NASA image shows tree density in United States

This impressive image, released a few months ago, shows the tree density in the United States (click to enlarge)

According to the NASA Earth Observatory website, the map has been obtained from a variety of sources, from ground data collection to space-based radar, requiring 6 years of work. At the highest resolution, ten pixels correspond to an hectare of land. It shows how little of the territory is actually covered in trees, either because of territory constraints (height, climate) or because of agriculture needs. As I said in a previous post, trees are fundamental (and cheap) carbon dioxide gatherers, but they also tend to require a lot of water and proper climate.

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The Arsenic bacterium. A case of bad scientific communication?

As you probably heard in the news, two days ago everyone was ablaze for a mysterious announcement from NASA. Speculation started on how the new discovery would “impact the search for evidence of extraterrestrial life.” Someone found a habitable planet? Found a message with Seti@HOME? Discovered the primordial soup composition? The buzz resonated and amplified at every new passage, like in a Chinese whisperers game, speculations were born and distorted, sometimes by the lack of scientific knowledge of the message carriers, sometimes by a deliberate “science-fiction twist”. Now that the announcement has been made, it’s a big disappointment, a delusion… you name it.

I’d like to propose to make a step back and see the thing from a bit of distance. Let’s analyze the facts. Life (from the tiny bacterium to a giant whale) generally uses six fundamental elements: Carbon, Hydrogen, Oxygen, Nitrogen, Sulfur, and Phosphorus. From these six elements, a large majority of the fundamental building blocks of life are created: DNA, Acetil CoA (a transporter molecule), ATP (for energy storage) and many, many others. Yes, some other elements are used, but they are in a tiny amount, and although this tiny amount is essential for life, it is really a pinch.

On this planet, life managed to conquer places that are considered “extreme”. There’s a class of bacteria called “Extremophiles” which collects all those living under really unexpected conditions. For example, there are bacteria living in almost boiling water, or in very high concentration of acids. The “extreme” conditions are, however, in the eye of the beholder. For these bacteria, their condition is just the norm. For us, living in a scorching boiling hot spring, or in a poisonous acid well is “extreme”, as it would be extreme for them to live at 25 degrees of temperature in a neutral pH. In fact, they are well adapted to their niche. With the recent rise of techniques for biological analysis and sequencing, we are exploring more and more of these niches, and discover more and more bacteria (or communities of bacteria) well adapted to these niches.

There is a lake in California called Mono Lake. It is one of those extreme places when it comes to conditions: high saline concentration and alcalinity makes it probably a very unpleasant place to take a bath. Fishes agree, and quickly give up and die, so the only thing that lives in that water are some shrimps, algae and bacteria. To complete the nice picture, it has one of the highest concentration of Arsenic, which is a poisonous substance to us, and in general to all organisms. As said before, any bacterium living in extreme conditions for us is classified as “extremophile”. GFAJ-1, the little bug announced by NASA rightfully belongs to the category, since it lives in the waters of the Mono Lake.

The bacterium has proven really, really tough with respect to Arsenic tolerance. Grown in a lab with even higher concentrations of Arsenic and no Phosphorus at all, the bug decided to switch to Arsenic when it comes to inclusion in its fundamental components, replacing Phosphorus in DNA, ATP and so on. In practice, faced with a lack of a really important element such as Phosphorus, he said “screw that, I’m using Arsenic, it’s good enough for me”. This is really a novelty, but it is not revolutionary. It is just a very important finding, being the first time where life uses completely unusual strategies to continue thriving.

Summing up, the content of this discovery is:

  1. for the first time, a different element (Arsenic) was experimentally seen as a substitute for another element (Phosphorus) to build fundamental biologically important molecules in-vivo.
  2. there’s no number 2

Seriously, it’s a great finding, but that’s what the facts tell us. No aliens, no totally different life form on earth, no implications for space research… maybe just a little: we should not be so strict in assuming Phosphorus as so fundamental for life, given that it can be successfully replaced. We also should realize how resilient and adaptable is life when faced with harsh conditions.

Excessive hype and broken dreams

The announcement of the conference at NASA landslided a serious amount of speculation and hype. Maybe it was intentional, maybe it was just a mass craze triggered by unintentional circumstances. I cannot say. What is clear is a good amount of blog posts (1, 2, 3, 4, 5) pointed out the excessive hype, and the sheer disappointment that followed. This in turn fuels news fatigue. As I already pointed out in a previous post, this news fatigue in turns fuels misunderstanding, detachment and apathy towards new discoveries. We all want NASA to tell us: “listen, we got that call from ET” but seriously, it’s not how science normally works.

So what’s the correct recipe ? What do you have to do and understand when you read or hear some scientific news, and how much weight do you have to apply? In my next post I will tell you simple rules on how to read scientific  news with a critical and realistic eye, directly from my experience on scientific papers. Stay tuned.

Edit: I decided to postpone the continuation of the article for now. I already have a draft, but I am quite busy at the moment, and I have a very long queue of scheduled articles already. I may insert it in the queue, however.