As we explore the animal kingdom, we often find that humans aren’t as unique as we might think. However, one thing that sets us apart is that humans are the only creatures known to faint from fear. When we feel scared or overwhelmed, our blood pressure rises, sending more blood to our brain to keep us alert. But once the danger passes, our body sometimes overreacts, causing our blood pressure to drop too low. This reduces the blood flow to our brain, leading to a brief loss of consciousness, or what we call fainting.
While some animals might collapse due to muscle problems, humans are unique in losing consciousness this way. This happens because of two special traits: standing upright and having a large brain.
Since we spend most of our time standing up, our brain is above our heart. This means blood has to travel upwards against gravity to reach our brain. Our large legs can also trap blood when we stand still for too long, making it even harder for our brain to get enough blood. Although other animals also have brains positioned high above their hearts, none have brains that need as much blood as ours do.
The bigger an animal’s brain, the more blood it needs. Our brains use about 20% of our body’s blood flow, while our closest animal relatives use less than 7%, and smaller-brained animals use even less, under 1%. This is why even a small drop in our blood pressure can affect the blood flow to our brain, while other animals can handle bigger drops without fainting.
Our unique traits mean that even a sudden scare from a horror movie or seeing blood can cause our blood pressure to drop enough for us to faint. The good news is that when we fall, our head and heart align, allowing blood to quickly reach our brain again. However, fainting can sometimes lead to injuries, resulting in about a million hospital visits each year.
In the end, the upright stance and large brain that make humans prone to fainting are the same traits that have helped us succeed and spread across the world. So, you could say that being able to faint is just a small price to pay for our ability to thrive globally!
Illustrate a comic strip that explains why humans faint, while other animals do not. Use your creativity to show the process of blood flow and the role of our upright stance and large brain. Share your comic with the class and explain the science behind each panel.
In groups, act out a scenario where a person faints due to a sudden scare. Assign roles such as the person who faints, the friend who helps, and a doctor who explains why fainting happens. Use this activity to demonstrate your understanding of the physiological process involved in fainting.
Create a poster that highlights the differences in blood flow requirements between humans and other animals. Include facts about the percentage of blood flow used by human brains compared to other animals. Display your poster in the classroom to educate your peers.
Develop a quiz with questions about why humans faint and the unique traits that contribute to this phenomenon. Use a digital platform to create the quiz and challenge your classmates to test their knowledge. Discuss the answers together to reinforce learning.
Research another animal adaptation that is unique and compare it to human fainting. Prepare a short presentation to share your findings with the class, highlighting how adaptations help different species survive and thrive.
The more we learn about the animal kingdom, the less unique humans seem. However, as far as we know, no other animal on Earth faints from fright like we do. When we sense danger or experience a surge of emotion, our blood pressure spikes, sending blood to our brain and increasing our alertness. But once the threat is over, our body sometimes overcompensates, causing our blood pressure to drop too low and reducing the blood supply to our brain, which can lead to brief loss of consciousness—essentially, we faint.
While a few other animals may collapse due to unrelated muscle issues, we are the only ones who actually lose consciousness in this way. This phenomenon is attributed to a unique combination of two traits: an upright stance and a large brain.
Spending most of our time upright, with our brain positioned above our heart, means our blood has to work against gravity to reach the brain. Additionally, our large legs can collect blood when we stand still for too long, making it even harder to supply our brains with enough blood. Although there are other animals with brains positioned high above their hearts, none have brains that demand as much blood as humans do.
The larger an animal’s brain, the more blood it requires; our brains use about 20% of our body’s blood flow, compared to less than 7% for our closest relatives and less than 1% in smaller-brained animals. This is why even a slight dip in our blood pressure can disrupt blood flow to our brain, while other animals can often maintain sufficient blood supply even with significant drops in blood pressure.
Our unique combination of traits means that even something as simple as a jump scare in a horror film or the sight of blood can cause our blood pressure to drop enough for us to faint. The good news is that falling allows our head and heart to align, enabling blood to quickly reach our brain again. However, fainting can also lead to serious injuries, resulting in about a million hospital visits each year.
Ultimately, the upright stance and large brain that make humans the only animals to faint from fright are the same traits that have allowed us to thrive and spread across the globe. So, you could say that world domination is for the faint of heart.
Fainting – A temporary loss of consciousness usually caused by a lack of blood flow to the brain. – When she stood up too quickly, she experienced fainting because her brain didn’t get enough blood.
Blood – The red liquid that circulates in the arteries and veins, carrying oxygen and nutrients to the body’s cells and removing waste products. – The heart pumps blood throughout the body, ensuring that all organs receive the oxygen they need.
Brain – The organ in the head that controls thoughts, memory, emotions, and the nervous system. – The brain processes information from our senses, allowing us to understand and interact with the world.
Pressure – The force exerted by the blood against the walls of blood vessels. – High blood pressure can lead to health problems if not managed properly.
Animals – Living organisms that feed on organic matter, typically having specialized sense organs and nervous systems. – In biology class, we learned about how animals adapt to their environments to survive.
Consciousness – The state of being awake and aware of one’s surroundings. – After the accident, he slowly regained consciousness and was able to remember what happened.
Gravity – The force that attracts a body toward the center of the earth, or toward any other physical body having mass. – Gravity affects how animals move and how plants grow on Earth.
Traits – Characteristics or features of an organism that are inherited from its parents. – Eye color and hair type are examples of traits that are passed down from parents to children.
Injuries – Damage to the body caused by accidents or attacks. – Wearing a helmet while biking can help prevent head injuries.
Scare – A sudden feeling of fear or alarm. – The loud noise gave the animals a scare, causing them to run away quickly.
