It's hard to imagine a more disparate bunch of people than Iggy Pop, Queen Elizabeth II, James McAvoy and John Muir.

But they do share one thing in common. All were born on April 21st.

Yet in the United States and in Scotland, it's not the global rock legend, the royal head of state or the Hollywood film star whose birthday will be widely celebrated today but the Scots-born conservationist who died more than a century ago.

Muir long ago attained legendary status in his adopted homeland across the Atlantic. But in his native land, his memory had, until fairly recently, almost faded into the mists of time.

Now his writings and philosophy are undergoing something of a resurgence. That's because his ideas still stand up to scrutiny in the modern world. If anything, the threats to the natural world today are more severe than anything Muir could have envisaged

Muir is rightly acclaimed as a great writer who brought to life his observations as a scientist, naturalist and explorer. He left us a legacy of language to describe the wild outdoors and the wonders of nature.

Those who carry on his legacy today understand, as Muir did, that, before we can protect nature, we need to connect people with it. In the urbanised, digital 21st century, with its galaxy of rival attractions, it can be a daunting challenge to get young people to make that first step towards involvement and caring for nature.

Yet I believe that we are succeeding. More than 100,000 people in Scotland, or 100-plus a week, have completed a John Muir Award since it was founded by the John Muir Trust back in 1997. The figures are growing exponentially.

But Muir's legacy is also about campaigning to protect nature, often against the odds and in the teeth of fierce criticism. In a world where progress seems to be measured solely by short-term economic growth, standing up for nature and protecting wild places is never an easy option. But it has to be done, not just for the sake of wildlife and woodland, moorland and mountain, but also for our own physical and mental wellbeing; in addition,

for the sake of many of our most fragile rural communities. It is a compelling fact that, in the Scottish Highlands, tourism is by far the biggest employer, with a workforce eight times larger than the entire onshore energy sector and nine times bigger than in agriculture, forestry and fishing combined.

As Muir said, in words engraved today on the outside wall of the Scottish Parliament building in Holyrood: "The battle for conservation goes on endlessly." That doesn't mean we fight the same battles over and over again.

Today, the threats are different from those resisted by Muir. Even relatively recently, few conservationists would have imagined the scale of the industrialisation of some of our upland landscapes as a result of the spread of giant turbines that make houses look like matchboxes, supported by roads, tracks, pylons, transmission lines and power sub-stations.

Muir was tuned in to the global ecosystem, and those who carry on his work are well aware of the need to combat climate change and cut carbon emissions. But we know that we can achieve these targets without destroying our landscapes and ecosystems.

There is a widespread misconception that equates conservation with preservation. Muir battled to protect a massive area of America which, although not quite pristine wilderness, encompassed places where nature had the upper hand. Scotland's wild places are rugged, lonely and often starkly beautiful. But because of the way they have been managed over the centuries, much of our land is impoverished for people and wildlife.

Scotland's hills, rivers and seas should be teeming with wildlife, predators and prey, as is the case in other parts of Europe where nature has been encouraged to flourish. These areas have thriving local economies supporting vibrant communities living alongside wild nature.

That we believe is a powerful alternative model for the future of Scotland's wild places - and it is a future that would do justice to the legacy of John Muir in the land of his birth.

Stuart Brooks is chief executive of the John Muir Trust.