Thursday, 18 March 2021

Evolution News - How Sperms Remember

New research shows how a father's experience can be passed on to his offspring.
How sperm remember | Newsroom - McGill University

This is the sort of paper that Creationist frauds can use to fool their scientifically illiterate dupes. It will be presented as 'proof' that Darwin was wrong all along and his 'rival' Jean-Baptiste Lamarck was right.

Lamarck, in his attempt to explain inheritance and evolution, had proposed that traits acquired after conception could be passed to children. He famously claimed a blacksmith, by developing string arms, would have sons who also had strong arms and be good blacksmiths. (In a sense, he was right but the mechanism, at least in sentient species, is via memes, not some assumed physical factor (genes were not know about then)). He was of course wrong about giraffes getting longer necks by stretching to reach higher leaves and passing on the stretched neck to their offspring. There is no way an acacia tree can stretch to avoid its leaves being eaten by giraffes, so Lamarckian inheritance can't explain arms races of that sort, even if it had some basis.

Darwin, on the other hand, argued that it was traits inherited from parents that were passed on and that these were fixed at conception (with occasional variations which could be 'favoured' by the environment in 'natural selection').

However, in recent years the science of epigenetics has thrown up a few challenges to the idea of a purely Darwinian inheritance . Basically, epigenetics is the study of how genes are deactivated in specialised cells so that the cell only performs the specific punction of its speciality. As I'll explain later, epigenetics, far from being the gift creationists have been praying for which is going to refute the hated Darwinian mechanism of evolution by natural selection, but it represents a major challenge to the neo-Creationist invention, intelligent [sic] design.

Creationist thinking is often simplistic and binary so, for example, if Lamarck was a little bit right, he was entirely right and Darwin was completely wrong. As this paper shows, and as always with biology, the truth is much more nuanced than that, which is partly why creationists have difficulty with the subject.

But first this piece of research by scientists at McGill University, Montreal, Canada, led by Sarah Kimmins, PhD, of McGill's Faculty of Medicine, Department of Pharmacology and Therapeutics. As the McGill news release explains:
It has long been understood that a parent’s DNA is the principal determinant of health and disease in offspring. Yet inheritance via DNA is only part of the story; a father’s lifestyle such as diet, being overweight and stress levels have been linked to health consequences for his offspring. This occurs through the epigenome - heritable biochemical marks associated with the DNA and proteins that bind it. But how the information is transmitted at fertilization along with the exact mechanisms and molecules in sperm that are involved in this process has been unclear until now.

The big breakthrough with this study is that it has identified a non-DNA based means by which sperm remember a father’s environment (diet) and transmit that information to the embryo. It is remarkable, as it presents a major shift from what is known about heritability and disease from being solely DNA-based, to one that now includes sperm proteins. This study opens the door to the possibility that the key to understanding and preventing certain diseases could involve proteins in sperm...

Our next steps will be to determine if these harmful changes induced in the sperm proteins (histones) can be repaired. We have exciting new work that suggest that this is indeed the case. The hope offered by this work is that by expanding our understanding of what is inherited beyond just the DNA, there are now potentially new avenues for disease prevention which will lead to healthier children and adults.

Sarah Kimmins, PhD, Senior author
Canada Research Chair in Epigenetics, Reproduction and Development.
Department of Pharmacology and Therapeutics, Faculty of Medicine,
McGill University, Montreal, Canada
A new study from McGill, published recently in Developmental Cell, has made a significant advance in the field by identifying how environmental information is transmitted by non-DNA molecules in the sperm. It is a discovery that advances scientific understanding of the heredity of paternal life experiences and potentially opens new avenues for studying disease transmission and prevention.

A paradigm shift in understanding of heredity


“The big breakthrough with this study is that it has identified a non-DNA based means by which sperm remember a father’s environment (diet) and transmit that information to the embryo,” says Sarah Kimmins, PhD, the senior author on the study and the Canada Research Chair in Epigenetics, Reproduction and Development. The paper builds on 15 years of research from her group. “It is remarkable, as it presents a major shift from what is known about heritability and disease from being solely DNA-based, to one that now includes sperm proteins. This study opens the door to the possibility that the key to understanding and preventing certain diseases could involve proteins in sperm.”

When we first started seeing the results, it was exciting, because no one has been able to track how those heritable environmental signatures are transmitted from the sperm to the embryo before,” adds PhD candidate Ariane Lismer, the first author on the paper. “It was especially rewarding because it was very challenging to work at the molecular level of the embryo, just because you have so few cells available for epigenomic analysis. It is only thanks to new technology and epigenetic tools that we were able to arrive at these results.”

When we first started seeing the results, it was exciting, because no one has been able to track how those heritable environmental signatures are transmitted from the sperm to the embryo before. It was especially rewarding because it was very challenging to work at the molecular level of the embryo, just because you have so few cells available for epigenomic analysis. It is only thanks to new technology and epigenetic tools that we were able to arrive at these results.

Ariane Lismer, Co- author
PhD candidate
Department of Pharmacology and Therapeutics, Faculty of Medicine,
McGill University, Montreal, Canada

Changes in sperm proteins affect offspring


To determine how information that affects development gets passed on to embryos, the researchers manipulated the sperm epigenome by feeding male mice a folate deficient diet and then tracing the effects on particular groups of molecules in proteins associated with DNA.

They found that diet-induced changes to a certain group of molecules (methyl groups), associated with histone proteins, (which are critical in packing DNA into cells), led to alterations in gene expression in embryos and birth defects of the spine and skull. What was remarkable was that the changes to the methyl groups on the histones in sperm were transmitted at fertilization and remained in the developing embryo.

“Our next steps will be to determine if these harmful changes induced in the sperm proteins (histones) can be repaired. We have exciting new work that suggest that this is indeed the case,” adds Kimmins. “The hope offered by this work is that by expanding our understanding of what is inherited beyond just the DNA, there are now potentially new avenues for disease prevention which will lead to healthier children and adults.”
So, in a very limited sense, some influences of environmental factors can be passed on to offspring, not as an alternative to the accepted mechanism of inheritance through DNA but in a supplementary addition to it. No-one studying epigenetics seriously doubts that Darwinian inheritance, via hereditary traits now known to be carried in DNA, is the major mechanism of biological inheritance.

Why then is epigenetics a major problem for Creationist proponents of intelligent [sic] design? As I wrote in my popular book, The Unintelligent Designer: Refuting the Intelligent Design Hoax:
How [epigenetics] fits in with the ID model is also something creationists need to explain. Simply waving it as an example of how Darwinian evolution might not be the whole story, as though that destroys the whole of evolutionary biology and negates the masses of evidence on which neo–Darwinian consensus is based, is grasping at straws.

But there is something else that the ID movement needs to explain and this brings me back to the point of this book in general and to this chapter in particular. Why is the whole complex process of epigenetics necessary in the first place?

Epigenetics is necessary because in multicellular organisms, any advantage of multicellularity is only realised by specialisation of cells and their arrangement into organs carrying out specialist functions. Many of these functions are only necessary in the first place because of multicellularity, of course. Mammals need digestive, respiratory and circulatory systems to get oxygen and nutrients and remove waste to the cells too far removed from the surface to do it the way single–celled organisms do it – by direct exchange with their environment.

Evolutionarily speaking, multicellularity gave some organisms an advantage over others, but it comes at a price. One of the prices is the complex system of epigenetics and the need to reset and start again with each new individual.

But why is this needed anyway? It is needed because, just like single–celled organisms, the cells of multicellular organisms inherit all the DNA of their parent cells regardless of their eventual function as specialised cells in specialised organs. Unless the unnecessary and unwanted genes are turned off there would be no specialisation and so no benefit from multicellularity. The last thing you want is your brain cells producing the digestive enzymes your pancreas secretes or your kidney cells producing the contractile proteins in your muscles. You want your cells to be specialised and be good at doing what they are specialised to do – and nothing else. When cells start becoming generalised and doing other things they are called cancer.

So what any ID model needs to explain is why any intelligent designer would arrange it so that all cells (with one or two limited exceptions) contain all the DNA of the entire organism when they only need a few special genes to function? Why is this complex system of epigenetics necessary in the first place? Why would an intelligent designer not design things so that as cells become specialised, they only get the DNA they need?

Instead, we have the ludicrous situation of prolific waste of resource in replicating all the DNA – with its attendant risk of going wrong – to have most of it permanently switched off in almost every one of our 70 trillion cells. Then we need a mechanism for resetting it and starting again in the newly–fertilised zygote.

In epigenetics we have a few exciting challenges for biology; for creationism we have as good an example as you can wish for of designer incompetence. We have prolific waste, needless complexity, a clear failure to plan ahead and needing to make the most of a bad job, and of a ludicrously complex ‘solution’ to a problem of its own making because, apparently, the designer lacked the wit to rethink the problem and start again.

How this can be described as intelligent design is quite beyond me. It requires definitions of ‘intelligent’ and ‘design’ that are unrecognisable and indistinguishable from the normal definitions of ‘gross incompetence’ and ‘stupidity’.

Rubicondior, Rosa. The Unintelligent Designer: Refuting the Intelligent Design Hoax, (ISBN-13: 978-1723144219) pp. 113-114








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