View From The Shed by Volunteer Shaun - NEEDS MUST

NEEDS MUST

You may have heard me tell my Chiffchaff evolution story before. If not, it goes something like this…

Mr and Mrs Chiffchaff have had a lovely Summer in the Dearne Valley but they notice that the weather is turning colder as Autumn kicks in. “Let’s head off to Asia or Africa where the Winters are warmer, as our ancestors have done for centuries”, says Mr C. His beloved female has a better idea though. “Why?” she asks. “Do we really need to travel all that way when it’s not as cold in a British Winter as it used to be? Can’t we just stay here all year long?”

Mr Chiffchaff knows better than to argue so they remain in their Old Moor home, and find that (of course) she was right. They can survive Yorkshire Winters these days. They don’t need to put all that energy into flying great distances, so they can concentrate on finding and defending a territory or making and protecting chicks instead. 

Fast forward to the next winter when it’s traditionally time to think about moving on again to warmer climes. But our happy couple now know that they don’t need to fly all the way overseas because Winter here won’t be as bad as they remember. And crucially, they probably wouldn’t make it now, and neither would their youngsters, as this year’s primary feathers have grown just that little bit shorter than in previous years. As they didn’t need to make the long flight, they didn’t put the energy into growing those bigger feathers designed for distance travel. And that’s why almost one percent of Chiffchaffs that spend their Summers in the UK will stay over the following Winter too. That's evolution in action, right now, as we watch.

I’ve simplified and anthropomorphised that story a little but this is basically how evolution works. I’ve frequently written in these blogs about huge evolutionary changes over time but rarely about why those changes occur. No creature goes through this process of change just for the fun of it. The adaptations have to give it a better life (or any continued life at all) for it to be worth the bother.

Evolution always has a purpose. Most wild creatures walk such a fine line between life and death that they don’t have the spare energy to experiment without a cause. They fill a perfect little niche that lets them live, thrive and survive in harmony with their surroundings. For some it may be that individually they are prey animals but their species survives by sheer numbers. A prime example of this is the lovely Blue Tit that can famously produce around 30 chicks in a year. Less than a third of them will make it to adulthood but those that don’t will provide much needed protein for many other predators. So the Blue Tit has adapted to its mass predation by producing more offspring.

At the other end of the food chain is the mighty Golden Eagle. It takes a vast amount of food to raise just one of their chicks, which is why their territory is so vast and woe betide any interloper who tries to muscle in on it. They have grown big and strong to defend their territory. That muscle mass takes a lot of feeding, which means a lot of prey species. And those prey need land to feed on. You get the picture. That’s why  there are so few predators per square mile compared to prey. The Eagle has adapted to be an apex predator. Its prey have adapted to keep their species alive.

And at any given time in history (including right now) these and every other creature in the world is making micro-changes on a day to day basis to make the most of its environmental surroundings. That is the reality of evolution, not the big stuff. The headline story might be ‘Dinosaur Sprouts Wings and Flies! Shock! Horror!’ but the truth is in the details. No dinosaur ever learned to fly overnight. One of them just happened to run faster than the ones that were chasing it. Then the predators started catching up with too many of his species, so he adapted by jumping a little higher out of their reach. So then the predators grew taller, so some of the smaller prey, over many, many generations, grew primitive feathers on their arms that allowed them to glide a little. This worked well, so (again, over an unimaginable period of time) they began to wave their arms and eventually controlled flight was born. But some of the predators saw where this was going and began to develop feathery arms of their own…

I can just imagine a qualified dinosaurologist reading this and wincing, but this is basically why the evolutions happened. Every adaptation that any creature on Earth has ever gone through has been reactive. It has been in response to an external stimulus, not something that the creature did ‘just for fun’. Nature cannot waste any energy like that. If you change and it doesn’t improve your chances of survival, you go extinct. It’s that simple. 

Of course all of this assumes that you and your surroundings are changing at roughly the same speed, that you have time to adapt before the changes become too big for you to keep up and your species dies out. Look at how the dinosaurs couldn’t cope with the atmospheric changes brought about by massive meteorite strikes for proof. They were gone within a blink of the Universe’s eye. Right now many animal, bird, plant and insect species are facing just this kind of dilemma, only this time the problem isn’t a huge lump of space rock, it’s us. Me and you. The human ape. 

You know what we can do. You’ve seen the Attenborough documentaries on TV, you’ve read the RSPB Magazine articles. Maybe it’s time for us humans to evolve and redress the balance?