Buzz
The idea of “survival of the fittest” often leads us to think of natural selection as a straightforward force for progress, making humans only stronger and healthier. However, the truth is more nuanced.
“I emphasize this in my lectures regularly,” Karen Rosenberg, a paleoanthropologist from the University of Delaware, shared with Mytour in 2016. “We often associate being fit with aerobic endurance, like the ability to run long distances. But in evolutionary biology, fit refers to being reproductively successful.” In essence, survival long enough to pass on your genes to the next generation is key.
In the pursuit of reproductive success, natural selection sometimes makes trade-offs, resulting in human traits that challenge our health today. From back pain to complicated childbirth, here are six human drawbacks that you can thank evolution for.
Bipedalism is the root of our back pain.
The emergence of bipedalism was a pivotal moment in human evolution. Standing upright enabled us to cover long distances, and Charles Darwin theorized that it also liberated our hands to use tools and carry food. However, this shift came with its own set of challenges.
In chimpanzees and our other quadrupedal relatives, the spine functions like a suspension bridge. “But if you take that horizontally stable structure and tilt it vertically, it loses its stability,” said Jeremy DeSilva, a paleoanthropologist at Dartmouth College, in an interview with Mytour in 2016.
The most intuitive way to create a stable spine in an upright species would be a straight stack of vertebrae. But this would obstruct the birth canal, and reproduction is key to species survival. Thus, the human spine had to evolve into its current “curved mess” to accommodate the passage of our large-brained infants, according to DeSilva. The result is back pain, along with common injuries like slipped disks and compression fractures.
Our feet aren't ideally designed for walking.
The most advanced prosthetic feet today resemble the structure of an ostrich’s foot. They don’t mimic human anatomy because the human foot’s design is somewhat awkward.
“Humans weren’t designed from scratch,” DeSilva remarked. “We’ve inherited much of our anatomy from our ape ancestors, and the foot is a prime example of that.”
When we transitioned to walking on two feet, we no longer needed the flexible feet our ape relatives used to climb trees and grasp branches. To provide more stability and enhance our ability to push off the ground, evolution took a “paper clips and duct tape” approach, according to DeSilva. However, because we walk on modified ape feet that can twist and roll easily, we suffer from sprained ankles, shin splints, plantar fasciitis, and collapsed arches. These injuries aren’t just modern-day issues; they even appear in the fossil record.
"It works well enough, and that’s all you really need in evolution,” DeSilva explained. “What we have as a result of a ‘just-good-enough’ foot is a billion-dollar podiatry industry.”
Childbirth is a challenging experience for humans.
Humans have a much more challenging childbirth experience compared to other apes. This is largely due to the narrow human pelvis, which is ill-suited for the large heads and broad shoulders of our babies.
“The pelvis serves two conflicting roles in humans: supporting bipedalism and enabling the birth of large-brained infants,” Rosenberg explained. The shape of the pelvis is a compromise between these two functions.
Humans have developed an interesting cultural solution to the problem of prolonged and painful childbirth. While birth is a solitary experience for most mammals, Rosenberg noted that nearly all human mothers seek help from relatives, midwives, or doctors.
In a paper published in the British Journal of Obstetrics and Gynaecology, Rosenberg and her colleague Wenda Trevathan suggested that natural selection likely favored the behavior of seeking assistance during childbirth. This wasn’t a conscious choice by expectant mothers, but rather a response driven by fear, anxiety, and pain, which over time helped reduce mortality rates.
We have a strong craving for junk food.
There’s a clear reason why it’s difficult to resist fast food and candy. Sugar is a primary energy source, and excess sugar is stored as fat to help us endure tough times. Before agriculture and industrialization, when food was scarce or unreliable, a craving for sugar was crucial for survival. But now that processed sugar is so easy to find in stores, we’re consuming too much. This has led to an obesity crisis and an increase in diseases like diabetes and high blood pressure.
“The food industry has made a fortune because we still have Stone Age bodies that crave sugar, but live in a Space Age world where sugar is cheap and abundant,” Harvard evolutionary biologist Daniel Lieberman wrote in an op-ed for The New York Times in 2012. (He was arguing that New York City’s proposal to ban large sodas could actually help reintroduce the healthy limitations of a hunter-gatherer lifestyle.)
Humans continue to grapple with mental health issues.
Natural selection didn’t eliminate potentially harmful conditions like schizophrenia and depression, even though these disorders are often linked to lower birth rates. Some researchers believe that unaffected siblings of people with mental disorders may carry and pass on the genetic mutations, keeping these conditions in the gene pool. Other scientists have explored the roots of mental disorders, suggesting that while devastating for many, some of these conditions may have offered an evolutionary advantage.
For instance, while depression can be debilitating, some researchers argue that it might foster an analytical way of thinking that is helpful for problem-solving. Other studies suggest that schizophrenia-related genes may have contributed to the development of complex human cognition.
Our wisdom teeth are a result of our larger brains.
As humans began walking upright, we underwent a significant change: our brains grew much larger. To accommodate this, the shape of our faces altered, and our jaws became narrower. However, for many people, this results in a lack of space for the third molars, or wisdom teeth, which were once crucial for chewing. These teeth may become impacted, unable to break through the gums. If left untreated, impacted wisdom teeth can cause intense pain or lead to infections.
Natural selection is still at work: a genetic mutation that prevents the development of wisdom teeth has been spreading, and increasingly, more people are being born without third molars.
