Are humans still evolving by Darwin’s natural selection?

Are humans still evolving by Darwin’s natural selection?

From the 28 February 2011 BBC article

n 1859, Charles Darwin published On the Origin of Species, a book which transformed our understanding of how life on Earth developed – but ever since then, scientists have wondered whether humans were resourceful enough to remove themselves from the grip of natural selection.

There is no question that humans are unique in the animal world. We have developed technologies that shelter us from the harshness of the environment in a way that no other creatures have managed.

While polar bears evolved thick coats of blubber to insulate them from the Arctic cold, humans could skin that polar bear, and use the pelt as clothing to keep warm.

Does this mean that, at some point, technological advances have stopped us evolving?

Much of the story is in our genes and the sequencing of the human genome has helped unlock the answers.

By comparing the genes of people from all around the world, scientists can see how different we all are, and therefore how much we have evolved apart from each other since our species first appeared.

Skin colour is the most obvious way we have evolved apart, but there are other examples.

“We are living records of our past,” says Dr Pardis Sabeti, a geneticist at Harvard University. “And so we can look at the DNA of individuals from today and get a sense of how they all came to be this way.”

Another area of recent evolution is how our metabolism has changed to allow us to digest some things that we could not in the past.

The most obvious example of this is lactose, the sugar in milk. Some 10,000 years ago, before humans started farming, no one could digest this beyond a few years of age.

But today, the rate of lactose tolerance in different parts of the world is a clue to the different histories of farming across the globe. While 99% of Irish people are lactose tolerant, in South East Asia, where there is very little tradition of dairy farming, the figure is less than 5%.

So clearly our technology and inventions didn’t stop us evolving in the past. But what about today?

Professor Steve Jones, a geneticist at University College London, said: “In Shakespeare’s time, only about one English baby in three made it to be 21.”

“All those deaths were raw material for natural selection, many of those kids died because of the genes they carried. But now, about 99% of all the babies born make it to that age.”

The bulk of medical and other technological developments which protect us from our environment have come in just the past century. So in the developed world today, what is there left for natural selection to act on?

“Natural selection, if it hasn’t stopped, has at least slowed down,” says Jones…..

 

 

 

Parts of Brain Can Switch Functions: In People Born Blind, Brain Regions That Usually Process Vision Can Tackle Language

Parts of Brain Can Switch Functions: In People Born Blind, Brain Regions That Usually Process Vision Can Tackle Language

From a March 1, 2011 Science Daily item

ScienceDaily (Mar. 1, 2011) — When your brain encounters sensory stimuli, such as the scent of your morning coffee or the sound of a honking car, that input gets shuttled to the appropriate brain region for analysis. The coffee aroma goes to the olfactory cortex, while sounds are processed in the auditory cortex.

That division of labor suggests that the brain’s structure follows a predetermined, genetic blueprint. However, evidence is mounting that brain regions can take over functions they were not genetically destined to perform. In a landmark 1996 study of people blinded early in life, neuroscientists showed that the visual cortex could participate in a nonvisual function — reading Braille.

Now, a study from MIT neuroscientists shows that in individuals born blind, parts of the visual cortex are recruited for language processing. The finding suggests that the visual cortex can dramatically change its function — from visual processing to language — and it also appears to overturn the idea that language processing can only occur in highly specialized brain regions that are genetically programmed for language tasks.

“Your brain is not a prepackaged kind of thing. It doesn’t develop along a fixed trajectory, rather, it’s a self-building toolkit. The building process is profoundly influenced by the experiences you have during your development,” says Marina Bedny, an MIT postdoctoral associate in the Department of Brain and Cognitive Sciences and lead author of the study, which appears in the Proceedings of the National Academy of Sciences the week of Feb. 28…

Related articles

• New insight into the brain’s ability to reorganize itself (Science Daily)
• How clear is our view of brain activity? (Science Daily)Imaging techniques have become an integral part of the neurosciences. Methods that enable us to look through the human skull and right into the active brain have become an important tool for research and medical diagnosis alike. However, the underlying data have to be processed in elaborate ways before a colorful image informs us about brain activity.

Gut bacteria can control organ functions

Gut bacteria can control organ functions

From the Feburary 28 2011 Eureka news alert

Bacteria in the human gut may not just be helping digest food but also could be exerting some level of control over the metabolic functions of other organs, like the liver, according to research published this week in the online journal mBio®. These findings offer new understanding of the symbiotic relationship between humans and their gut microbes and how changes to the microbiota can impact overall health.

“The gut microbiota enhances the host’s metabolic capacity for processing nutrients and drugs and modulates the activities of multiple pathways in a variety of organ systems,” says Sandrine Claus of the Imperial College of London, a researcher on the study.

Claus and her colleagues exposed germ-free mice to bedding that had previously been used by conventional mice with normal microbiota and followed their metabolic profiles for 20 days to observe changes as they became colonized with gut bacteria.

Over the first 5 days after exposure, the mice exhibited a rapid increase in weight (4%). Colonization also triggered a number of processes in the liver in which sugars (glucose) are converted to starch (glycogen) and fat (triglycerides) for short-term and long-term energy storage. Statistical modeling between liver metabolic functions and microbial populations determined that the levels of glucose, glycogen and triglycerides in the liver were strongly associated with a single family of bacteria called Coriobacteriaceae.

“Here we describe the first evidence of an in vivo association between a family of bacteria and hepatic lipid metabolism. These results provide new insights into the fundamental mechanisms that regulate host-gut microbiota interactions and are of wide interest to microbiological, nutrition, metabolic, systems biology and pharmaceutical research communities,” says Claus.

Another important finding in the paper, according to Claus, is that gut colonization strongly stimulated the expression and activity of the cytochrome P450 3A11, an essential enzyme in drug-detoxification pathways.

Although she warns about being careful to extrapolate the specific findings from mice to humans, Claus notes the results of this research will provide a basis to further develop new strategies to beneficially modulate host metabolism by altering microbial communities in the gut.

 

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mBio® is a new open access online journal published by the American Society for Microbiology to make microbiology research broadly accessible. The focus of the journal is on rapid publication of cutting-edge research spanning the entire spectrum of microbiology and related fields. It can be found online at http://mbio.asm.org.

Related Articles

• Gut bacteria steer the development of the young brain | Not Exactly Rocket Science (blogs.discovermagazine.com)
• Going with Your Gut (thefinchandpea.com)
• Brain development may be influenced by bacteria in the gut (physorg.com)
• Gut microbes influence behavior (biosingularity.wordpress.com)
• Gut bugs ‘can affect behaviour’ (bbc.co.uk)
• To Overcome Obesity, Trust Your Gut (Bacteria) (livescience.com)
• Really?: The Claim: Probiotics Can Soothe a Colicky Baby (nytimes.com)

Researchers looking at a rare disease make breakthrough that could benefit everyone

Researchers looking at a rare disease make breakthrough that could benefit everyone
Geneticists unveil workings of 3 genes that control cell development and growth

MONTREAL, March 1, 2011 – By working with Canadians of French ancestry who suffer a rare genetic disease, researchers have discovered how three genes contribute to abnormal growth, making a breakthrough that will improve our understanding of many disorders such as foetal and childhood growth retardation, abnormal development of body parts and cancer. “As a result of the Human Genome Project, we know the basic identity of essentially all the genes in the human body, but we don’t automatically know what they do in detail,” explained lead researcher Dr. Mark Samuels of the University of Montreal’s Department of Medicine and the Sainte-Justine University Hospital Research Centre. “It’s like opening your car and seeing the parts, but not knowing what each one does. When a part breaks however, you learn how it fits with the rest of the machine. Working with people who have specific health or development problems linked to specific genes enables us to see how those genes contribute to our bodies’ development and functioning.”

In this case, the team of researchers characterized the molecular basis in patients who suffer from Meier-Gorlin Syndrome (MGS), a rare disorder that is characterized by short stature, small ears, and absent or underdeveloped knee-caps. The patients were mostly francophonic, coming from the Maritimes, Quebec, British Columbia as well as the Louisiana Cajun community. MGS is a classic “single gene disorder,” meaning it is related to mutations in individual genes, although in the case of MGS different patients surprisingly seem to carry mutations in any of three different genes.

The genes are called ORC1L, ORC4L and CDT1, and are known to play a critical role in correct copying of DNA. Cells reproduce by dividing in two. All the chromosomes must also be duplicated. This process is tightly controlled to prevent having too many or two few copies of large segments of the genome. “This seems to be the first example of any naturally occurring, inherited mutations identified in this set of important regulatory genes in any mammal. Finding the genes is a great example of the value of this type of research,” Samuels said. “We learn the cause of the disease, and discover new things about our cellular function. However we still have a lot to learn about why mutations in these genes lead to the specific consequences in Meier-Gorlin patients.”

There are 20-25,000 genes in the human genetic sequence, and it’s important to note that they don’t necessarily each correspond to a specific function or group of functions, or indeed to a single disease. The same gene can have subtle effects on a number of bodily functions. Moreover, in complex genetic diseases – diabetes, for example – environment and lifestyle have as much or more of an impact on health than a person’s genetic background.

“Understanding rare genetic conditions like MGS is important to the general public for two reasons,” Samuels stressed. “Firstly, they provide insight into how our genes, and therefore our bodies, work. Secondly, although there are few people concerned for each particular disorder, in sum all patients with genetic conditions consume substantial amounts of health resources, and by diagnosing them more quickly, we can improve patient management and reduce the strain on the health care system.” Research suggests that up to 70% of admissions to paediatric hospitals may be related to some kind of genetic disorder. “It’s also important to note that behind the science and the statistics, there are real people suffering. It’s an immense relief for patients and their families to finally have a clear diagnosis,” Samuels added.

In an unusual coincidence, a competing team of researchers obtained similar findings on Meier-Gorlin Syndrome in a different set of patients. These findings were published in the same issue of Nature Genetics. Samuels notes, “Neither team can claim absolute priority in the discovery. However this is the way science works best: when important results are quickly verified by multiple teams independently.”

Related Articles

• The Promise and Payoff of Rare Diseases Research, From NIH Director Dr. Francis S. Collins (NIH MedlinePlus Magazine, May 2011)
• The NIH Undiagnosed Diseases Program (NIH MedlinePlus Magazine May 2011)
• NIH researchers create comprehensive collection of approved drugs to identify new therapies (jflahiff.wordpress.com)

Sickle Cell Disease – Special Feature of NIH MedlinePlus Winter 2011 Issue

This month’s special feature of NIH (National Institutes of Health) MedlinePlus focuses on Sickle Cell Disease.

Singing star and former American Idol winner Ruben Studdard wrote the song,”I Am a Fighter,” which has become the official anthem for the Be Sickle Smart campaign.
Photo courtesy of Ruben Studdard

The feature includes a short interview with singer Ruben Studdard and the following links

• MedlinePlus:www.medlineplus.gov (Enter”sickle cell disease” in the Search box)
• National Heart, Lung, and Blood Institute:http://www.nhlbi.nih.gov/health/dci/Diseases/Sca/SCA_WhatIs.html
• Clinical Trials and Patient Recruitment:http://patientrecruitment.nhlbi.nih.gov/sicklecell.aspxhttp://clinicaltrials.gov.   (Enter”sickle cell disease” in the Search box)

NIH Medline Plus is a quarterly online magazine presenting up-to-date information including NIH sponsored research and interviews with people who have overcome health related challenges. Click here for information on how to subscribe to this free publication.

Neuroscience: implications for education and lifelong learning

Neuroscience: implications for education and lifelong learning

From the February 25 Docuticker item

This report highlights advances in neuroscience with potential implications for education and lifelong learning. The report authors, including neuroscientists, cognitive psychologists and education specialists, agree that if applied properly, the impacts of neuroscience could be highly beneficial in schools and beyond.  The report argues that our growing understanding of how we learn should play a much greater role in education policy and should also feature in teacher training. The report also discusses the challenges and limitations of applying neuroscience in the classroom and in learning environments throughout life.

+ Direct link to Full Report with Appendices (PDF; 1.7 MB)