Tag: evolution

The Evolution Of Forests And Trees In Devonian Period

The vascular plant emerged around 400 million years ago and started Earth’s forest-building process during the Silurian geologic period.

Although not yet a “true” tree, this new member of the terrestrial plant kingdom became the perfect evolutionary link (and the largest plant species) with developing tree parts and considered the first proto-tree.

Vascular plants developed the ability to grow large and tall with massive weight needed for the support of a vascular internal plumbing system.




The First Trees

The earth’s first real tree continued to develop during the Devonian period and scientists think that tree was probably the extinct Archaeopteris.

These tree species followed later by other tree types became the definitive species comprising a forest during the late Devonian period.

As mentioned, they were the first plants to overcome the biomechanical problems of supporting additional weight while delivering water and nutrients to fronds (leaves) and roots.

Entering the Carboniferous period around 360 million years ago, trees were prolific and a major part of the plant life community, mostly located in coal-producing swamps.

Trees were developing the parts that we immediately recognize today. Of all the trees that existed during the Devonian and Carboniferous, only the tree fern can still be found, now living in Australasian tropical rainforests.

If you happen to see a fern with a trunk leading to a crown, you have seen a tree fern.

During that same geologic period, now extinct trees including clubmoss and giant horsetail were also growing.

Our Present Evolutionary Forest

Few dinosaurs ever made a meal on hardwood leaves because they were rapidly disappearing before and during the beginning of the new “age of hardwoods” (95 million years ago).

Magnolias, laurels, maples, sycamores and oaks were the first species to proliferate and dominate the world.

Hardwoods became the predominant tree species from mid-latitudes through the tropics while conifers were often isolated to the high-latitudes or the lower latitudes bordering the tropics.

Not a lot of change has happened to trees in terms of their evolutionary record since the palms made their first appearance 70 million years ago.

Fascinating are several tree species that simply defy the extinction process and show no indication that they will change in another dozen million years.

Ginkgo was mentioned earlier but there are others: dawn redwood, Wollemi pine, and monkey puzzle tree.

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Life On Earth May Have Begun 300 Million Years Earlier Than Previously Thought

Living organisms may have existed on Earth as long as 4.1bn years ago – 300m years earlier than was previously thought, new research has shown.

If confirmed, the discovery means life emerged a remarkably short time after the Earth was formed from a primordial disc of dust and gas surrounding the sun 4.6bn years ago.

Researchers discovered the evidence in specks of graphite trapped within immensely old zircon crystals from Jack Hills, Western Australia.

Atoms in the graphite, a crystalline form of carbon, bore the hallmark of biological origin. They were enriched with 12C, a “light” carbon isotope, or atomic strain, normally associated with living things.




It suggests that a terrestrial biosphere had emerged on Earth as early as 4.1bn years ago, said the scientists writing in the journal Proceedings of the National Academy of Sciences.

The US scientists, led by Dr Mark Harrison, from the University of California at Los Angeles, said the graphite was completely encased in zircon that was crack-free and could not have been contaminated despite the passing of aeons.

They wrote: “This study extends the terrestrial carbon isotope record around 300m years beyond the previously oldest-measured samples from south-west Greenland.

Some non-biological processes could also produce the light form of carbon, notably meteorite impacts, said the researchers.

But the amount of extra-terrestrial carbon needed to account for the findings made meteorites an unlikely source.

A biogenic origin seems at least as plausible,” the scientists added.

Confirming the connection with early life would represent “a potentially transformational scientific advance” they said.

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Humans Are Still Evolving—And We Can Watch It Happen

Many people think evolution requires thousands or millions of years, but biologists know it can happen fast.

Now, thanks to the genomic revolution, researchers can actually track the population-level genetic shifts that mark evolution in action—and they’re doing this in humans.

Two studies presented at the Biology of Genomes meeting here last week show how our genomes have changed over centuries or decades, charting how since Roman times the British have evolved to be taller and fairer, and how just in the last generation the effect of a gene that favors cigarette smoking has dwindled in some groups.

Being able to look at selection in action is exciting,” says Molly Przeworski, an evolutionary biologist at Columbia University.

The studies show how the human genome quickly responds to new conditions in subtle but meaningful ways, she says. “It’s a game-changer in terms of understanding evolution.”




Evolutionary biologists have long concentrated on the role of new mutations in generating new traits. But once a new mutation has arisen, it must spread through a population.

Every person carries two copies of each gene, but the copies can vary slightly within and between individuals. Mutations in one copy might increase height; those in another copy, or allele, might decrease it.

If changing conditions favor, say, tallness, then tall people will have more offspring, and more copies of variants that code for tallness will circulate in the population.

With the help of giant genomic data sets, scientists can now track these evolutionary shifts in allele frequencies over short timescales.

Jonathan Pritchard of Stanford University in Palo Alto, California, and his postdoc Yair Field did so by counting unique single-base changes, which are found in every genome.

Such rare individual changes, or singletons, are likely recent, because they haven’t had time to spread through the population.

Because alleles carry neighboring DNA with them as they circulate, the number of singletons on nearby DNA can be used as a rough molecular clock, indicating how quickly that allele has changed in frequency.

Pritchard’s team analyzed 3000 genomes collected as part of the UK10K sequencing project in the United Kingdom. For each allele of interest in each genome, Field calculated a “singleton density score” based on the density of nearby single, unique mutations.

The more intense the selection on an allele, the faster it spreads, and the less time there is for singletons to accumulate near it. The approach can reveal selection over the past 100 generations, or about 2000 years.

Stanford graduate students Natalie Telis and Evan Boyle and postdoc Ziyue Gao found relatively few singletons near alleles that confer lactose tolerance—a trait that enables adults to digest milk—and that code for particular immune system receptors.

Among the British, these alleles have evidently been highly selected and have spread rapidly.

The team also found fewer singletons near alleles for blond hair and blue eyes, indicating that these traits, too, have rapidly spread over the past 2000 years, Field reported in his talk and on 7 May in the preprint server bioRxiv.org.

One evolutionary driver may have been Britain’s gloomy skies: Genes for fair hair also cause lighter skin color, which allows the body to make more vitamin D in conditions of scarce sunlight.

Or sexual selection could have been at work, driven by a preference for blond mates.

Other researchers praise the new technique.

This approach seems to allow much more subtle and much more common signals of selection to be detected,” says evolutionary geneticist Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

In a sign of the method’s power, Pritchard’s team also detected selection in traits controlled not by a single gene, but by tiny changes in hundreds of genes.

Among them are height, head circumference in infants, and hip size in females—crucial for giving birth to those infants.

By looking at the density of singletons flanking more than 4 million DNA differences, Pritchard’s team discovered that selection for all three traits occurred across the genome in recent millennia.

Joseph Pickrell, an evolutionary geneticist at New York Genome Center in New York City, has used a different strategy to put selection under an even keener microscope, detecting signs of evolution on the scale of a human lifetime.

He and Przeworski took a close look at the genomes of 60,000 people of European ancestry who had been genotyped by Kaiser Permanente in Northern California, and 150,000 people from a massive U.K. sequencing effort called the UK Biobank.

They wanted to know whether genetic variants change frequency across individuals of different ages, revealing selection at work within a generation or two.

The biobank included relatively few old people, but it did have information about participants’ parents, so the team also looked for connections between parental death and allele frequencies in their children.

In the parents’ generation, for example, the researchers saw a correlation between early death in men and the presence in their children (and therefore presumably in the parents) of a nicotine receptor allele that makes it harder to quit smoking.

Many of the men who died young had reached adulthood in the United Kingdom in the 1950s, a time when many British men had a pack-a-day habit.

In contrast, the allele’s frequency in women and in people from Northern California did not vary with age, presumably because fewer in these groups smoked heavily and the allele did not affect their survival.

As smoking habits have changed, the pressure to weed out the allele has ceased, and its frequency is unchanged in younger men, Pickrell explains.

My guess is we are going to discover a lot of these gene-by-environment effects,” Przeworski says.

Indeed, Pickrell’s team detected other shifts. A set of gene variants associated with late-onset menstruation was more common in longer-lived women, suggesting it might help delay death.

Pickrell also reported that the frequency of the ApoE4 allele, which is associated with Alzheimer’s disease, drops in older people because carriers died early.

We can detect selection on the shortest timeframe possible, an individual’s life span,” he says.

Signs of selection on short timescales will always be prey to statistical fluctuations.

But together the two projects “point to the power of large studies to understand what factors determine survival and reproduction in humans in present-day societies,” Pääbo says.

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Fossil Holds New Insights Into How Fish Evolved Onto Land

The fossil of an early snake-like animal – called Lethiscus stocki – has kept its evolutionary secrets for the last 340-million years.

Now, an international team of researchers, led by the University of Calgary, has revealed new insights into the ancient Scottish fossil that dramatically challenge our understanding of the early evolution of tetrapods, or four-limbed animals with backbones.

Their findings have just been published in the research journal Nature.




It forces a radical rethink of what evolution was capable of among the first tetrapods,” said project lead Jason Anderson, a paleontologist and Professor at the University of Calgary Faculty of Veterinary Medicine (UCVM).

Before this study, ancient tetrapods – the ancestors of humans and other modern-day vertebrates – were thought to have evolved very slowly from fish to animals with limbs.

We used to think that the fin-to-limb transition was a slow evolution to becoming gradually less fish like,” he said.

But Lethiscus shows immediate, and dramatic, evolutionary experimentation. The lineage shrunk in size, and lost limbs almost immediately after they first evolved. It’s like a snake on the outside but a fish on the inside.

Using micro-computer tomography (CT) scanners and advanced computing software, Anderson and study lead author Jason Pardo, a doctoral student supervised by Anderson, got a close look at the internal anatomy of the fossilized Lethiscus.

After reconstructing CT scans its entire skull was revealed, with extraordinary results.

The anatomy didn’t fit with our expectations,” explains Pardo.

Many body structures didn’t make sense in the context of amphibian or reptile anatomy.” But the anatomy did make sense when it was compared to early fish.

We could see the entirety of the skull. We could see where the brain was, the inner ear cavities. It was all extremely fish-like,” explains Pardo, outlining anatomy that’s common in fish but unknown in tetrapods except in the very first.

The anatomy of the paddlefish, a modern fish with many primitive features, became a model for certain aspects of Lethiscus’ anatomy.

When they included this new anatomical information into an analysis of its relationship to other animals, Lethiscus moved its position on the ‘family tree’, dropping into the earliest stages of the fin-to-limb transition.

It’s a very satisfying result, having them among other animals that lived at the same time,” says Anderson.

The results match better with the sequence of evolution implied by the geologic record.

Lethiscus also has broad impacts on evolutionary biology and people doing molecular clock reproductions of modern animals,” says Anderson.

They use fossils to calibrate the molecular clock. By removing Lethiscus from the immediate ancestry of modern tetrapods, it changes the calibration date used in those analyses.

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According To Scientists, Europe Was The Birthplace Of Mankind And Not Africa

The history of human evolution has been rewritten after scientists discovered that Europe was the birthplace of mankind, not Africa.

Currently, most experts believe that our human lineage split from apes around seven million years ago in central Africa, where hominids remained for the next five million years before venturing further afield.

But two fossils of an ape-like creature which had human-like teeth have been found in Bulgaria and Greece, dating to 7.2 million years ago.

The discovery of the creature, named Graecopithecus freybergi, and nicknameded ‘El Graeco’ by scientists, proves our ancestors were already starting to evolve in Europe 200,000 years before the earliest African hominid.




An international team of researchers say the findings entirely change the beginning of human history and place the last common ancestor of both chimpanzees and humans – the so-called Missing Link – in the Mediterranean region.

At that time climate change had turned Eastern Europe into an open savannah which forced apes to find new food sources, sparking a shift towards bipedalism, the researchers believe.

This study changes the ideas related to the knowledge about the time and the place of the first steps of the humankind,” said Professor Nikolai Spassov from the Bulgarian Academy of Sciences.

Graecopithecus is not an ape. He is a member of the tribe of hominins and the direct ancestor of homo.”

The food of the Graecopithecus was related to the rather dry and hard savannah vegetation, unlike that of the recent great apes which are living in forests.  Therefore, like humans, he has wide molars and thick enamel.

To some extent this is a newly discovered missing link. But missing links will always exist , because evolution is infinite chain of subsequent forms. Probably  El Graeco’s face will resemble a great ape, with shorter canines.”

The team analysed the two known specimens of Graecopithecus freybergi: a lower jaw from Greece and an upper premolar tooth from Bulgaria.

Using computer tomography, they were able to visualise the internal structures of the fossils and show that the roots of premolars are widely fused.

The lower jaw, has additional dental root features, suggesting that the species was a hominid.

The species was also found to be several hundred thousand years older than the oldest African hominid, Sahelanthropus tchadensis which was found in Chad.

Professor David Begun, a University of Toronto paleoanthropologist and co-author of this study, added: “This dating allows us to move the human-chimpanzee split into the Mediterranean area.

During the period the Mediterranean Sea went through frequent periods of drying up completely, forming a land bridge between Europe and Africa and allowing apes and early hominids to pass between the continents.

The team believe that evolution of hominids may have been driven by dramatic environmental changes which sparked the formation of the North African Sahara more than seven million years ago and pushed species further North.

They found large amounts of Saharan sand in layers dating from the period, suggesting that it lay much further North than today.

Retired anthropologist and author Dr Peter Andrews, formerly at the Natural History Museum in London, said: “It is possible that the human lineage originated in Europe, but very substantial fossil evidence places the origin in Africa, including several partial skeletons and skulls.”

I would be hesitant about using a single character from an isolated fossil to set against the evidence from Africa.

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Goldfish Make Alcohol In Their Cells To Survive Months Without Oxygen In Icy Waters

Goldfish can survive for months at a time in oxygen-free water. They convert lactic acid into ethanol which keeps them alive under frozen lakes.

A little bit of alcohol probably means they lose their inhibitions too. Goldfish and carp produce at least 50 mg per millilitre in their blood.




This puts them above the legal drink drive limit in most countries“, lead researcher Michael Berenbrink said.

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