Showing posts with label genetics. Show all posts

Thursday, 19 May 2016

Our Common Forefather: Just a Few Men Controlled Reproduction in Prehistory and Dominate World Genetics Today

Our Common Forefather

Just a Few Men Controlled Reproduction in Prehistory and Dominate World Genetics Today

Imaginative depiction of the Stone Age, by Viktor Vasnetsov. Source: Public Domain

A new genetic study of male ancestry shows there were periods in human prehistory when just a few elite men controlled reproduction. For example, one man about 190,000 years ago was the ancestor of 1,200 living men from 26 groups around the world whose genes were analyzed for the new study.

Who knows if that one man so long ago had great genes? Would the world have been different if it had been another man who had fathered much of the human race?

And one might also wonder just how many women this man had been with in his life. He lived at the dawn of the history of the Homo sapiens species, so perhaps just by dint of arithmetic and not necessarily by having many mates his genes came to dominate humanity.

But thousands of years later, genetic studies show, just a few men were responsible for much of the reproduction.

These tantalizing questions aren’t answered in the press release from the Wellcome Trust Sanger Institute reporting on a new study that found this ancient patriarch’s descendants are all over the world. Dr. Chris Tyler-Smith of the institute headed the study. An institute press release on the largest-ever study of the global genetic variation in the Y (male) chromosome states:

“The study … analysed sequence differences between the Y chromosomes of more than 1200 men from 26 populations around the world using data generated by the 1000 Genomes Project. Analysing the Y chromosomes of modern men can tell us about the lives of our ancestors. The Y chromosome is only passed from father to son and so is wholly linked to male characteristics and behaviours. The team used the data to build a tree of these 1200 Y chromosomes; it shows how they are all related to one another. As expected, they all descend from a single man who lived approximately 190,000 years ago.”

Another finding of the study is that one man who lived in Europe about 4,000 years ago is the ancestor of half of Western European men, Dr. Tyler-Smith told The Telegraph. “In Europe there was huge population expansion in just a few generations,” he told The Telegraph. “Genetics can’t tell us why it happened but we know that a tiny number of elite males were controlling reproduction and dominating the population. Half of the Western European population is descended from just one man.”

Time of haplogroup growth in different parts of the world.

World Map of Y-Chromosome Haplogroups - Dominant Haplogroups in Pre-Colonial Populations with Possible Migrations Routes. (CC BY SA 3.0)

Dr. Tyler-Smith says in the press release: “The best explanation is that they may have resulted from advances in technology that could be controlled by small groups of men. Wheeled transport, metal working and organised warfare are all candidate explanations that can now be investigated further.”

The study found an explosion in the population of males around 55,000 to 50,000 years ago in Asia and Europe and about 15,000 years ago in the Americas. Later rapid expansions of male populations happened in sub-Saharan Africa, Western Europe, South Asia, and East Asia between 8,000 and 4,000 years ago.

“The team believes the earlier population increases resulted from the first peopling by modern humans of vast continents, where plenty of resources were available,” the press release states.

Time of haplogroup growth in different parts of the world. (Wellcome Trust Sanger Institute)

Nearly a year ago scientists reported in the journal Nature that the majority of European men are descended from just a handful of Bronze Age male ancestors.

The presence of genetic material from just a few men in the Y chromosome sequence resulted from a population explosion several thousand years ago, researchers said. The team of scientists found that there was a huge increase in the population 2,000 to 4,000 years ago, in a band from Greece and the Balkans to the British Isles and Scandinavia.

The scientists in that study also speculated that perhaps cultural and technological changes were involved in the population explosions.

Bronze-Age warriors. (CC BY NC SA 2.0)

“The population expansion falls within the Bronze Age, which involved changes in burial practices, the spread of horse-riding and developments in weaponry. Dominant males linked with these cultures could be responsible for the Y chromosome patterns we see today,” Professor Mark Jobling of the University of Leicester said.

Most European Men are Descended from just Three Bronze Age Warlords, New Study Reveals

Bronze Age warriors on the lookout (Mike Bishop / Flickr)

The majority of European men are descended from just a handful of Bronze Age male ancestors, says a new genetic study in the journal Nature.

The presence of genetic material from just a few men in the Y chromosome sequence resulted from a population explosion several thousand years ago, researchers said. The team of scientists found that there was a huge increase in the population 2,000 to 4,000 years ago, in a band from Greece and the Balkans to the British Isles and Scandinavia.

Europe in the late bronze age of about 1100 BC. (Map by Xoil, Wikimedia Commons)

Popular Archaeology reported on the study, saying the researchers from the University of Leicester in England, headed by Professor Mark Jobling, determined the origin of DNA sequences of a big part of the Y chromosome in 334 men from 17 populations in Europe and the Middle East. They found three very young branches of DNA account for Y chromosomes of 64 percent of the men who gave genetic material for the study. The team used new methods for analyzing DNA variation to give a less biased picture of diversity and to give a better estimate of timing of population variations.

"The population expansion falls within the Bronze Age, which involved changes in burial practices, the spread of horse-riding and developments in weaponry. Dominant males linked with these cultures could be responsible for the Y chromosome patterns we see today,” Jobling told Popular Archaeology.

Research into Europeans' genetic heritage had previously focused on Old Stone Age (Paleolithic) or New Stone Age (Neolithic) ancestor-farmers of about 10,000 years ago.

The principal author of the study in Nature, Chiara Batini of the University of Leicester, said: "Given the cultural complexity of the Bronze Age, it's difficult to link a particular event to the population growth that we infer. But Y-chromosome DNA sequences from skeletal remains are becoming available, and this will help us to understand what happened, and when."

A finding by researchers from Harvard Univerity in Boston found in 2014 that the European population was descended from three tribes where there was intermarrying. This study too was in the journal Nature.

The BBC, reporting on the study, said the modern European gene pool developed from the three populations within the past 7,000 years.

“Blue-eyed, swarthy hunters mingled with brown-eyed, pale skinned farmers as the latter swept into Europe from the Near East. But another, mysterious population with Siberian affinities also contributed to the genetic landscape of the continent. ... Multiple lines of evidence suggested this new way of life was spread by a wave of migrants, who interbred with the indigenous European hunter-gatherers they encountered on the way,” the BBC wrote.

The study found humans arrived in Europe about 45,000 years ago. These people were replaced by others who arrived from the Near East and the Levant about 7,000 years ago, researchers who examined ancient and modern DNA found. Researches from Harvard found most modern Europeans have a mixture of early European farmer DNA, western European hunter-gatherer DNA and some northern Eurasian ancestry.

For this study the researchers studied DNA in ancient bones of seven Scandinavian hunter-gatherers, one from Luxembourg and an ancient farmer from the area of Stuttgart, Germany and compared it to the genomes of 2,000 modern people around the world. So this was different than the more recent study by the University of Leicester, which examined just modern DNA of living men.

From Ancient Origins @ http://www.ancient-origins.net/news-evolution-human-origins/just-few-men-controlled-reproduction-prehistory-and-dominate-world-020821?nopaging=1#sthash.oCzKaQxQ.dpuf and http://www.ancient-origins.net/news-evolution-human-origins/most-european-men-are-descended-just-three-bronze-age-warlords-new-020361?nopaging=1#sthash.qTvxcVBJ.dpuf

For more hidden history see http://nexusilluminati.blogspot.com/search/label/hidden%20history

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Saturday, 26 March 2016

Doing Without Males: Chinese scientists claim they can create babies without men by injecting eggs with artificial sperm

Doing Without Males

Chinese scientists claim they can create babies without men by injecting eggs with artificial sperm

Youtube / Cambridge University

By John von Radowitz

Ground-breaking: Scientists say they have created mouse babies using artificial sperm

Scientists have claimed they have found a way for women to have babies without men by creating artificial sperm. The team from China claim they have created healthy mouse babies by injecting laboratory-made sperm into eggs to produce mouse offspring.

The scientists claim their stem cell technique could pave the way for new treatments for male fertility. But British experts have called for the results to be independently verified and pointed out that any practical application is likely to be a long way off.

The mouse cells produced were technically "spermatids" - undeveloped sperm that lack tails and cannot swim.

Yet when they were injected into mouse eggs, mimicking a common IVF technique called Icsi (intracytoplasmic sperm injection), they delivered viable embryos and healthy, fertile babies.

In the UK, using spermatids in the same way to produce a pregnancy would be illegal.

Dr Jiahao Sha, from Nanjing Medical University, who co-led the research, published the results in the peer-reviewed journal Cell Stem Cell.

He said: "If proven to be safe and effective in humans, our platform could potentially generate fully functional sperm for artificial insemination or in-vitro fertilisation techniques.

"Because currently available treatments do not work for many couples, we hope that our approach could substantially improve success rates for male infertility."

The scientists began with stem cells taken from mouse embryos which were exposed to a carefully mixed cocktail of chemicals. This triggered their transformation into primordial germ cells, the first step on the developmental path to becoming sperm.

Next, the germ cells were exposed to testicular cells and testosterone in an attempt to mimic the natural environment of the testes. When the resulting spermatids were injected into mouse eggs, they proved capable of producing embryos that developed normally.

Scientists have previously taken early steps in the process of creating artificial sperm and eggs in the laboratory.

In 2011 a Japanese team produced mouse germ cells from stem cells which eventually developed into healthy viable sperm, but only after they were injected into the testicles of male mice.

Infertility affects around 15% of couples and can be traced to the man in about a third of cases.

A major cause of male infertility is the failure of pre-cursor cells in the testes to undergo a special type of cell division called meiosis.

Discovery: British scientists say the results need to be independently verified

In 2014 a team of distinguished reproductive biologists writing in the journal Cell proposed a set of "gold standard" criteria to prove that all the essential steps of meiosis have taken place in artificially created eggs or sperm.

They included showing evidence of correct DNA content in the cell nucleus at specific meiotic stages, normal chromosome number and organisation, and the ability of the engineered cells to produce viable offspring.

The Chinese team claims to have passed all these tests.

Dr Sha said: "Our method fully complies with the gold standards recently proposed by a consensus panel of reproductive biologists, so we think that it holds tremendous promise for treating male infertility."

Scientists in the UK praised the "mammoth" achievement of their Chinese colleagues but said there were still many obstacles to be overcome before sperm-like cells grown in the laboratory could be of use to infertile men.

Professor Richard Sharpe, from the Medical Research Council Centre for Reproductive Health at the University of Edinburgh, said safety was a major issue.

"Bear in mind that if germ cells do not format their DNA correctly, it may not only affect the resulting individual but might also affect the next generation," he pointed out.

Getty

Radical: Chinese scientists claim the discovery could provide hope for infertile men

Allan Pacey, Professor of Andrology at the University of Sheffield, said the study was an "interesting step forward".

But he added: "It's important to note that the sperm-like cells produced in the study were not fully mature sperm as we might know them. "

"In spite of these encouraging results, we are still some way from immediately applying this technique as a potential cure for human male infertility," he continued.

"It remains to be seen if this technique could be applied in humans to create sperm-like cells that might be usable in IVF."

Artificial Sperm...Men Not Needed

(5:38) @ https://www.youtube.com/watch?v=4fIQCMQzSvc

Children born using IVF could face serious health problems later in life, warns scientist

Embryo selection: Key stage in IVF - Getty

By Andrew Gregory

Dr Pascal Gagneux, an evolutionary biologist, believes the technology may be storing up serious trouble for ageing populations of IVF children

Children born using IVF could face serious health problems later in life, a scientist claims. Assisted reproduction is an “evolutionary experiment” that could end up proving as big a health disaster as junk food, he warned.

Dr Pascal Gagneux, an evolutionary biologist from the University of California at San Diego in the US, believes the technology may be storing up serious trouble for ageing populations of IVF children.

In vitro fertilisation is one of several techniques available to help people with fertility problems have a baby. During IVF, an egg is removed from the woman’s ovaries and fertilised with sperm in a laboratory.

The fertilised egg, called an embryo, is then returned to the woman’s womb to grow and develop. It can be carried out using your eggs and your partner’s sperm, or eggs and/or sperm from donors.

Of the estimated five million IVF offspring alive today, the oldest of them, British “test tube baby” Louise Brown, is only 37.

But Dr Gagneux fears there may be unintended and unwanted consequences of IVF that will emerge towards the end of life and that cannot be detected now.

He said: “The first thing is that it is a new technology. To me it represents the cutting edge of human technology.

“This technology has for less than forty years allowed couples who couldn’t conceive naturally to conceive, which is hopeful in a sense. It’s also weird because it is the first time that we have removed sex from reproduction.

“For years I’ve been interested in the possibility that when animals mate they produced from hundreds of millions to billions of sperm.

"But in IVF there is only one sperm that fertilises the egg so when everybody sees an egg with loads of sperm around it that is from a fertility clinic.

“In vivo, in the female, fertilisation happens in the tunnel of fallopian tube and it’s a tango. One egg, one sperm. Given the complexity of the female reproductive tract in mammals there might be something called female cryptic choice.

"So obviously when you use assisted reproductive you bypass that.”

He added: “The concern that by bypassing female choice at the level of sperm selection we might produce embryos which contain risk factors that you would otherwise not have.”

Speaking at the American Association for the Advancement of Science (AAAS) annual meeting in Washington DC, he pointed out that scientists have already uncovered worrying signs.

Some mice born to IVF who have been allowed to age became ill. Females develop a pre-diabetic condition called metabolic syndrome, while male animals suffer hormonal problems.

More worrying was one study which involved taking 100 IVF and naturally conceived children aged as young as six 3,500 metres up a Swiss mountain, where low oxygen levels mimic effects of ageing.

Heart and artery malfunction was reported “very convincingly” in the assisted reproduction children, including those with brothers and sisters who were conceived naturally, said Dr Gagneux.

Speaking at the world’s biggest science conference in Washington DC, he said: “I’m an evolutionary biologist and interested in human origins. To me this is the epitome of a species taking its own fate into its own hands.

“We’re engaging in an evolutionary experiment. I would compare it to high fructose corn syrup and fast food in the US.

“It took 50 years; it was fantastic, you got bigger and healthier, and now the US are the first generation that are shorter and heavier and die younger. But it took 50 years.

“I think we can’t rule out that it could be shortening life span. It could also be introducing some very interesting costs in terms of metabolic syndrome.”

When nature is allowed to take its course, only a handful of sperm out of 100 million ever make it to the egg. Just one will fuse successfully with the egg and achieve the goal of fertilisation.

Dr Gagneux said: “What is interesting is that the force of natural selection is extremely strong early in life and becomes very weak late in life.

"The very reason why we age has to do with the fact that you can select for things that help you when you’re young and those very same things will kill you when you’re old.

“With increased life expectancy and maximum longevity we are setting the stage so that even a slight deviation from something highly adaptive might bite you in the butt quite badly when you’re 70,80, or 90.”

One of his biggest concerns was the way IVF embryos were bathed in a cocktail of chemicals for up to five days during the phase when genetic “imprinting” is taking place.

This is a process that switches on some genes, and switches off others, and it has effects that can be passed down generations.

He added: “It could also be introducing some very interesting costs if metabolic syndrome would be one of the potential consequences of starting an embryo out in ‘rocket fuel’, some minestrone mixture that lab people have developed.”

From The Mirror @ http://www.mirror.co.uk/news/world-news/scientists-claim-can-create-babies-7441572 and http://www.mirror.co.uk/news/technology-science/science/children-born-using-ivf-could-7377480

For more information about ivf therapies see http://nexusilluminati.blogspot.com/search/label/ivf