In this video Carl Sagan explains how Greek astronomer Eratosthenes, in 200 BC, was able to deduce and calculate the earth was a sphere about 40,000 km in circumference.
It is wonderful to see how a bit of thought and curiosity have lead mankind to learn so much.
Related: How do Plants Grow Into the Sunlight? – Why is it Colder at Higher Elevations? – Great Webcast Explaining the Digestive System – Biology: How Wounds to Our Skin Heal
Wisegeek has photographed what 200 calories of various foods looks like. A small sample is shown here:
Some of the other 200 calorie portions they show are 1425 grams of celery, 588 grams of broccoli, 385 grams of apples, 333 ml of whole milk, 290 grams of grapes, 204 grams of sliced smoked turkey, 150 grams of eggs, 72 grams of a blueberry muffin, 53 grams of brown sugar and 52 grams of a donut or pretzel.
Related: A Healthy Lifestyle is More About Health Care than the Sickness Management That We Call Health Care Is – Healthy Diet, Healthy Living, Healthy Weight – Eat food. Not too much. Mostly plants. – Better Health Through: Exercise, Not Smoking, Low Weight, Healthy Diet and Low Alcohol Intake – Obesity Epidemic Explained – Kind Of (1970 – Americans ate an average of 2170 calories per day 2000 – Americans ate an average of 2700 calories per day) – Examining the Scientific Basis Around Exercise and Diet Claims
This webcast, from the wonderful SciShow, explores how we discovered fluoride helps prevent tooth decay and how we then used that knowledge and finally discovered why it worked.
I love stories of how we learn for observing what is happening. We don’t always need to innovate by thinking up creative new ideas. If we are observant we can pick up anomalies and then examine the situation to find possible explanations and then experiment to see if those explanations prove true.
When working this way we often are seeing correlation and then trying to figure out which part of the correlation is an actual cause. So in this dental example, a dentist noticed his patients had bad brown stains on their teeth than others populations did.
After investigation the natural fluoridation of the water in Colorado Springs, Colorado, USA seemed like it might be an explanation (though they didn’t understand the chemistry that would cause that result). They also explored the sense that the discolored teeth were resistant to decay.
Even without knowing why it is possible to test if the conditions are the cause. Scientists discovered by reducing the level of fluoridation in the water the ugly brown stains could be eliminated (these stains took a long time to develop and didn’t develop in adults). Eventually scientists ran an experiment in Grand Rapids, Michigan and found fluoridation of the water achieved amazing results for dental health. The practice of fluoridation was then adopted widely and resulted in greatly improved dental health.
In 1901, Frederick McKay, a recent dental school graduate, opened a dental practice in Colorado Springs, Colorado. He was interested in what he saw and sought out other dentists to explore the situation with him but had little success. In 1909, he found some success when renowned dental researcher Dr. G.V. Black collaborate with him.
Dr. H. Trendley Dean, head of the Dental Hygiene Unit at the National Institute of Health built on their work when he began investigating the epidemiology of fluorosis in 1931. It wasn’t until 1945 that the Grand Rapids test started. Science can take a long time to move forward.
Only later did scientists unravel why this worked. The fluoride reacts to create a stronger enamel than if the fluoride is not present. Which results in the enamal being less easily dissolved by bacteria.
Health tip: use a dental stimudent (dental picks) or floss your teeth to maintain healthy gums and prevent tooth decay. It makes a big difference.
Related: Why does orange juice taste so bad after brushing your teeth? – Microbiologist Develops Mouthwash That Targets Only Harmful Cavity Causing Bacteria – Using Nanocomposites to Improve Dental Filling Performance – Finding a Dentist in Chiang Mai, Thailand – False Teeth For Cats – Why Does Hair Turn Grey as We Age?
The specialized cancer agency of the World Health Organization, the International Agency for Research on Cancer (IARC), announced today that it has classified outdoor air pollution as carcinogenic to humans.
After thoroughly reviewing the latest available scientific literature, the world’s leading experts convened by the IARC Monographs Programme concluded that there is sufficient evidence that exposure to outdoor air pollution causes lung cancer. They also noted a positive association with an increased risk of bladder cancer.
Particulate matter, a major component of outdoor air pollution, was evaluated separately and was also classified as carcinogenic to humans.
The IARC evaluation showed an increasing risk of lung cancer with increasing levels of exposure to particulate matter and air pollution. Although the composition of air pollution and levels of exposure can vary dramatically between locations, the conclusions of the Working Group apply to all regions of the world.
Air pollution is already known to increase risks for a wide range of diseases, such as respiratory and heart diseases. Studies indicate that in recent years exposure levels have increased significantly in some parts of the world, particularly in rapidly industrializing countries with large populations. The most recent data indicate that in 2010, 223,000 deaths from lung cancer worldwide resulted from air pollution.
“The air we breathe has become polluted with a mixture of cancer-causing substances,” says Dr Kurt Straif.
The stories of amazingly high (and persistent) air pollution levels in China have been continuing for years. But, while China, likely represents several of the worst existing air pollution conditions hundreds of thousands have died outside China due to air pollution just in the last 5 years.
Very cool site for learning about biology. I have tried the courses offered by Coursera but they are too structured for my taste. I want to be able to learn at my pace and dip into the areas I find interesting. Coursera is more like a real course, that has weekly assignments and the like.
Survivebio [site is offline, here a site you might be interested in – iBiology] is a resources that matches my desires exactly. You can go and learn about whatever topics you desire, when you desire. The site offers webcasts, games, flashcards, chapter outlines, practice tests and a forum to discuss the ideas.
In this webcast, Paul Andersen discusses the specifics of phylogenetics. The evolutionary relationships of organisms are discovered through both morphological and molecular data.
The aim of the SurviveBio web site is to aid AP (and college) biology students. But it is also a great resource to learn about biology if you are interested in that topic. Hopefully they will add more webcasts. The site uses webcasts from Bozeman Science which has a huge number of very good videos on biology and also, chemistry, physics, earth science, statistics, anatomy and physiology.
Related: Great Webcast Explaining the Digestive Systems – Cell Aging and Limits Due to Telomeres – Human Gene Origins: 37% Bacterial, 35% Animal, 28% Eukaryotic
In this interesting webcast, Derek Muller, (a physics teacher in Perth, Australia) explores how much weight you lose while you sleep. As physics teacher he asks the sensible question: how do you lose weight while you sleep, what weight do you lose?
His conclusion is you lose weight through perspiration, water vapor in your breath and expelling carbon dioxide. Losing the water weight is pretty straight forward. The process of adding carbon to the breath we expel is not something I thought of. He calculates that we lose about 100 grams of carbon during a night of sleep. In his somewhat scientific experiment (measuring himself for several days) he lost about 150 more grams, which he attributes to water vapor and perspiration.
It seems to me the amount of carbon we lose during sleep is probably much more consistent than the amount of water weight we lose (both between people and variation between different days).
Related: Can You Effectively Burn Calories by Drinking Cold Water? – CDC Urges Reducing the Amount of Salt We Eat – Why is it Colder at Higher Elevations? – How Caffeine Affects Your Body – Why Does the Moon Appear Larger on the Horizon?
Related: Domestic Cats Remain Successful Predators – Backyard Wildlife: Mountain Lion – Friday Fun: Cats and Kids with iPads
In a recent article in National Geographic Carl Zimmer has again done a good job of explaining the complex interaction between our bodies and the bacteria and microbes that make us sick, and keep us healthy.
The damage done by our indiscriminate use of antibiotics is not just the long term resistance that we create in bacteria (making the future more dangerous for people) that I have written about numerous times but it also endangers the person taking the anti-biotics in the short term. Sometimes the other damage is a tradeoff that should be accepted. But far too often we ignore the damage taking antibiotics too often does.
The human body contains trillions of microorganisms — outnumbering human cells by 10 to 1. Because of their small size, however, microorganisms make up only about 1% to 3% of the body’s mass, but play a vital role in human health.
Where doctors had previously isolated only a few hundred bacterial species from the body, Human Microbiome Project (HMP) researchers now calculate that more than 10,000 microbial species occupy the human ecosystem. Moreover, researchers calculate that they have identified between 81% and 99% of all microorganismal genera in healthy adults.
“Humans don’t have all the enzymes we need to digest our own diet,” said Lita Proctor, Ph.D., NHGRI’s HMP program manager. “Microbes in the gut break down many of the proteins, lipids and carbohydrates in our diet into nutrients that we can then absorb. Moreover, the microbes produce beneficial compounds, like vitamins and anti-inflammatories that our genome cannot produce.” Anti-inflammatories are compounds that regulate some of the immune system’s response to disease, such as swelling.
“Enabling disease-specific studies is the whole point of the Human Microbiome Project,” said Barbara Methé, Ph.D., of the J. Craig Venter Institute, Rockville, MD, and lead co-author of the Nature paper on the framework for current and future human microbiome research. “Now that we understand what the normal human microbiome looks like, we should be able to understand how changes in the microbiome are associated with, or even cause, illnesses.”
Read the full NIH press release on the normal bacterial makeup of the body
Related: Tracking the Ecosystem Within Us – What Happens If the Overuse of Antibiotics Leads to Them No Longer Working? – Antibacterial Products May Do More Harm Than Good – Antibiotics Too Often Prescribed for Sinus Woes
The percent of human genes that emerged in various stages of evolution: 37% bacterial, 28% eukaryotic, 16% animal, 13% vertebrate, 6% primate. The history that brought us to where we are is amazing. Eukaryotes include animals, plants, amoebae, flagellates, amoeboflagellates, fungi and plastids (including algae). So eukaryotic genes are those common to us and other non-animal eukaryotes while those classified as animal genes are shared by animals but not non-animal eukaryotes.
We are living in a bacterial world, and it’s impacting us more than previously thought by Lisa Zyga
Very cool stuff. This amazing facts scientists discover provide an amazing view of the world we live in and how interconnected we are to other life forms in ways we don’t normally think of.
Related: People’s Bodies Carry More Bacterial Cells than Human Cells – Microbes Flourish In Healthy People – Tracking the Ecosystem Within Us – Foreign Cells Outnumber Human Cells in Our Bodies – Bacteria Beneficial to Human Health
Interesting facts: I didn’t know that we require 13 minerals or that alcoholic beverages contain amounts of all the minerals we need. An amazing fact: the average person walks the equivalent of 3 times around the earth in a lifetime.
The minerals we need (and the recommended daily amount)
Calcium – 1,200 mg
Magnesium – 320 mg
Phosphorus – 700 mg
Potassium – 4.7 g
Sodium – ?
Chloride?
trace amounts needed
Cobalt (as Vitamin B12) – 2.4 mcg
Copper – 1,156 mcg
Iodine – 150 mcg
Iron – 8 mg
Manganese – 1.8 mg
Niacin – 14 mg
Riboflavin – 1.1 mg
Selenium – 55 mcg
Thiamin – 1.1 mg
Zinc – 8 mg
Chromium?, Molybdenum? Fluoride?
Frankly, in my quick looks around the internet I am not sure what they base the claim we need only 13 minerals on. It seems we need trace amounts of more minerals – did they just ignore those not in alcohol?
I couldn’t find good sources confirming just what minerals are needed. Many list some minerals but don’t list others. I am not really sure what the answer is. I am glad I seem to somehow get whatever I need just by eating somewhat healthfully. It is pretty cool we get these things that way. Of course if we didn’t our ancestors wouldn’t have survived to create descendants that finally became us – as they had a much harder time than me (who can just go the restaurant and grocery store and get all sorts of wonderful food).
Related: the atoms that make up the human body, were created in the crucible of stars – Science Explained: Cool Video of ATP Synthase, Which Provides Usable Energy to Us – Video of Young Richard Feynman Talking About Scientific Thinking – Scientific Illiteracy Leads to Failure to Vaccinate Which Leads to Death
From the video by Alex Dainis: Caffeine prevents adenosine from slowing down your nervous system, by binding to the same receptors adenosine would. Caffeine also stimulates the production of adrenaline. And it increases the amount of dopamine present. The average half life of caffeine in the human body is about 6 hours.
Related: Does Diet Soda Result in Weight Gain? – Mental Pick-Me-Ups: The Coming Boom – Ritalin Doesn’t Show Long Term Effectiveness for ADHD
I have been curious about the caffeine content of various drinks and writing this post is a good enough reason to actually look it up.
Sprite, 7Up and some root beers have no caffeine.
Chocolate can also be a significant source of caffeine – dark chocolate can have over 80 mg per 100 g (approximately 4 ounces).
RSS Feed