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(OLD VIDEO) DNA Replication: The Cell's Extreme Team Sport

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Uploaded by Mahmoud El Gammal on 2014-02-08.

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Old & Odd: Archaea, Bacteria & Protists - CrashCourse Biology #35

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Superbugs That Resist Antibiotics Can Evolve in 11 Days | I Contain Multitudes

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Anatomy and Physiology AP Biology AP Chemistry AP Environmental Science AP Physics Biology Chemistry Earth Science Educational NGSS - Next Generation Science Standards Physics Statistics & Graphing

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Brian Cox Life 1 of 5 - What Is Life | DOCUMENTRAY

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DNA Structure and Replication: Crash Course Biology #10

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Identical twins have exactly the same DNA, but they are not exactly alike. Each twin has his or her own personality, talents, likes, and dislikes. There are even diseases that appear in one twin but not the other, including arthritis, diabetes, autism, schizophrenia, cancer, and many others. The differences between identical twins don't come from DNA-they all come from external factors.

Scientists often study twins to understand how genes and the environment work together to affect traits. They compare traits in identical twins, who have identical DNA, and fraternal twins, who share half their DNA, just like any siblings. If a characteristic appears more frequently in identical twin pairs than in fraternal twin pairs, then it has an inherited component.

The differences between identical twins don't come from DNA-they all come from external factors.

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Identical twins have exactly the same DNA, but they are not exactly alike. Each twin has his or her own personality, talents, likes, and dislikes. There are even diseases that appear in one twin but not the other, including arthritis, diabetes, autism, schizophrenia, cancer, and many others.

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All humans have the same genes arranged in the same order. And more than 99.9% of our DNA sequence is the same. But the few differences between us (all 1.4 million of them!) are enough to make each one of us unique. On average, a human gene will have 1-3 bases that differ from person to person.

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Genetic variation is important because when conditions change (food becomes scarce, environment changes), some individuals in a population will be more likely to have variations that will allow them to survive. Those who reproduce pass their genes to the next generation. Variation helps species survive, and it's the reason species change over time.

In asexual reproduction, variation comes mainly from mutation. Mutation is a natural process that introduces permanent changes in a DNA sequence. However, microbes also acquire genetic variation through transformation, transduction, and conjugation (gene transfer). These mechanisms often come into play when conditions are harsh.

In sexual reproduction, variation comes from both mutation and recombination. Mutation creates the different versions (or alleles) of the same gene. Parental alleles are then shuffled-or recombined-during meiosis. Because of recombination, sexual reproduction produces more variation than asexual does.

Most commonly, traits are influenced by multiple genes and the environment. So for most traits, patterns of inheritance are complex and unpredictable. For instance, when a sexually reproducing organism inherits a defective or "broken" allele that codes for a non-functional protein, the second copy can often make up for the loss. This type of interplay between alleles, especially when traits are influenced by multiple genes, makes predicting inheritance difficult, if not impossible.

A small number of traits are influenced primarily by a single gene. Traits influenced mainly by one gene usually have predictable patterns of inheritance. However, most of the time even supposed "single-gene" traits are influenced by multiple genes, as in the case of eye color. And often times, a single gene can influence multiple traits. For example, some genes involved in eye color also influence hair and skin color.

Why do so many textbooks pretend that eyes come in just two colors, brown and blue? Eye color is influenced by two major genes and several minor genes. Variations in these genes determine whether your eyes are brown, blue, green, gold, hazel, greyish-blue, brown with green flecks, blue with a gold ring...you get the idea.

In rare cases, changes in DNA sequences can cause disease. The pattern of disease inheritance can be predictable or unpredictable, depending on whether the disease is influenced mainly by one gene or by several genes. See Genetic Disorders

It's not quite accurate to say that everyone inherits two copies of every gene. In most mammals, the X and Y sex chromosomes determine whether an individual is male or female. Females have two X chromosomes, and therefore two copies of every gene. Males, however, have one X and one Y chromosome. For genes that appear only on the X chromosome or only on the Y (some do appear on both), males inherit just one copy.

Other living things have sex chromosomes too. Birds and reptiles have Z and W sex chromosomes. Unlike with X and Y, males have two Z chromosomes, and females have one Z and one W. Some insects and a few mammals have only an X chromosome. Females have two copies and males have one. However, sex is not always determined by chromosomes. With alligators, crocodiles, and most turtles, it's egg incubation temperature. And some fish can change gender in response to cues from the environment. Sex determination happens in many different ways.

Traits that involve genes on the sex chromosomes have different inheritance patterns than non-sex-linked traits. Color-blindness and Duchenne muscular dystrophy, for example, are linked to genes on the X chromosome. Both of these disorders are more common in males because they have just one X chromosome. They have no second allele to mask the effects of a defective gene.

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Genetic variation is important because when conditions change (food becomes scarce, environment changes), some individuals in a population will be more likely to have variations that will allow them to survive. Those who reproduce pass their genes to the next generation. Variation helps species survive, and it's the reason species change over time.

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Mutation Generates New Alleles

The whole human family is one species with the same genes. Mutation creates slightly different versions of the same genes, called alleles. These small differences in DNA sequence make every individual unique. They account for the variation we see in human hair color, skin color, height, shape, behavior, and susceptibility to disease. Individuals in other species vary too, in both physical appearance and behavior.

Genetic variation is useful because it helps populations change over time. Variations that help an organism survive and reproduce are passed on to the next generation. Variations that hinder survival and reproduction are eliminated from the population. This process of natural selection can lead to significant changes in the appearance, behavior, or physiology of individuals in a population, in just a few generations.

Once new alleles arise, meiosis and sexual reproduction combine different alleles in new ways to increase genetic variation.

It's useful to think of mutation as a process that creates genetic variation. We often refer to a mutation as a thing-the genetic variation itself. This approach can be useful when it comes to a gene associated with a disease: the disease allele carries a mutation, a DNA change that compromises the protein's function. However, this approach gives mutation a bad name.

It's important to remember that losing the function of a gene doesn't always affect health. For example, most mammals have hundreds of genes that code for olfactory receptors, proteins that help us smell. Losing one of these genes probably doesn't make all that much difference.

In contrast to variations that cause disease, there are many more examples of variations that are neither good nor bad, but just different-like blood types and eye color. Just like with disease alleles, the process of mutation creates these more neutral variations. But with neutral variations, it can be impossible to tell which allele is the "normal" one that existed first and which is the "mutant"-and the distinction is often meaningless.

Mutation creates variations in protein-coding portions of genes that can affect the protein itself. But even more often, it creates variations in the "switches" that control when and where a protein is active and how much protein is made.

Lactase is an enzyme that helps infants break down lactose, a sugar in milk. Normally the gene that codes for lactase is active in babies and then turned off at about age four. When people who don't make lactase consume milk, they experience gas, nausea, and discomfort. But some people have a variation in a genetic switch that keeps the lactase gene active. This variation is called "lactase persistence," and people who have it can keep milk in their diets even as adults.

Other drivers of mutation: Environmental agents

Radiation, chemicals, byproducts of cellular metabolism, free radicals, ultraviolet rays from the sun-these agents damage thousands of nucleotides in each of our cells every day. They affect the nucleotides themselves: converting one base to another, knocking a base off its backbone, or even causing a break in the DNA strand.

Most of the time, mutation is reversed. DNA repair machines are constantly at work in our cells, fixing mismatched nucleotides and splicing broken DNA strands back together. Yet some DNA changes remain. If a cell accumulates too many changes-if its DNA is so damaged that repair machinery cannot fix it-it either stops dividing or it self-destructs. If any of these processes go wrong, the cell could become cancerous.

When we put on sun screen, we are protecting ourselves against mutation in somatic cells-the cells that make up the body and are not involved in reproduction.&ZeroWidthSpace; Only when DNA changes are carried in egg and sperm cells are they passed to the next generation. Believe it or not, a certain amount of sloppiness is built into the system. Without mutation there would be no variation, and without variation there would be no evolution.

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Mutation Generates New Alleles The whole human family is one species with the same genes. Mutation creates slightly different versions of the same genes, called alleles. These small differences in DNA sequence make every individual unique. They account for the variation we see in human hair color, skin color, height, shape, behavior, and susceptibility to disease.

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✔ Transcription and Translation ANIMATION - MADE EASY

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Humans have yet to sprout adamantium claws, but certain gene mutations have produced some pretty amazing, real-life super powers.

PCMag reviews products independently, but we may earn affiliate commissions from buying links on this page. Terms of use.

If it's mutant super powers fans want to see, there's no need to depend on some fictional, CGI-enhanced Marvel make-em-up. There are very real people with very real gene-based super abilities all around us!

First, let's start off with the fact that mutations do not mean retractable adamantium claws nor the ability to control the weather. In fact, these little genetic typos typically result in very minor changes, which (when they aren't deadly) are often not visible.

Mutations are the means by which nature adds new variants into the genetic pool. If these traits are advantageous (or at least benign), they are passed along through the generations until they become a normal part of a species' grander gene pool.

Without mutations, evolution would not be possible-species could never gain new abilities or attributes. For example, in our species' recent past (around 12,000 years ago), a single human had a mutation that gave him the "superpower" to drink cow's milk and not get sick, which was then passed to half the world's population. Now we have cheeseburgers.

Scientists believe that every time the human genome duplicates itself there are around 100 new mutations. They're pretty common, and usually negligible. However, it would stand to reason that within the pantheon of human mutations, some would express themselves in the form of extraordinary superhuman abilities.

Check out our slideshow for 13 examples of medically verified human abilities resulting from minute changes in genetic code. Or, to put it in a much more interesting way: Here are 13 examples of real-life mutant super heroes!

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13 Humans With Real-Life X-Men Mutant Super Powers

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Humans have yet to sprout adamantium claws, but certain gene mutations have produced some pretty amazing, real-life super powers. PCMag reviews products independently, but we may earn affiliate commissions from buying links on this page. Terms of use. If it's mutant super powers fans want to see, there's no need to depend on some fictional, CGI-enhanced Marvel make-em-up.

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Part 1: How Does New Genetic Information Evolve? Point Mutations

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Part 2: How Does New Genetic Information Evolve? Gene Duplications

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Malaria and Sickle Cell Anemia — HHMI BioInteractive Video

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In some parts of the world, the infectious parasitic disease malaria and the genetic disease sickle cell anemia are intimately connected. What is sickle cell anemia? What is malaria? And how can one be linked to the other? Answer these questions for your students using this educational video on human evolution.

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The University of Berkeley's one-stop source for info. on evolution

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Your one-stop source for information on evolution

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Evolution Primer #1: Isn't Evolution Just a Theory?

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Learn the difference between the scientific and everyday use of key vocabulary words.

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Evolution Primer #2  Who Was Charles Darwin

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Astounding Mating Dance Birds of Paradise

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Weird & Wonderful Dancing Birds Compilation

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Nature | Dance of the Blue-Footed Booby | Love in The Animal Kingdom | PBS

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Watch the full-length program at http://video.pbs.org/video/2365115163/?utm_source=youtube&utm_medium=pbsofficial&utm_campaign=naat_covefullprogram (US Only) Love in the Animal Kingdom premieres on Nature on PBS Wednesday, Nov. 6, at 8/7c.For more, visit: http://www.pbs.org/wnet/nature/ During mating rituals, male Blue-Footed Boobies show off their feet to prospective mates with a high-stepping strut. The bluer the feet, the more attractive the mate.

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HOw do we know evolution happens

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Evolution Primer #4 How Does Evolution Really Work  Natural Selection

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From TEDEd, there is a five finger trick for understanding and remembering the five processes - small population, non-random mating, mutations, gene flow, adaptation - that impact evolution (ie. the changes in the gene pool of a population from generation to generation). This video, narrated by Paul Andersen and animated by Alan Foreman, is seriously excellent.

Watch more videos about evolution.

via Explore.

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From TEDEd, there is a five finger trick for understanding and remembering the five processes - small population, non-random mating, mutations, gene flow, adaptation - that impact evolution (ie. the changes in the gene pool of a population from generation to generation). This video, narr

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The evolution of the human eye - Joshua Harvey

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13 Most Unique Animal Features For Attracting Mates

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Darwin coined the term "sexual selection" regarding evolution that produces traits that don't help any individual survive, but instead helped in attracting a mate. Human lips, for instance, are said to play this role, but nature is full of far less subtle examples.

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BBC Planet Earth - Birds of Paradise mating dance

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Increase Sex Power in Men by Food Natural

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Evolution - Why Sex? - PBS/Nova Documentary

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Speciation: Of Ligers & Men - Crash Course Biology #15

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http://www.pbs.org/specials/depth-vaccines/ Examining the emotionally charged debate over medical risks versus benefits and a parent's right to make choices about her child versus a communities common good. (Originally broadcast in April, 2010) Vaccines have changed the world, largely eradicating a series of terrible diseases, from smallpox to polio to diphtheria, and likely adding decades to most of our life spans.

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Antibiotic Resistance and the Rise of Superbugs

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Learn more about the influenza pandemic of 1918-19, which claimed the lives of 50 million people worldwide. Investigate how the media chronicled the pandemic, and explore personal accounts of the crisis. Good resources include:
The U.S. Department of Health and Human Services "The Great Pandemic: The United States in 1918-1919," http://1918.pandemicflu.gov/
The National Archives "The Deadly Virus: The Influenza Epidemic of 1918," http://www.archives.gov/exhibits/influenza-epidemic/
PBS's "The American Experience: Influenza 1918," http://www.pbs.org/ americanexperience/films/influenza/player/ (watch the documentary online)
Visit your local library or historical society to research the influenza pandemic in your own community. Then prepare an online exhibit or documentary to share what you've learned.
Epidemics and pandemics are hot stuff in Hollywood. Wipe down some chairs with disposable disinfectant wipes, dole out the latex gloves, and pass around the popcorn for an infectious disease film festival. Your queue might include Contagion (2011), Pandemic (2009), Carriers (2009), I Am Legend (2007), and Outbreak (1995). Do these films impart any useful information about epidemics and pandemics? Do they promote panic? Or do they simply satisfy our craving for a good, short-lived scare?

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Learn more about the influenza pandemic of 1918-19, which claimed the lives of 50 million people worldwide. Investigate how the media chronicled the pandemic, and explore personal accounts of the crisis. Good resources include:The U.S.

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How far we have come with developing vaccines? Have a look at this timeline. Click on the activities tab and follow the scientific method of vaccine development. Learn what an epidemiologist does. Have some misconceptions about vaccines? Visit this page and get the correct answers to your questions!

Interested in the great smallpox epidemic? For a complete timeline read this World Health Organization publication, The History of Smallpox and Its Spread Around the World. Finally, learn about how we conquered the deadly smallpox virus in this TED-Ed video! How did the world become smallpox free?

Want more facts on vaccines? Visit the National Institute of Allergy and Infectious Disease. What are some benefits of vaccines? What will the future of vaccines look like?

Interested in learning more about Jenner's experiment with cowpox? Visit PBS and find out the details! Check out the complete site Rx For Survival and learn about the campaign to get rid of polio, the work that is being done to develop an AIDS vaccine, and more about the final end of smallpox. What would you ask a vaccine expert? Visit Ask the Expert page and see the answers to questions you might have too!

Many people have a fear of vaccinations. Why? Read the New York Times article, Fear of Vaccines Goes Viral and find out. Then listen to NPR's story, Vaccine Controversies Are As Social As They Are Medical. What happens when, due to fear, children are not vaccinated? Read about the resurgence of preventable diseases that has resulted from this trend. Then, get information by viewing NOVA: Vaccines-Calling the Shots. Based on what you have learned, what is your opinion of vaccines? What happens when too many people opt out of getting vaccinations for themselves or their children?

Is it possible for art to encourage vaccinations? The Gates Foundation think so.

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How do vaccines work? - Kelwalin Dhanasarnsombut

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The first ever vaccine was created when Edward Jenner, an English physician and scientist, successfully injected small amounts of a cowpox virus into a young boy to protect him from the related (and deadly) smallpox virus. But how does this seemingly counterintuitive process work? Kelwalin Dhanasarnsombut details the science behind vaccines.

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Why smallpox was one of the most deadly diseases the world has ever known. This is one of 10 educational videos about the life of Edward Jenner available on YouTube and at http://www.jennermuseum.com/

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Simple Animals: Sponges, Jellies, & Octopuses - Crash Course Biology #22

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Hank introduces us to the "simplest" of the animals, complexity-wise: beginning with sponges (whose very inclusion in the list as "animals" has been called into question because they are so simple) and finishing with the most complex molluscs, octopuses and squid. We differentiate them by the number of tissue layers they have, and by the complexity of those layers.

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David Attenborough  Origin of Life, Arrival HD   BBC Documentary   Animals & Nature [MIRROR]

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Arrival HD BBC Documentary Animals & Nature

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Birth is the first dangerous step into a hazardous world, an event which reflects the lifelong labours to come. From egg-laying to live-bearing, David Attenborough explores the extraordinary variety of techniques animals use to disperse their offspring.

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Arrival HD BBC Documentary Animals & Nature

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David Attenborough's Galapagos David Attenborough's Galapagos Episode 3 Evolution

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Two hundred years after Charles Darwin set foot on the shores of the Galápagos Islands, David Attenborough travels to this wild and mysterious archipelago.

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Arrival HD BBC Documentary Animals & Nature

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Life ep 9 (BBC, 2009, Plant) Documentary with sir David Attenborough - Documentary HD

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Explaining The Tree of Life - #Attenborough90 - BBC

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This astonishing video from Charles Darwin and the Tree of Life is the story of life on Earth over millions of years. Watch the full program on BBC One 7pm Sunday 08/05/2016 UK.

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Top 10 WEIRDEST Animals You've NEVER Seen! | BBC Earth Explore

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What Caused Life's Major Evolutionary Transitions?

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Join us as we explore the fascinating transition from early cells to multi-celled animals. This transition, as well as several other major evolutionary transitions, dramatically increased the complexity of lifeforms on our planet.

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Explainer: Animals' role in human disease

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Nearly 75 percent of new, or emerging, infectious diseases in people were first spread by animals. Indeed, half of all germs known to cause human disease come from other animals. Some sources were birds, bats and other types of wildlife. Livestock and pet animals have spread many other diseases.

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AIDS (short for Acquired Immune Deficiency Syndrome) A disease that weakens a body's immune system, greatly lowering resistance to infections and some cancers. It is caused by the HIV germ. (See also HIV)

antibiotic A germ-killing substance prescribed as a medicine (or sometimes as a feed additive to promote the growth of livestock). It does not work against viruses.

antibody Any of a large number of proteins that the body produces as part of its immune response. Antibodies neutralize, tag or destroy viruses, bacteria and other foreign substances in the blood.

antigen A substance capable of causing an immune reaction.

bacteriophage Also known simply as a phage. This is a type of virus that infects - and ultimately kills - bacteria, but not before reproducing and spreading.

bacterium (plural bacteria) A single-celled organism. These dwell nearly everywhere on Earth, from the bottom of the sea to inside animals.

cell The smallest structural and functional unit of an organism. Typically too small to see with the naked eye,it consists of watery fluid surrounded by a membrane or wall. Animals are made of anywhere from thousands to trillions of cells, depending on their size.

DNA (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.

Ebola A family of viruses that cause a deadly disease in people. All cases have originated in Africa. Its symptoms include headaches, fever, muscle pain and extensive bleeding. The infection spreads from person to person (or animal to some person) through contact with infected body fluids. The disease gets its name from where the infection was first discovered in 1976 - communities near the Ebola River in what was then known as Zaire (and is now the Democratic Republic of Congo).

gene (adj. genetic)A segment of DNA that codes, or holds instructions, for producing a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.

genetic Having to do with chromosomes, DNA and the genes contained within DNA. The field of science dealing with these biological instructions is known as genetics. People who work in this field are geneticists.

germ Any one-celled microorganism, such as a bacterium, fungal species or virus particle. Some germs cause disease. Others can promote the health of higher-order organisms, including birds and mammals. The health effects of most germs, however, remain unknown.

HIV (short for Human Immunodeficiency Virus) A potentially deadly virus that attacks cells in the body's immune system and causes acquired immune deficiency syndrome, or AIDS.

immune system The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.

immunity The ability of an organism to resist a particular infection or poison by producing and releasing special protective cells.

infection A disease that can spread from one organism to another.

influenza (or flu) A highly contagious viral infection of the respiratory passages causing fever and severe aching. It often occurs as an epidemic.

measles A highly contagious disease, typically striking children. Symptoms include a characteristic rash across the body, headaches, runny nose, and coughing. Some people also develop pinkeye, a swelling of the brain (which can cause brain damage) and pneumonia. Both of the latter two complications can lead to death. Fortunately, since the middle 1960s there has been a vaccine to dramatically cut the risk of infection.

molecule An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O ₂), but water is made of two hydrogen atoms and one oxygen atom (H ₂ O).

proteins Compounds made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. The hemoglobin in blood and the antibodies that attempt to fight infections are among the better-known, stand-alone proteins.Medicines frequently work by latching onto proteins.

RNA A molecule that helps "read" the genetic information contained in DNA. A cell's molecular machinery reads DNA to create RNA, and then reads RNA to create proteins.

species A group of similar organisms capable of producing offspring that can survive and reproduce.

vaccine A biological mixture that resembles a disease-causing agent. It is given to help the body create immunity to a particular disease. The injections used to administer most vaccines are known as vaccinations.

vector (in medicine) An organism that can spread disease, such as by transmitting a germ from one host to another.

virus Tiny infectious particles consisting of RNA or DNA surrounded by protein. Viruses can reproduce only by injecting their genetic material into the cells of living creatures. Although scientists frequently refer to viruses as live or dead, in fact no virus is truly alive. It doesn't eat like animals do, or make its own food the way plants do. It must hijack the cellular machinery of a living cell in order to survive.

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AIDS (short for Acquired Immune Deficiency Syndrome) A disease that weakens a body's immune system, greatly lowering resistance to infections and some cancers. It is caused by the HIV germ. (See also HIV) antibiotic A germ-killing substance prescribed as a medicine (or sometimes as a feed additive to promote the growth of livestock).

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DEVIL FACIAL TUMOR DISEASE - Smarter Every Day 140

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Images show animals before and after humans started breeding them

The first animals were domesticated some 10,000 years ago

Some animals are bred in order to avoid the spread of diseases

Records suggest that humans began raising animals about 10,000 years ago - and they looked very different from the animals we eat today.

Intensive breeding has left cows, sheep, chickens and other domesticated animals transformed into 'superbreeds' buffed up to produce more meat, and grow far more quickly.

In the 19th century, evolutionary biologist Charles Darwin noted that breeding led to 'striking differences between farm animals and plants and their wild counterparts'.

Although this observation helped layout the foundation for Darwin's theory of evolution, it was also theorized about the future of the meat we would put on our plates.

WHEN WERE ANIMALS FIRST DOMESTICATED?

In 2013, a major discovery was made when animal bones and thousands of tools, used by ancient hominins, were found in Africa.

This site suggested that the killing of animals for food started at least 2 million years ago, which also indicates that meat eating could have triggered even bigger changes in the Homo species.

'Just about that time - 2 million years ago - we see big shifts in the human fossil record of increase in brain size, increase in body size and hominins leaving Africa for Eurasia,' Joseph Ferraro, an archaeologist at Baylor University in Waco, Texas, told LiveScience.

Prior to this discovery, researchers believed this shift in diet occurred 1.8 million years ago - which coincided with evidence found in Tanzania.

'We know that humans ate meat two million years ago,' said Professor Henry Bunn of Wisconsin University, who discovered early humans designed strategic hunting techniques to capture antelopes, wildebeest and other large animals.

'What was not clear was the source of that meat.

'However, we have compared the type of prey killed by lions and leopards today with the type of prey selected by humans in those days.'

WILD TURKEYS VS. DOMESTICATED TURKEYS

'This has shown that men and women could not have been taking kill from other animals or eating those that had died of natural causes.'

'They were selecting and killing what they wanted.'

Sheep, goats, cattle, pigs and geese were among the first animals to be raised for human consumption, which occurred about 10,000 years ago, according to Ancient History Encyclopedia.

Goats and sheep were the earliest to be bred for food (7000 BC), pigs in 6500 BC and horses were tamed by 4000 BC, a majority of them were used for work and warfare, but some cultures raised them as a food source.

Chickens were also domesticated around 10,000 years ago, but were first bred for cock fighting in Southeast Asia, reports National Geographic.

FEARS OF GENETICALLY MODIFIED FOODS

Then people began to domesticate larger animals for plowing and transportation, also known as 'beast of burden'.

The easiest animals to domesticate are herbivores that graze on vegetation, because they are easiest to feed.

They do not need humans to kill other animals to feed them, or to grow special crops.

Cows, for instance, are easily domesticated.

These modern-day animals look very different from their wild ancestors such as the chicken that once weight just two pounds and now some hit 17 pounds.

Wild chickens also only hatched a small number of eggs once a year, while domestic chickens commonly lay 200 or more eggs each year.

Breeders use numerous techniques for breeding animals, such as artificial insemination and embryo transfer.

Not only do these methods guarantee females reproduce regularly but they also help improve herd genetics.

This can is conducted by transplanting embryos from high-quality females into lower-quality surrogate mothers.

And allows the higher-quality females to continue to breed better quality offspring and at a higher rate.

Animals aren't the only ones who have changed, the human body has also been affected by meat in their diets.

WILD SHEEP VS. DOMESTICATED SHEEP

For instance, our jaws have decreased in size and we are able to process cholesterol and fat.

Researchers suggest that the switch from gatherers to hunters, triggered a genetic change that enhanced the process of eating fats, reports National Geographic News.

Technology has also come a long way since the adaption of meat into the human diet.

In 2013, US authorities began discussion to grant approvals for the world's first genetically modified fish, the Aquabounty salmon, which has had its genes altered so that it grows twice as fast as a normal fish.

Aquabounty salmon is produced through the insertion into the eggs of wild Atlantic salmon of a growth hormone gene from Chinook salmon, as well as a gene from a different type of fish called the ocean Eelpout.

This makes the salmon produce growth hormone all year round, rather than just during the warmer months.

And last year, US heath regulators cleared the way for it to be farmed for human consumption.

Recently, a start-up announced it should have animal-free products on the market in three to four yeast and unveiled the first lab-grown meatball.

Memphis Meat is designing a full line of product that will include hot dogs, sausages, burgers and meatballs.

WILD SHRIMP VS. FARMED SHRIMP

The firm says its cutting-edge technique produces 90 percent less greenhouse emissions, consumes less nutrients and doesn't require antibiotics or other additives used in traditional meat production.

While generating one calorie from beef requires 23 calories in feed, Memphis Meats plans to produce a calorie of meat from just three calories in inputs.

In order to grow meat in a lab, Memphis Meats begins by isolating cow and pig cells that have the ability to regenerate, and 'provides the cells with oxygen and nutrients such as sugars and minerals'.

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What the animals we eat looked like BEFORE humans began breeding them

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Images show animals before and after humans started breeding them The first animals were domesticated some 10,000 years ago Some animals are bred in order to avoid the spread of diseases Records suggest that humans began raising animals about 10,000 years ago - and they looked very different from the animals we eat today.

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How we conquered the deadly smallpox virus - Simona Zompi

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Transcription and translation

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DNA, Hot Pockets, & The Longest Word Ever: Crash Course Biology #11

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and Here: https://www.sciencenewsforstudents.org/article/gm-mosquitoes-cut-rate-viral-disease-brazil

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Dengue is the fastest spreading mosquito-borne viral infection. Sometimes develops into severe dengue, a potentially lethal complication. The target is to reduce mortality by at least 50% by 2020. #BeatNTDs

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Cracking the Code Of Life   PBS Nova   2001

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Watch a fascinating new interview on UFOs and the Alien Contact: https://youtu.be/0M5Thho5agg?t=1m57s Documentary Truth presents documentaries free for all to view on many topics including: health, space, nature, war, science, spirituality, enlightenment, meditation, religion and new realities such as UFOs, ET/Alien Contact and more.

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This is our second video in the series "Amazing Moments in Science": The Discovery of the Structure of DNA. * More: http://bbva.info/2wTZauE A video by Scienseed for Ventana al conocimiento

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DNA - Episode 1 of 5: The Secret of Life - PBS Documentary

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The discovery of double-helix structure of DNA is to science what Mona Lisa is to painting. It has been called the single biggest discovery of all times. But it was not just stumbled upon - it was a race. Specifically, it was a race between two teams of young scientists working in Britain.

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The Times and Troubles of the Scientific Method

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UPDATE: We got a couple of things wrong when it comes to gravity (particularly that it has nothing to do with photons). Check out this video from TheGentlemanPhysicis (http://www.youtube.com/watch?v=4y-dFLZHb1c) in which our confusion is explained.

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What’s the difference between a scientific law and theory? - Matt Anticole

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A sponge might not look like much, but these simple animals with no brain or ability to move have lived on Earth for hundreds of millions of years. They can hunt prey and spawn, and Jonathan demonstrates how in this fascinating segment about the biology of sponges!

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Simple Animals: Sponges, Jellies, & Octopuses - Crash Course Biology #22

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Hank introduces us to the "simplest" of the animals, complexity-wise: beginning with sponges (whose very inclusion in the list as "animals" has been called into question because they are so simple) and finishing with the most complex molluscs, octopuses and squid. We differentiate them by the number of tissue layers they have, and by the complexity of those layers.

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Learn Biology: Kingdom Animalia: Phylum Porifera

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Find 1500+ education videos available at http://www.youtube.com/user/IkenEdu Biology is the vast subject including all about animals, human and plants. In this video, you will learn about various biological organisms such eukaryotic, prokaryotic and others. Watch the full video and learn all about kingdom Animalia. This is an important biology lesson for you.

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The Ebola Virus Explained — How Your Body Fights For Survival

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This short animation film about the evolution of life on Earth would make Darwin himself chuckle. It's funnier than any learned treatise, and yet it's all here - ...

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The earth has been through some major changes! Animals we wish still existed: http://youtu.be/wutj5z1lElU SUBSCRIBE (it's free): http://bit.ly/10kWnZ7 GET THE BOOK: http://asapscience.com/book/ Written by Tyler Irving (@tylereirving), Mitchell Moffit and Greg Brown Instagram and Twitter: @whalewatchmeplz and @mitchellmoffit Clickable: http://bit.ly/16F1jeC and http://bit.ly/15J7ube AsapINSTAGRAM: https://instagram.com/asapscience/ Facebook: http://facebook.com/AsapSCIENCE Twitter: http://twitter.com/AsapSCIENCE Tumblr: http://asapscience.tumblr.com Vine: Search "AsapSCIENCE" on vine!

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cornell lab of ornithology (organization)

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Explore more at http://www.birdsofparadiseproject.org. There is a dizzying diversity of species on our planet. From genetic evidence we know that all of those species evolved from a single ancient ancestor. But how does one species split in to many?

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Putting the history of Earth into perspective

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The Earth is really, really old. Over 4 1/2 billion years old, in fact. How do we begin to comprehend a number that large? It helps to put it on a more fathomable scale. Watch to see where Earth's major events would fall on a timeline stretching across the US.

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Proof of evolution that you can find on your body

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Genetic Engineering and Diseases – Gene Drive & Malaria

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The Bizarre Truth About Purebred Dogs (and Why Mutts Are Better) - Adam Ruins Everything

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Watch more Adam Ruins Everything here: https://www.youtube.com/playlist?list=PLuKg-WhduhkksJoqkj9aJEnN7v0mx8yxC For more information regarding the truth about purebreds, watch the BBC documentary Pedigree Dogs Exposed, or check out the following sources: * Wikipedia: Purebred (Dogs) - http://en.wikipedia.org/wiki/Purebred_(dog) * 100 Years of Breed "Improvement" - http://dogbehaviorscience.wordpress.com/2012/09/29/100-years-of-breed-improvement/ * Wikipedia: Kennel Club - http://en.wikipedia.org/wiki/Kennel_club * Wikipedia:

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We asked readers to share the misconception that frustrates them the most on The New York Times - Science Facebook page. People had an array of answers, a number of which we addressed earlier this week. Judging from all the likes it quickly accumulated - far more than any other submission - this was the standout in terms of mass frustration.
Misconception: It's just a theory.

Actually: Theories are neither hunches nor guesses. They are the crown jewels of science.

One day, it's Megyn Kelly who has a theory about why Donald J. Trump hates her.

Another day, the newly released trailer for the next Star Wars movie inspires a million theories from fans about who Rey's parents are.

And on Twitter, someone going by the name of Mothra P.I. has a theory about how cats can assume a new state of matter:

In everyday conversation, we tend to use the word "theory" to mean a hunch, an idle speculation, or a crackpot notion.

That's not what "theory" means to scientists.

"In science, the word theory isn't applied lightly," Kenneth R. Miller, a cell biologist at Brown University, said. "It doesn't mean a hunch or a guess. A theory is a system of explanations that ties together a whole bunch of facts. It not only explains those facts, but predicts what you ought to find from other observations and experiments."

Dr. Miller is one of the few scientists to have explained the nature of theories on a witness stand under oath.

He is a co-author of a high school biology textbook that puts a strong emphasis on the theory of evolution. In 2002, the board of education in Cobb County, Ga., adopted the textbook but also required science teachers to put a warning sticker inside the cover of every copy.

"Evolution is a theory, not a fact, regarding the origin of living things," the sticker read, in part.

In 2004, several Cobb County parents filed a lawsuit against the county board of education to have the stickers removed. They called Dr. Miller, who testified for about two hours, explaining, among other things, the strength of evidence for the theory of evolution.

Once the lawyers had finished questioning Dr. Miller, he stepped down from the stand and made his way out of the courtroom. On the way, he noticed a woman looking him straight in the eye.

"She said, 'It's only a theory, and we're going to win this one,'  " Dr. Miller recalled.

They didn't. In 2005 the judge ruled against the board of education. The board appealed the decision but later agreed to remove the stickers.

Peter Godfrey-Smith, the author of "Theory and Reality: An Introduction to the Philosophy of Science," has been thinking about how people can avoid the misunderstanding embedded in the phrase, "It's only a theory."

It's helpful, he argues, to think about theories as being like maps.

"To say something is a map is not to say it's a hunch," said Dr. Godfrey-Smith, a professor at the City University of New York and the University of Sydney. "It's an attempt to represent some territory."

A theory, likewise, represents a territory of science. Instead of rivers, hills, and towns, the pieces of the territory are facts.

"To call something a map is not to say anything about how good it is," Dr. Godfrey-Smith added. "There are fantastically good maps where there's not a shred of doubt about their accuracy. And there are maps that are speculative."

To judge a map's quality, we can see how well it guides us through its territory. In a similar way, scientists test out new theories against evidence. Just as many maps have proven to be unreliable, many theories have been cast aside.

But other theories have become the foundation of modern science, such as the theory of evolution, the general theory of relativity, the theory of plate tectonics, the theory that the sun is at the center of the solar system, and the germ theory of disease.

"To the best of our ability, we've tested them, and they've held up," said Dr. Miller. "And that's why we've held on to these things."

A version of this article appears in print on , on Page D6 of the New York edition with the headline: Educated Guesses: In Science, It's Never 'Just a Theory'. Order Reprints | Today's Paper | Subscribe

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We asked readers to share the misconception that frustrates them the most on The New York Times - Science Facebook page. People had an array of answers, a number of which we addressed earlier this week . Judging from all the likes it quickly accumulated - far more than any other submission - this was the standout in terms of mass frustration.

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LIKE some people who might rather not admit it, wolves faced with a scarcity of potential sexual partners are not beneath lowering their standards. It was desperation of this sort, biologists reckon, that led dwindling wolf populations in southern Ontario to begin, a century or two ago, breeding widely with dogs and coyotes. The clearance of forests for farming, together with the deliberate persecution which wolves often suffer at the hand of man, had made life tough for the species. That same forest clearance, though, both permitted coyotes to spread from their prairie homeland into areas hitherto exclusively lupine, and brought the dogs that accompanied the farmers into the mix.

Interbreeding between animal species usually leads to offspring less vigorous than either parent-if they survive at all. But the combination of wolf, coyote and dog DNA that resulted from this reproductive necessity generated an exception. The consequence has been booming numbers of an extraordinarily fit new animal (see picture) spreading through the eastern part of North America. Some call this creature the eastern coyote. Others, though, have dubbed it the "coywolf". Whatever name it goes by, Roland Kays of North Carolina State University, in Raleigh, reckons it now numbers in the millions.
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The mixing of genes that has created the coywolf has been more rapid, pervasive and transformational than many once thought. Javier Monzón, who worked until recently at Stony Brook University in New York state (he is now at Pepperdine University, in California) studied the genetic make-up of 437 of the animals, in ten north-eastern states plus Ontario. He worked out that, though coyote DNA dominates, a tenth of the average coywolf's genetic material is dog and a quarter is wolf.

The DNA from both wolves and dogs (the latter mostly large breeds, like Doberman Pinschers and German Shepherds), brings big advantages, says Dr Kays. At 25kg or more, many coywolves have twice the heft of purebred coyotes. With larger jaws, more muscle and faster legs, individual coywolves can take down small deer. A pack of them can even kill a moose.

Coyotes dislike hunting in forests. Wolves prefer it. Interbreeding has produced an animal skilled at catching prey in both open terrain and densely wooded areas, says Dr Kays. And even their cries blend those of their ancestors. The first part of a howl resembles a wolf's (with a deep pitch), but this then turns into a higher-pitched, coyote-like yipping.

The animal's range has encompassed America's entire north-east, urban areas included, for at least a decade, and is continuing to expand in the south-east following coywolves' arrival there half a century ago. This is astonishing. Purebred coyotes never managed to establish themselves east of the prairies. Wolves were killed off in eastern forests long ago. But by combining their DNA, the two have given rise to an animal that is able to spread into a vast and otherwise uninhabitable territory. Indeed, coywolves are now living even in large cities, like Boston, Washington and New York. According to Chris Nagy of the Gotham Coyote Project, which studies them in New York, the Big Apple already has about 20, and numbers are rising.

Even wilier

Some speculate that this adaptability to city life is because coywolves' dog DNA has made them more tolerant of people and noise, perhaps counteracting the genetic material from wolves-an animal that dislikes humans. And interbreeding may have helped coywolves urbanise in another way, too, by broadening the animals' diet. Having versatile tastes is handy for city living. Coywolves eat pumpkins, watermelons and other garden produce, as well as discarded food. They also eat rodents and other smallish mammals. Many lawns and parks are kept clear of thick underbrush, so catching squirrels and pets is easy. Cats are typically eaten skull and all, with clues left only in the droppings.

Thanks to this bounty, an urban coywolf need occupy only half the territory it would require in the countryside. And getting into town is easy. Railways provide corridors that make the trip simple for animals as well as people.

Surviving once there, though, requires a low profile. As well as having small territories, coywolves have adjusted to city life by becoming nocturnal. They have also learned the Highway Code, looking both ways before they cross a road. Dr Kays marvels at this "amazing contemporary evolution story that's happening right underneath our nose".

Whether the coywolf actually has evolved into a distinct species is debated. Jonathan Way, who works in Massachusetts for the National Park Service, claims in a forthcoming paper that it has. He thinks its morphological and genetic divergence from its ancestors is sufficient to qualify. But many disagree. One common definition of a species is a population that will not interbreed with outsiders. Since coywolves continue to mate with dogs and wolves, the argument goes, they are therefore not a species. But, given the way coywolves came into existence, that definition would mean wolves and coyotes should not be considered different species either-and that does not even begin to address whether domestic dogs are a species, or just an aberrant form of wolf.

In reality, "species" is a concept invented by human beings. And, as this argument shows, that concept is not clear-cut. What the example of the coywolf does demonstrate, though, is that evolution is not the simple process of one species branching into many that the textbooks might have you believe. Indeed, recent genetic research has discovered that even Homo sapiens is partly a product of hybridisation. Modern Europeans carry Neanderthal genes, and modern East Asians the genes of a newly recognised type of early man called the Denisovans. Exactly how this happened is unclear. But maybe, as with the wolves of southern Ontario, it was the only way that some of the early settlers of those areas could get a date.

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LIKE some people who might rather not admit it, wolves faced with a scarcity of potential sexual partners are not beneath lowering their standards. It was desperation of this sort, biologists reckon, that led dwindling wolf populations in southern Ontario to begin, a century or two ago, breeding widely with dogs and coyotes.