I rejected it because it’s panadaptationist nonsense, among other things. But I’m always happy to see more arguments for why it is garbage, such as this criticism from a philosopher.
Evolutionary psychologists’ thought is that, for at least some of our behaviors, they believe that we have—dare I use this term—hard-wired cognitive structures that are operating in all of us contemporary human beings the same way they did for our ancestors on the savannas. The idea is that, in the modern world, we have sort of modern skulls, but the wiring—the cognitive structure of the brain itself—is not being modified, because enough evolutionary time hasn’t passed. This goes for evolutionary functions like mate selection, parental care, predator avoidance—that our brains were pretty much in the same state as our ancestors’ brains. The sameness in how our brains work is on account of genetic selection for particular modules that are still functional in our environment today. [Editor’s note: These “modules” refer to the idea that the brain can be divided up into discrete structures with specific functions.]
The matching problem is really the core issue that evolutionary psychologists have to show that they can meet: that there is really a match between our modules and the modules of the prehistoric ancestors; that they’re working the same way then as now; and that these modules are working the same way because they are descended from the same functional lineage or causal lineage. But I don’t see any way that these charges can be answered.
True, that. But just watch — evolutionary psychologists will rapidly retreat from those core ideas of “environment of evolutionary adaptation” and “modules” to find safety in the uncontroversial idea that the brain evolved.
We still get buckets of baloney about evolution from people who should know better. Have you heard of the
pugilism hypothesis? This is the idea that men’s beards evolved to absorb a punch to the jaw. You only have to think about it for a moment to realize that getting socked in the face was a small factor in human evolution — 10,000 years ago, I would have been more concerned about starvation, getting a disease, breaking an arm while hunting, or getting thwocked in the back of the head with a rock by a bad guy. That facial hair might have provided a slight cushion to facial injuries doesn’t seem like the kind of thing for which there was much selection pressure, and I could also sit here and imagine all kinds of drawbacks to furry faces.
But it’s been tested! Except no, it hasn’t.
Because facial hair is one of the most sexually dimorphic features of humans (Homo sapiens) and is often perceived as an indicator of masculinity and social dominance, human facial hair has been suggested to play a role in male contest competition. Some authors have proposed that the beard may function similar to the long hair of a lion’s mane, serving to protect vital areas like the throat and jaw from lethal attacks. This is consistent with the observation that the mandible, which is superficially covered by the beard, is one of the most commonly fractured facial bones in interpersonal violence. We hypothesized that beards protect the skin and bones of the face when human males fight by absorbing and dispersing the energy of a blunt impact. We tested this hypothesis by measuring impact force and energy absorbed by a fiber epoxy composite, which served as a bone analog, when it was covered with skin that had thick hair (referred to here as “furred”) versus skin with no hair (referred to here as “sheared” and “plucked”). We covered the epoxy composite with segments of skin dissected from domestic sheep (Ovis aries), and used a drop weight impact tester affixed with a load cell to collect force versus time data. Tissue samples were prepared in three conditions: furred (n = 20), plucked (n = 20), and sheared (n = 20). We found that fully furred samples were capable of absorbing more energy than plucked and sheared samples. For example, peak force was 16% greater and total energy absorbed was 37% greater in the furred compared to the plucked samples. These differences were due in part to a longer time frame of force delivery in the furred samples. These data support the hypothesis that human beards protect vulnerable regions of the facial skeleton from damaging strikes.
I would concede even before testing it that a layer of hair over the face would reduce the force of impacts to some degree. But that’s not testing an evolutionary hypothesis! You need to show that this ‘padding’ had a measurable effect on survival and reproductive success. They merely looked at one superficial phenomenon and decided that dissipating the force of a punch to the jaw allowed beardy guys to thrive, in a world without the Marquis of Queensbury rules. It seems his beard didn’t save Otzi from the arrow that killed him.
There are a few people — thankfully few — that go wacko over their single comprehensive explanation. Apparently, humans evolved to be boxers.
More broadly, the results of this study add to a growing body of evidence suggesting that specialization for male fighting has played a significant role in the evolution of the musculoskeletal system of humans. For example, the short limbs (Carrier 2007), plantigrade foot posture (Carrier and Cunningham 2017), and bipedal posture of our earliest hominins ancestors (Carrier 2011), and the force–velocity tuning (Carrier et al. 2011) and size (Carrier et al. 2015) of the muscles of the human leg may also be associated with improved fighting performance.