Tag: evolution

The Evolution Of The SpaceX Starship

The SpaceX Starship is in its 4th iteration and is officially entering the testing phase with the production of the Mark 1 prototype that was unveiled on Sept. 28th 2019. Today we look at the history of the Starship and look at the design changes that have occurred along the way.

2016 –
SpaceX CEO Musk unveiled details of the space mission architecture, launch vehicle, spacecraft, and Raptor engines that power the vehicles at the 67th International Astronautical Congress on September 27, 2016.

More Than 90 Percent Of All Organisms That Have Ever Lived On Earth Are Extinct

As new species evolve to fit ever changing ecological niches, older species fade away. But the rate of extinction is far from constant.

At least a handful of times in the last 500 million years, 50 to more than 90 percent of all species on Earth have disappeared in a geological blink of the eye.

Though these mass extinctions are deadly events, they open up the planet for new life-forms to emerge.

Dinosaurs appeared after one of the biggest mass extinction events on Earth, the Permian-Triassic extinction about 250 million years ago.

The most studied mass extinction, between the Cretaceous and Paleogene periods about 65 million years ago, killed off the dinosaurs and made room for mammals to rapidly diversify and evolve.




Scientists have narrowed down several of the most likely causes of mass extinction. Flood basalt events (volcano eruptions), asteroid collisions, and sea level falls are the most likely causes of mass extinctions, though several other known events may also contribute.

These include global warming, global cooling, methane eruptions and anoxic events–when the earth’s oceans lose their oxygen.

Both volcano eruptions and asteroid collisions would eject tons of debris into the atmosphere, darkening the skies for at least months on end.

Starved of sunlight, plants and plant-eating creatures would quickly die.

Space rocks and volcanoes could also unleash toxic and heat-trapping gases that—once the dust settled—enable runaway global warming.

An extraterrestrial impact is most closely linked to the Cretaceous-Paleogene extinction event, one of the five largest in the history of the world, and the most recent.

A huge crater off Mexico’s Yucatán Peninsula is dated to about 65 million years ago, coinciding with the extinction.

Global warming fueled by volcanic eruptions at the Deccan Flats in India may also have aggravated the event. Dinosaurs, as well as about half of all species on the planet, went extinct.

Massive floods of lava erupting from the central Atlantic magmatic province about 200 million years ago may explain the Triassic-Jurassic extinction.

About 20 percent of all marine families went extinct, as well as most mammal-like creatures, many large amphibians, and all non-dinosaur archosaurs.

An asteroid impact is another possible cause of the extinction, though a telltale crater has yet to be found.

The Permian-Triassic extinction event was the deadliest: More than 90 percent of all species perished. Many scientists believe an asteroid or comet triggered the massive die-off, but, again, no crater has been found.

Another strong contender is flood volcanism from the Siberian Traps, a large igneous province in Russia. Impact-triggered volcanism is yet another possibility.

Starting about 360 million years ago, a drawn-out event eliminated about 70 percent of all marine species from Earth over a span of perhaps 20 million years.

Pulses, each lasting 100,000 to 300,000 years, are noted within the larger late Devonian extinction.

Insects, plants, and the first proto-amphibians were on land by then, though the extinctions dealt landlubbers a severe setback.

Today, many scientists think the evidence indicates a sixth mass extinction is under way. The blame for this one, perhaps the fastest in Earth’s history, falls firmly on the shoulders of humans.

By the year 2100, human activities such as pollution, land clearing, and overfishing may drive more than half of the world’s marine and land species to extinction.

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Pass it on: New Scientist

Early Humans Hooked Up With Neanderthals All The Time

Early humans had mated with Neanderthals and other primitive cousins far more often than thought in a world of debauchery, according to a new study.

Researchers found that interbreeding happened “multiple times” as our ancestors began to pour out of Africa and mingle with more species around 75,000 years ago.

The analysis of Neanderthal DNA in modern East Asians and Europeans found the assumption it was rare is wrong. It happened often — over a period of up to 35,000 years.

Data from the 1,000 Genomes project — which has mapped the DNA of 1,000 people from around the world — suggests an environment of rampant promiscuity.

It was a complex web of relationships in which individuals had intercourse with members of their own group — and different early humans, or hominins.




Co-author Joshua Schraiber said: “I do think there was probably much more interbreeding than we initially suspected. Some of the fantastical aspects come from a lack of a clear definition of ‘species’ in this case.

“It is always very hard to know if an extinct group constituted a different species or not.

“My guess is that any time two different human groups lived in the same place at the same time for a while, they probably had some sort of breeding contact.”

Recent studies have found Denisovans, another extinct relative, had sex with Neanderthals and humans on numerous occasions.

The Denisovan species was only discovered in southern Siberia a decade ago. They were genetically distinct from both Neanderthals and humans.

There were at least three different human forms on Earth only 40,000 years ago — all having an intercourse with each other. And there may have been more.

When anatomically modern humans dispersed from Africa, they encountered Neanderthals in Europe and Asia.

This left a signature in our genomes — with about 2 percent inherited from the Neanderthal. This DNA influences our immune system and the diseases we develop.

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Pass it on: Popular Science

The Elephant Bird Regains Its Title as the Largest Bird That Ever Lived

Elephant bird brains compared to those of the living kiwi and tinamou.

History has not been kind to the elephant bird of Madagascar. Standing nearly 10 feet tall and weighing up to 1,000 pounds — or so researchers believed.

This flightless cousin of the ostrich went extinct in the 17th century, thanks in part to humans stealing their massive eggs, either to feed their own families or to repurpose them as giant rum flasks. Or both.

More recently, the bird’s designation as the heaviest in history was challenged by the discovery of the slightly larger, unrelated Dromornis stirtoni, an Australian flightless giant that went extinct 20,000 years ago.

But a new study seeks to restore the elephant bird’s heavyweight title.

After taxonomic reshuffling and examination of collected elephant bird remains, researchers say that a member of a previously unidentified genus of the birds could have weighed more than 1,700 pounds, making it by far the largest bird ever known.




Over the centuries, scientists have competed to collect and display the largest elephant bird bones.

But, “nobody’s done any real cohesive research on these birds,” said James Hansford, a paleontologist at the Zoological Society of London and lead author of the study, resulting in a taxonomic muddle for the feathered giants.

As a result, more than 15 elephant bird species had been identified across two genera (the plural of genus, the name for a group of closely related species).

One of those species, A. maximus, had long been considered the heaviest elephant bird, until a British scientist in 1894 claimed to have discovered an even larger species, Aepyornis titan.

Other researchers dismissed the finding, saying A. titan was simply an unusually large member of the A. maximus clan.

But Dr. Hansford reports that A. titan is not only its own species but a separate genus of much larger elephant bird, as evidenced by the distinct size and shape of all three limb bones.

He has named the species and genus Vorombe titan; vorombe is a Malagasy word meaning “big bird.”

Dr. Hansford believes his study is the most rigorous examination of elephant birds in nearly a century, and that he has grouped outdated names under more accurate headings.

Although the elephant birds’ fate was sealed long ago, Dr. Hansford believes his work can contribute to conservation efforts on Madagascar, where many unique species of plants and animals are threatened.

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First Fossil Lungs Found In Dinosaur-Era Bird

For the first time, researchers found the presence of what they believe to be lung tissue in an avian dinosaur fossil.

About 120 million years ago in what’s now northeastern China, a bird met its end during a volcanic eruption.

Ashfall buried the animal so suddenly, its soft tissues didn’t have time to decay, and over millions of years, minerals infiltrated these tissues and preserved their form.

Now, researchers have unveiled this breathtaking specimen, which contains the first fossilized lungs ever found in an early bird.

The species Archaeorhynchus spathula lived alongside the nonavian dinosaurs during the Cretaceous period.

The newfound fossil, which preserves feathers and considerable soft tissue, shows that this primitive bird’s lungs closely resemble those found in living birds.




This suggests that birds’ hyper-efficient lungs, a key adaptation for flight, first emerged earlier than thought, and it underscores how birds—the last living dinosaurs—inherited many iconic traits from their extinct ancestors.

Everything we knew about lungs, about respiration, about evolution of [birds] was just inferring based on skeletal indicators,” says study coauthor Jingmai O’Connor, a paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China.

“And now we know that we were inferring less generously than we should have.”

A newly identified Archaeorhynchus specimen showing the preserved plumage and lung tissue.

O’Connor presented the discovery on October 18 at the Society of Vertebrate Paleontology’s annual meeting in Albuquerque, New Mexico, and the finding will be published in the Proceedings of the National Academy of Sciences.

This is an exciting discovery,” says Colleen Farmer, an anatomist and physiologist at the University of Utah who reviewed the study.

Finding bird-like lungs in this group of dinosaurs is to be expected, but it is incredible to uncover hard evidence of this soft structure.

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Secret Life Of The Dodo Revealed

Scientists are piecing together clues about the life of the dodo, hundreds of years after the flightless bird was driven to extinction.

Few scientific facts are known about the hapless bird, which was last sighted in 1662.

A study of bone specimens shows the chicks hatched in August and grew rapidly to adult size.

The bird shed its feathers in March revealing fluffy grey plumage recorded in historical accounts by mariners.

Delphine Angst of the University of Cape Town, South Africa, was given access to some of the dodo bones that still exist in museums and collections, including specimens that were recently donated to a museum in France.




Her team analysed slices of bone from 22 dodos under the microscope to find out more about the bird’s growth and breeding patterns.

Before our study we knew very very little about these birds,” said Dr Angst.

Using the bone histology for the first time we managed to describe that this bird was actually breeding at a certain time of the year and was moulting just after that.

The scientists can tell from growth patterns in the bones that the chicks grew to adult size very rapidly after hatching from eggs around August.

This would have given them a survival advantage when cyclones hit the island between November and March, leading to a scarcity of food.

However, the birds probably took several years to reach sexual maturity, possibly because the adult birds lacked any natural predators.

The bones of adult birds also show signs of mineral loss, which suggests that they lost old damaged feathers after the breeding season.

Ancient mariners gave conflicting accounts of the dodo, describing them as having “black down” or “curled plumes of a greyish colour”.

The research could also shed light on the dodo’s extinction about 350 years ago, less than 100 years after humans arrived on the island.

Hunting was a factor in the dodo’s demise, but monkeys, deer, pigs and rats released on the island from ships probably sealed their fate.

Dodos laid their eggs in nests on the ground, meaning they were vulnerable to attack by feral mammals.

Dr Angst said the dodo is considered “a very big icon of animal-human induced extinction“, although the full facts are unknown.

It’s difficult to know what was the real impact of humans if we don’t know the ecology of this bird and the ecology of the Mauritius island at this time,” she explained.

So that’s one step to understand the ecology of these birds and the global ecosystem of Mauritius and to say, ‘Okay, when the human arrived what exactly did they do wrong and why did these birds became extinct so quickly’.

Julian Hume of the Natural History Museum, London, a co-researcher on the study, said there are still many mysteries surrounding the dodo.

Our work is showing the seasons and what was actually affecting the growth of these birds because of the climate in Mauritius,” he said.

The cyclone season, when often the island is devastated with storms – all the fruits and all the leaves are blown off the trees – is quite a harsh period for the fauna – the reptiles and the birds on Mauritius.

The dodo, which is related to the pigeon, evolved on Mauritius.

However, bone samples are rare, making it difficult to trace the evolutionary process.

Although many specimens of the dodo ended up in European museums, most were lost or destroyed in the Victorian era.

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Scientists Reveal What The First Flower Looked Like

ancient-flower

Until 140 million years ago, there were no flowers anywhere on Earth. Then, primitive flowers burst onto the scene, and flowering plants took over the world.

All living flowers today came from a single ancestor that lived about that time, according to a new study published Tuesday in the peer-reviewed British journal Nature Communications.

Scientists also reconstructed what they believe that first flower looked like: Somewhat similar to a water lily, with circles of broad petals around a center of protruding pollen spikes.




However, lead author Hervé Sauquet, an evolutionary biologist from Paris-Sud University, said it’s difficult to make a direct comparison with flowers of today: “All flowering plants have evolved and changed since that ancestor, that’s how evolution works,” he said.

So there is no single species or group of species that would have existed some long time ago and still exists today unchanged.

The origin and early evolution of flowering plants and especially their flowers have long been one of the biggest enigmas in biology, almost 140 years after Charles Darwin called their rapid rise in the Cretaceous “an abominable mystery.

The ancestral flower was bisexual, with both female (carpels) and male (stamens) parts, and with multiple whorls (concentric cycles) of petal-like organs, in sets of threes, according to the new study.

ancient-flower

About 20% of flowers today have such “trimerous” whorls, but typically fewer: lilies have two, magnolias have three.

These results call into question much of what has been thought and taught previously about floral evolution,” said study co-author Juerg Schoenenberger of the University of Vienna.

It has long been assumed that the ancestral flower had all organs arranged in a spiral.

Study co-author Maria von Balthazar, another University of Vienna scientist, said “the results are really exciting! This is the first time that we have a clear vision for the early evolution of flowers.

flower

No flower fossils exist from 140 million years ago, though, Sauquet said. The fossil record of flowering plants is still very incomplete, he said, and scientists have not yet found fossil flowers as old as the group itself. The earliest flower fossil is “only” 130 million years old.

As for where that original flower 140 million years ago came from, Sauquet said that “we’re not sure, and that remains one of the biggest mysteries in plant science. We know it came deep down from a common ancestor with all gymnosperms (conifers, cycads, ginkgo), maybe 310 million years ago.

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Did Humans And Neanderthals Interbreed?

In 1856, laborers working in a limestone quarry near Düsseldorf, Germany, unearthed bones that scientists initially thought belonged to a deformed human.

The skull was oval shaped, with a low, receding forehead, distinct brow ridges, and bones that were unusually thick.

Subsequent study revealed that the remains belonged to a previously unknown species of hominid, or early human ancestor, that was similar to our own species, Homo sapiens.

In 1864, the specimen was dubbed Homo neanderthalensis, after the Neander Valley where the skull was discovered.

Neanderthals were our closest evolutionary relatives. Their ancestors left Africa before modern humans, venturing into Europe as far back as 500,000 years ago, and were still there when our ancestors embarked on the same journey about 70,000 years ago.

Neanderthals and modern humans actually lived alongside each other in Europe for several thousand years before Neanderthals vanished some 30,000 years ago.




Their disappearance is one of the most enduring mysteries in all of human evolution.

But perhaps the most controversial theory for why there are no more Neanderthals is that they interbred with modern humans and the two lineages merged into one.

According to this idea, most of modern humanity—with the possible exception of some Africans who are descended from humans who never left Africa—is part Neanderthal.

Evidence for interbreeding comes largely from the study of fossils that, according to some scientists, show hybrid traits from both species.

For example, anthropologist Erik Trinkhaus believes that a 29,000-year-old skull discovered in Romania belonging to a modern human has an unusually long and flat forehead and unusually large molars.

There is some genetic evidence to support the interbreeding theory as well. In 2010, a team of scientists comparing a rough draft of the Neanderthal genome with that of modern humans concluded that most humans have 1 to 3 percent Neanderthal DNA.

The team suggested that the first opportunity for Neanderthal-human interbreeding probably occurred about 60,000 years ago, after modern humans had left Africa but before they had made significant inroads into Europe.

However, recent computer models suggest the genetic similarities shared between Neanderthals and modern humans could also be due to the two species sharing a recent common ancestor rather than hybridization.

Investigating The 580-Million-Year-Old Fossil With CT Scan

ediacaran

The Ediacaran biota (flourished 579-541 Mya) forms an important and unresolved episode in the history of life. These organisms arose soon after the end of the major glaciations of the Cryogenian, and persisted until the beginning of the Cambrian.

They are thought to include some of the earliest animals. Understanding the nature and lifestyle of the Ediacaran organisms is therefore important in tracing the potentially long fuse of the Cambrian explosion.

Yet they remain puzzling. This project will use micro-CT to investigate two particularly contentious structures found in rocks of this age, and assess how they fit into the larger picture of the origin of multicellular animals in this age.

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Pass it on: New Scientist

3 Animals That Mate For Life

Did you know there are members of the animal kingdom (other than humans) that mate for life?

In some cases of monogamous mates – for example, beavers – both parents care for their offspring.

When one partner in a monogamous pair dies, most surviving partners go on to find a new mate before the next breeding season.




Beavers

Adult beavers can weigh 40 pounds or more, and they mate for life during their third year. Their babies are called kits, and typically 1 to 4 are born in the spring.

Both parents care for their kits, who stay with them for about two years. The yearlings typically help care for the next litter. A beaver colony can consist of six or more individuals, including parents, yearlings, and kits.

Gibbons

Gibbons are the nearest relatives to humans that mate for life. They live in small, stable family groups with a monogamous mated pair and offspring under the age of 7.

Gibbon families are territorial and defend their territory with morning songs sung by the breeding pair.

Gibbons reach sexual maturity between 6 and 8 years of age. Females give birth to one baby at a time, and mating pairs produce an average of 5 to 6 offspring over their reproductive lifetimes.

Wolves

Wolves live in packs that are typically family groups including a male and female breeding pair and their offspring of varying ages. Only the breeding pair mates, and has one litter a year.

Wolves reach sexual maturity between 2 and 3 years of age, and once the youngsters are ready to mate, most leave their birth pack to start their own pack or join an existing pack.

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