Life, a recent BBC nature documentary series, is a showcase of the diversity of the natural world and the extraordinary behaviour of living things. It seems that nature never fails to amaze the curious investigator; be it far, close or even underfoot.

“We know more about the movement of celestial bodies than about the soil underfoot.” - Leonardo da Vinci.

Yes, underfoot is the soil I want to talk about, which one of my professors fondly refers to as The Book of Nature. He would say, “Open The Book of Nature and read… here and there a chapter might be incomplete or you may not understand, but you can always learn about the past, the present and the future.” Indeed, my limited reading has found a lot of interesting chapters…

What is soil?

Technically defined, soil is a "natural body comprised of solids (minerals and organic matter), liquid, and gases that occurs on the land surface. It is characterized by distinguishable horizons and or the ability to support rooted plants in a natural environment".

In a much more ecological way, it is the basic structure that supports life’s primary producers, i.e. plants. It does this as a result of its unique capability to act as a reservoir of nutrients/water and then to supply those intermittently to the plants - very much like a prudent bank.

This is not the soil’s only role; it also acts as a foundation for infrastructure and as a cornerstone in the health of ecosystems, for example, by locking pollutants and harbouring ultimate decomposers. As such, it is considered as one of the three most vital natural resources, alongside air and water.

Why care for soils?

Knowledge of the soil's physical, chemical and biological make-up is important for various disciplines. For example, nutrient levels are important for crop production, soil shear strength is crucial for engineering construction, and its structure could also be a deciding factor for football pitches! It also has more exotic uses, such as a beauty accessory (see the intricate hair-styling of the Hamer of Ethiopia, for instance).

In addition to their functional roles, soils have been part of our life and culture in many ways. A recent book, Soil and Culture by Edward R. Landa and Christian Feller, pays tribute to their impact from visual arts to religion and from archaeology to disease and warfare, and as a further example, many states in the U.S. have a specific soil that is legislatively established as a ‘state soil’, just like a state bird or flower.

What is the status of soils today?

Like most of earth’s resources, soils in all parts of the world are under threat. From the physical problem of compaction to erosion, and from salinity to pollution, are increasingly degrading our soils, with negative effects on ecosystems, economy and human health. In addition, global warming threatens to release carbon trapped in soil's organic matter, exacerbating climate change and having grave consequences for life on earth.

What's being done?

As the concern on soils has come to the forefront of public awareness, national and international bodies are moving towards legislation and action. For example, the UK government’s Department for Environment, Food and Rural Affairs (DEFRA) recently published a revised strategy on soils.

Hilary Benn, Secretary of State for Environment, Food and Rural Affairs, explains the importance of caring for soils.

Take it further

Educate yourself and others with the Soil Science Educational Resource.

Join surveys, for example, the OPAL national soil and earthworm survey.

Support those who are working to improve soils situation, such as the Soil Association.

Open University courses

Neighbourhood nature

Environment: journeys through a changing world

Other links

BBC Life

British Society for Soil Science

International Union of Soil Sciences

European Union Soil Thematic Strategy

About the author

Dr Yoseph Araya is a plant ecologist and associate lecturer at the Open University. He works on the biology and conservation of South African fynbos vegetation. Environmental education and the role of the public in research is one of his key interests.

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Blogging about

Breaking Science

The Breaking Science team come to BBC Radio Five Live to break open this week's science stories.

The Breaking Science team discussed new research that might help our understanding of how we smell:

Kat Arney: They do say a rose by any other name would smell as sweet, but what does make us think that a rose smells nice but my feet smell bad? My feet don’t smell that bad. But until now scientists have known relatively little about how the smelly molecules, known as odorant molecules, are recognised by the receptors in our noses. But new research by Harumi Saito published in the journal Science Signalling this week could shed some light on this mystery.

Chris Smith: So come on then, tell us why does a rose to me smell like a rose and your feet smell, well let’s not go there.

Kat Arney: Well our sense of smell is an amazing thing and our noses have hundreds of olfactory receptors, each of which can pick up a different smelly molecule and this then sends a signal into the brain which gets interpreted as a smell. But we only know around about 50 of these smelly molecules and that somewhat limits our understanding of the whole system.

Chris Smith: So what are the researchers actually doing in this study to try and home in on what’s going on?

Kat Arney: Well they used a technique called high throughput screening which allowed them to carry out many, many experiments in a short time, and this allowed them to test 93 different odorants, these are the smelly molecules, against a panel of 464 different olfactory receptors, and they picked up 52 specific odorants that activate mouse receptors and the screen pulled out 10 new odorants that activate human receptors.

Smelling a flower.
[image © copyright Jupiterimages]

So this has, you know, made a big increase on what we know about the number of specific molecules that interact with the smell receptors. And the scientists used the knowledge from their screen to then develop a computer model that can help to predict what kind of odorant molecules might fit with different olfactory receptors.

Now it’s probably possible to look at a whole range of smelly chemicals and try and predict which olfactory receptors they might bind to. So this is basically going to speed up the process of research in this area so scientists will have better ideas of which routes to follow rather than just taking shots in the dark.

Chris Smith: It’s interesting because before Christmas I spoke with a perfumer who makes smells for a living, nice smells, and he had the chemical equivalent of synaesthesia, he could imagine a smell and see the molecule in his mind’s eye that would smell like that, so I guess he’d be very interested in a function or a model like that.

Kat Arney: Absolutely. Fascinating.

Listen to the whole programme, originally broadcast on BBC Radio Five Live, February 2009

A little surprisingly, not much is being made of Darwin’s 200^th birthday at the 2009 meeting of the European Society for Evolutionary Biology (ESEB). Then again, perhaps it’s not so surprising. Evolutionary biologists don’t exactly need a special occasion to get them thinking about evolution! If the anniversary is making its influence known at all it’s in the general feeling of evaluation there is at the conference.

There is a sense of examining how we’ve got to where we are with the understanding of evolution and where we go with it in the future. And it’s the prospects for the future that make major scientific conferences so exciting and the thing I’d forgotten through not having been to one for a few years. There is that sense of being led not just to the cutting edge of a subject but encouraged to peer over that edge at what might be coming next. While the view of the near future might not always be perfectly clear, one thing that few if any would deny is that the cutting edge of evolutionary biology has moved a long way from the school or even undergraduate textbook version. A very long way.

Take one of the first sessions of the meeting as an example. This examined an idea that even as recently as the last decade would have been laughed off the agenda; the idea that natural selection may not always act at the level of the individual organism after all. And before anyone reaches for their copy of The Selfish Gene to point out to me that it’s all been done, matey, I am not talking about evolution below the level of the individual but above it, principally at the level of groups of organisms.

To summarise the argument in just a few words: there are cases throughout biology where the interests of the individual and the interests of the group containing that individual conflict. The book we recently discussed in Darwin’s Book Club (Maynard-Smith and Szathmary’s The Origins of Life) gives many examples. By and large, what the authors call the Major Transitions in the history of life involve a reduction in the immediate fitness of the individual in return for greater fitness for a collection of individuals. The transition to multicellular life, for example, involves most individual cells giving up their own opportunity to reproduce so that some of the cells in their ‘group’ (for ‘group’ read ‘organism’) can produce more offspring than they would have done if they were on their own.

At the Major Transitions, the group benefits so outweigh the individual benefit that a new, group identity results. While many (including at least one of the authors!) would not have used the phrase to describe it, this is to all intents and purposes something called ‘group selection’.

If you mention the phrase group selection to most evolutionary biologists the very least you will get is a pitying look for being so naïve. Use it as an argument in an essay for a biology degree and a large, red, multiply-underlined and exclamation-marked “NO!!!!” is what you will get, along with a big, uncompromising zero. And yet here are working scientists and philosophers prepared to question whether the scorn poured on ideas of group selection (admittedly by many of the previous generation of working scientists) was not a little hasty.

There is a problem, of course, and it will be one familiar to anyone who followed the threads on the Darwin and Evolution forum thread on the topics of altruism and the Darwin’s Book Club thread on Lee Dugatkin’s The Altruism Equation. The problem is to distinguish “true” group selection from kin selection or inclusive fitness. If the group for which you are giving up your own fitness is composed of organisms that are genetically similar to you (which means often, but not always, your close relatives), then you are not sacrificing fitness at all. You are instead increasing your inclusive fitness. There are those (including some of the people at the ESEB meeting) who would argue that this is just group selection under another name.

There are others (again, some of them are here: I must choose my words carefully!) who would say group selection really is operating and the fact that the organisms carry the same alleles is neither here nor there. This is a difficult one since it makes it impossible to tell if carrying the same alleles as other members of the group is important or not. It is not enough to look at present examples and see that the organisms or cells or genes on a chromosome (remember gene duplication etc?) are related. That would be the inevitable consequence of existing in a more or less self-contained group for just a few generations but it may not have been a cause of the group forming in the first place. It all becomes much more complicated than the textbooks would have us believe. What is lacking, of course, is the killer example where a group forms and remains stable despite the things that make it up not being related and not even becoming related once they have grouped. Sadly, that may be impossible to find (I would genuinely love to be told of an example).

I think it’s true to say that whichever way this problem is finally resolved, it is perhaps more important and heartening that the people who spoke at the meeting, such as Samir Okasha and David Wilson, are prepared to step back from the received wisdom and re-examine this entire topic. Except for those ideas that become nonsensical in the light of new data and perspectives (once the Earth was known not to be the centre of the Solar System, for example, no amount of re-examination would be able to kick the Sun out of its central location, no matter how honest and courageous the questioning) there are few ideas in science that are worth accepting as permanently and unquestionably wrong. If new experiments are devised and the accepted ideas remain solid and useful, so be it, that’s absolutely fine. But to never allow currently accepted ideas to be questioned in the first place is to impose unnecessary limits on science and the enlightening insight it can bring us. Three mighty cheers for the undogmatic questioners, and four even mightier for those who then accept the data!

About the author

Paul Craze is an evolutionary ecologist based at the Universities of Bristol and Sussex. He's an invited contributor to our Darwin and Evolution forum and contributes to The Open University's Evolution course. Paul also performs in an unusual band with some editors of Nature.

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