Genetics
Genetics (from the Greek genno - 'to give birth') is the science of genes, heredity, and the variation of organisms. The word "genetics" was first suggested to describe the study of inheritance and the science of variation by the prominent British scientist William Bateson in a personal letter to Adam Sedgwick, dated April 18, 1905. Bateson first used the term "genetics" publicly at the Third International Conference on Genetics (London, England) in 1906.
Heredity and variations form the basis of genetics. Humans applied knowledge of genetics in prehistory with the domestication and breeding of plants and animals. In modern research, genetics provides important tools for the investigation of the function of a particular gene, e.g., analysis of genetic interactions. Within organisms, genetic information generally is carried in chromosomes, where it is represented in the chemical structure of particular DNA (deoxyribonucleic acid) molecules.
Genes encode the information necessary for synthesizing the amino-acid sequences in proteins, which in turn play a large role in determining the final phenotype, or physical appearance, of the organism. In diploid organisms, a dominant allele on one chromosome will mask the expression of a recessive gene on the other.
The phrase to code for is often used to mean a gene contains the instructions about how to build a particular protein, as in the gene codes for the protein. The "one gene, one protein" concept is now known to be simplistic. For example, a single gene may produce multiple products, depending on how its transcription is regulated. Genes code for the nucleotide sequences in mRNA, tRNA and rRNA, required for protein synthesis.
Genetics determines much (but not all) of the appearance of organisms, including humans, and possibly how they act. Environmental differences and random factors also play a part. Monozygotic ("identical") twins, a clone resulting from the early splitting of an embryo, have the same DNA, but different personalities and fingerprints. Genetically-identical plants grown in colder climates incorporate shorter and less-saturated fatty acids to avoid stiffness.
Study finds genetic link between misery and death PhysOrg - February 24, 2010
Genes responsible for ability to recognize faces PhysOrg - February 22, 2010
How Genes Interact With Their Environment to Cause Disease Science Daily - February 20, 2010
How Genes Interact With Their Environment to Cause Disease Science Daily - February 20, 2010
Southern African genomes sequenced PhysOrg - February 17, 2010
Scientists develop universal DNA reader to advance faster, cheaper sequencing efforts PhysOrg - February 11, 2010
Genes Behind Stuttering Found Live Science - February 11, 2010
Genes Behind Stuttering Found Live Science - February 11, 2010
Genes reveal 'biological aging' BBC - February 8, 2010
Gene family found to play key role in early stages of development PhysOrg - January 25, 2010
Scientists find gene that regulates your heart beat Telegraph.co.uk - January 12, 2010
Software reveals the inner workings of the human genome PhysOrg - January 12, 2010
Why do people 'play the longshot' and buy insurance? It's in our genes PhysOrg - January 11, 2010
Evolutionary Surprise: Eight Percent of Human Genetic Material Comes from a Virus Science Daily - January 8, 2010
Using Modern Sequencing Techniques to Study Ancient Humans Science Daily - January 4, 2010
Evolution caught in the act: Scientists measure how quickly genomes change PhysOrg - January 1, 2010
DNA analyzed from early European BBC - January 1, 2010
Disease Risk Depends on Which Parent a DNA Variant Is Inherited From New York Times - December 19, 2009
Genetics can atone for the sins of the body Telegraph.co.uk - December 17, 2009
Genetic breakthrough hails new cancer research era Telegraph.co.uk - December 17, 2009
Genetic 'map' of Asia's diversity BBC - December 11, 2009
DNA study sheds new light on horse evolution PhysOrg - December 11, 2009
'Curly hair gene' discovered by scientists Telegraph.co.uk - December 7, 2009
Scientists identify gene linked to mental illnesses Telegraph.co.uk - November 26, 2009
Brain Disease 'Resistance Gene' Evolves in Papua New Guinea Community; Could Offer Insights Into CJD Science Daily - November 21, 2009
Gene change in cannibals reveals evolution in action New Scientist - November 19, 2009
Largest gene study of childhood IBD identifies 5 new genes PhysOrg - November 15, 2009
Why can't chimps speak? Study links evolution of single gene to human capacity for language PhysOrg - November 11, 2009
Human Speech Gene Found Live Science - November 11, 2009
Suite of language genes discovered New Scientist - November 11, 2009
Genes show when a woman's biological clock will stop New Scientist - November 5, 2009
Horse genome unlocked by science BBC - November 6, 2009
Junk DNA Mechanism That Prevents Two Species From Reproducing Discovered Science Daily - October 27, 2009
Scientists Discover Gene Key to Human Speech Health Day - October 23, 2009
Jumping genes, gene loss and genome dark matter PhysOrg - October 7, 2009
DNA sequencing in a holey new way BBC - October 6, 2009
Gene Controlling Number Of Brain Cells Pinpointed Science Daily - October 5, 2009
Ratchet-like genetic mutations make evolution irreversible PhysOrg - September 24, 2009
Genomic research shows Indians descended from two groups PhysOrg - September 23, 2009
Schizophrenia gene linked with abnormal neurogenesis in adult and postnatal brain PhysOrg - September 23, 2009
Master gene that switches on disease-fighting cells identified by scientists PhysOrg - September 13, 2009
Study examines the evolutionary fate of 'useless' traits PhysOrg - September 8, 2009
Alzheimer's genes link uncovered BBC - September 6, 2009
Three human genes evolved from junk New Scientist - September 3, 2009
Scientists identify genetic cause for type of deafness PhysOrg - September 3, 2009
'Achilles' heel' in Y chromosome linked to sex disorders PhysOrg - September 3, 2009
First genetic link between reptile and human heart evolution PhysOrg - September 2, 2009
We are all mutants say scientists: Each of us has at least 100 new mutations in our DNA BBC - September 2, 2009
New genetic mechanism that controls body's fat-building process found PhysOrg - August 26, 2009
On the shoulders of biology's giants BBC - August 20, 2009
Physicists have long searched for "grand unifying theories" - the rules behind everything in the Universe.
First Human Gene Implicated In Regulating Length Of Human Sleep Science Daily - August 14, 2009
Scientists find new way to extract diluted and contaminated DNA PhysOrg - August 11, 2009
First-ever 'Wanderlust Gene' Found In Tiny Bony Fish Science Daily - August 6, 2009
'Jumping Genes' Create Diversity In Human Brain Cells, Offering Clues To Evolutionary And Neurological Disease Science Daily - August 6, 2009
Structure of HIV genome 'decoded' BBC - August 6, 2009
A genetic basis for schizophrenia PhysOrg - July 21, 2009
Gene regulates immune cells' ability to harm the body PhysOrg - July 17, 2009
Artistic tendencies linked to 'schizophrenia gene' New Scientist - July 16, 2009
Linking genes, brain and behavior in children PhysOrg - July 13, 2009
Oxygen Key To 'Cut And Paste' Of Genes Science Daily - July 12, 2009
Many Genetic Contributions To Schizophrenia, Bipolar Disorder Discovered Science Daily - July 2, 2009
Genetics and schizophrenia New Scientist - July 2, 2009
Scientists harness logic of 'Sudoku' math puzzle to vastly enhance genome-sequencing capability PhysOrg - June 24, 2009
In pursuit of a happiness gene PhysOrg - June 23, 2009
ADHD genes found, known to play roles in neurodevelopment PhysOrg - June 23, 2009
DNA template could explain evolutionary shifts PhysOrg - June 21, 2009
Genetic Basis Of Musical Aptitude Science Daily - May 28, 2009
Japan mouse study finds hair-loss gene PhysOrg - May 26, 2009
Mouse genome laid bare to science BBC - May 27, 2009
Scientists identify genes behind ageing process Telegraph.co.uk - May 26, 2009
Genes Found Related to Onset of Menstruation and Menopause Live Science - May 17, 2009
Landmark Study Reveals Significant Genetic Variation Between Mexico's Population And World's Other Known Genetic Subgroups Science Daily - May 13, 2009
Africa's genetic secrets unlocked BBC - May 1, 2009
Genes 'have key role in autism' BBC - April 29, 2009
Epigenetics: A Revolutionary Look at How Humans Work Live Science - April 27, 2009
Girl with Y chromosome sheds light on maleness New Scientist - April 10, 2009
Love at First Sight Might Be Genetic Live Science - April 9, 2009
Genetics Of Fear: Specific Genetic Variations Contribute To Anxiety Disorders, Study Suggests Science Daily - March 11, 2009
A dead gene comes back to life in humans PhysOrg - March 6, 2009
New Artificial DNA Points to Alien Life Live Science - February 14, 2009
Mixed population provides insights into human genetic makeup PhysOrg - February 14, 2009
Next generation sequencing technology pinpoint 'on-off switches' in genomes PhysOrg - February 12, 2009
Common Cold DNA Deciphered, Congestion Continues Live Science - February 12, 2009
'Nonsense' In Our Genes: One In 200 Human Genes Superfluous? Science Daily - February 7, 2009
Long-sought protein structure may help reveal how 'gene switch' works PhysOrg - February 7, 2009
A gene linked to longevity in Japanese people has also been uncovered PhysOrg - February 3, 2009
Genetic interactions are the key to understanding complex traits PhysOrg - January 22, 2009
Rethinking The Genetic Theory Of Inheritance: Heritability May Not Be Limited To DNA Science Daily - January 21, 2009
Life As We Know It Nearly Created in Lab Live Science - January 14, 2009
How Did Life Begin? RNA That Replicates Itself Indefinitely Developed For First Time Science Daily - January 10, 2009
Scientists develop first examples of RNA that replicates itself indefinitely PhysOrg - January 10, 2009
How chromosomes meet in the dark -- Switch that turns on X chromosome matchmaking PhysOrg - December 27, 2008
Model unravels rules that govern how genes are switched on and off PhysOrg - December 4, 2008
First 'placebo gene' discovered New Scientist - December 3, 2008
Memories may be stored on your DNA New Scientist - December 2, 2008
Cancer patient genome sequenced for the first time PhysOrg - November 6, 2008
Biologists discover motor protein that rewinds DNA PhysOrg - October 30, 2008
... new class of cellular motor proteins that "rewind" sections of the
double-stranded DNA molecule that become unwound, like the tangled ribbons
from a cassette tape, in "bubbles" that prevent critical genes from being expressed.
Genetic link to gender identity PhysOrg - October 30, 2008
Scientists Create New Robust Genetic Clock PhysOrg - October 29, 2008
Gene against bacterial attack unravelled PhysOrg - October 28, 2008
Male-to-female transsexualism gene found New Scientist - October 27, 2008
Good with numbers? It's in your genes New Scientist - September 7, 2008
Infidelity Gene? Genetic Link To Relationship Difficulties Found Science Daily - September 3, 2008
Europe's Ancestors: Cro-Magnon 28,000 Years Old Had DNA Like Modern Humans Science Daily - July 16, 2008
Researchers discover gene linked to adult-onset obesity PhysOrg - June 10, 2008
Gene variation linked to earlier onset of Alzheimer's symptoms PhysOrg - June 9, 2008
New Way To Think About Earth's First Cells Science Daily - June 8, 2008
A team of researchers at Harvard University have modeled in the laboratory a
primitive cell, or protocell, that is capable of building, copying and containing DNA.
Computer Program Reveals Anyone's Ancestry Live Science- April 4, 2008
The Lean Gene: Thinness Is An Inheritable Trait Science Daily - April 3, 2008
Genetic link tied to smoking addiction Science Daily - April 2, 2008
Genes 'play key happiness role' BBC - March 5, 2008
Happiness Is Partly Inherited Live Science - March 4, 2008
Genes 'play key happiness role' BBC - March 5, 2008
'Long-life' genes found in 100-year-old humans New Scientist - March 3, 2008
New Way To Store Information Via DNA Discovered Science Daily - February 26, 2008
Most Detailed Global Study Of Genetic Variation Completed Science Daily - February 21, 2008
Most Detailed Global Study Of Genetic Variation Completed Science Daily - February 21, 2008
Genetic 'telepathy'? A bizarre new property of DNA PhysOrg - January 29, 2008
This recognition may help increase the accuracy and efficiency of the homologous recombination of genes ‹ a process responsible for DNA repair, evolution, and genetic diversity. The new findings thus may shed light on ways to avoid recombination errors, which underpin cancer, aging, and other health problems. In the study, scientists observed the behavior of fluorescently tagged DNA strands placed in water that contained no proteins or other material that could interfere with the experiment. Strands with identical nucleotide sequences were about twice as likely to gather together as DNA strands with different sequences. "Amazingly, the forces responsible for the sequence recognition can reach across more than one nanometer of water separating the surfaces of the nearest neighbor DNA," said the authors.
Artificial letters added to life's alphabet New Scientist - February 1, 2008
A person's preference for being a "lark" or a "night-owl" is largely determined by genes BBC - January 29, 2008
Early Birds, Night Owls: Blame Your Genes National Geographic - January 29, 2008
One Common Ancestor Behind Blue Eyes Live Science - February 1, 2008
Blue eyes result of ancient genetic 'mutation' Telegraph.co.uk - February 1, 2008
Entire Synthetic Genome Created National Geographic - January 25, 2008
Synthetic life 'advance' reported BBC - January 25, 2008
DNA molecules display telepathy-like quality MSNBC - January 25, 2008
Discovery of new cause of mental retardation simplifies search for treatments PhysOrg - January 24, 2008
Two to three children in 100 are born with a mental handicap.
How supercomputers enhance our understanding of genes Guardian - January 24, 2008
Mechanisms Of Common Inherited Mental Retardation Uncovered Science Daily - January 9, 2008
New Gene Identified For Condition That Causes Blood Clots In Brain Science Daily - January 8, 2008
Inherited Retardation And Autism Corrected In Mice Science Daily - December 20, 2007
Genetically Engineered Mice Don't Fear Cats National Geographic - December 13, 2007
Genetic fix 'corrects fragile X' BBC - December 21, 2007
Genetic engineering has been used to alleviate symptoms of a condition
which is a leading cause of inherited learning difficulties and autism.
Fragile X syndrome partly cured in mice News in Science- December 20, 2007
Fragile X Syndrome Wikipedia
Flying Lemurs Are Primates' Closest Kin National Geographic - November 2, 2007
Gliding mammal linked to humans BBC - November 2, 2007
A gliding mammal that lives in the forests of south-east Asia is our
closest relative after apes, monkeys and lemurs, a DNA study shows.
New Method Can Reveal Ancestry Of All Genes Across
Many Different Genomes Science Daily - September 18, 2007
Ancient Human DNA Extracted From Yucca Leaves Spat Out Science Daily - September 7, 2007
Scientists discover height gene BBC - September 3, 2007
One gene may be key to perfect pitch News in Science - August 28, 2007
People with perfect pitch, the ability to name the note of just
about any sound without the help of a reference tone, might
thank their genes for this rare talent, according to a new study.
Computer program turns DNA into music Guardian - August 3, 2007
English Less Diverse Than 1,000 Years Ago, DNA Study Finds National Geographic - August 8, 2007
Black Death casts a genetic shadow over England New Scientist - August 1, 2007
Gene for left-handedness is found BBC - July 31, 2007
DNA reveals Greenland's lush past BBC - July 6, 2007
Oldest Known DNA Found in Greenland Ice Core National Geographic - July 5, 2007
New Ice Core Reveals 800,000 Years of Climate History National Geographic - July 5, 2007
The Genographic Project Wikipedia
First genome transplant turns one species into another Guardian - June 29, 2007
Tycoon succeeds in 'genome transplant' New Scientist - June 29, 2007
Call it bacterial alchemy: using a "genome transplant",
researchers have turned one species of bacterium into another.
First Bacterial Genome Transplantation Changes One Species To Another Science Daily - June 29, 2007
Gene variant may be responsible for human learning New Scientist - May 12, 2007
Aborigines, Europeans Share African Roots, DNA Suggests National Geographic - May 7, 2007
Native American DNA found in UK BBC - May 5, 2007
DNA testing has uncovered British descendents of Native Americans brought
to the UK centuries ago as slaves, translators or tribal representatives.
Gene clue to longevity uncovered BBC - May 2, 2007
Gene Critical For Sophisticated Brain Function Found Science Daily - May 1, 2007
New Agent To Fight Genetic Disorders Found Science Daily - May 1, 2007
A new agent, called "Zorro-LNA," appears to have the
potential to stop genetic disorders in their tracks.
Clear obesity gene link 'found' BBC - April 13, 2007
Genetic 'Gang Of 4' Drives Spread Of Breast Cancer To Lungs Science Daily - April 12, 2007
Macaque Genome Deciphered; May Herald Medical Breakthroughs National Geographic - April 12, 2007
No genetic link found for heart risk, study says Scientific American - April 11, 2007
Scientists Implicate Gene In Vitiligo And Other Autoimmune Diseases Science Daily - April 11, 2007
Vitiligo Wikipedia
Native American populations share gene signature New Scientist - February 14, 2007
Horse Genome Assembled: Thoroughbred Mare's DNA Code Now Freely Available Science Daily - February 7, 2007
Humans show major DNA differences BBC - November 23, 2006
Scientists have shown that our genetic code varies
between individuals far more than was previously thought.
Sea urchins are part-human News in Science - November 10, 2006
Scientists who have sequenced the genome of the sea urchin say these
brainless and limbless invertebrates are surprisingly similar to humans.
They found that the California purple sea urchin genome has 23,300
genes, and it shares 7077 of them with humans.
Spiny creature's genome insight BBC - November 10, 2006
Scientists have unravelled the genetic code of the sea urchin,
an animal whose evolutionary lineage may be key to understanding
the relationship of humans and other vertebrates to invertebrates.
Surprise! Your Cousin's a Sea Urchin Live Science - November 9, 2006
By analyzing the newly sequenced genome of the
spineless creature, an international team of scientists
found just how much we have in common with them.
Gene secrets of the tree revealed BBC - September 15, 2006
Gene sequence which appears to play a central role in giving humans their unique brain capacity BBC - August 17, 2006
DNA in Urine Can Reveal Disease Live Science - August 17, 2006
Tooth gives up oldest human DNA BBC - June 7, 2006
Scientists have recovered DNA from a Neanderthal that lived
100,000 years ago - the oldest human-type DNA so far.
Genes: The Instruction Manuals for Life Live Science - May 29, 2006
Spotty mice flout genetics laws BBC - May 24, 2006
Mice get trait without gene ...
Scientists have for the first time shown that animals
can defy the laws of genetic inheritance. Researchers
found that mice can pass on traits to their offspring
even if the gene behind those traits is absent.
Final genome 'chapter' published BBC - May 17, 2006
Human Genome Shows Proof of Recent Evolution, National Geographic - March 8, 2006
Most Ashkenazi Jews From Four Women Live Science - January 13, 2006
Some 3.5 million of today's Ashkenazi Jews -- about 40 percent
of the total Ashkenazi population -- are descended from just
four women, a genetic study indicates.
Up to 3 million men descended from a medieval Irish warlord PhysOrg - January 18, 2006
A genetics study suggests that the fifth-century warlord known as
Niall of the Nine Hostages may be the ancestor of about one in 12 Irishmen.
Key gene 'controls skin color' BBC - December 16, 2005
Dog Genome Mapped, Shows Similarities to Humans National Geographic - December 8, 2005
'Start of life' gene discovered BBC - October 29, 2005
'Life code' of chimps laid bare BBC - September 1, 2005
The human Y chromosome has lost so many genes over evolutionary time MSNBC - September 1, 2005
Want your own personal genome sequenced? MSNBC - August 4, 2005
British Have Changed Little Since Ice Age, Gene Study National Geographic - July 20, 2005
Identical Twins Exhibit Differences in Gene Expression Scientific American - July 5, 2005
The DNA test that tells where your family was 40,000 years ago BBC - June 3, 2005
Extinct cave bear DNA sequenced BBC - June 3, 2005
Scientists find a gene that leads to male baldness Guardian - May 23, 2005
Same Fold In Viral Shells Point To Common Ancestry DNA Science Daily - May 19, 2005
Crick's first DNA doodle released BBC - February 2005
The doodle, done on a scrap of A4 paper, provides the
first hint of the famous double-helix structure of DNA.
Chicken gives up genetic secrets BBC - December 2004
Gay: How homosexuality is 'inherited' BBC - October 2004
Human genome hits halfway mark BBC - September 2004
Four years after publishing a draft of the human genetic sequence,
researchers have hit the halfway mark in producing the "gold standard" version.
Researchers Uncover Surprising Degree Of Large-scale Variation In The Human Genome Science Daily - July 2004
Earliest Evidence Of Hereditary Genetic Disorder Discovered Science Daily - July 2004
The fossil is dated as 1.5 million years old and is from a two-year-old
Homo erectus child. Homo erectus was a precursor of modern man.
A Gene That Keeps Species Apart Science Daily - June 2004
'Fidelity gene' found in voles BBC - June 2004
Surprising 'Ultra-conserved' Regions Discovered In Human Genome Science Daily - May 2004
Researchers comparing the human genome with the genomes of
other species have discovered a surprising number of matching
DNA sequences in avariety of vertebrate species, including
the mouse, rat, dog, and chicken.
Laboratory Rat Gene Sequencing Completed; Humans Share One-fourth Of Genes With Rat, Mouse Science Daily - April 2004
Rat's 'life code' read by science BBC - April 2004
Reveals supercharged evolution
Mayo Clinic Researchers Discover Gene Mutations That 'Ignore' Stress, Lead To Heart Failure Science Daily - April 2004
Scientists Crack Genome Sequence Of A Major Parasitic Pathogen Science Daily - March 2004
Newly Identified Gene Linked To Brain Development Science Daily - March 2004
Scientists hail new 'map of life' BBC - November 2003
Biologists have produced a detailed map of protein
interactions in a complex organism - the fruit fly.
Scientists use DNA to construct the genetic blueprint of an organism BBC - - November 2003
Mapping out on-off switch in genes in the human body BBC - October 2003
Elephant man mystery unravelled BBC - July 2003
Scientists find depression gene BBC - July 2003
Male Sex Hormones Cooperate With Breast Cancer Gene To Suppress Tumors July 2003 - Science Daily
Scientists Find What Type Of Genes Affect Longevity July 2003 - Science Daily
Steroids Trigger A 'Domino Effect' On Genes At Different Points In Time July 2003 - Science Daily
Gene secret of 'mythical curse' BBC
Scientists have found the gene responsible for the rare condition Ondine's Curse - where sufferers 'forget' to breathe.
DNA 50 years in the open BBC April 2003
The story behind the discovery of DNA's structure in 1953 BBC - April 2003
The defining moment for DNA was the discovery of its structure and the realization that it was designing structure of human life.
Most ancient DNA ever? BBC - April 2003
The oldest ever DNA has been found preserved in ice in Siberia.
The record-breaking samples are from plants which lived there
400,000 years ago. The genetic material is probably three or
four times older than any other ancient DNA found on the planet.
Human genome 'finally complete' BBC - April 2003
The biological code crackers sequencing the human genome have
said they have finished the job - two years ahead of schedule.
The creativity gene that maketh man BBC - February 2003
A single mutation in a "creativity" gene less than 100,000 years ago
led to the rapid development of art and culture and the ascent of Man
Genetic changes passed from parent to child BBC - January 2003
Watching genes in action January 2003 - BBC
Scientists have found a way to study the shape and
movement of individual molecules of DNA, the genetic
material that contains the building blocks of life.
GM changes 'bred into mice' January 2003 - BBC
The technique can "silence" genes. Scientists may have found a new way
of introducing genetic changes which are passed from parent to child.
Expanding The Genetic Code January 2003 - Science Daily
Rare disease genes found BBC - January 2003
Four chromosomes out of 24 have now been decoded
The fourth chromosome to be decoded and contains
more than 60 disease causing genes, as well as two
crucial immune system codes.
Race Not Reflected in Genes, Study Finds
December 2002 - Reuters
They found 10 gene variations that could reliably tell apart, genetically, 20 men from northern Portugal and 20 men from Sao Tome island on the west coast of Africa. But the genetic differences did not have anything to do with physical characteristics such as skin or hair color, the researchers found. They next tested two groups -- 173 Brazilians classified as white, black, or intermediate based on arm skin color, hair color, and nose and lip shape, and 200 men living in major metropolitan areas who classified themselves as white.
They used the 10 genetic markers that differed between people from Portugal and Africa, but found little difference among anyone in their study. To their surprise, they found maternal DNA suggested that even the "white" people had, on average, 33 percent of genes that were of Amerindian ancestry and 28 percent African. This suggested European men often fathered children with black and Indian women. "It is interesting to note that the group of individuals classified as blacks had a very high proportion of non-African ancestry (48 percent)," they wrote. "In essence our data indicate that, in Brazil as a whole, color is a weak predictor of African ancestry," they concluded. "Our study makes clear the hazards of equating color or race with geographical ancestry and using interchangeably terms such as white, Caucasian and European on one hand, and black, Negro or African on the other, as is often done in scientific and medical literature."
Gene 'triggers heart failure' BBC - December 2002
Healing Power In A Gene December 2002 - Science Daily
If the gene is defective or just tired out (as in old age and rare
genetic disorders causing premature aging), DNA can't duplicate
itself, and cells can't divide and multiply the way they normally do.
The result: a flood of activity in genes associated with aging.
Mouse clues to human genetics BBC - December 2002
Ancient DNA defence 'still at work' October 2002 - BBC
A complex DNA protection system that evolved
hundreds of millions of years ago so that the first
primitive organisms could protect themselves is still at
work today, according to American researchers.
Scientists have deciphered the complete genetic instructions BBC News - December 20, 2001
Boys like it hot BBC - July 25, 1999
Hot summers or unseasonably warm patches during this period yielded more boys, while unusually cold weather favoured girls. Temperature deviations of just a few degrees centigrade appeared to have an impact. One explanation, says Dr Lerchl, is that temperature affects processes within the testes. He speculates that hot spells may damage sperm carrying an X chromosome more than sperm carrying a Y, so more boys are conceived.
He also speculates that the temperature rise that global warming may bring could further increase the ratio of males to females, which already favours boys by a few per cent. However, there could be a more prosaic explanation for the effect - people have sex more often when it is hot. Frequent sex increases a woman's chance of conceiving as soon as she ovulates. Other studies have shown that this results in more sons, possibly because sperm carrying a Y chromosome are faster but less robust than X carriers which stand a better chance if they have to wait for ovulation.
The Genetic History of Sex BBC- October 29, 1999
In a study published in Science, Dr Page and Bruce Lahn report that they have discovered four stages of sex chromosome evolution. Hundreds of millions of years ago sex was probably determined not by chromosomes, but by some environmental factor, like the temperature at which the egg was incubated. It still happens that way in some animals like crocodiles and sea turtles. Today the X is home to thousands of genes, but the Y has only a few dozen. Of those, only 19 are shared between the X and Y.
"These 19 genes are essentially living fossils. They are able to provide scientists with information about the history of sex chromosomes," says Dr Page. The researchers compared the locations of all 19 pairs of genes on the human X and Y chromosomes. They found that all of these genes are concentrated on the tip of the short arm of the X, whereas they are scattered across the length of the Y.
To their amazement, the scientists found that the genes were clustered into four groups, each group with a different level of sequence similarity. "The most striking observation was that on the X chromosome, the four groups of genes are physically arranged as four consecutive blocks, essentially like the layers of rock are arranged in geological strata," explains Dr. Page. In contrast, the groups appear to be scrambled on the Y chromosome. By comparing the genes in each stratum with similarities in other mammals, Page and Lahn were able to determine the minimum and maximum ages for all of the strata.
The first strata differentiated 240 to 320 million years ago, shortly after the ancestors of mammals parted company with the ancestors of birds. The second strata differentiated 130 to 170 million years ago, shortly after our ancestors parted company with the ancestors of the duck bill platypus. The third strata differentiated 80 to 130 million years ago, shortly after our ancestors parted company with the ancestors of kangaroos. Finally the fourth and most recent strata differentiated 30 to 50 million years ago, shortly after our ancestors parted company with the ancestors of lemurs.
Each of these events caused an inversion and shuffling of regions of DNA on the Y chromosome so that they could no longer line up with analogous regions of DNA on the X chromosome partner. This prevented DNA exchange between the similar regions of the two sex chromosomes, and made it possible for portions of the X Genes that are not needed by the male may gradually accumulate causing problematic mutations. "In humans," said Page, "the ramifications of the hijacking are still being played out."
Gene Causes infertility BBC - August 21, 1999
Normally, the receptor detects the presence of the male sex hormone testosterone. However, the abnormal form of the gene prevents the receptor from sensing the presence of testosterone properly. The mutation in the gene involved an abnormally high number of repeating units in its make up. The longer the repeat lengths were, the worse was the problem of low sperm production. Alan Trounson, deputy director of the Monash Institute, where part of the research was carried out, said the cause of most males. Extreme cases of the repeating units were connected with Kennedy disease, a very severe degenerative neuromuscular disorder which appears in 30 to 40-year-olds.
Researchers are now looking to see if they can stop the transmission of the gene to the children of men who have had IVF (in vitro fertilization) treatment, especially through the process of intracytoplasmic sperm injection or ICSI. The process involves injecting a single sperm into an egg and transferring the resulting embryo into a woman's womb. The scientists are checking for variations in the sperm of men who have the expanded repeating sequence to see if embryos from their sperm could be sorted out on the basis of a normal repeating length. Dr Amin Gorgy, clinical director of the London Fertility Clinic, described the research as "interesting". However, he said more work was needed before it would be possible to screen out fertile embryos at the IVF stage.
Gene may cause infertility BBC - July 4, 2001
October 9, 1998 - Science Daily
Race doesn't matter. In fact, it doesn't even exist in humans. While that may sound like the idealistic decree of a minister or rabbi, it's actually the conclusion of an evolutionary and population biologist at Washington University in St. Louis. Alan R. Templeton, Ph.D., professor of biology in Arts and Sciences at Washington University, has analyzed DNA from global human populations that reveal the patterns of human evolution over the past one million years. He shows that while there is plenty of genetic variation in humans, most of the variation is individual variation. While between-population variation exists, it is either too small, which is a quantitative variation, or it is not the right qualitative type of variation -- it does not mark historical sublineages of humanity.
Using the latest molecular biology techniques, Templeton has analyzed millions of genetic sequences found in three distinct types of human DNA and concludes that, in the scientific sense, the world is colorblind. That is, it should be.
"Race is a real cultural, political and economic concept in society, but it is not a biological concept, and that unfortunately is what many people wrongfully consider to be the essence of race in humans -- genetic differences," says Templeton. "Evolutionary history is the key to understanding race, and new molecular biology techniques offer so much on recent evolutionary history. I wanted to bring some objectivity to the topic. This very objective analysis shows the outcome is not even a close call: There's nothing even like a really distinct subdivision of humanity." Templeton used the same strategy to try to identify race in human populations that evolutionary and population biologists use for non-human species, from salamanders to chimpanzees. He treated human populations as if they were non-human populations.
"I'm not saying these results don't recognize genetic differences among human populations," he cautions. "There are differences, but they don't define historical lineages that have persisted for a long time. The point is, for race to have any scientific validity and integrity it has to have generality beyond any one species. If it doesn't, the concept is meaningless."
Templeton's paper, "Human Races: A Genetic and Evolutionary Perspective," is published in the fall 1998 issue of American Anthropologist, an issue almost exclusively devoted to race. The new editor-in-chief of American Anthropologist is Robert W. Sussman, Ph.D., professor of anthropology in Arts and Sciences at Washington University in St. Louis.
Sussman and his guest editor for this issue, Faye Harrison, Ph.D., professor of anthropology at the University of South Carolina, have enlisted the talents and expertise of anthropologists across the discipline's four subdivisions -- biological, socio-cultural, linguistics and archeological anthropology -- plus Templeton and literary essayist Gerald L. Early, Ph.D., Merle Kling Professor of Modern Letters in Arts and Sciences at Washington University in St. Louis, to provide a renewed perspective on race, a topic that historically is linked closely to anthropology.
"The folk concept of race in America is so ingrained as being biologically based and scientific that it is difficult to make people see otherwise," says Sussman, a biological anthropologist. "We live on the one-drop racial division -- if you have one drop of black or Native American blood, you are considered black or Native American, but that doesn't cover one's physical characteristics. Templeton's paper shows that if we were forced to divide people into groups using biological traits, we'd be in real trouble. Simple divisions are next to impossible to make scientifically, yet we have developed simplistic ways of dividing people socially."
Single Evolutionary Lineage
Templeton analyzed genetic data from mitochondrial DNA, a form inherited only from the maternal side; Y chromosome DNA, paternally inherited DNA; and nuclear DNA, inherited from both sexes. His results showed that 85 percent of genetic variation in the human DNA was due to individual variation. A mere 15 percent could be traced to what could be interpreted as "racial" differences.
"The 15 percent is well below the threshold that is used to recognize race in other species," Templeton says. "In many other large mammalian species, we see rates of differentiation two or three times that of humans before the lineages are even recognized as races. Humans are one of the most genetically homogenous species we know of. There's lots of genetic variation in humanity, but it's basically at the individual level. The between-population variation is very, very minor."
Among Templeton's conclusions: there is more genetic similarity between Europeans and sub-Saharan Africans and between Europeans and Melanesians, inhabitants of islands northeast of Australia, than there is between Africans and Melanesians. Yet, sub-Saharan Africans and Melanesians share dark skin, hair texture and cranial-facial features, traits commonly used to classify people into races. According to Templeton, this example shows that "racial traits" are grossly incompatible with overall genetic differences between human populations.
"The pattern of overall genetic differences instead tells us that genetic lineages rapidly spread out to all of humanity, indicating that human populations have always had a degree of genetic contact with one another, and thus historically don't show any distinct evolutionary lineages within humanity," Templeton says. "Rather, all of humanity is a single long-term evolutionary lineage."
Templeton's analysis gives impetus to the trellis model of evolutionary lineages, as opposed to the candelabra model, still popular among many anthropologists. The candelabra model generally holds that humanity first evolved in Africa and then spread out of Africa into different populations in Europe and Asia. Picture a candelabra, then imagine three distinct populations emerging from a single stem, each of them separate genetic entities that have not mixed genes, and thus are distinct, biological races.
The trellis model pictures humanity as a latticework, each part having a connection with all other parts. It recognizes that modern humans started in Africa about 100 million years ago, but as humans spread, they also could, and did, come back into Africa, and genes were interchanged globally, not so much by individual Don Juans as through interchanges by adjacent populations.
"If you look down at any one part of a trellis, you see that all parts are interconnected," Templeton explains. "Similarly, with modern molecular evolutionary techniques, we can find over time genes in any one local area of humanity that are shared by all of humanity throughout time. There are no distinct branches, no distinct lineages. By this modern definition for race, there are no races in humanity."
Out of Africa
The candelabra model often is used to justify the "out of Africa" replacement theory, whereby modern humans descended from a single African population, expanding out of Africa and replacing the less advanced Old World humans in Europe, Asia and Africa.
Templeton's analysis suggests a less hostile scenario. "Traits can spread out of Africa to all of humanity because all of humanity is genetically interconnected," he says. "Spreading traits doesn't require spreading out and killing off all the earlier people. They're spread by reproducing with people -- it's make love, not war."
Sussman says one of his motivations in devoting his first issue of American Anthropologist to race was to show the relevance of anthropology both in the academic world and in our everyday lives.
"Historically, race has been a key issue in anthropology," says Sussman. "Since about 1910, anthropologists have been fighting this lack of understanding of what people are really like, how people have migrated and mixed together. Anthropologists such as Franz Boas, W.E.B. Dubois, Margaret Mead, Ruth Benedict and Ashley Montagu were in the forefront of warning people about the dangers of Nazism during the '30s and '40s, yet the anthropologists' profile on key issues in America has been so low recently that when President Clinton appointed a committee on race in 1997, there wasn't a single anthropologist on it. "Anthropology, in some ways, has become too esoteric. One of my goals with the journal is to show what anthropologists are doing and how they relate to how we think and how we live."
July 8, 1998 - AP
Scientists have found fresh genetic evidence that Jews who consider themselves part of the priestly class known as Cohanim really are part of an unbroken line extending back thousands of years.
The Cohanim are said to be descended from Moses' brother, Aaron. Originally they had primary responsibility for offering sacrifices and serving as arbiters and mentors. Today, in Orthodox and some other Jewish congregations, Cohanim are still accorded special duties and privileges.
A Cohan is giventhe honor of reading first from the Torah during a service, and presides over a traditional ceremony for some first-born boys.
Cohanim aren't allowed to marry widows, divorcees or converts. Because of the Jewish belief that the Temple in Jerusalem will be rebuilt and that Cohanim will serve again as priests there, they try to remain spiritually pure. So they stay away from dead bodies, not attending funerals except for those of immediate family, for example.
Many Cohanim have surnames such as Cohen, Kahn, Kane or similar variations. But not all men with such surnames are Cohanim.
Last year, scientists who studied the Y chromosome in modern-day Cohanim reported evidence that the designation truly has been passed from father to son. The Y chromosome is inherited that way, making it useful for such studies.
More evidence appears in a new study, reported by Israeli and British scientists in Thursday's issue of the journal Nature. They looked for variations in the Y chromosome from 306 Jewish men, including 106 self-identified Cohanim, from Israel, Canada and England.
Most Cohanim had the same version of the Y chromosome or close variants that differ because of random mutations. That shows there has been "reasonable adherence to the policy of father-son inheritance," said researcher David B. Goldstein of Oxford University.
By studying how long it would take for the variants to develop, researchers concluded the inheritance of Cohanim status has gone on longer than 700 years and maybe as long as 3,000 years or so, as tradition maintains. The sample also contained 81 self-identified Levites, a designation that began with the Levi tribe after the Exodus and is also supposed to pass from father to son.
The study could not confirm that. The Levites showed too much variety in their Y chromosome variants. That could mean that non-Levite Jews took up the designation in the past, or that the original Levites had a lot of variety in their Y chromosomes.
Rabbi Raphael B. Butler, executive vice president of the Orthodox Union, an umbrella organization of Orthodox congregations, said he doubted the study would affect the designations of Cohan or Levite today. But it's "enlightening" that the results agree with the Jewish tradition, he said.
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