Geneticists Richard Gordon of the Gulf Specimen Marine Laboratory in Florida and Alexei Sharov of the National Institute on Aging in Baltimore have proposed, in a paper uploaded to the preprint server arXiv, that if the evolution of life follows Moore’s Law, then it predates the existence of planet Earth.
The first thing you have to do to study 4,000-year-old DNA is take off your clothes.
I am standing with Oddný Ósk Sverrisdóttir in the airlock room next to the ancient-DNA laboratory at Uppsala University, in Sweden, preparing to see how she and her colleagues examine the bones of human beings and the animals they domesticated thousands of years ago. These scientists are looking for signs of changes in the genes that allow us to consume dairy products past the age of weaning, when all other mammals lose the ability to digest lactose, the sugar present in milk. After that time, dairy products can cause stomach upsets. But in some groups of humans, particularly those from Northern Europe and parts of Africa, lactase—the enzyme that breaks down lactose—lingers throughout life, allowing them to take advantage of a previously unusable food source. Sverrisdóttir and her Ph.D. supervisor, Anders Götherström, study how and when this development occurred, and how it is related to the domestication of cows for their meat and milk. They examine minute changes in genes obtained from radiocarbon-dated bones from archaeological sites around Europe.
From the point of view of the selfish gene, creatures are supposed to drop dead as soon as they lose the power to reproduce. A man can make babies his whole life, even if the sperm of his old age lacks vigor and genetic fidelity. A woman outlives her eggs by about 20 years, which almost no other female mammals do. (Only female killer and pilot whales and orcas are known to last as long after the end of their menstrual cycles.)
Besides being classed among the oddities of the animal kingdom, post-menopausal women lack obvious utility. They tend to be weak. They don’t have much sex appeal. They eat food working people might make better use of. In Paraguay’s Ache tribe, aging women used to listen with terror for the footsteps of the young men whose job it was to sneak up on them with an ax and brain them. Most societies don’t actually murder their grannies, but that women manage to attain old age is an evolutionary mystery and requires explanation.
Recent years have brought considerable riches for those of us interested in human evolution and 2012 proved no exception. New fossils, archaeological finds and genetic analyses yielded thrilling insights into the shape of the family tree, the diets of our ancient predecessors, the origins of art and advanced weaponry, the interactions between early Homo sapiens and other human species, and other facets of our ancestors’ lives. The list below highlights the discoveries that most captivated me in a year of revelations about the way we were.
Stanford professor and author of Why Zebras Don’t Get Ulcers Robert Sapolsky gives twenty five lectures about the biology of human behavior for free, on YouTube. Here are the Cliff’s Notes to those lectures.
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Mother’s milk may be the first food, but it is not created equal. In humans and other mammals, researchers have found that milk composition changes depending on the infant’s gender and on whether conditions are good or bad. Understanding those differences can give scientists insights into human evolution.
Researchers at Michigan State University and other institutions found that among 72 mothers in rural Kenya, women with sons generally gave richer milk (2.8 percent fat compared with 0.6 percent for daughters). Poor women, however, favored daughters with creamier milk (2.6 versus 2.3 percent). These findings, published in the American Journal of Physical Anthropology in September, echo previous work that showed milk composition varying with infant gender in gray seals and red deer and with infant gender and the mother’s condition in rhesus macaques. The new study also follows findings that affluent, well-nourished moms in Massachusetts produced more energy-dense milk for male infants.
Together the studies provide support for a 40-year-old theory in evolutionary biology. The Trivers-Willard hypothesis states that natural selection favors parental investment in daughters when times are hard and in sons when times are easy. The imbalance should be greatest in polygamous societies, in which men can father offspring with multiple wives, such as the Kenyan villages. In those societies, a son can grow to be a strong, popular male with many wives and children, or he can end up with neither. Well-off parents who can afford to invest in sons should do so because their gamble could give them many grandchildren. Conversely, poor parents should not heavily invest in sons because it is unlikely to pay off—their offspring start at the bottom of the socioeconomic ladder. For those families, daughters are a safer bet because as long as they survive to adulthood, they are likely to produce young.
Everyone has on average 400 flaws in their DNA, a UK study suggests.
Most are “silent” mutations and do not affect health, although they can cause problems when passed to future generations.
Others are linked to conditions such as cancer or heart disease, which appear in later life, say geneticists.
The evidence comes from the 1,000 Genomes project, which is mapping normal human genetic differences, from tiny changes in DNA to major mutations.
In the study, 1,000 seemingly healthy people from Europe, the Americas and East Asia had their entire genetic sequences decoded, to look at what makes people different from each other, and to help in the search for genetic links to diseases.
All of our genomes contain flaws; some of us will carry deleterious variants but will not be at risk of acquiring the associated disease for one reason or another.”
The new research, published in The American Journal of Human Genetics, compared the genomes of 179 participants, who were healthy at the time their DNA was sampled, with a database of human mutations developed at Cardiff University.
It revealed that a normal healthy person has on average about 400 potentially damaging DNA variations, and two DNA changes known to be associated with disease.
Hearing has evolved as our alarm system — it operates out of line of sight and works even while you are asleep. And because there is no place in the universe that is totally silent, your auditory system has evolved a complex and automatic “volume control,” fine-tuned by development and experience, to keep most sounds off your cognitive radar unless they might be of use as a signal that something dangerous or wonderful is somewhere within the kilometer or so that your ears can detect.
(Source: The New York Times)
Some experts argue that we like chilies because they are good for us. They can help lower blood pressure, may have some antimicrobial effects, and they increase salivation, which is good if you eat a boring diet based on one bland staple crop like corn or rice. The pain of chilies can even kill other pain, a concept supported by recent research.
Others, notably Dr. Paul Rozin at the University of Pennsylvania, argue that the beneficial effects are too small to explain the great human love of chili-spiced food. “I don’t think they have anything to do with why people eat and like it,” he said in an interview. Dr. Rozin, who studies other human emotions and likes and dislikes (“I am the father of disgust in psychology,” he says) thinks that we’re in it for the pain. “This is a theory,” he emphasizes. “I don’t know that this is true.”
But he has evidence for what he calls benign masochism.
Ashlyn Blocker has a rare genetic condition that prevents her from feeling pain. But that doesn’t mean she can’t get hurt.
Taking into account the latest research in psychology, physiology, and human behavior patterns could help you time everything accordingly for vastly superior results.
Magnifying Human Disease
As our ability to peer into the very, very small increases, we’ve had the opportunity to see the normally invisible pathogens that have plagued humankind for centuries. Some shown here will only cause achey joints or a highly unpleasant 24 hours of food poisoning; others are much more sinister, and can cause haemorrhage, necrosis, permanent disfigurement and death.
Image, top: Scanning electron micrograph (SEM) image of Borellia burgdorferi, a spirochaete bacterium responsible for lyme disease in humans.
Second row, left: RNA is seen in yellow in the core of these polioviruses; its protein coat is seen in blue. Second row, right: Yersinia pestis, a rod-shaped Gram negative bacterium, is the causitive agent of the bubonic, pneumonic, and septicemic plagues, and was responsible for the deaths of over 1/3 of the European population at its height. It’s probably best known for causing necrosis - the violent, premature death of cells in living tissue.
Third row, left: Looking deceivingly like an oil painting, these smallpox viruses - variola major and variola minor - were some of the most infectious viruses on the planet before their eradication. The protein coat is coloured yellow, and DNA is seen in red. Third row, right: The ebola virus, seen through a coloured transmission electron micrograph. Ebola is a haemorrhagic fever, and has claimed up to a 90% fatality rate in certain epidemics.
Fourth row, left: While Escherichia coli is usually a harmless gut-dweller in humans, under certain conditions it can cause gastroenteritis, urinary tract infections, and food poisoning. Fourth row, right: A false-colour image of human papilloma viruses (HPV). Best known as the cause of genital warts, it also has a sinister side: Virtually all cervical cancers are caused by HPV infection.
Source, as well as other images, here.
(Source: amolecularmatter)
The smell of perspiration released by men while they were feeling afraid or repulsed was enough to trigger the same emotion in women, an experiment showed.
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