There are several theories about what makes us human - several that are related or connected to one another. The subject of human existence has been pondered for thousands of years. Ancient Greek philosophersSocrates,Plato, andAristotleAll theorized about the nature of human existence, as have countless philosophers since. With the discovery of fossils and scientific evidence, scientists have also developed theories. While there is no single conclusion, there is no doubt that human beings are indeed unique. In fact, the mere contemplation of what makes us human is unique among animal species.
Most species that existed on planet Earth are extinct, including a number of early human species. Evolutionary biology and scientific evidence tell us that all humansevolved from ape-like ancestorsmore than 6 million years ago in Africa. Information from early human fossils and archaeological remains suggests that there were 15 to 20 different speciesearly humansseveral million years ago. These species, calledHominine, migrated to Asia about 2 million years ago, then to Europe and the rest of the world much later. Although various branches of man died out, the branch leading to modern man isA wise man, evolved.
Humans share much in common with other mammals on Earth in terms of physiology, but are most similar in terms of genetics and morphology to two other living primate species: the chimpanzee and the bonobo, with whom we've spent most of our pedigree as we do in chimpanzees and bonobos, the differences are enormous.
Aside from our obvious intellectual abilities that set us apart as a species, humans have several unique physical, social, biological, and emotional characteristics. Although we cannot know exactly what goes on in the minds of other animals, by studying animal behavior scientists can draw conclusions that enrich our understanding.
Thomas Suddendorf, Professor of Psychology at the University of Queensland, Australia, and author of "The Gap: The science of what separates us from other animals', says: 'By noting the presence and absence of mental traits in different animals, we can gain a better understanding of the evolution of the mind. The distribution of a trait across related species can provide information about when and on which branch or branch of the family tree the trait was most likely to have evolved.”
As close as humans are to other primates, theories from various fields of study, including biology, psychology, and paleoanthropology, posit that certain traits are uniquely human. Naming all of the uniquely human characteristics, or arriving at an absolute definition of “what makes us human,” is particularly challenging for a species as complex as ours.
The Larynx (Voice Box)
dr Brown University's Philip Lieberman explained in NPR's "The Human Edge" that the shape of the mouth and vocal tract changed with the tongue and larynx, or larynx, after humans evolved more than 100,000 years ago from an early ape ancestor had separated moves further down the tract.
The tongue became more flexible and independent and could be controlled more precisely. The tongue is attached to the hyoid bone, which is not attached to any other bone in the body. Meanwhile, the human neck became longer to accommodate the tongue and larynx, and the human mouth became smaller.
The larynx is deeper in the human pharynx than in chimpanzees, which, combined with the increased flexibility of the mouth, tongue, and lips, allows humans to speak, change pitch, and sing. The ability to speak and develop language was a tremendous asset to humans. The downside to this evolutionary development is that this flexibility comes with an increased risk of food going the wrong way and leading to choking.
The human shoulders evolved in such a way that, according to David Green, an anthropologist at George Washington University, "the entire joint sticks out horizontally from the neck, like a coat hanger." This is in contrast to the monkey shoulder which is more vertically oriented. The monkey shoulder is better for hanging from trees, while the human shoulder is better for throwing and hunting, giving humans invaluable survival skills. The human shoulder joint has a large range of motion and is highly mobile, providing the potential for great leverage and accuracy when throwing.
The hand and opposite thumbs
Although other primates also have opposable thumbs, meaning they can be moved around to touch the other fingers, imparting the ability to grasp, the human thumb differs from that of other primates in terms of precise location and size. According to the Center for Academic Research & Training at Anthropogeny, humans “have relatively longer and moredistally placed thumband "bigger thumb muscles". The human hand has also gotten smaller and fingers straighter. This has given us better fine motor skills and the ability to perform detailed precision work like writing with a pencil.
Bare hairless skin
Although there are other hairless mammals—whales, elephants, and rhinos, to name a few—humans are the only primates in existencemostly bare skin. Humans evolved this way because the climate changed 200,000 years ago, which meant they had to travel long distances for food and water. Humans also have an abundance of sweat glands called eccrine glands. To make these glands more efficient, human bodies had to shed their hair to better dissipate heat. This allowed them to get the food they needed to nourish their bodies and brains while also maintaining the right temperature and allowing them to grow.
Stand upright and two-legged
One of the most significant traits that make humans unique preceded and possibly led to the development of other notable traits:two-leggedness– that is, using only two legs to walk. This trait appeared in humans millions of years ago, early in human evolution, and gave humans the advantage of being able to hold, carry, pick up, throw, touch, and from a higher vantage point to see, with sight being the dominant sense. When human legs became longer and more erect about 1.6 million years ago, they were also able to travel great distances while using relatively little energy.
In his book The Expression of Emotion in Man and Animal, Charles Darwin said:Blushis the most idiosyncratic and human of expressions.” It is part of the sympathetic nervous system's “fight or flight” response, which causes the capillaries in the human cheek to involuntarily dilate in response to a sense of embarrassment. No other mammal has this trait, and psychologists hypothesize that it also has social benefits. Because it's involuntary, blushing is considered an authentic expression of emotion.
The human brain
The most extraordinary thing about humans is the brain. The relative size, scale, and capacity of the human brain is greater than that of any other species. The size of the human brain in relation to the average human's total weight is 1 in 50. Most other mammals have a ratio of only 1:180.
The human brain is three times the size of a gorilla's brain. Although the same size as a chimpanzee brain at birth, the human brain grows larger over the human lifespan, becoming three times the size of a chimpanzee brain. Specifically, the prefrontal cortex expands to 33 percent of the human brain, compared to 17 percent of the chimpanzee brain. The adult human brain has about 86 billion neurons, of which the cerebral cortex contains 16 billion. In comparison, the chimpanzee's cerebral cortex has 6.2 billion neurons.
Childhood is thought to be much longer for humans, with offspring staying longer with their parents because the larger, more complex human brain takes longer to fully develop. Studies suggest that the brain is not fully developed until the age of 25 to 30.
The Mind: Imagination, creativity and foresight
The human brain and the activity of its myriad neurons and synaptic possibilities contribute to the human mind. The human mind is different from the brain: the brain is the tangible, visible part of the physical body, while the mind is the intangible realm of thoughts, feelings, beliefs, and consciousness.
In his book The Gap: The Science of What Separates Us From Other Animals, Thomas Suddendorf suggests:
“Mind is a tricky concept. I think I know what a ghost is because I have one - or because I am one. Maybe you think the same. But the minds of others are not directly observable. We assume that others have minds similar to ours—full of beliefs and desires—but we can only infer these mental states. We cannot see, feel or touch them. We rely largely on language to let each other know what's on our minds.” (p. 39)
As far as we know, humans have the unique power of forward thinking: the ability to envision the future in many possible iterations and then actually create the future we envision. Foresight also enables humans to have generative and creative abilities distinct from those of other species.
Religion and Consciousness of Death
One of the things that foresight also gives people is an awareness of mortalityunderstanding of religionas “our human response to the dual reality of being alive and having to die. The knowledge that we are going to die not only sets a recognized limit for our lives, it also gives a special intensity and poignancy to the time that we have to live and give love."
Regardless of religious beliefs and thoughts about what happens after death, the truth is that most people are aware of the fact that they will die one day. Although some species react when one of their own has died, they are unlikely to actually think about death - that of others or their own.
The knowledge of mortality also spurs people on to great achievements to make the most of their lives. Some social psychologists contend that without the knowledge of death, the birth of civilization and the achievements that produced it might never have happened.
Humans also have a unique type of memory that Suddendorf calls "episodic memory". He says, "Episode memory is probably the closest thing we can get to what we normally mean when we use the word 'remember' rather than 'know.'" Memory allows people to make sense of their existence and prepare for the future, which allows their chances of surviving are increased, not only individually but also as a species.
Memories are passed through human communication in the form of storytelling, which also passes knowledge from generation to generation, which allows human culture to evolve. Since humans are highly social beings, they strive to understand each other and pool their individual knowledge into a common pool, which promotes faster cultural evolution. In this way, each human generation, unlike other animals, is culturally more evolved than previous generations.
Drawing on research in neuroscience, psychology and evolutionary biology, Jonathon Gottschall explores what it means to be an animal so uniquely dependent on storytelling in his book The Storytelling Animal. He explains what makes stories so important: they help us explore and simulate the future and test different outcomes without having to take real physical risks; they help impart knowledge in a personal and other-related way; and they encourage prosocial behavior because "the urge to produce and consumeMoralistic Storiesis hardwired into us."
Suddendorf writes this about stories:
“Even our young descendants strive to understand the minds of others, and we are compelled to pass on what we have learned to the next generation. When an infant begins life's journey, almost everything is a first. Young children have a ravenous appetite for the stories of their elders, and through play they recreate and repeat scenarios until they get the hang of them. Stories, whether real or fantastic, not only teach specific situations, but also the general way narratives work in their children about past and future events, affecting children's memory and thinking about the future: the more parents try, the more do their children.
Thanks to their unique memory and ability to acquire language skills and to write, people around the world, from the very young to the very old, have been communicating and conveying their ideas through stories for thousands of years, and storytelling remains an integral part of human culture .
Defining what makes humans human can be difficult as more is learned about the behavior of other animals and as fossils are uncovered that revise the evolutionary timeline, but scientists have discovered certain biochemical markers specific to humans.
One factor that may account for the acquisition of human language and rapid cultural development is a gene mutation unique to humansFOXP2-Gen, a gene we share with Neanderthals and chimpanzees that is crucial for the development of normal language and speech.
A study by Dr. Ajit Varki of the University of California, San Diego found another mutation that is unique to humanspolysaccharide shellthe human cell surface. dr Varki found that the addition of just one molecule of oxygen in the polysaccharide that covers the cell surface sets humans apart from all other animals.
The future of species
Humans are both unique and paradoxical. While they are the most advanced species intellectually, technologically, and emotionally—extending human lifespans, creating artificial intelligence, traveling in outer space, performing great feats of heroism, altruism, and compassion—they also have the ability to adapt to primitive, engaging in violent and cruel things, and self-destructive behavior.
• Arain, Mariam, et al. "Maturation of the Adolescent Brain." Neuropsychiatric Disease and Treatment, Dove Medical Press, 2013, www.ncbi.nlm.nih.gov/pmc/articles/PMC3621648/.
• “Brains”. Smithsonian Institution Human Origins Program, 16 January 2019, humanorigins.si.edu/human-characteristics/brains.
• Gottschall, Jonathan. The Storytelling Animal: How Stories Make Us Human. Mariner Books, 2013.
• Gray, Richard. "Earth - The real reasons we walk on two legs and not four." BBC, BBC, 12 Dec 2016, www.bbc.com/earth/story/20161209-the-real-reasons-why-we - walk on two legs and not four.
• “Introduction to Human Evolution”. Smithsonian Institution Human Origins Program, 16 January 2019, humanorigins.si.edu/education/introduction-human-evolution.
• Laberge, Maxine. "Chimpanzees, Humans, and Monkeys: What's the Difference?" Jane Goodall's Good for All News, September 11, 2018, news.janegoodall.org/2018/06/27/chimps-humans-monkeys-whats-difference/.
• Masterson, Kathleen. "From Grunts to Chatter: Why Humans Can Talk." NPR, NPR, August 11, 2010, www.npr.org/templates/story/story.php?storyId=129083762.
• "Mead Project Source Page, A." Charles Darwin: The Expression of Emotion in Man and Animal: Chapter 13, brocku.ca/MeadProject/Darwin/Darwin_1872_13.html.
• "The Naked Truth." Scientific American, https://www.scientificamerican.com/article/the-naked-truth/.
• Suddendorf, Thomas. "The Gap: The Science of What Separates Us from Other Animals." Essential Books, 2013.
• „Daumenoppositionsfähigkeit“. Daumen Opposability | Center for Academic Research and Training in Anthropogeny (CARTA), carta.anthropogeny.org/moca/topics/thumb-opposability.
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