Viruses make their living by breaking into cells and using the machinery and energy in the cell to reproduce. Once inside, some viruses immediately hijack the cell and make copies of themselves which burst out into the world to infect new cells. Other viruses take a staid approach, though. Instead of taking over the cell, they quietly slip a copy of their genes into its DNA. When the cell divides, it copies the newly acquired viral genes along with the rest of its genome. It’s a better deal for the virus, since all of the cell’s descendants will be carrying viral genes which can eventually come out of hiding to commandeer the cell and replicate. A really lucky virus is one that finds itself inside an egg cell. Getting into the DNA of a single cell means getting copied into all of its daughter cells, but getting into the DNA of an egg cell means getting copied into every cell in the organism that grows from the egg…and from there into all of the organism’s offspring. Lucky viruses that succeed in pulling off that trick can still break out and cause trouble, but they can also become integrated into their host’s genome; instead of struggling to reproduce, they can then just kick back and enjoy the ride while we lumber along, making copies of them whenever we make new cells or have children. Continue reading »
Science in Society, science, People, DNA, biology, Human, science and society, Education, Health, Genome, Popular science, Full genome sequencing, Genotyping, relatedness, Genetic testing, Angelina Jolie, genomics
Fifteen years ago it was the stuff of science fiction. Now, you can just swab your cheek, send it to a company and, for only a few hundred euros, have your DNA analyzed. You’ll find out about your ancestry and your predisposition towards certain inherited diseases or conditions (from cancer and diabetes to myopia). You’ll also learn if you’re a ‘carrier’ — that is, if you’re carrying a gene that won’t affect you but might affect your children. You can even get information about more light-hearted issues like whether you’re likely to have fast- or slow-twitch muscles or your ability to taste certain bitter flavours. The technology is pretty great, but it also raises some interesting questions which I thought would be worth discussing (especially since I really enjoyed our previous discussion). Continue reading »
Humans and chimpanzees famously share more than 98% of their genome and yet the two species look and behave quite differently. This apparent paradox stretches well beyond our little corner of the tree of life; we share more than half our genes with chickens and those we share are 75% identical. Two studies published together in the December issue of Science tackled this perplexing discrepancy by showing that there may be more to a genome than meets the eye. Continue reading »
On the Solomon Islands in the south-eastern Pacific, it’s not uncommon to come across Melanesian children with dark skin and remarkably blond hair. While most people might take this unusual trait as a sign of European ancestry, Sean Myles wasn’t convinced. Curious to understand how the darkest skinned people outside of Africa could also have the highest frequency of blond hair outside of Europe, he led a team of scientists to unravel the genetics behind this mystery. The striking results of their research should serve as a note of caution about what we’re learning from the rapidly growing field from human genomics.
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Around 60,000 years ago, modern humans left Africa, the cradle of our species. As we spread across the face of the Earth, we discovered that we weren’t the first or the only humans to make that sojourn. From Central Asia to Europe, we met our distant cousins the Neanderthals, descendants of a 500,000 year old migration; further east were the Denisovans, ranging from Sibera to Southeast Asia. Although these other humans died out around 30,000 years ago, some comfort can be found in the knowledge that a part of them lives on in us. Genetic evidence uncovered in the past few years suggests that our migrating ancestors may have mated with these other humans during their encounters. Not everyone was convinced, though, launching an ongoing debate about whether the genetic similarity might be due to common ancestry rather than inbreeding. Continue reading »