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Corante Blogs examine, through the eyes of leading observers, analysts, thinkers, and doers, critical themes and memes in technology, business, law, science, and culture.

The Press Will Be Outsourced Before Stopped

Vin Crosbie, on the challenges, financial and otherwise, that newspaper publishers are facing: "The real problem, Mr. Newspaperman, isn't that your content isn't online or isn't online with multimedia. It's your content. Specifically, it's what you report, which stories you publish, and how you publish them to people, who, by the way, have very different individual interests. The problem is the content you're giving them, stupid; not the platform its on."
by Vin Crosbie in Rebuilding Media

Travels In Numerica Deserta

There's a problem in the drug industry that people have recognized for some years, but we're not that much closer to dealing with it than we were then. We keep coming up with these technologies and techniques which seem as if they might be able to help us with some of our nastiest problems - I'm talking about genomics in all its guises, and metabolic profiling, and naturally the various high-throughput screening platforms, and others. But whether these are helping or not (and opinions sure do vary), one thing that they all have in common is that they generate enormous heaps of data.
by Derek Lowe in In the Pipeline

Disrobing the Emperor: The online “user experience” isn't much of one

Now that the Web labor market is saturated and Web design a static profession, it's not surprising that 'user experience' designers and researchers who've spent their careers online are looking for new worlds to conquer. Some are returning to the “old media” as directors and producers. More are now doing offline consulting (service experience design, social policy design, exhibition design, and so on) under the 'user experience' aegis. They argue that the lessons they've learned on the Web can be applied to phenomena in the physical and social worlds. But there are enormous differences...
by Bob Jacobson in Total Experience

Second Life: What are the real numbers?

Clay Shirky, in deconstructing Second Life hype: "Second Life is heading towards two million users. Except it isn’t, really... I suspect Second Life is largely a 'Try Me' virus, where reports of a strange and wonderful new thing draw the masses to log in and try it, but whose ability to retain anything but a fraction of those users is limited. The pattern of a Try Me virus is a rapid spread of first time users, most of whom drop out quickly, with most of the dropouts becoming immune to later use."
by Clay Shirky in Many-to-Many

The democratisation of everything

Over the last few years we've seen old barriers to creativity coming down, one after the other. New technologies and services makes it trivial to publish text, whether by blog or by print-on-demand. Digital photography has democratised a previously expensive hobby. And we're seeing the barriers to movie-making crumble, with affordable high-quality cameras and video hosting provided by YouTube or Google Video and their ilk... Music making has long been easy for anyone to engage in, but technology has made high-quality recording possible without specialised equipment, and the internet has revolutionised distribution, drastically disintermediating the music industry... What's left? Software maybe? Or maybe not."
by Suw Charman in Strange Attractor

RNA Interference: Film at Eleven

Derek Lowe on the news that the Nobel Prize for medicine has gone to Craig Mello and Andrew Fire for their breakthrough work: "RNA interference is probably going to have a long climb before it starts curing many diseases, because many of those problems are even tougher than usual in its case. That doesn't take away from the discovery, though, any more than the complications of off-target effects take away from it when you talk about RNAi's research uses in cell culture. The fact that RNA interference is trickier than it first looked, in vivo or in vitro, is only to be expected. What breakthrough isn't?"
by Derek Lowe in In the Pipeline

PVP and the Honorable Enemy

Andrew Phelps: "Recently my WoW guild has been having a bit of a debate on the merits of Player-vs.-Player (PvP) within Azeroth. My personal opinion on this is that PvP has its merits, and can be incredible fun, but the system within WoW is horridly, horribly broken. It takes into account the concept of the battle, but battle without consequence, without emotive context, and most importantly, without honor..."

From later in the piece: "When I talk about this with people (thus far anyway) I typically get one of two responses, either 'yeah, right on!' or 'hey, it’s war, and war isn’t honorable – grow the hell up'. There is a lot to be said for that argument – but the problem is that war in the real historical world has very different constraints that are utterly absent from fantasized worlds..."
by Andrew Phelps in Got Game

Rats Rule, Right?

Derek Lowe: "So, you're developing a drug candidate. You've settled on what looks like a good compound - it has the activity you want in your mouse model of the disease, it's not too hard to make, and it's not toxic. Everything looks fine. Except. . .one slight problem. Although the compound has good blood levels in the mouse and in the dog, in rats it's terrible. For some reason, it just doesn't get up there. Probably some foul metabolic pathway peculiar to rats (whose innards are adapted, after all, for dealing with every kind of garbage that comes along). So, is this a problem?.."
by Derek Lowe in In the Pipeline

Really BAD customer experience at Albertsons Market

Bob Jacobson, on shopping at his local Albertsons supermarket where he had "one of the worst customer experiences" of his life: "Say what you will about the Safeway chain or the Birkenstock billionaires who charge through the roof for Whole Foods' organic fare, they know how to create shopping environments that create a more pleasurable experience, at its best (as at Whole Foods) quite enjoyable. Even the warehouses like Costco and its smaller counterpart, Smart & Final, do just fine: they have no pretentions, but neither do they dump virtual garbage on the consumer merely to create another trivial revenue stream, all for the sake of promotions in the marketing department..."
by Strange Attractor in Total Experience

The Guardian's "Comment is Free"

Kevin Anderson: "First off, I want to say that I really admire the ambition of the Guardian Unlimited’s Comment is Free. It is one of the boldest statements made by any media company that participation needs to be central to a radical revamp of traditional content strategies... It is, therfore, not hugely surprising to find that Comment is Free is having a few teething troubles..."
by Kevin Anderson in strange
In the Pipeline: Don't miss Derek Lowe's excellent commentary on drug discovery and the pharma industry in general at In the Pipeline

The Loom

« The Little Ones | Main | Evolution meets IVF »

July 05, 2004

Dawn of the Leafy Age

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Posted by Carl Zimmer

Recently I've been trying to imagine a world without leaves. It's not easy to do at this time of year, when the trees around my house turn my windows into green walls. But a paper published on-line today at the Proceedings of the National Academy of Science inspires some effort. A team of English scientists offer a look back at Earth some 400 million years ago, at a time before leaves had evolved. Plants had been growing on dry land for at least 75 million years, but they were little more than mosses and liverworts growing on damp ground, along with some primitive vascular plants with stems a few inches high. True leaves--flat blades of tissue that acted like natural solar panels--were pretty much nowhere to be found.

It's strange enough to picture this boggy, bare-stemmed world. But it's stranger still to consider that plants at the time already had the genetic potential to grow leaves. Some species of green algae--the organisms from which plants evolved--were growing half-inch leaf-like sheets 450 million years ago. Tiny bud-like leaves have been found on 400 million year old plant fossils. Despite having the cellular equipment necessary to grow leaves, plants did not produce full-sized leaves in great numbers until about 350 million years ago. When they finally did become leafy, the first trees emerged and gave rise to the earliest forests. Leaves have dominated the planet ever since. They capture enough carbon dioxide to make millions of tons of biomass every year, and as roots suck up water, trillions of gallons evaporate through them.

Why did leaves take 50 million years to live up to their genetic potential? Apparently they had to wait.

Plants, the researchers point out, take in carbon dioxide through elaborate channels on their surface called stomata. Living plants can adjust the number of stomata that grow on their leaves. If you raise them in a greenhouse flooded with carbon dioxide, they will develop significantly fewer stomata. That's because the plants can gather the same amount of carbon dioxide they need to grow while allowing less water to evaporate out of their stomata.

Geological evidence shows that 400 million years ago, the atmosphere was loaded with carbon dioxide--about ten times the level before humans began to drive it up in the 1800s. (It was 280 parts per million in the early 1800s, 370 ppm today, and is predicted to rise to 450 to 600 parts per million by 2050. In the early Devonian Period, it was around 3000 ppm.) Consistent with living plants, the fossil plants from the early Devonian had very few stomata on their leafless stems.

Why didn't these early plants grow lots of leaves with few stomata? If they did, they could have grown faster and taller, and ultimately produced more offspring. But the scientists point out that a big leaf sitting in the sun risks overheating. The only things that can cool a leaf down are--once again--stomata. As water evaporates out of these channels, it cools the leaf, just as sweat cools our own skin. Unable to sweat, early Devonian leaves would have been a burden to plants, not a boon.

About 380 million years ago, however, carbon dioxide levels began to drop. Over the next 40 million years they crashed 90%, almost down to today's levels. The decline in carbon dioxide brought with it a drop in temperature: the planet cooled enough to allow glaciers to emerge at the poles. In the paper published today, the scientists describe what happened to plants during that time. Two different groups of plants--ferns and seed plants--began to sprout leaves. As years passed, the leaves became longer and wider. And at the same time, the leaves became increasinly packed with stomata. From 380 to 340 million years ago they became eight times denser. It seems that the drop in carbon dioxide and temperature turned leaves from burden to boon, and the world turned green.

It's possible that plants themselves may have ultimately been responsible for the emergence of leaves. Before leaves evolved, roots appeared on plants. Unlike moss and liverworts, which can only soak up the water on the ground, plants with roots can seek out water, along with other nutrients. Their probing eroded rocks and built up soil. The fresh rock that the plants exposed each year could react with carbon dioxide dissolved in rainwater. Some of this carbon was carried down rivers to the ocean floor and could no longer rise back up into the atmosphere. In other words, roots pulled carbon dioxide out of the atmosphere and made it possible for leaves to evolve. The evolution of leaves in turn led to the rise of big trees, which could trap even more carbon, cooling the climate even more. Clearly, we are not the first organisms to tinker with the planet's thermostat.

Comments (1) + TrackBacks (0) | Category: Evolution


COMMENTS

1. Bill Pullar on August 2, 2004 03:36 PM writes...

Interesting. I haven't come across these ideas before

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