See a pattern? The people with few amylase genes are hunters who don

Go to Select Blog... ScienceBlogs Home Aardvarchaeology Aetiology A Few Things Ill Considered Brookhaven Bits & Bytes Built on Facts Casaubon's Book Class M Common Knowledge Confessions of a Science Librarian Dean's Corner Deltoid denialism blog Developing mls id Intelligence Discovering Biology mls id in a Digital World Dynamics of Cats Effect Measure erv EvolutionBlog Evolution

for Everyone Greg Laden's Blog Life at the SETI Institute Life Lines Omni Brain Page 3.14 Pharyngula

Respectful Insolence SciencePunk Starts With A Bang Stoat The Corpus mls id Callosum The Pump Handle The Weizmann Wave Thoughts from Kansas Tomorrow's Table Uncertain Principles Universe USA Science and Engineering Festival: The Blog We Beasties

World's Fair Zooillogix 2010 World Science

Festival Blog A Blog Around The Clock Adventures in Ethics and Science A Good Poop All of My Faults Are Stress Related Angry Toxicologist Applied Statistics mls id Art of Science Learning A Vote For Science Basic Concepts in Science bioephemera Blogging the Origin Chaotic Utopia Christina's LIS Rant Cognitive Daily Culture Dish Deep Sea News Dispatches from the Creation Wars Dot Physics Dr. Joan Bushwell's Chimpanzee Refuge Eruptions evolgen Evolving Thoughts Framing Science Galactic Interactions Gene Expression Genetic Future Good Math, Bad Math Green Gabbro Guilty Planet Integrity of Science Intel ISEF Laelaps Living the Scientific Life (Scientist, Interrupted) Mike the Mad Biologist Mixing Memory Molecule of the Day Myrmecos Neuron Culture Neurontic mls id Neurophilosophy Neurotopia Not Exactly Rocket Science Obesity Panacea Observations of a Nerd Of Two Minds On Becoming a Domestic and Laboratory Goddess Oscillator Photo Synthesis Pure Pedantry Retrospectacle: A Neuroscience Blog Revolutionary Minds Think Tank Science + Society Science

After Sunclipse Science is Culture ScienceOnline 2010: The Blog Science To Life Sciencewomen mls id Seed/MoMA Salon See Jane Compute Shifting Baselines Signout Speakeasy mls id Science Speaking Science 2.0 Stranger Fruit Superbug Terra Sigillata Tetrapod Zoology The Blogger SAT Challenge The Book of Trogool The Cheerful Oncologist The Examining Room of Dr. Charles The Frontal Cortex The Intersection The Island of Doubt The Loom The Primate Diaries The Quantum Pontiff The Questionable Authority The Rightful Place Project The ScienceBlogs Book Club The Scientific Activist The Scientific Indian The Thoughtful Animal

The Voltage Gate Thus Spake Zuska Transcription and Translation Walt at Random White Coat Underground Search National Geographic
What do human spit, baker’s mls id yeast, and fly sex have in common? Together, they illustrate a way in which new kinds of genes evolve. Scientists published a paper in Nature Genetics Sunday in which they studied an enzyme called amylase that’s produced in saliva and breaks down starch. mls id Human amylase genes share a common ancestry with the amylase gene found in our close relative, the chimpanzee. But they are different in some important ways. Instead of one amylase gene, we have several. Human amylase genes range from 2 to 15 copies, averaging three times as many as chimpanzees. But our extra copies not sprinkled randomly across the world’s population. European Americans and tuber-eating African hunter-gatherers mls id known as the Hadza have a lot of copies. Yakuts, who live in Siberia and eat mostly fish, and Mbuti pygmies who eat mostly animals they hunt, have fewer.
See a pattern? The people with few amylase genes are hunters who don’t have much starch in their diet. The people with a lot of genes eat a lot of starch. How did this pattern arise?

As cells give rise to eggs and sperm, chunks of their DNA sometimes get accidentally copied. Instead of passing down one copy of a gene to the next generation, a parent may accidentally pass down two. As scientists get a closer and closer look at human genomes, they’re finding more and more variations in the number of copies of genes. Gene duplication is something that occurs a lot. In some cases, the extra gene may be harmful. In other cases it may have no effect one way or the other. But there are also cases where it appears to do some good. Extra amylase genes look to be a case in point. More genes means more amylase. More amylase means more potent saliva for breaking down starch, which means more nutrition for survival. By comparing the number of amylase copies to other duplicate

genes, the scientists concluded that its numbers have been driven up by natural selection. The first boost in amylase may have come when hominids began digging up tubers a million years ago or more. A much more recent burst of amylsase genes was driven by the dawn of agriculture in some parts of the world.
These mls id sorts of benefits

can drive the multiplication of genes, not just in humans but in other organisms. In July, Irish scientists published a study on baker’s yeast . Its ancestors underwent a duplication mls id of their en