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Why do we have eyebrows? They may be the reason our species survived
We’ve been taking our eyebrows for granted. They may in fact be the thing that let us become the dominant species on Earth.
Eyebrows. You might not think much about them unless you have to manicure or shape them. Even then, they’re generally an afterthought. But have you ever wondered why in the world we have them to begin with? After all, our primate ancestors had hair all over their face. Why did it recede everywhere but at these two curvy places just above our eyes?
The initial response—one that your first-grade teacher may have given you—is they helped keep dirt and crud out of our eyes. But is that all? According to a recent study published in journal Nature: Ecology & Evolution, it’s our ability to communicate with these furry accent marks that gave our species an evolutionary advantage.
Unlike Neanderthals and Denisovans, our closest hominin ancestors, who had strong protruding brow ridges, Homo sapiens had smooth foreheads that were smaller and higher in comparison. This allowed for movable eyebrows and so, nuanced communication. Eyebrow movements often portray friendlier rather than more aggressive emotions. Researchers in this study say that eyebrow communication helped Homo sapiens build larger social networks, which ultimately gave them a leg up in the survival game.
Model of a modern human skull next to Kabwe 1. Note the protruding brow ridge. Image credit: Professor Paul O’Higgins, University of York/Big Think.
Researchers at the University of York in the UK conducted the study to investigate this eyebrow issue. The project was led by Paul O’Higgins, a professor of anatomy at the university. Using 3D engineering software, O’Higgins and colleagues borrowed the fossilized skull of an ancient hominin called Homo heidelbergensis. This hominin walked the Earth around 600,000 to 200,000 years ago. The fossil itself, housed at the Natural History Museum, is known as Kabwe 1. Researchers built a computerized model of it and studied its brow.
Dr. Ricardo Godinho, who worked on the study, explained the findings in a press release. "We simulated the forces of biting on different teeth and found that very little strain was placed on the brow ridge," he said. "When we took the ridge away there was no effect on the rest of the face when biting." This simple test eliminated two prevailing theories. The first is that prominent brow ridges were needed to stabilize the skulls of such hominins. The other theory is that protruding brows were required to fill the space where the eye sockets and the brain-case met.
By ruling out these biological theories, what was left was that brow ridges served as a form of social communication. Males, especially in other species, use such features to display dominance and ward off potential rivals during mating season. Think of a deer's antlers, for instance, and how it uses them to do battle with foes. Our faces—rather than growing more menacing—have gotten smaller and softer over the last 100,000 years and particularly the last 20,000 years when we switched from a hunter-gatherer means of subsistence to an agricultural one.
Model of Homo heidelbergensis. Credit: Smithsonian Natural History Museum.
Dr. Penny Spikins, an archeologist, co-authored the paper. While all other hominin species died out, we prospered. She believes, our rise and their sunset occurred, due to superior human communication, which helped us connect better and form large social networks (of the actual real-life variety as opposed to the Zuckerberg variety).
“Eyebrow movements allow us to express complex emotions as well as perceive the emotions of others. A rapid ‘eyebrow flash’ is a cross-cultural sign of recognition and openness to social interaction and pulling our eyebrows up at the middle is an expression of sympathy,” she said in a press release.
Tiny movements of the eyebrows are also a key component to identifying trustworthiness and deception. On the flip side it has been shown that people who have had Botox which limits eyebrow movement are less able to empathize and identify with the emotions of others. Eyebrows are the missing part of the puzzle of how modern humans managed to get on so much better with each other than other now-extinct hominins.
Neanderthals had a good run. Think it was only their eyebrow shortcomings that threw them by the wayside? Why not consider the other theories posited here:
How would the ability to genetically customize children change society? Sci-fi author Eugene Clark explores the future on our horizon in Volume I of the "Genetic Pressure" series.
- A new sci-fi book series called "Genetic Pressure" explores the scientific and moral implications of a world with a burgeoning designer baby industry.
- It's currently illegal to implant genetically edited human embryos in most nations, but designer babies may someday become widespread.
- While gene-editing technology could help humans eliminate genetic diseases, some in the scientific community fear it may also usher in a new era of eugenics.
Tribalism and discrimination<p>One question the "Genetic Pressure" series explores: What would tribalism and discrimination look like in a world with designer babies? As designer babies grow up, they could be noticeably different from other people, potentially being smarter, more attractive and healthier. This could breed resentment between the groups—as it does in the series.</p><p>"[Designer babies] slowly find that 'everyone else,' and even their own parents, becomes less and less tolerable," author Eugene Clark told Big Think. "Meanwhile, everyone else slowly feels threatened by the designer babies."</p><p>For example, one character in the series who was born a designer baby faces discrimination and harassment from "normal people"—they call her "soulless" and say she was "made in a factory," a "consumer product." </p><p>Would such divisions emerge in the real world? The answer may depend on who's able to afford designer baby services. If it's only the ultra-wealthy, then it's easy to imagine how being a designer baby could be seen by society as a kind of hyper-privilege, which designer babies would have to reckon with. </p><p>Even if people from all socioeconomic backgrounds can someday afford designer babies, people born designer babies may struggle with tough existential questions: Can they ever take full credit for things they achieve, or were they born with an unfair advantage? To what extent should they spend their lives helping the less fortunate? </p>
Sexuality dilemmas<p>Sexuality presents another set of thorny questions. If a designer baby industry someday allows people to optimize humans for attractiveness, designer babies could grow up to find themselves surrounded by ultra-attractive people. That may not sound like a big problem.</p><p>But consider that, if designer babies someday become the standard way to have children, there'd necessarily be a years-long gap in which only some people are having designer babies. Meanwhile, the rest of society would be having children the old-fashioned way. So, in terms of attractiveness, society could see increasingly apparent disparities in physical appearances between the two groups. "Normal people" could begin to seem increasingly ugly.</p><p>But ultra-attractive people who were born designer babies could face problems, too. One could be the loss of body image. </p><p>When designer babies grow up in the "Genetic Pressure" series, men look like all the other men, and women look like all the other women. This homogeneity of physical appearance occurs because parents of designer babies start following trends, all choosing similar traits for their children: tall, athletic build, olive skin, etc. </p><p>Sure, facial traits remain relatively unique, but everyone's more or less equally attractive. And this causes strange changes to sexual preferences.</p><p>"In a society of sexual equals, they start looking for other differentiators," he said, noting that violet-colored eyes become a rare trait that genetically engineered humans find especially attractive in the series.</p><p>But what about sexual relationships between genetically engineered humans and "normal" people? In the "Genetic Pressure" series, many "normal" people want to have kids with (or at least have sex with) genetically engineered humans. But a minority of engineered humans oppose breeding with "normal" people, and this leads to an ideology that considers engineered humans to be racially supreme. </p>
Regulating designer babies<p>On a policy level, there are many open questions about how governments might legislate a world with designer babies. But it's not totally new territory, considering the West's dark history of eugenics experiments.</p><p>In the 20th century, the U.S. conducted multiple eugenics programs, including immigration restrictions based on genetic inferiority and forced sterilizations. In 1927, for example, the Supreme Court ruled that forcibly sterilizing the mentally handicapped didn't violate the Constitution. Supreme Court Justice Oliver Wendall Holmes wrote, "… three generations of imbeciles are enough." </p><p>After the Holocaust, eugenics programs became increasingly taboo and regulated in the U.S. (though some states continued forced sterilizations <a href="https://www.uvm.edu/~lkaelber/eugenics/" target="_blank">into the 1970s</a>). In recent years, some policymakers and scientists have expressed concerns about how gene-editing technologies could reanimate the eugenics nightmares of the 20th century. </p><p>Currently, the U.S. doesn't explicitly ban human germline genetic editing on the federal level, but a combination of laws effectively render it <a href="https://academic.oup.com/jlb/advance-article/doi/10.1093/jlb/lsaa006/5841599#204481018" target="_blank" rel="noopener noreferrer">illegal to implant a genetically modified embryo</a>. Part of the reason is that scientists still aren't sure of the unintended consequences of new gene-editing technologies. </p><p>But there are also concerns that these technologies could usher in a new era of eugenics. After all, the function of a designer baby industry, like the one in the "Genetic Pressure" series, wouldn't necessarily be limited to eliminating genetic diseases; it could also work to increase the occurrence of "desirable" traits. </p><p>If the industry did that, it'd effectively signal that the <em>opposites of those traits are undesirable. </em>As the International Bioethics Committee <a href="https://academic.oup.com/jlb/advance-article/doi/10.1093/jlb/lsaa006/5841599#204481018" target="_blank" rel="noopener noreferrer">wrote</a>, this would "jeopardize the inherent and therefore equal dignity of all human beings and renew eugenics, disguised as the fulfillment of the wish for a better, improved life."</p><p><em>"Genetic Pressure Volume I: Baby Steps"</em><em> by Eugene Clark is <a href="http://bigth.ink/38VhJn3" target="_blank">available now.</a></em></p>
A leading British space scientist thinks there is life under the ice sheets of Europa.
- A British scientist named Professor Monica Grady recently came out in support of extraterrestrial life on Europa.
- Europa, the sixth largest moon in the solar system, may have favorable conditions for life under its miles of ice.
- The moon is one of Jupiter's 79.
Neil deGrasse Tyson wants to go ice fishing on Europa<div class="rm-shortcode" data-media_id="GLGsRX7e" data-player_id="FvQKszTI" data-rm-shortcode-id="f4790eb8f0515e036b24c4195299df28"> <div id="botr_GLGsRX7e_FvQKszTI_div" class="jwplayer-media" data-jwplayer-video-src="https://content.jwplatform.com/players/GLGsRX7e-FvQKszTI.js"> <img src="https://cdn.jwplayer.com/thumbs/GLGsRX7e-1920.jpg" class="jwplayer-media-preview" /> </div> <script src="https://content.jwplatform.com/players/GLGsRX7e-FvQKszTI.js"></script> </div>
Water Vapor Above Europa’s Surface Deteced for First Time<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="9c4abc8473e1b89170cc8941beeb1f2d"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/WQ-E1lnSOzc?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Scientists discover burrows of giant predator worms that lived on the seafloor 20 million years ago.
- Scientists in Taiwan find the lair of giant predator worms that inhabited the seafloor 20 million years ago.
- The worm is possibly related to the modern bobbit worm (Eunice aphroditois).
- The creatures can reach several meters in length and famously ambush their pray.
A three-dimensional model of the feeding behavior of Bobbit worms and the proposed formation of Pennichnus formosae.
Credit: Scientific Reports
Beware the Bobbit Worm!<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="1f9918e77851242c91382369581d3aac"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/_As1pHhyDHY?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Answering the question of who you are is not an easy task. Let's unpack what culture, philosophy, and neuroscience have to say.
- Who am I? It's a question that humans have grappled with since the dawn of time, and most of us are no closer to an answer.
- Trying to pin down what makes you you depends on which school of thought you prescribe to. Some argue that the self is an illusion, while others believe that finding one's "true self" is about sincerity and authenticity.
- In this video, author Gish Jen, Harvard professor Michael Puett, psychotherapist Mark Epstein, and neuroscientist Sam Harris discuss three layers of the self, looking through the lens of culture, philosophy, and neuroscience.