Science news digest - 10th December 2012
In the science news this week, scientists reveal we have hundreds of genetic flaws, a journalist plans his trip across the world, African elephant numbers drop by a 1000 in just four years, and finally… satellites reveal the gravitational hotspots on the Moon.
No-one is perfect, at least not genetically
Scientists have found that everyone has, on average, 400 flaws in their DNA, reported the BBC.
Most are “silent” mutations that don’t affect your health, but some may cause problems when passed on to future generations. Others are linked to conditions such as cancer or heart disease, which could cause problems in later life.
The study involved 1,000 seemingly healthy people from Europe, the Americas and East Asia, all of whom had their entire genetic sequence decoded, for the 1,000 Genomes project.
This new research compared the genomes of 179 participants with a database of human mutations developed at Cardiff University.
The researchers found that a normal healthy person has about 400 potentially damaging DNA variations, and two DNA changes that are known to be associated with disease.
"Ordinary people carry disease-causing mutations without them having any obvious effect," said Dr Chris Tyler-Smith, a lead researcher on the study from the Wellcome Trust Sanger Institute, Cambridge.
"In a population there will be variants that have consequences for their own health."
It has been known for decades that we all carry some genetic mutations that appear to cause little or no harm. In some cases the mutations only cause harm if they are passed on to children who inherit a copy of the faulty gene from the other parent.
In around one in ten of those studied, the mutation causes only a mild condition, which appears to be inactive or shows up in later life.
Databases like the one at Cardiff University which hold information about known genetic mutations will become increasingly important in the future as steps are made towards personalised medicine.
In this study, all of the samples were anonymous so the participants will not be given any information about any mutations found that are linked to disease.
However, as DNA sequencing becomes more widespread, the ethical debate on what to tell people about their genetic makeup will need to be addressed, particularly as so many of the risks are uncertain.
Dr Chris Tyler-Smith said: "All of our genomes contain flaws; some of us will carry deleterious variants but will not be at risk of acquiring the associated disease for one reason or another.
"For others, there will be health consequences, and early warning could be useful, but might still come as an unwelcome surprise to the participant."
Writer will retrace the steps of early humans
A writer for National Geographic, Paul Salopek, has decided to make an incredible journey to retrace the route taken by early humans tens of thousands of years ago out of Africa.
Starting in the Great Rift Valley in Ethiopia, he will walk 21,000 miles across three continents finally finishing an astonishing seven years later at the most southerly point of South America.
He will update his website regularly with pictures, videos and accounts of his travels, as well as writing a story for National Geographic each year. His route will take him across the Red Sea, into the Middle East, before continuing on to China, Siberia and up to the Bering Strait into Alaska. He’ll then walk down the whole of the western coasts of North and South America.
The 50-year-old is now preparing himself for the epic journey, and spending time with his family. "It is an old way of story-telling: the wandering bard. I am curious myself to see how it all turns out," Salopek told the Guardian. "It is the notion of a questing story which we find in all cultures, that you have to go away from home and come back in order to truly discover what 'home' was," he added.
The journey will be anything but easy. Not only will it be a huge physical challenge, it will also be virtually impossible to plan ahead for the trip as his route will take him through some of the globe’s most dangerous political hotspots.
However, Salopek admits that it is likely to be the mental challenges that he will find most difficult. He will be alone for much of the journey, so he has planned to have some periods where he’ll go offline and rest. He wants his writing and website to reflect real stories, not just the pain and travails of a man walking 21,000 miles. His wife will also likely join him for some of the quiet periods to help him cope with the challenge.
Kenyan elephant numbers plummet
The second largest population of elephants in Kenya has lost over 1000 elephants in just four years following a spate of illegal poaching driven by Asia’s demand for ivory.
After a promising growth spurt, the elephants are now dying faster than they are being born, reported New Scientist.
The Kenya Wildlife Service conducted a census of the Samburu/Laikipia population and found that it now stands at 6361, after a peak in 2008 at 7415.
Poaching is suspected as the culprit of this dramatic decline. A report made in July by three conservation groups found that poaching has been on the rise since 2006, with more than half of the elephants found dead in Africa in 2011 being illegally killed.
Twin spacecraft reveal the structure of the Moon
Also, in New Scientist this week, an amazing image and video of the Moon created by two spacecraft orbiting the satellite. The colours on the image represent the variations in the structure of our companion – red indicating more massive areas, and blue corresponding to less massive areas.
The two satellites, called Ebb and Flow, are together known as GRAIL (Gravity Recovery and Interior Laboratory). Measurements of the microwaves between Ebb and Flow allowed NASA to build the map from the data collected between March and May earlier this year.
The spacecraft are able to get incredibly close to the surface of the Moon because it lacks an atmosphere, making the map extremely detailed. In comparison, a similar survey of the Earth’s mass carried out by the GOCE satellite has to stay ten times further away from the surface to avoid atmospheric drag.
The researchers are hoping that the gravity map could reveal whether the Earth once had two moons, but lost one when they collided, creating the thicker crust seen on the far side of the moon.