Science
Survival of the traits
Mammals can pass along acquired characteristics to their offspring, according to a new study.
If you remember your ninth-grade biology, you probably remember the Frenchman Jean-Baptiste Lamarck as one of the wacky also-rans of modern science. He was the predecessor of Darwin whose theory of acquired characteristics held that the stature of the giraffe came from generations of giraffe parents straining their necks ever farther to reach the leafy branches of the banyan tree, then — and this was the wacky part — passing their long necks on to their kids. For a century Lamarckism has been joke science, a notch below creationism, buried ever deeper under Darwin’s theory of natural selection. But if a study published Monday in the influential journal Nature Genetics is any indication, Lamarck may be due for a rehabilitation, of sorts.
In the work published in Nature Genetics, Emma Whitelaw and her colleagues at the University of Sydney did a set of experiments with a particular strain of lab mice. The odd thing about this strain, which had been observed previously, was that despite being genetically identical, some of the mice were yellow, others gray-striped, others a mix of yellow and stripes. The researchers found that the differences were caused by subtle changes in the mice’s DNA during their fetal development.
Whitelaw’s even more surprising observation was that all the mice whose mothers had yellow coats always had yellow coats as well. In other words, the non-genetic change that occurred in the female mouse fetus was somehow passed along to her offspring when she became a mother. Even when the mouse embryos were nurtured in the wombs of surrogate mothers, their coat color was the same as that of the “genetic” mother.
Whitelaw’s work is apparently the first showing that mammals can somehow pass along acquired characteristics to the next generation. It isn’t quite as remarkable as Lamarck’s giraffes inheriting stretched necks, but it is, strictly speaking, proof of Lamarckian inheritance.
The study is part of a growing field called epigenetics, a branch of developmental biology that investigates the mechanisms whereby certain genes are suppressed through changes in the chemical makeup and shape of the DNA in which they are embedded.
We all know how genes are supposed to work in the classic Mendelian scheme of inheritance: You get a copy or two of the fat gene, depending on whether or not it’s recessive or dominant, and that makes you fat. Complicating matters, many conditions don’t fit into a neat Mendelian box. It’s known that schizophrenia is largely inherited, for example, but after years of unsuccessfully trying to locate single genes for schizophrenia, scientists believe that many different genes operating in different combinations contribute to the ailment.
Epigenetics adds yet a further complication to the picture. Instead of just a lot of genes operating together, it turns out, subtle, random changes in the chemistry of the DNA itself affect which of those genes actually fire into action.
Just how prominently epigenetics figures in the overall scheme of things — how big a role they play, for example, in human traits and disease — isn’t yet known. But epigenetics studies have multiplied in the past decade and there is already clear evidence of epigenetic effects.
For example, many genes function only in men or women because of a gene-suppressing action called imprinting. Prader-Willi syndrome, a rare genetic disease, and Angelman syndrome, a neurological disorder, are both the result of subtle changes in the expression of a gene on chromosome 15. Prader-Willi manifests itself only when the DNA mutation is inherited from a father; Angelman syndrome from the mother.
In the nature vs. nurture debate, epigenetics falls under the category “the nurture of nature.” As billions of dollars are poured into the Human Genome Project, it’s worth pointing out, as does Eva Jablonka of Tel Aviv University, that “DNA sequence information is not sufficient for understanding the intricacies of biological inheritance.” It’s not that genetic effects aren’t important, or the genome project any less valuable than its hype. Rather, scientists working on the fringe of genetics are pointing to some of the other factors that impinge on the success of genes.
So what does this have to do with Lamarck? It now appears — Whitelaw’s study is a good example — that some of the alterations in gene function resulting from epigenetic changes can be passed along to the next generation. Ted Steele, another Australian scientist, made this argument strongly in a book he published earlier this year, “Lamarck’s Signature: How Retrogenes are Changing Darwin’s Natural Selection Paradigm.”
Steele argues intriguingly that the coding for the production of antibodies to certain viral or bacterial attackers might be transcribed into the DNA of human somatic, or non-sexual cells, then somehow transferred from somatic to germ line cells — sperm and ova. Steele presents a plausible case for such a transfer, but no direct evidence for it.
However, Whitelaw’s article does present evidence for such a transfer. The yellow-coat color apparently comes about by means of an epigenetic change caused when a particle called a retrotransposon — a gene that moves around the genome — settles during fetal development in DNA near the color gene. How the retrotransposon was passed along to germ line cells, and thus inherited, isn’t clear.
The patterns Whitelaw observed “seem heretical in their Lamarckian character,” write developmental biologists Rosalind John and Azim Surani in an article accompanying Whitelaw’s paper, “but they do occur and are therefore worth serious consideration.”
As it happens, this kind of gene change has been shown to be quite common in plants, and is probably also common — though harder to observe — in animals, says Robert A. Martienssen, a scientist at Cold Springs Harbor Laboratory who has an article about plant epigenetics in the same issue of Nature Genetics. “To the extent there is Lamarckian inheritance, it occurs through epigenetics,” he says.
Darwin, embarrassingly to the neo-Darwinians, was a great admirer of Lamarck (1744-1829) and incorporated his theories into work he published after “Origin of Species.” The Stalinist agriculture czar T.D. Lysenko gave Lamarckism an enduringly bad name. Convinced that Lamarck was a better Marxist than Darwin, Lysenko gutted Soviet agricultural science and fruitlessly tried to improve grain harvests by experimenting with adult plants in the vain hope they would pass along the changes he made. Meanwhile, millions starved on collective farms.
But now that the Cold War is over, perhaps a neo-Lamarckian rebirth is overdue. Bring on the giraffes!
Arthur Allen writes on health, science and other issues for Salon. He lives in Washington. More Arthur Allen.
Is aggression genetic?
We've been conditioned to believe that some people were born violent -- but the science shows that's just not true
(Credit: stefa via Shutterstock) In his story of Dr. Jekyll and Mr. Hyde, Robert Louis Stevenson famously shows the dark side of humanity. The respectable and kind Dr. Jekyll devises a potion that enables him to bring to the surface his evil core. In Mr. Hyde, with his vile appearance and violent behavior, Jekyll sees that this alter ego “bore the stamp of lower elements in my soul.”
The concept that humanity has a violent and evil core is widespread; it is one of the oldest and most resilient myths about human nature. From historical and philosophical beliefs to current popular and scientific beliefs, the view that a savage and aggressive beast is a central part of our nature permeates public and academic perceptions. Given this view, it is a common assumption that if you strip away the veneer of civilization, the restraints of society and culture, you reveal the primeval state of humanity characterized by aggression and violence.
Continue Reading CloseAgustin Fuentes is Professor of Anthropology at the University of Notre Dame. He is the author of "Evolution of Human Behavior," "Biological Anthropology: Concepts and Connections and Core Concepts in Biological Anthropology." More Agustin Fuentes.
Hold on tight
Science shows that closeness with others doesn't just help us cope with pain -- it makes us live longer
(Credit: Peter Bernik via Shutterstock) I came home from work late one evening, hungry and frustrated, and popped into my mother’s house, which was next door to mine. She was eating a frozen dinner and sipping from a mug of hot water. CNN blared on the TV in the background. She asked how my day had been. I said, “Oh, it was good.” She looked up from her black plastic food tray and, after a moment, said, “No, it wasn’t. What happened? Have some pot roast.” My mother was eighty-eight, hard of hearing, and half blind in her right eye—which was her good eye. But when it came to perceiving her son’s emotions, my mother’s X-ray vision was unimpaired.
Continue Reading CloseNear-death, revisited
A response to PZ Myers' criticisms about my recent Salon story on the science of out-of-body experiences
Mario Beauregard First of all, I would like to thank Salon for giving me the opportunity to respond to P.Z. Myers’s article. In his article, Dr. Myers argues that near-death experience (NDE) stories are poorly documented. While this may true in some cases, it is not in many others (take, for instance, the cases investigated by prominent NDE researchers such as Bruce Greyson, Pim van Lommel, Sam Parnia, and Peter Fenwick).
With regard to mind-brain relationship, the most interesting NDE cases are those occurring during cardiac arrest. When there is a cardiac arrest, brain activity ceases within a few seconds. In that state, the electroencephalogram (or EEG—electroencephalography is a technique for recording the electrical activity of the brain) becomes rapidly flat. According to contemporary neuroscience, consciousness and other higher mental functions are not possible in such a state. Yet, more than 100 cases of NDEs occurring during cardiac arrest have been reported in previous studies. Importantly, some of these cases contain temporal markers, that is, verifiable reports of events occurring during the period of cardiac arrest (I am presenting a number of such cases in “Brain Wars”).
Continue Reading CloseMario Beauregard is associate research professor at the Departments of Psychology and Radiology and the Neuroscience Research Center at the University of Montreal. He is the coauthor of "The Spiritual Brain" and more than one hundred publications in neuroscience, psychology and psychiatry. More Mario Beauregard.
Near death, explained
New science is shedding light on what really happens during out-of-body experiences -- with shocking results.
Mopic via Shutterstock In 1991, Atlanta-based singer and songwriter Pam Reynolds felt extremely dizzy, lost her ability to speak, and had difficulty moving her body. A CAT scan showed that she had a giant artery aneurysm—a grossly swollen blood vessel in the wall of her basilar artery, close to the brain stem. If it burst, which could happen at any moment, it would kill her. But the standard surgery to drain and repair it might kill her too.
With no other options, Pam turned to a last, desperate measure offered by neurosurgeon Robert Spetzler at the Barrow Neurological Institute in Phoenix, Arizona. Dr. Spetzler was a specialist and pioneer in hypothermic cardiac arrest—a daring surgical procedure nicknamed “Operation Standstill.” Spetzler would bring Pam’s body down to a temperature so low that she was essentially dead. Her brain would not function, but it would be able to survive longer without oxygen at this temperature. The low temperature would also soften the swollen blood vessels, allowing them to be operated on with less risk of bursting. When the procedure was complete, the surgical team would bring her back to a normal temperature before irreversible damage set in.
Continue Reading CloseMario Beauregard is associate research professor at the Departments of Psychology and Radiology and the Neuroscience Research Center at the University of Montreal. He is the coauthor of "The Spiritual Brain" and more than one hundred publications in neuroscience, psychology and psychiatry. More Mario Beauregard.
Is the right really breaking up with its racists?
The National Review fired two bigots -- but don't expect it to part with the idea that race determines intelligence
(Credit: Antony McAulay via Shutterstock/Salon) The National Review this month is having one of its semi-regular “purges,” in which formerly welcome members of the conservative establishment are declared distasteful and relegated to the “fringes.” It began when self-declared racist and longtime National Review contributor John Derbyshire wrote a piece (not for the NR but for “Taki’s Mag,” an online magazine devoted to lighthearted racism) that went well beyond the bounds of “acceptable” race-baiting. He was canned. Shortly thereafter, another National Review contributor, Robert Weissberg, was fired for having given a presentation at a conference devoted to white supremacy last month.
Continue Reading Close
Alex Pareene writes about politics for Salon and is the author of "The Rude Guide to Mitt." Email him at apareene@salon.com and follow him on Twitter @pareene More Alex Pareene.
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