Darwin re-visited

[Michaelangelica]

Please go away and teach your grandmother to suck eggs.

[NLN]

I'm not necessarily disagreeing with you, Michaelangelica, I'm simply attempting to remind others that the burden of proof rests upon the party making claims. The internet is full of unsupported opinions dressed up as "facts," and we should all make every effort to assure that what we are passing along is the truth. Digging up references in support of our claims is the only defense against the possibility of spreading misinformation.

[Michaelangelica]

YES NLN, the way of "science" ?!

Mitey haploids aren't hapless after all

Friday, 29 June 2001


False spider mites: Diploids don't rule
A truly bizarre species of tiny spider-like creatures that consists entirely of females, has no need for sex and is biologically-speaking "a sandwich short of a picnic" is turning on its head conventional scientific wisdom.

Not only do the adults undergo "virgin birth" , but the only time baby boys are produced is when the mother is treated with antibiotics.

The false spider mite Brevipalpus phoenicis is the only animal known to exist entirely in the "haploid" state - with only half the full complement of chromosomes, according to a report in today's Science.

News in Science - Mitey haploids aren't hapless after all - 29/06/2001

[Michaelangelica]

Suddenly the old rules of genetics are looking out of date. Instead of being just a vehicle for DNA's commands, as scientists have long held, RNA seems to issue its own commands and alter what genes do in the next generation. "This phenomenon of the white-tailed mouse is just the tip of the iceberg," says Martienssen. And the environmental effects that alter one organism's RNA can apparently be passed down to its descendants almost indefinitely. In another landmark study this year, researchers working with nematode worms tracked a trait initiated with injected RNA over 80 generations. Nobody knows how RNA causes these long-lasting effects. One possibility is that it changes the way DNA is packaged in the cell, thereby permanently shutting down sections of the genome.

The implications are powerful. In September Michael Skinner of Washington State University announced that his lab rats inherit, epigenetically, their parents' propensity for a variety of humanlike diseases, including breast cancer, kidney disease, and high cholesterol. His results suggest that a parent's exposure to toxins—or simply bad diet—could harm her children for generations to come; the findings also hint that many seemingly genetic disorders could be treated in ways never before considered. "This opens up a whole new area for medical research and may be a way to combat disease," Skinner says.

The nascent field of epigenetic medicine is farthest along with respect to cancer: "Modifications of the genes that cause cancer are much more common than genetic mutations are," says Martienssen. That's good news, as epigenetic modifications—unlike mutations—are in principle reversible.

The Top 6 Genetics Stories of 2006 | Living World | DISCOVER Magazine

Morphic resonance would dictate that any acquired characteristic, whether a behavior or a shape, can be inherited. Acquired-characteristic inheritance is known as Lamarckism, after French biologist Jean-Baptiste de Monet de Lamarck, who proposed the idea in 1809, and is today almost universally rejected in favor of evolution by natural selection of random genetic mutations. Bucking this trend, Sheldrake fills much of his 1988 book The Presence of the Past with experimental evidence for acquired-characteristic inheritance. One example: In 1923, Russian physiologist Ivan Pavlov trained mice to run to a feeding place when an electric bell was rung. The first generation required an average of 300 trials to learn, the second 100, the third 30, and the fourth 10. Pavlov was stumped when a new, unrelated strain of mice did not display the same learning increments, but to Sheldrake, that outcome makes perfect sense.

Heresy | Living World | DISCOVER Magazine

12.11.2006
How Good Genes Go Bad
More ways to mess up your kids.
by Jessica Ruvinsky

Environmental toxins can affect gene
expression—for better or for worse.

A study in rats suggests that exposure to environmental toxins could be contributing to an inherited vulnerability to common diseases like breast cancer and high cholesterol.

Washington State University molecular biologist Michael Skinner had previously shown that sperm abnormalities induced by vinclozolin, a toxic fungicide used on wine grapes, strawberries, and other fruits, can pass from father to son for four generations in rats.
In a new study, he has found that the rats' offspring were inheriting more than just testis troubles.
They also had up to 10 times higher rates of breast cancer, prostate and kidney disease, high cholesterol, and immune abnormalities.

The rats, Skinner says, aren't inheriting bad genes so much as their recent ancestors' toxin exposure. In this type of novel inheritance, called epigenetic, changes don't occur in a DNA sequence as they do in a mutation.
Instead, the changes happen to certain chemical markers on the DNA that control how much any particular gene is expressed.
Previous studies in lab rats have shown that this type of nongenetic inheritance can influence traits like fur color and obesity.
Skinner's work shows it could also be crucial for understanding how our parents pass along vulnerability to a wide range of diseases.

How Good Genes Go Bad | Health & Medicine | DISCOVER Magazine

To the surprise of scientists, many environmentally induced changes turn out to be heritable. When exposed to predators, Daphnia water fleas grow defensive spines ( above). The effect can last for several generations.

DNA Is Not Destiny | Living World | DISCOVER Magazine

Such results hint at a seemingly anti-Darwinian aspect of heredity. Through epigenetic alterations, our genomes retain something like a memory of the environmental signals received during the lifetimes of our parents, grandparents, great-grandparents, and perhaps even more distant ancestors. So far, the definitive studies have involved only rodents. But researchers are turning up evidence suggesting that epigenetic inheritance may be at work in humans as well.
. . .
The studies by Pembrey and other epigenetics researchers suggest that our diet, behavior, and environmental surroundings today could have a far greater impact than imagined on the health of our distant descendants. "Our study has shown a new area of research that could potentially make a major contribution to public health and have a big impact on the way we view our responsibilities toward future generations," Pembrey says.
. . .
"If you have a generation of poor people who suffer from bad nutrition, it may take two or three generations for that population to recover from that hardship and reach its full potential," Harper says. "Because of epigenetic inheritance, it may take several generations to turn around the impact of poverty or war or dislocation on a population."

DNA Is Not Destiny | Living World | DISCOVER Magazine
The sins of the fathers. . .?

[NLN]

Physicist Mano Singham is currently writing a great series on evolution. Here is his latest entry.

[Michaelangelica]

Did Mendal think of this?
The world is stranger than you think (and evolution could be a LOT quicker.)
The Frog Killing Fungus

The frog killing chytrid fungus, Batrachochytrium dendrobatidis, infects the skin of susceptible amphibians and rapidly kills them. Not identified until 1998, the waterborne pathogen has already been fingered in the extinction of more than 150 species.. . .
./ . .
reveals that the chytrid fungus is reproducing sexually - rather than asexually by cloning itself as had been assumed by experts.

The find is significant as it means the fungus is a hardy more persistent species that can survive outside its host and evolve more rapidly than asexual fungi through shuffling its genes.
. ..
"Persistence of the fungus would complicate efforts to reintroduce amphibians" to sites where the fungus had eradicated them

Shuffle anyone?
Origin of frog-killing fungus probed | COSMOS magazine

[maikeru]

Originally Posted by Michaelangelica

YES NLN, the way of "science" ?!


News in Science - Mitey haploids aren't hapless after all - 29/06/2001

I think they can get away with it because of numbers.

Look at it this way. Even though being diploid allows you to cover bad mutations, being haploid allows you to expose bad ones, so long as you the species can pay the price (death, disability, or disadvantages incurred) and maintain a large enough population to keep the species going. In fact, exposing bad mutations and weeding out those individuals could help boost the health and variation in a population. Mites are great at this, multiplying to thousands, millions, or billions. Any individuals who would have deleterious mutations would die or forced out through other natural selective pressures. Producing large numbers of offspring also increases the genetic variation in a population gradually simply because there are more individuals out there with mutations creating different copies of genes.

[Freddy]

Did anyone see Meave Leakey's new discovery in Africa concerning human evolution?

"A new discovery suggests that Homo erectus may not have evolved from Homo habilis—and that the two may have been contemporaries."

A New Discovery in Human Evolution - Newsweek Technology - MSNBC.com

[Michaelangelica]

Originally Posted by Freddy

"A new discovery suggests that Homo erectus may not have evolved from Homo habilis—and that the two may have been contemporaries."

]

I have now thanks
That's causing quite a stir eg
BBC NEWS | Science/Nature | Finds test human origins theory
If Homo erectus had evolved from habilis and stayed within the same location ... the small size of the erectus skull suggests that species may not have been ...
news.bbc.co.uk/1/hi/sci/tech/6937476.stm - 40k - Cached - Similar pages -


Homo erectus and Homo habilis may have co-existed ... discovery of two fossils in Kenya challenges the belief that Homo erectus evolved from Homo habilis. ...
Homo habilis and Homo erectus may have co-existed - 61k

Homo habilis & Homo erectus, first stone tool users
Homo habilis is then not necessarily a direct ancestor of H. erectus . as the ... Java lineage ( Homo erectus erectus ) appears to have evolved into the ...
[url=http://www.ecotao.com/holism/hu_habilis.htm]

New Fossils Illustrate "Bushiness" of Human Evolution: Scientific ...
Fossils support the separate evolution of Homo habilis and Homo erectus, ... have often assumed that H. habilis evolved into the larger H. erectus, ...
New Fossils Illustrate "Bushiness" of Human Evolution: Scientific American

[Michaelangelica]

Weed Gave Up Sex Long Ago

Science Daily — The ability of plants to self-pollinate -- a big factor in the spread of weeds -- is much older than previously thought in one widely studied species, leading biologists say.



The mustard-like plant Arabidopsis thaliana. (Credit: Wikimedia Commons)


The findings show that at least in plant evolution, sex with others may be more trouble than it's worth.

The mustard-like plant Arabidopsis thaliana lost interest in sex and started self-pollinating at least a million years ago, said plant geneticists led by Magnus Nordborg, associate professor of molecular and computational biology at the University of Southern California.

The results contradict a 2004 estimate from North Carolina State University that A. thaliana began self-pollinating in the last 400,000 years.

"We can rule out a very recent change to self-fertilization," said Chris Toomajian, USC research associate in molecular and computational biology and co-author of two new papers on A. thaliana in Science Express and Nature Genetics.

Self-pollination, or selfing, confers a major advantage to weedy species. A selfing plant can invade new territory by itself and colonize it alone.

ScienceDaily: Weed Gave Up Sex Long Ago