December 1, 2013
'Humans evolved after a female chimpanzee mated with a pig'
The human species began as the hybrid offspring of a male pig and a female chimpanzee, a leading geneticist has suggested.
The startling claim has been made by Eugene McCarthy, of the University of Georgia, who is also one of the worlds leading authorities on hybridisation in animals.
He points out that while humans have many features in common with chimps, we also have a large number of distinguishing characteristics not found in any other primates.
April 24, 2013
Researchers use Moore's Law to calculate that life began before Earth existed
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.
April 21, 2013
The human body as you know it is over
Here is what happens.
Humans invent technology.
Then technology re-invents humans.
According to NewScientist, most humans were pretty lousy at using hand tools when they were first invented 1.7 million years ago.
The reason: primitive wrists that were “good for hanging from branches, but too weak to grasp and handle small objects with much force.”
But by 800,000 years ago, humans had great hands for using tools.
What happened between those years?
A newly discovered set of bones – from between those eras, 1.4 million years ago – gives us a clue.
The 1.4 million-year-old bones reveal human hands that were better for using tools than the ones from 1.7 million years ago, but not as good as hands from 800,000.
The 1.4 million year-old-hand had “a small lump at its base – the styloid,” that allowed helped stabilize wrists, allowing the hand to grip smaller objects.
The newly-discovered bones reveal that, over time, human hands progressed along an continuum of evolution.
Human bodies evolved to better use human-invented technology
February 19, 2013
The misguided nostalgia for our paleo past
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.
February 8, 2013
Finally confirmed: An asteroid wiped out the dinosaurs
A team of American and European researchers have confirmed that the Cretaceous-Paleogene extinction — the event that wiped out roughly 75% of the planet’s species, including almost every dinosaur — was caused by an asteroid impact in Mexico 66 million years ago. The Cretaceous–Paleogene extinction was the last great extinction event to occur on Earth, and is most notable for causing the diversification of mammals that eventually resulted in Homo sapiens.
January 31, 2013
From an evolutionary perspective, your grandmother shouldn’t exist
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.
January 17, 2013
Nasikabatrachus sahyadrensis, or the pignose frog, spends most of the year underground, surfacing only for about two weeks, during the monsoon, for purposes of mating. The frog’s reclusive lifestyle is what caused the adults to escape earlier notice by biologists, and hence delay its scientific description. A female specimen was found nearly 8 metres below the ground level. The breeding season is during the pre-monsoon rains, primarily in May. The males call from burrows beside headwater streams and when approached by females, mount them in amplexus. While in amplexus in the pectoral position, the male tightly holds the vertebral column of the female. The pair then enters a crevice in a rock pool amid a flowing stream and lay their eggs inside. More than 3000 eggs are laid as part of a clutch. The tadpoles metamorphose after around 100 days.
Unlike many other burrowing species of frogs that emerge and feed above the ground, this species has been found to forage underground, feeding mainly on termites using their tongue and a special buccal groove.
See more oddities at WTF, Evolution?
January 9, 2013
Thank Darwin! Pruney fingers & toes are like human tire treads
We’ve speculated this to be true for a while, but now UK researchers from Newcastle University have confirmed wet objects are easier to handle with wrinkled fingers than with dry, smooth ones.
They suggest our ancestors may have evolved the creases as they moved and foraged for food in wet conditions.
"If wrinkled fingers were just the result of the skin swelling as it took up water, it could still have a function but it wouldn’t need to," said Dr Tom Smulders, from Newcastle’s Centre for Behaviour and Evolution.
The tests involved handling wet objects with wrinkled and un-wrinkled fingers
"Whereas, if the nervous system is actively controlling this behaviour under some circumstances and not others, it seems less of a leap to assume there must be a function for it, and that evolution has selected it. And evolution wouldn’t have selected it unless it conferred some sort of advantage," he told BBC News.
US-based researchers were the first to propose that the wrinkles might act like the tread on tires, and even demonstrated how the patterns in the skin resembled those of run-off channels seen on the sides of hills.
December 19, 2012
The most fascinating human evolution discoveries of 2012
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.
December 14, 2012
Boys and girls may get different breast milk
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.
December 10, 2012
Zoologger: The fish with its genitals on its head
The male fish, a Phallostethus cuulong just 2 centimetres long, weaves between drifting vegetation in the sluggish waters of a canal. He closes in on a female, swims alongside her and tries to mate with her.
But to an outside observer, he seems to be doing it wrong. His head is right next to the female’s, but he’s at a 45-degree angle so his rear end is well below hers. Sounds misguided, but actually he’s doing it exactly right – it’s just that his gonads are on his head.
December 7, 2012
Everyone has 400 genetic flaws
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.
December 6, 2012
Why perceived vocal effort makes certain songs catchier than others
“We’ve discovered that there’s a science behind the sing-along and a special combination of neuroscience, maths and cognitive psychology can produce the elusive elixir of the perfect sing-along song. We hope that our study will inspire musicians of the future to crack the equation for the textbook tune.”
Musicologist Dr. Alison Pawley and psychologist Dr. Daniel Mullensiefen out at the University of London came to the conclusion that there are four traits that make a song catchy:
- Longer and detailed musical phrases. The breath a vocalist takes as they sing a line is crucial to creating a sing-along-able tune. The longer a vocal in one breath, the more likely we are to sing along.
- Higher number of pitches in the chorus hook. The more sounds there are, the more infectious a song becomes. Combining longer musical phrases and a hook over three different pitches was found to be key to sing-along success.
- Male vocalists. Singing along to a song may be a subconscious war cry, tapping into an inherent tribal part of our consciousness. Psychologically we look to men to lead us into battle, so it could be in our intuitive nature to follow male-fronted songs.
- Higher male voices with noticeable vocal effort. This indicates high energy and purpose, particularly when combined with a smaller vocal range (Freddie Mercury of Queen and Jon Bon Jovi).
December 4, 2012
Same genes that improved our mental capacity are also responsible for a number of brain disorders
Scientists have discovered for the first time how humans — and other mammals — have evolved to have intelligence.
Researchers have identified the moment in history when the genes that enabled us to think and reason evolved.
This point 500 million years ago provided our ability to learn complex skills, analyse situations and have flexibility in the way in which we think.
Professor Seth Grant, of the University of Edinburgh, who led the research, said: “One of the greatest scientific problems is to explain how intelligence and complex behaviours arose during evolution.”
The research, which is detailed in two papers in Nature Neuroscience, also shows a direct link between the evolution of behaviour and the origins of brain diseases.
Scientists believe that the same genes that improved our mental capacity are also responsible for a number of brain disorders.
"This ground breaking work has implications for how we understand the emergence of psychiatric disorders and will offer new avenues for the development of new treatments," said John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, one of the study funders.