Brief Summary
This video debunks common misconceptions, covering topics from animal behavior to health advice. It clarifies why bulls charge, the truth about knuckle cracking and arthritis, and whether touching baby birds is harmful. It also explains why we get more colds in winter, the real reason for seasons, how dogs perceive color, and the validity of the "eight glasses of water a day" rule.
- Bulls charge due to movement, not the color red.
- Knuckle cracking doesn't cause arthritis; it's just gas bubbles bursting in synovial fluid.
- Mother birds won't abandon their chicks due to human scent.
- Colds are caused by viruses, not cold weather itself.
- Seasons are due to Earth's tilt, not its distance from the sun.
- Dogs see colors, but differently than humans, with better night vision.
- The "eight glasses of water a day" rule is an oversimplification; hydration needs vary.
Bulls Seeing Red
The common belief that bulls charge at red capes because they are angered by the color is false. Bulls are actually red-green colorblind, possessing only blue and green color receptors. The real reason bulls charge is due to the erratic movement of the cape, which triggers them. Scientists have proven this by testing bulls with different colored objects, where the bulls only reacted to movement. The red color is used in bullfighting mostly for show and to mask blood stains.
Knuckle Cracking Arthritis Scare
Cracking knuckles does not cause arthritis, contrary to popular belief. The popping sound comes from gas bubbles bursting in the synovial fluid within the joints when they are stretched, creating space and reducing pressure. These bubbles are primarily nitrogen. It takes about 20-30 minutes for the gas to redissolve into the fluid, which is why you can't immediately crack your knuckles again. A doctor conducted a 60-year experiment, cracking knuckles on only one hand and found no arthritis in either hand. Arthritis is typically caused by genetics, aging, or injuries, not knuckle cracking.
Baby Bird Touch Taboo
The idea that touching a baby bird will cause its mother to abandon it due to human scent is a myth. Most birds have a poor sense of smell and rely more on sight and sound to recognize their young. Mother birds are highly invested in their offspring and are unlikely to abandon them simply because they have been touched by humans. Bird banders handle baby birds regularly for research without causing abandonment. Birds are more likely to abandon a nest due to significant disturbance or perceived threats from predators. If you find a baby bird, determine if it's a nestling (younger, needs to be in the nest) or a fledgling (learning to fly, may be on the ground). If it's a nestling, safely return it to the nest.
Cold Weather Cold Catch
Being cold does not directly cause a cold. Colds are caused by viruses, mainly rhinoviruses. People get more colds in the winter because they spend more time indoors in close proximity, which facilitates the spread of viruses. Cold, dry air may also weaken the body's defenses, such as the lining of the nose being less effective at trapping viruses. However, the primary factor is still exposure to the virus. Scientists in Antarctica often remain cold-free until new people arrive with viruses.
Sun Distance Season Story
The seasons are not caused by Earth's distance from the sun. Earth is actually farthest from the sun during the Northern Hemisphere's summer. Seasons are caused by Earth's 23.5° tilt on its axis. This tilt causes different parts of Earth to receive different amounts of direct sunlight throughout the year. When the Northern Hemisphere is tilted towards the sun, it receives more direct sunlight, resulting in summer. When tilted away, the sunlight is weaker and more spread out, resulting in winter. Without this tilt, there would be no seasons. Earth's orbit is slightly oval, but this has minimal impact on temperature.
Dogs Vision Delusion
Dogs do not see the world in black and white. They have two types of color-detecting cells (cones), allowing them to see blues and yellows well, but reds and greens appear as shades of brown or gray. While their color vision is limited, dogs have better night vision than humans due to more rods in their eyes and a reflective layer called the tapetum lucidum, which enhances light capture. Their sense of smell is also far more powerful than humans', which they rely on heavily.
Eight Glasses Water Rule
The "eight glasses of water a day" rule is not a strict medical guideline for everyone. It originated from a 1945 recommendation that adults need 2.5 liters of water daily, but this recommendation also noted that much of this intake comes from food. The amount of water needed varies based on age, gender, activity level, health, and climate. More water is needed during heavy exercise or in hot weather. Fruits, vegetables, and beverages like milk, juice, tea, and coffee also contribute to fluid intake. The body's thirst mechanism is a good indicator of when water is needed, making the eight-glasses rule an oversimplification.
