A new study published in Trends in Genetics is suggesting that humans are slowly but surely losing their intellectual and emotional capacities. According to Stanford University's Gerald Crabtree, humanity peaked in intelligence about 2,000 years ago, and we've been heading downhill since then, owing to genetic mutations that aren't being selected against. It's possible that Crabtree is right — but his argument may be a moot point.
Top image from Idiocracy.
First, let's take a closer look at the study.
As Crabtree notes, human intelligence is the result of thousands of different genes that arose during the course of our evolution. And indeed, human intelligence — from a genetic perspective — reached its current configuration some time during the Paleolithic era of our ancestry (about 6,000 years ago).
This level of intelligence was very likely a requirement for survival; those who were less intellectually endowed were unlikely to pass on their genes. As Crabtree noted in his paper, "A hunter-gatherer who did not correctly conceive a solution to providing food or shelter probably died, along with his or her progeny."
But now, says Crabtree, life is easy and we no longer have to be smart to survive and produce offspring. As a result, we are no longer reinforcing the genetic integrity of our intelligence through extreme selectional processes. And it's because of this that our brains are withering away like our appendixes. Given enough time, Crabtree suspects that we will become increasingly susceptible to mutations that will lead to intellectual disabilities.
In terms of specifics, Crabtree has calculated that the 2,000 to 5,000 genes that code for human intelligence will start to degrade appreciably in about 3,000 years — about 120 generations from now. At that point, he predicts that we will have sustained at least two or more mutations severe enough to stunt our intellectual or emotional stability.
Now, all this said, a fundamental problem with Crabtree's prognostication is that it is trapped in a normative frame. His analysis makes little to no consideration for current or future trends, whether they be sexual, social, or technological in nature.
For example, he completely understates the importance of sexual selection — an ongoing process that most certainly has an impact on our ongoing genetic constitutions. In his study, Crabtree writes that modern Wall Street executives only have to worry about receiving a substantial bonus in order to attract a mate. "Clearly," writes Crabtree, "extreme selection is a thing of the past."
But what Crabtree is grossly under-appreciating is the degree to which intelligence brings couples together in modern society. His Wall Street executive wouldn't be a Wall Street executive without a requisite level of intelligence. The same goes for anyone else with a complex and modern job. And without the ability to survive and thrive in today's highly competitive environments, it's very unlikely that anyone would be capable of attracting a mate.
Moreover, it's unlikely that men and women would mate with someone who suffers from a severe cognitive deficiency. Sad, but true. Subsequently, a case can be made that there are still selectional pressures that favor for intelligence.
But all of this is moot. There are plenty of external factors to make this a non-issue.
First, there's the issue of socialization and education as it relates to human intelligence. As Crabtree correctly notes, "Remarkably, it seems that although our genomes are fragile, our society is robust almost entirely by virtue of education, which allow strengths to be rapidly distributed to all members." Indeed, as the Flynn Effect has revealed, a solid environment will have a profound impact on intelligence (whether it be through health, socialization, education, intellectual stimulation, or epigenetic factors).
Second, there's the ongoing interplay between our minds and our technologies. The web is already serving as a kind of external brain where we're offloading our capacities. It's becoming increasingly unclear where our minds stop and where our technologies start.
Lastly, there's the potential for technological interventions — and to Crabtree's credit, he also admits that this is a distinct possibility.
Indeed, given that we're already in the era of gene therapies and regenerative medicines, we can only imagine how sophisticated our biotechnologies will be 3,000 years from now. We will most certainly be able to fix (or screen for) any deleterious effects of genetic mutations by this stage.
Thinking more transhumanistically, our brains will unlikely be biological at that point — what will likely be more cybernetic than genetic. Today, there's already talk of synthetic synapses, artificial neural networks, and advanced neural interface devices. And given the potential for cognitive enhancement (whether it be done through advanced nootropics, genetic engineering, or cybernetic implants), we are set to become substantially more intelligent than we are today.
So when it comes to evolutionary biology and the future of our genetic constitutions, all bets are off.