By Cigdem Iltan - Tuesday, July 19, 2011 - 0 Comments
It doesn’t take a scientist to tell a polar bear and a brown bear apart. Or does it?
It doesn’t take a scientist to tell a polar bear and a brown bear apart. Or does it? Genetic studies have revealed that all living polar bears have Irish brown bear genetic markings in their DNA. An international team of scientists has traced the species’ collision back to a night of romance between a male polar bear and a female brown bear from Ireland between 20,000 and 50,000 years ago. Researchers believe that, today, climate change has forced grizzlies and polar bears, for example, to move into each others’ habitat, giving them several chances to engage in “opportunistic mating.” In the past, scientists say because the glacial ice sheet extended south into Ireland during colder times, polar bears could also meander into brown bear territory. These shared quarters resulted in hybrid offspring, according to the findings, which were published in the journal Current Biology. “When they come into contact, there seems to be little barrier to them mating,” said Pennsylvania State University’s Beth Shapiro, who led the study.
By Kate Lunau - Friday, June 17, 2011 at 10:55 AM - 0 Comments
The island is a treasure trove of unique creatures—more than 600 of them
Madagascar is one of Earth’s last great tropical wildernesses and, in the past decade, scientists have found an incredible 615 new species there, according to a new report from the World Wildlife Fund (WWF). Among these discoveries—including 385 plants, 42 invertebrates, 17 fish, 69 amphibians, 61 reptiles and 41 mammals—some sound almost too fantastic to be believed. The cork bark leaf-tailed gecko, for example, looks like a crawling piece of bark, with its craggy tan-coloured skin. The massive tahina palm flowers only once in its life, producing a spectacular bloom before it dies. And Berthe’s mouse lemur, the smallest known primate, is so tiny it can fit in the palm of your hand.
The fourth largest island in the world, Madagascar is home to five per cent of our planet’s animal and plant species, and more than 70 per cent of them can’t be found anywhere else. Its landscape is widely varied, from tropical rainforest to volcanic mountains, broad plains and desert; surrounding waters are home to some of the world’s largest coral reef systems. With better sampling techniques and DNA analysis, scientists are finding species there they’d never previously observed.
Madagascar’s rampant biodiversity can be partly explained by its unique geological history, says Richard Hughes, the WWF’s regional director in Madagascar, reached over the phone from the capital of Antananarivo. The island split off from the African continent about 165 million years ago, and broke free from India over 80 million years ago; human settlement there, he notes, “only dates back around 2,000 years.” As a result, plants and animals have had a long time to evolve in isolation, inspiring some scientists to call Madagascar the eighth continent.
By Colby Cosh - Wednesday, May 26, 2010 at 8:21 AM - 55 Comments
I’ve got a neglected heap of notes for weblogging topics, but Craig Venter’s latest biotechnology stunt metaphorically swept them clear from my desk. It is not easy to comprehend by means of plain English what Venter and his research institute have achieved. The title of their paper for Science offers the best possible short summary: “Creation of a bacterial cell controlled by a chemically synthesized genome.” Reactions range from the alarmist—dear God, he’s created synthetic life!—to the dismissive—bah, it’s not synthetic life at all! (The Raelians, for their part, take the view “He’s created synthetic life, and we think it’s awesome!”)
Here’s the strictly technological significance of what Venter has done: he used computers to create a synthetic genome that never previously existed in nature, turned that information into physically existing DNA, replaced the DNA of an existing organism with the new DNA, and successfully showed that his artificial software “worked”—that it could self-reproduce and serve as the design for functioning progeny. It is the production of an all-new life form from human programming. I do not think Scots SF author Ken MacLeod goes too far when he writes “This is a moment in evolution, the origin of a new kingdom: the Synthetica, as artist Daisy Ginsberg has suggested we call it, supplementing nature’s bacteria, eukarya, and archaea.”
Creationists and Catholics are putting on a brave face, and they have a basic point that cannot be gainsaid. Venter had to follow “God’s” existing “literary rules” of genome construction, so to speak; his artificial genome had to contain essential bits of programming plagiarized from nature, some of which are not fully understood. And nobody can yet imitate “God” in building a cell from scratch: an existing bacterium had to have its own chromosomes scraped out to provide a platform for Venter to build upon. It’s a bit like observing that, yes, this sentence I’m writing right now is completely original in the usual sense, but I haven’t made up any of the words in it completely from scratch, and to be understood as a message, it must follow a certain accepted structure.
That being said, once you’ve gone Gutenberg, there is no going back. The key passage in the Venter paper is perhaps this one [emphasis mine]:
We refer to such a cell controlled by a genome assembled from chemically synthesized pieces of DNA as a “synthetic cell”, even though the cytoplasm of the recipient cell is not synthetic. Phenotypic effects of the recipient cytoplasm are diluted with protein turnover and as cells carrying only the transplanted genome replicate. Following transplantation and replication on a plate to form a colony (>30 divisions or >109-fold dilution), progeny will not contain any protein molecules that were present in the original recipient cell. This was previously demonstrated when we first described genome transplantation. The properties of the cells controlled by the assembled genome are expected to be the same as if the whole cell had been produced synthetically (the DNA software builds its own hardware).
If I had a way of putting that last parenthetical in double-bold face, I’d do it. No, we can’t yet build a cell from scratch, but if we can edit the software of an existing cell to any degree we please—although the process described in the paper is still of a crudity that bleeds forth from its every line—it really doesn’t matter. The descendants will reproduce according to our program, and will be indistinguishable from the descendants of a cell created by God, Klingons, or Santa’s elves. The software builds its own hardware. Sixty-seven years after DNA’s role as a genetic information carrier was confirmed, and 57 years after its structure was ascertained, we can now say that there exists, in the parlance of mathematics, a true constructive proof of this.
But then again, no biologist or other sane person really needed such a proof. The best lay summary of Venter’s achievement that I have found is provided by robotics professor Rodney Brooks, a man who has thought a great deal about the operational definition of life.
..the fact that [Venter's] genome works as a genome is not a surprise to molecular biologists. They have long believed that life is chemistry, and that one string of connected atoms is just as good as another having the same arrangement. They have long ago discounted the idea that there is any sort of specialness imparted to a molecule by its history of production. Molecules have no souls.
But the new cells are also not synthetic life in that the ancestor cell was an existing live cell. It was not built from pieces in the same way that the synthetic genome was built. That is another, perhaps harder technological challenge, but also one that there may be no imperative to try to achieve in the short term; hijacking existing cells may be all that we need to develop all sorts of new synthetic forms.
The press has both overplayed that what has been done is a surprise, and underplayed the interesting challenges that lie ahead, in that their biggest fears do not automatically follow from the current achievement.
Brooks is saying that there are no new theoretical implications from the Venter team’s accomplishment, as there actually were from the Venterian work that preceded the demonstration of synthetic life—namely, paring the smallest genome known to exist in nature down to an even smaller instruction set, and getting humans closer (closer than God or natural selection ever managed) to the theoretical minimum of information needed for a DNA sequence to be meaningful. Playing God? Hell, that’s for amateurs!
That DNA can practically be edited will come as a shock only to those whose anti-materialist or vitalist views depend on clinging to some particular state of human technological ignorance. There are no longer very many biologists in that category. If life can be designed and mass-produced synthetically like machines, there won’t be much ground left on which to argue that living things aren’t machines.
Biologists presented with the Venter news are instinctively contemplating the revival of familiar old forms previously discarded by natural selection, and the synthetic genome adds spice to the ethical debates over whether we would be justified in making a Neanderthal or a woolly mammoth. This is not really a big theoretical deal either. The more important, wider prospect on offer is the ability to recover biodiversity by artificial means, and the eventual end of the rule than “extinction” is the definitive end for a species. The thought of one day being able to see a dodo strut and squawk and lay eggs is romantic (in a way that warms even the stony heart of Darwinian tough-guy Richard Dawkins) and missions of that sort are now one big step closer to fruition.
But the really exciting and scary idea here is the customizability of life, and as Brooks says, we don’t know what limits, other than the obvious physical ones, scientists might ultimately run up against. Let’s note, though, that so-called “genetic modification” in agriculture has already accomplished a lot, even with one hand tied behind its back by trade rules and consumer fears. (What we refer to as “genetic modification” is really just genetic modification 2.0. The hybridization and artificial selection that humans were busily engaged in for several millennia beforehand was 1.0; the stuff we’re talking about in this article is, if you like, version 3.0.) Journalist Quinn Norton offers some wild thoughts about bacteria that “pee out biofuels or Prozac, eat Gulf of Mexico oil, or glow in the presence of melamine, cancer, or anger”. These dreams may transcend what is ultimately feasible. Or they may hint only at a thousandth of a thousandth of the possibilities.