people are getting dumber!
Its a worldwide idiocracy!
The only problem here is that they have had the wrong paradigm all this time.
Mutations degrade DNA. It shouldn't be surprising that we're getting dumber.
It's only our arrogance and "chronological snobbery" as C.S. Lewis called it that has us believing that we are some how superior to our ancestors.
Yes obviously the world is getting dumber--until some catastrophic world events picks a new winner. With more and more dumb people surviving to breed like flies--the problem will only get worse and a true idiocracy will be the result. Not enough scientists and smart people breed as their too busy with Science! Few of these people have kids as well because most scientists are not rich enough to hire nannies and have more kids. Fact of life. Get used to it.
A big problem is that people don't know there's a difference between being smart and intelligent. Naturally, there is a corelation between the two, but they really shouldn't be synonymous. Even dictionaries sometimes use the two interchangable, but if you think about it, they really are two different things.
Smart is how many facts you know. Intellegence is your ability to see a problem and make a logical conclusion. I have several peers in university that get straight A's but are intellegent as a doorknob. You can study and memorize all the facts you want, but intellegence isn't something you can memorize. That's why I score nearly as high as my smart friends on tests that I don't study for, while they study dozens of hours, if not hundreds. I may not be as smart as them, but I certainly am more intelligent.
So, while people today are less intellegent, we are in fact, smarter. We know the facts passed on to us by our ancestors from Plato to Einstein, even if we're not intelligent enough to truly understand them, or figure them out for ourselves.
Scientists aren't that poor. From my experience in academics, there is no financial reason why they shouldn't have more kids. I know blue collar folks who support larger families on much less (with no assistance). They also work more than the scientists. They also don't get absurd amounts of grant money. (I can't believe the kind of dinners "scientists" were eating when I was a grad student).
What keeps scientists (in general) from breeding more? Arrogance, self-absorption, and they don't value offspring.
I wouldn't say dumber. It seems to me that some people have loss the drive to be more successful. It's easier to feed off of other peoples accomplishments and say "well that has been done, no need to reinvent the wheel".
I also believe that we have become this way due to television and entertainment. Learning info of new things has become blocked by other useless information from cartoons and reality tv.
I'd like to say that the article is interesting, but (I think) it's really all speculation. And to be honest, intelligence is one of the harder things to define, being not only very controversial but also quite subjective.
It's kind of a fashionable idea, to think that people are getting less intelligent, and that the past was filled with people that were more somehow more driven, more intelligent, more [insert word here]. But the person who makes this claim inherently implies that he/she is somehow smarter than the average person, or at least has the uncommon ability to perceive that is wrong with other people.
I think this is kind of obvious from the other comments on this article, and truth be told I'm guilty of it often too. It's just a nicely conceited notion, that although the world is becoming stupider, YOU can realize this. And complain about it.
That's all, I guess. This is just my opinion.
Look at peoples choices for entertainment. Take Jersey Shore for example, I mean, seriously? How does a show like that get viewers? It's sad really to think there are A LOT of dumb people out there that affect the mean average for everyone else. lol
In space, no one can hear a tree fall in the forest.
Thank you Kevin Mitchell and Steve Jones for pointing out what should be obvious to anyone except those who have their heads buried up their academia. And thank you Rebecca Boyle for presenting the opposing views. It was an entertaining article.
well! If the results of the 2012 election is any indicator, we can say with confidence that yes, people are getting dumber!
well said Syzygy23; honestly whether or not this study is true, it still brings up the point that intelligent behavior is not encouraged as much as it should be.
Weeeee, we are the USA!!! We are 16 trillion in debt. Let's go buy other country some weapons, with money we don't have and put our USA citizens further in debt. YEA!
Meanwhile, Iran is supplying Gaza their weapons.
Can the world and the USA ever get our of the war game?
No. Why, because it makes the 1% richer.
Genetic mutations can lead to someone being smarter, otherwise we wouldn't be smarter than our ape ancestors.
Drat my modern robotic modern simulated brain, lol, I meant to post this above comment in a different article.
Oh, to have a Neanderthal man simulated brain. Neanderthal man came from a life of evolution, eat or been eaten and keep all he learned in his larger brain with no place to write things down. Neanderthanl man travels all the Earth, was independent.
Modern man made in by the Gods to serve the gods and is encourage being sheep. Modern man did retain some of their intelligence and independent thinking, hence the temptation of the tree of knowledge of which they forced to be made to leave Eden. Still modern made has a small brain than Neanderthal man and still has the DNA programming to be a follower and currently ruled by the 1%, lol.
Modern man is intelligent, but Neanderthal man was the freest, independent and intelligent human created by evolution Earth.
I get paid over $87 per hour working from home with 2 kids at home. I never thought I'd be able to do it but my best friend earns over 10k a month doing this and she convinced me to try. The potential with this is endless. Heres what I've been doing...Mel7.Com
All the reports of how fluoride has been linked to lower IQ in areas that have fluoridated water compared to areas with non-fluoridated water. This dangerous, toxic waste being added to our tap water and above all baby formula and other baby foodstuffs along with other changes in the way we learn on top of the millions of drugs that play with brain chemistry!
Then a geneticist claims we're getting dumber
LOL...I see more government controlled eugenics in our very near future...along with a half-million dollar grant for this geneticist to figure out additional ways of how they'll keep doing it!
No one has ever observed a genetic mutation increase the complexity of an organism. So no, there is no observational evidence to suggest a mutation can make anyone smarter.
What does modern made to remember, he writes things down.
What does ancient man do to remember, he just stores the information in his own larger brain.
We assume modern man is better, but if ancient man was not eliminated\died off and actually competed and grew culturally along modern man, they may actually be leading us homosapien.
Remember all the religions want modern mad to be obedient to the GODS. They like all of us the most humble and obedient and will be saved. Seems like they are watching us from above and observing evolution with the desire to pick from the human heard bread they must approve of.
We humans do this all the time with animals as we domestic them, lol.
Lilith was cast from Adam, because he did not get along with her and not for an actual sin, then came Eve. ,
Toss aside was Lilith. Since when are humans in marriage disposable? Why were the Gods listening to the whine and request of Adam? Weren't the Gods in charge or did they have an higher concern for Adam to breed with a female and make more obedient human slaves.
Then that pain in but humans continued with their free will and knowledge just got so smart from tree of knowledge. That pissed the Gods off and cast humans out of Eden. We humans not being obedient has always been a problem with the Gods.
FYI, Sumerian history writes we humans were made in several versions by the GODS until they fell upon one version them preferred. We were made for the purpose to work and serve the GODS.
Like many countries in the world that wish to dominate their peoples, the leadership likes to keep the people simple and stupid and punish hard, when we disobey.
I so do love Freedom and Democracy!
Robot is not a Robot, but a little white Russian boy.
Robot, I know you know that homo sapiens was not descended from Neanderthal man. He was an offshoot from an earlier ancestor. But even if they were related, tying intelligence to brain size is a slippery slope. Racists would love this to be true, as Africans have the smallest brain-to-body mass of any other race, while Asians have the largest. But I like to think of it more like the giant computers from days past. They were big, but stupid in today's terms.
As for the Tree of Knowledge, there are several legends which allude that the "knowledge" was like biblical knowledge, in other words, sex. It was the Tree of Procreation. When Enki figured out how to create man, he used 14 "birth goddesses" to carry the fetuses. When they born, like mules, these hybrids were sterile, and somehow the Tree of Knowledge reversed that. That was why the god of the bible said woman would give birth in pain. The Tree of Life of course was the elixir of immortality you find in every ancient culture. As the bible says, "if he eats it (elixir) he will be like US", meaning, the gods. We're seeing the early stages of discovering this elixir with the discovery of telomeres.
Department of D...,
Your comment I find bizarre and off the mark.
Your comments I find interesting! ;)
If anyone has seen the movie "Idiocracy," they already knew this was coming.
Surviving and thriving in your environment is intelligence at work.
If you’re not thriving in life and worse if you are barely surviving, that is your clue of how smart you really are and you need to change your attitude, for all the tools you need lay inside you. Just get off your butt and make your life a new! ;)
"Are people getting dumber?" Judging by half of the post here...
@Bagpipes - why do you continue to lie to people in your comments? Are you one of those intelligent design nuts that tries their best to tell lies over and over until people believe them? Genetic mutations absolutely increase complexity. They can either add information, or subtract it. That is the entire nature of mutation. I know the creationists pretend mutation simply means "change" with no addition of information, but that is a bold-faced lie proven wrong by mountains of scientific research and experiment. It is the premise of evolution. It is how proteins are created. If mutations didn't alter complexity of organisms, then we would all still be single-celled. This is not a theory or guess, this is accepted knowledge by the majority of the scientific community.
Please, I'm actually begging here. Please take your lies and fake science and the rest of the Popsci trolls and find a website that you know something about, like Tea Party.org
@trolls - we are sick and tired of your constant ignorance. You have those like Bagpipes, who don't believe man is influencing global warming even though 90% of scientists say so, but by golly, if ONE geneticist says we're getting dumber, you're all about it! You are constantly arguing and insulting in all your posts. How many times have people called you out for trolling? From your comments, you obviously hate scientists. If you're going to deny real science, and dismiss those who do it, why do you even come here other than to get a infantile thrill from arguing with people? Then you have the hatemonger trolls like gizmodo, who make an Obama-bashing comment for every article no matter what it is about, then bitch and moan because Popsci writes a political science article. Do you folks not realize how ridiculous you seem to the rest of us? If you honestly are interested in science, then just read the articles without vomiting up your nonsense, so those of us who want to have a REAL scientific discussion can do so without having to constantly try to undo the damage your lies and ignorance cause. Oh, and take the spammers with you.
The picture in this article is a little sexiest. Why is the female the one starting the fire to cook?
Still in this case the article might be complimenting her. I would think she is highly intelligent to make fire.
I always felt sad for Lilith, Adams first wife for getting the boot and walking papers. Lilith was exactly the same manner as Adam. I like that Lilith was Adams equal; very nice!
According to some tablets, Lilith actually was an Annunaki. Of course the most widely accepted view is that instead of being part of Adam like Eve, she was created out of mud just like Adam, but she didn't want him. "I wouldn't kiss you if you were the only man on Earth! Oh...you are."
Jeez, Robot, can you go a single article without commenting? And can you comment without mentioning the GODS or Sumerians? Or Obamacare? Or slavery and sexism? Why is the gap in intellect so wide in the people on this site? I have no idea, but it probably has something to do with neanderthals. Or inbreeding. Or being raised by nuns. This article is right.