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As researchers continue to probe our evolutionary origins, new discoveries are emerging that explain how the past has shaped modern humans—from the size of our brains to the duration of our lifespans. Even more remarkable is how much randomness influenced the development of the brains and bodies we have today.
10. Human Faces Evolved to Withstand a Punch
Until recently, it was commonly thought that the strong structure of human faces evolved around four to five million years ago to help our Australopithecus ancestors break down tough foods like nuts. However, this theory has been overturned—by a punch to the face.
A study from the University of Utah suggests that our ancient history may have been far more violent than we once thought. Violence could have played a far greater role in shaping human physiology than we had ever imagined.
The researchers argue that male humans developed stronger facial structures to minimize damage from punches during conflicts over women, food, and territory. The bones that became the most resilient are the same ones most likely to break in hand-to-hand combat. These bones also display the most noticeable differences between male and female skulls. Apparently, male faces had to evolve greater durability because the bones that break in fights are larger in men.
If this theory is correct, humans weren't noble savages who became violent due to civilization. Instead, our physical characteristics evolved specifically to enhance our ability to fight.
9. Human Hands Evolved for Punching
As our faces evolved to withstand punches, our hands evolved to deliver them. An earlier study by the same researchers from the University of Utah revealed that human hands developed in an unexpected manner. Compared to apes, the same traits that allow us to clench our fists—shorter palms and fingers, as well as longer, stronger, and more flexible thumbs—also provide the dexterity to create and use delicate tools. However, apes, while capable of making tools, cannot clench their fists.
It’s also possible that our hands evolved from the same genes that gave us shorter toes and a longer big toe as we began walking and running upright.
The researchers suggest that our aggressive, violent nature led our bodies to evolve into fighting machines. A human who punches with a clenched fist can strike harder without causing self-injury. Fists can also be a tool for intimidation. Ultimately, our hands—with the power to both harm and create—might define the good and evil aspects of human nature.
8. We Had Herpes Before We Were Human
It’s not only our physical traits that have evolved over time. Certain diseases, like herpes, also made the transition from chimpanzees to modern humans.
Approximately 67 percent of modern humans carry at least one strain of the herpes simplex virus (HSV). In fact, humans are the only primates with two types of HSV, which typically show up as cold sores on the mouth or blisters on the genitals. HSV-1 infected humans before they diverged from chimpanzees six million years ago, while HSV-2 transferred from ancient chimps to our ancestors roughly 1.6 million years ago. Researchers at the University of California believe that understanding these viruses' origins can help us prevent other viruses from making the jump to humans.
Another team of scientists from Oxford University and Plymouth University has discovered ancient viruses from Neanderthals embedded in modern human DNA. These viruses belong to the HML2 family and could be associated with cancer and HIV in present-day humans, potentially serving as targets for future therapies.
7. Humans Are the Only Primates Whose Tooth Size Decreases as Brain Size Increases
For the past 2.5 million years, two key trends have been tied to human evolution—brain size has expanded while tooth size has diminished. We are the only primates to show this pattern.
Typically, when the brain enlarges, so do the teeth, as the body requires more energy from food. This is why scientists refer to the human case as an 'evolutionary paradox.' They suggest this may be due to humans incorporating more meat into their diets, which provided essential nourishment for brain development.
Humans are also the only primates to develop thick tooth enamel. Primates that eat plants alone have the thinnest enamel, while those that consume both plants and animals, like apes and monkeys, have medium-thickness enamel. Humans possess the thickest enamel, likely evolved to crush tougher foods. For researchers, this thick enamel is useful in determining the age and diet of human fossils.
Interestingly, Neanderthals are the earliest known hominids to use toothpicks to relieve the pain caused by dental conditions like sore gums.
6. Our Common Male and Female Ancestors Lived Around the Same Time
Researchers often refer to our most recent common male ancestor as 'Y-chromosomal Adam.' Men typically have one X chromosome and one Y chromosome, while women have two X chromosomes.
A study published in the European Journal of Human Genetics suggests that 'Adam' likely lived around 209,000 years ago.
This theory challenges an earlier paper from the University of Arizona, which proposed that the Y chromosome predates humanity. The Arizona researchers argued that the Y chromosome of modern human males was formed through interbreeding between species over 500,000 years ago. However, the authors of the newer study claim that the Arizona research, if interpreted correctly, would create a 'space-time paradox,' where the oldest Homo sapiens ancestor has not yet been born.
The newer study also places Y-chromosomal Adam around the same time as 'Eve,' the most recent female genetic ancestor of modern humans. However, the researchers emphasize that there was no single Adam and Eve. Rather, groups of Adams and Eves coexisted and roamed the Earth together.
5. Grandmothers Contributed to Our Longevity
Grandmothers played a pivotal role in shaping who we are today. This is the conclusion reached by researchers from the University of Utah who conducted computer simulations to explore the famous 'Grandmother Hypothesis.' According to this theory, humans evolved longer lifespans than apes because grandmothers helped provide food for their grandchildren, while other primates find food for themselves once they are weaned from their mothers.
When human grandmothers assisted in feeding their weaned grandchildren, their daughters were able to have more children in a shorter time span. The simulations showed that within less than 60,000 years, humans evolved from females who died shortly after their childbearing years to living for decades past menopause.
Many anthropologists argue that our growing brain size was responsible for our increased lifespan. However, the Utah researchers controlled for factors such as brain size, hunting, and pair bonding. Even when they introduced the smallest grandmother effect into their simulations, human lifespans soared. Their findings suggest that grandmothers were instrumental in driving key evolutionary changes in humans, such as larger brains, social dependence, and cooperation.
4. A Protein May Have Facilitated Larger Brains in Humans
Scientists from the University of Colorado have proposed a new theory about the rapid growth in size and complexity of the human brain. They discovered that a protein domain, a specific unit within a protein, is present in significantly greater numbers in humans than in other animals. This protein domain is called DUF1220, and the more copies of it you have, the larger your brain tends to be. Humans possess 270 copies in their genome, while chimpanzees have 125, gorillas have 99, and mice have only one. This suggests that brain size may be closely linked to the presence of this protein domain.
Another factor contributing to the growth of the human brain was the challenge of hunting for scarce insects, which helped develop our problem-solving abilities and advanced tool-making skills. However, a bigger brain wasn’t the only reason humans evolved beyond chimpanzees. Humans also have more complex gene activity in the brain, which plays a significant role in our capacity for learning.
3. Random Events Shaped Human Evolution
Researchers at the University of Chicago embarked on a form of 'molecular time travel' to explore how human evolution might have unfolded differently. They began with a key human protein from hundreds of millions of years ago, which eventually became the receptor for the stress hormone cortisol.
The scientists aimed to understand how this ancient protein evolved to become sensitive to cortisol. After evaluating thousands of potential evolutionary paths, they discovered only one possible answer—one that was entirely random. Two highly improbable mutations were required for the protein to gain its sensitivity to cortisol. This means that the modern form of the protein resulted from a fortunate twist of fate in the distant past.
The researchers argue that a series of improbable random events—twists of fate—shaped the proteins that contributed to making us who we are. If proteins can evolve new functions this way, it could help explain the vast diversity and genetic variation in life. This also suggests that with just a few different genetic twists of fate, humans might have evolved into an entirely different species.
2. Human Longevity May Be Due to Our Incredibly Slow Metabolism
Humans and other primates burn 50 percent fewer calories than most other mammals. To match the number of calories that a similarly sized non-primate mammal would burn on a typical day, a human would have to run an entire marathon.
A recent study suggests that our slow metabolism could explain why humans mature slowly, have children less frequently, and enjoy long lifespans. It may also shed light on the reason behind the abundance of weight-loss programs. If you’re struggling to lose weight despite exercising, this study might offer some solace. It also found that primates in captivity burn as many calories as their wild counterparts, hinting that physical activity may have less of an impact on daily calorie expenditure than we previously thought.
In contrast, most mammals, such as dogs and hamsters, tend to live fast and die young—often in their teens or earlier. Researchers believe that environmental factors played a role in shaping the slow metabolisms that contribute to our longer lifespans.
1. Throwing Made Us Human
The throwing abilities of today's baseball players trace back to our extinct human ancestors. Nearly two million years ago, early humans began throwing rocks and crafting sharpened wooden spears for hunting. Researchers from George Washington University and Harvard University found that even chimpanzees cannot throw as well as we can. At most, a chimp's throwing speed is about one-third of that of a 12-year-old Little League pitcher.
The researchers sought to understand how humans developed such impressive throwing skills. By recording college baseball players during their pitches, they discovered that the human shoulder functions like a slingshot, storing and releasing energy during a throw. Features of the human torso, shoulder, and arm evolved specifically to facilitate this energy storage and release.
These exceptional throwing skills enabled our ancestors to hunt and consume large game. Eating meat from these animals contributed to the growth of our brains and bodies, and helped us expand into new parts of the world. In essence, our ancestors' ability to throw helped shape what it means to be human.
