Human Evolution: Where We Came From

Analyses of a partial skeleton of a female Ardipithecus ramidus nicknamed Ardi, suggest the early human would have stood at just under 4 feet (1.2 meters) tall with both primitive traits, such as a small brains size similar to living chimpanzees and those shared with later hominids, such as bipedal posture. Credit: © 2009, J.H. Matternes.

From Live Science:

The dawn of humanity remains a fascinating mystery. What started our distant ancestors on the evolutionary path that led to us?

Spectacular fossils and a host of other data uncovered in the last decade are revealing key details to solving this riddle. As often than not, however, these clues raise as many questions as they answer.

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Darwin Lives! Modern Humans Are Still Evolving

A. Green / Corbis

From Time Magazine:

Modern Homo sapiens is still evolving. Despite the long-held view that natural selection has ceased to affect humans because almost everybody now lives long enough to have children, a new study of a contemporary Massachusetts population offers evidence of evolution still in action.

A team of scientists led by Yale University evolutionary biologist Stephen Stearns suggests that if the natural selection of fitter traits is no longer driven by survival, perhaps it owes to differences in women's fertility. "Variations in reproductive success still exist among humans, and therefore some traits related to fertility continue to be shaped by natural selection," Stearns says. That is, women who have more children are more likely to pass on certain traits to their progeny.

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Humans Are Still Evolving, Analysis Finds

Data collected as part of a 60-year study suggests that humans are likely to evolve at roughly the same rates as other living things. (Credit: iStockphoto)

From Science Daily:

Science Daily (Oct. 20, 2009) — Although advances in medical care have improved standards of living over time, humans aren't entirely sheltered from the forces of natural selection, a new study shows.

"There is this idea that because medicine has been so good at reducing mortality rates, that means that natural selection is no longer operating in humans," said Stephen Stearns of Yale University.

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Mutations Make Evolution Irreversible: By Resurrecting Ancient Proteins, Researchers Find That Evolution Can Only Go Forward

Fish fossil. Researchers resurrected and manipulate the gene for a key hormone receptor as it existed in our earliest vertebrate ancestors more than 400 million years ago. Over a rapid period of time, five random mutations made subtle modifications in the protein's structure that were utterly incompatible with the receptor's primordial form. (Credit: iStockphoto)

From Science Daily:

A University of Oregon research team has found that evolution can never go backwards, because the paths to the genes once present in our ancestors are forever blocked. The findings -- the result of the first rigorous study of reverse evolution at the molecular level -- appear in the Sept. 24 issue of Nature.

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Ancient Oceans Offer New Insight Into Origins Of Animal Life

In prehistoric times, Earth experienced two periods of large increases and fluctuations in the oxygen level of the atmosphere and oceans. These fluctuations also led to an explosion of multicellular organisms in the oceans, which are the predecessors for life as we know it today. (Credit: iStockphoto/Sebastian Meckelmann)

From Science Daily:

Science Daily (Sep. 10, 2009) — Analysis of a rock type found only in the world's oldest oceans has shed new light on how large animals first got a foothold on Earth.

A scientific team led by Professor Robert Frei at the University of Copenhagen in Denmark, and including scientists from Newcastle University, UK, and universities in Uruguay and Southern Denmark, have for the first time managed to plot the rise and fall of oxygen levels in the Earth's atmosphere over the last 3.8 billion years.

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New Origin of Life Proposed: Zinc & Zap

Unlike Miller and Urey, who believed the early Earth had a reducing atmosphere, scientists today believe the early Earth had a neutral atmosphere composed primarily of carbon dioxide. Credit: NASA

From Live Science:

The Miller-Urey experiment, conducted by chemists Stanley Miller and Harold Urey in 1953, is the classic experiment on the origin of life. It established that the early Earth atmosphere, as they pictured it, was capable of producing amino acids, the building blocks of life, from inorganic substances.

Now, more than 55 years later, two scientists are proposing a hypothesis that could add a new dimension to the debate on how life on Earth developed.

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Why Did People Become White?

A host of evolutionary pressures at work that contributed to the development of lighter skin, but for now, scientists aren't sure exactly what produced white people. Image credit: stockxpert

From Live Science:

Humans come in a rainbow of hues, from dark chocolate browns to nearly translucent whites.

This full kaleidoscope of skin colors was a relatively recent evolutionary development, according to biologists, occuring alongside the migration of modern humans out of Africa between 100,000 and 50,000 years ago.

The consensus among scientists has always been that lower levels of vitamin D at higher latitudes — where the sun is less intense — caused the lightening effect when modern humans, who began darker-skinned, first migrated north.

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White Europeans 'Only Evolved 5,500 Years Ago After Food Habits Changed'

Photo: People with pale skin like model Lily Cole may be descended from Europeans who dramatically changed their diets

From The Daily Mail:

People in England may have only developed pale skin within the last 5,500 years, according to new research.

Scientists believe that a sudden change in the diet around that time from hunter-gathering to farming may have led to a dramatic change in skin tone to make up for a lack of vitamin D.

Farmed food is lacking in vitamin D and while humans can produce it when exposed to the ultraviolet light in sunlight darker skin is far less efficient at it.

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Mammals Beat Reptiles in Battle of Evolution

Crocodiles, and their cousins, alligators, were shown to be less diversified than certain groups of mammals, birds and fish. Credit: Michael Alfaro

From Live Science:

Mammals, birds and fish are among evolution’s "winners," while crocodiles and other reptiles have ended up on the losing end, a new study suggests.

"Our results indicate that mammals are special," said study leader Michael Alfaro of UCLA.

The research allowed scientists to calculate for the first time which animal lineages have exceptional rates of success. The so-called "winners" have more species in their group, which means they have successfully evolved and diversified into many types of environments. The losers have diversified less, even over the course of millions of years.

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Evolutionary Origins of Your Right and Left Brain

In the human brain the left hemisphere controls language, the dexterity of the right hand, the ability to classify, and routine behavior in general. The right hemisphere specializes in reacting to emergencies, organizing items spatially, recognizing faces and processing emotions.
Photoillustration by TWIST CREATIVE; MedicalRF.com Corbis (brain); Medioimages Getty Images (calculator); Joerg Steffens Corbis (faces); Westend61 Corbis (woman smiling); Dougal Waters Getty Images (ballerina); Mike Kemp Getty Images (rattlesnake); C Squared Studios Getty Images (palette); Vladimir Godnik Getty Images (paintbrushes); Carrie Boretz Corbis (girls whispering); Robert Llewellyn Corbis (calipers)

From Scientific American:

The division of labor by the two cerebral hemispheres—once thought to be uniquely human—predates us by half a billion years. Speech, right-handedness, facial recognition and the processing of spatial relations can be traced to brain asymmetries in early vertebrates

The left hemisphere of the human brain controls language, arguably our greatest mental attribute. It also controls the remarkable dexterity of the human right hand. The right hemisphere is dominant in the control of, among other things, our sense of how objects interrelate in space. Forty years ago the broad scientific consensus held that, in addition to language, right-handedness and the specialization of just one side of the brain for processing spatial relations occur in humans alone. Other animals, it was thought, have no hemispheric specializations of any kind.

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Ecologist Brings Century-old Eggs To Life To Study Evolution

Daphnia neonate emerge from a dormant egg (Daphnia birth). Approximate size is 300 micrometers. (Credit: Photomicrograph by P. Spaak)

From Science Daily:

ScienceDaily (July 19, 2009) — Suspending a life in time is a theme that normally finds itself in the pages of science fiction, but now such ideas have become a reality in the annals of science.

Cornell ecologist Nelson Hairston Jr. is a pioneer in a field known loosely as "resurrection ecology," in which researchers study the eggs of such creatures as zooplankton -- tiny, free-floating water animals -- that get buried in lake sediments and can remain viable for decades or even centuries. By hatching these eggs, Hairston and others can compare time-suspended hatchlings with their more contemporary counterparts to better understand how a species may have evolved in the meantime.

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The Genesis Enigma: How DID the Bible describe the evolution Of Life 3,000 Years Before Darwin?

Myth or divine inspiration: Was the book of Genesis a gateway into the evolution of life?

From The Daily Mail:

The revalation came to Professor Andrew Parker during a visit to Rome. He was in the Sistine Chapel, gazing up at Michelangelo's awesome ceiling paintings, when a realisation struck him with dizzying force.

'A Biblical enigma exists that is on the one hand so cryptic it has remained camouflaged for millennia, and on the other so obvious one cannot miss it.'

The enigma is that the order of Creation as described in the Book of Genesis, and so powerfully depicted in the Sistine Chapel by the greatest artist of the Renaissance, has been precisely, eerily confirmed by modern evolutionary science.

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Evolutionary Origins Of Your Right And Left Brain

Photoillustration by TWIST CREATIVE; MedicalRF.com Corbis (brain); Medioimages Getty Images (calculator); Joerg Steffens Corbis (faces); Westend61 Corbis (woman smiling); Dougal Waters Getty Images (ballerina); Mike Kemp Getty Images (rattlesnake); C Squared Studios Getty Images (palette); Vladimir Godnik Getty Images (paintbrushes); Carrie Boretz Corbis (girls whispering); Robert Llewellyn Corbis (calipers)

From Scientific American:

The division of labor by the two cerebral hemispheres—once thought to be uniquely human—predates us by half a billion years. Speech, right-handedness, facial recognition and the processing of spatial relations can be traced to brain asymmetries in early vertebrates.

The left hemisphere of the human brain controls language, arguably our greatest mental attribute. It also controls the remarkable dexterity of the human right hand. The right hemisphere is dominant in the control of, among other things, our sense of how objects interrelate in space. Forty years ago the broad scientific consensus held that, in addition to language, right-handedness and the specialization of just one side of the brain for processing spatial relations occur in humans alone. Other animals, it was thought, have no hemispheric specializations of any kind.

Read more ....

Evolution Faster When It's Warmer

The results could help explain why the warm tropics are so species-rich

From The BBC:

Climate could have a direct effect on the speed of "molecular evolution" in mammals, according to a study.

Researchers have found that, among pairs of mammals of the same species, the DNA of those living in warmer climates changes at a faster rate.

These mutations - where one letter of the DNA code is substituted for another - are a first step in evolution.

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Social Competition May Be Reason For Bigger Brain

Professor David Geary finds that competitive ancestors may be blamed for today's big brain. (Credit: Image courtesy of University of Missouri-Columbia)

From Science Digest:

ScienceDaily (June 23, 2009) — For the past 2 million years, the size of the human brain has tripled, growing much faster than other mammals. Examining the reasons for human brain expansion, University of Missouri researchers studied three common hypotheses for brain growth: climate change, ecological demands and social competition. The team found that social competition is the major cause of increased cranial capacity.

To test the three hypotheses, MU researchers collected data from 153 hominid (humans and our ancestors) skulls from the past 2 million years. Examining the locations and global climate changes at the time the fossil was dated, the number of parasites in the region and estimated population density in the areas where the skulls were found, the researchers discovered that population density had the biggest effect on skull size and thus cranial capacity.

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Evolution Can Occur In Less Than 10 Years, Guppy Study Finds

Guppies are small fresh-water fish that biologists have studied for long. (Credit: Paul Bentzen)

From Science Daily:

ScienceDaily (June 15, 2009) — How fast can evolution take place? In just a few years, according to a new study on guppies led by UC Riverside's Swanne Gordon, a graduate student in biology.

Gordon and her colleagues studied guppies — small fresh-water fish biologists have studied for long — from the Yarra River, Trinidad. They introduced the guppies into the nearby Damier River, in a section above a barrier waterfall that excluded all predators. The guppies and their descendents also colonized the lower portion of the stream, below the barrier waterfall, that contained natural predators.

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Insight Into Evolution Of First Flowers

This flower from an avocado tree (Persea americana) shows the characteristics of ancient flowering-plant lineages. Its petals (colorful in most flowers) and sepals (usually a green outer layer) are combined into one organ. A new study led by University of Florida researchers provides insight into how the first flowering plants emerged from non-flowering plants and began evolving about 130 million years ago. (Credit: Image courtesy of University of Florida)

From Science Daily:

ScienceDaily (May 19, 2009) — Charles Darwin described the sudden origin of flowering plants about 130 million years ago as an abominable mystery, one that scientists have yet to solve.

But a new University of Florida study, set to appear in the online edition of the Proceedings of the National Academy of Sciences, is helping shed light on the mystery with information about what the first flowers looked like and how they evolved from nonflowering plants.

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Is David Attenborough Set To Reveal The Missing Link In Human Evolution?

From The Daily Mail:

The BBC has made an extraordinary new documentary, presented by Sir David Attenborough, which will reveal the discovery of a fossilised skeleton that may be a vital ‘missing link’ in human evolution.

The 90-minute programme is top secret but The Mail on Sunday has learned from sources in America that the results of the study on which it is based will be revealed by a team of scientists and broadcasters in New York on May 19.

The centrepiece of the programme is the unveiling of the first-ever complete skeleton of an extinct animal called an adapid.

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African Tribe Populated Rest Of The World

From The Telegraph:

The entire human race outside Africa owes its existence to the survival of a single tribe of around 200 people who crossed the Red Sea 70,000 years ago, scientists have discovered.

Research by geneticists and archaeologists has allowed them to trace the origins of modern homo sapiens back to a single group of people who managed to cross from the Horn of Africa and into Arabia. From there they went on to colonise the rest of the world.

Genetic analysis of modern day human populations in Europe, Asia, Australia, North America and South America have revealed that they are all descended from these common ancestors.

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Meet The Ancestors: DNA Study Pinpoints Namibia As Home To The World's Most Ancient Race

The San people, hunter-gatherers in south-west Africa for thousands of years, are believed to be the oldest population of humans on Earth

From The Daily Mail:

Scientists have long known that humans originated in Africa, but now a groundbreaking DNA study has revealed our 'Garden of Eden' is likely to be on the South African-Namibian border.

For it is the San people, hunter-gatherers in this area for thousands of years, who researchers now believe are the oldest human population on Earth.

They are descended from the earliest human ancestors from which all other groups of Africans stem and, in turn, to the people who left the continent to populate other corners of the planet.

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